Repository: gorilla/websocket
Branch: main
Commit: e064f32e3674
Files: 49
Total size: 235.2 KB

Directory structure:
gitextract_bnag3gt4/

├── .circleci/
│   └── config.yml
├── .github/
│   └── release-drafter.yml
├── .gitignore
├── AUTHORS
├── LICENSE
├── README.md
├── client.go
├── client_proxy_server_test.go
├── client_server_test.go
├── client_test.go
├── compression.go
├── compression_test.go
├── conn.go
├── conn_broadcast_test.go
├── conn_test.go
├── doc.go
├── example_test.go
├── examples/
│   ├── autobahn/
│   │   ├── README.md
│   │   ├── config/
│   │   │   └── fuzzingclient.json
│   │   └── server.go
│   ├── chat/
│   │   ├── README.md
│   │   ├── client.go
│   │   ├── home.html
│   │   ├── hub.go
│   │   └── main.go
│   ├── command/
│   │   ├── README.md
│   │   ├── home.html
│   │   └── main.go
│   ├── echo/
│   │   ├── README.md
│   │   ├── client.go
│   │   └── server.go
│   └── filewatch/
│       ├── README.md
│       └── main.go
├── go.mod
├── go.sum
├── join.go
├── join_test.go
├── json.go
├── json_test.go
├── mask.go
├── mask_safe.go
├── mask_test.go
├── prepared.go
├── prepared_test.go
├── proxy.go
├── server.go
├── server_test.go
├── util.go
└── util_test.go

================================================
FILE CONTENTS
================================================

================================================
FILE: .circleci/config.yml
================================================
version: 2.1

jobs:
  "test":
    parameters:
      version:
        type: string
        default: "latest"
      golint:
        type: boolean
        default: true
      modules:
        type: boolean
        default: true
      goproxy:
        type: string
        default: ""
    docker:
      - image: "cimg/go:<< parameters.version >>"
    working_directory: /home/circleci/project/go/src/github.com/gorilla/websocket
    environment:
      GO111MODULE: "on"
      GOPROXY: "<< parameters.goproxy >>"
    steps:
      - checkout
      - run:
          name: "Print the Go version"
          command: >
            go version
      - run:
          name: "Fetch dependencies"
          command: >
            if [[ << parameters.modules >> = true ]]; then
              go mod download
              export GO111MODULE=on
            else
              go get -v ./...
            fi
      # Only run gofmt, vet & lint against the latest Go version
      - run:
          name: "Run golint"
          command: >
            if [ << parameters.version >> = "latest" ] && [ << parameters.golint >> = true ]; then
              go get -u golang.org/x/lint/golint
              golint ./...
            fi
      - run:
          name: "Run gofmt"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              diff -u <(echo -n) <(gofmt -d -e .)
            fi
      - run:
          name: "Run go vet"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              go vet -v ./...
            fi
      - run:
          name: "Run go test (+ race detector)"
          command: >
            go test -v -race ./...

workflows:
  tests:
    jobs:
      - test:
          matrix:
            parameters:
              version: ["1.22", "1.21", "1.20"]


================================================
FILE: .github/release-drafter.yml
================================================
# Config for https://github.com/apps/release-drafter
template: |
  
  <summary of changes here>
  
  ## CHANGELOG
  $CHANGES


================================================
FILE: .gitignore
================================================
# Compiled Object files, Static and Dynamic libs (Shared Objects)
*.o
*.a
*.so

# Folders
_obj
_test

# Architecture specific extensions/prefixes
*.[568vq]
[568vq].out

*.cgo1.go
*.cgo2.c
_cgo_defun.c
_cgo_gotypes.go
_cgo_export.*

_testmain.go

*.exe

.idea/
*.iml


================================================
FILE: AUTHORS
================================================
# This is the official list of Gorilla WebSocket authors for copyright
# purposes.
#
# Please keep the list sorted.

Gary Burd <gary@beagledreams.com>
Google LLC (https://opensource.google.com/)
Joachim Bauch <mail@joachim-bauch.de>



================================================
FILE: LICENSE
================================================
Copyright (c) 2013 The Gorilla WebSocket Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

  Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

  Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


================================================
FILE: README.md
================================================
# Gorilla WebSocket

[![GoDoc](https://godoc.org/github.com/gorilla/websocket?status.svg)](https://godoc.org/github.com/gorilla/websocket)
[![CircleCI](https://circleci.com/gh/gorilla/websocket.svg?style=svg)](https://circleci.com/gh/gorilla/websocket)

Gorilla WebSocket is a [Go](http://golang.org/) implementation of the
[WebSocket](http://www.rfc-editor.org/rfc/rfc6455.txt) protocol.


### Documentation

* [API Reference](https://pkg.go.dev/github.com/gorilla/websocket?tab=doc)
* [Chat example](https://github.com/gorilla/websocket/tree/main/examples/chat)
* [Command example](https://github.com/gorilla/websocket/tree/main/examples/command)
* [Client and server example](https://github.com/gorilla/websocket/tree/main/examples/echo)
* [File watch example](https://github.com/gorilla/websocket/tree/main/examples/filewatch)

### Status

The Gorilla WebSocket package provides a complete and tested implementation of
the [WebSocket](http://www.rfc-editor.org/rfc/rfc6455.txt) protocol. The
package API is stable.

### Installation

    go get github.com/gorilla/websocket

### Protocol Compliance

The Gorilla WebSocket package passes the server tests in the [Autobahn Test
Suite](https://github.com/crossbario/autobahn-testsuite) using the application in the [examples/autobahn
subdirectory](https://github.com/gorilla/websocket/tree/main/examples/autobahn).


================================================
FILE: client.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"context"
	"crypto/tls"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http"
	"net/http/httptrace"
	"net/url"
	"strings"
	"time"
)

// ErrBadHandshake is returned when the server response to opening handshake is
// invalid.
var ErrBadHandshake = errors.New("websocket: bad handshake")

var errInvalidCompression = errors.New("websocket: invalid compression negotiation")

// NewClient creates a new client connection using the given net connection.
// The URL u specifies the host and request URI. Use requestHeader to specify
// the origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies
// (Cookie). Use the response.Header to get the selected subprotocol
// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
//
// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
// non-nil *http.Response so that callers can handle redirects, authentication,
// etc.
//
// Deprecated: Use Dialer instead.
func NewClient(netConn net.Conn, u *url.URL, requestHeader http.Header, readBufSize, writeBufSize int) (c *Conn, response *http.Response, err error) {
	d := Dialer{
		ReadBufferSize:  readBufSize,
		WriteBufferSize: writeBufSize,
		NetDial: func(net, addr string) (net.Conn, error) {
			return netConn, nil
		},
	}
	return d.Dial(u.String(), requestHeader)
}

// A Dialer contains options for connecting to WebSocket server.
//
// It is safe to call Dialer's methods concurrently.
type Dialer struct {
	// The following custom dial functions can be set to establish
	// connections to either the backend server or the proxy (if it
	// exists). The scheme of the dialed entity (either backend or
	// proxy) determines which custom dial function is selected:
	// either NetDialTLSContext for HTTPS or NetDialContext/NetDial
	// for HTTP. Since the "Proxy" function can determine the scheme
	// dynamically, it can make sense to set multiple custom dial
	// functions simultaneously.
	//
	// NetDial specifies the dial function for creating TCP connections. If
	// NetDial is nil, net.Dialer DialContext is used.
	// If "Proxy" field is also set, this function dials the proxy--not
	// the backend server.
	NetDial func(network, addr string) (net.Conn, error)

	// NetDialContext specifies the dial function for creating TCP connections. If
	// NetDialContext is nil, NetDial is used.
	// If "Proxy" field is also set, this function dials the proxy--not
	// the backend server.
	NetDialContext func(ctx context.Context, network, addr string) (net.Conn, error)

	// NetDialTLSContext specifies the dial function for creating TLS/TCP connections. If
	// NetDialTLSContext is nil, NetDialContext is used.
	// If NetDialTLSContext is set, Dial assumes the TLS handshake is done there and
	// TLSClientConfig is ignored.
	// If "Proxy" field is also set, this function dials the proxy (and performs
	// the TLS handshake with the proxy, ignoring TLSClientConfig). In this TLS proxy
	// dialing case the TLSClientConfig could still be necessary for TLS to the backend server.
	NetDialTLSContext func(ctx context.Context, network, addr string) (net.Conn, error)

	// Proxy specifies a function to return a proxy for a given
	// Request. If the function returns a non-nil error, the
	// request is aborted with the provided error.
	// If Proxy is nil or returns a nil *URL, no proxy is used.
	Proxy func(*http.Request) (*url.URL, error)

	// TLSClientConfig specifies the TLS configuration to use with tls.Client.
	// If nil, the default configuration is used.
	// If NetDialTLSContext is set, Dial assumes the TLS handshake
	// is done there and TLSClientConfig is ignored.
	TLSClientConfig *tls.Config

	// HandshakeTimeout specifies the duration for the handshake to complete.
	HandshakeTimeout time.Duration

	// ReadBufferSize and WriteBufferSize specify I/O buffer sizes in bytes. If a buffer
	// size is zero, then a useful default size is used. The I/O buffer sizes
	// do not limit the size of the messages that can be sent or received.
	ReadBufferSize, WriteBufferSize int

	// WriteBufferPool is a pool of buffers for write operations. If the value
	// is not set, then write buffers are allocated to the connection for the
	// lifetime of the connection.
	//
	// A pool is most useful when the application has a modest volume of writes
	// across a large number of connections.
	//
	// Applications should use a single pool for each unique value of
	// WriteBufferSize.
	WriteBufferPool BufferPool

	// Subprotocols specifies the client's requested subprotocols.
	Subprotocols []string

	// EnableCompression specifies if the client should attempt to negotiate
	// per message compression (RFC 7692). Setting this value to true does not
	// guarantee that compression will be supported. Currently only "no context
	// takeover" modes are supported.
	EnableCompression bool

	// Jar specifies the cookie jar.
	// If Jar is nil, cookies are not sent in requests and ignored
	// in responses.
	Jar http.CookieJar
}

// Dial creates a new client connection by calling DialContext with a background context.
func (d *Dialer) Dial(urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
	return d.DialContext(context.Background(), urlStr, requestHeader)
}

var errMalformedURL = errors.New("malformed ws or wss URL")

func hostPortNoPort(u *url.URL) (hostPort, hostNoPort string) {
	hostPort = u.Host
	hostNoPort = u.Host
	if i := strings.LastIndex(u.Host, ":"); i > strings.LastIndex(u.Host, "]") {
		hostNoPort = hostNoPort[:i]
	} else {
		switch u.Scheme {
		case "wss":
			hostPort += ":443"
		case "https":
			hostPort += ":443"
		default:
			hostPort += ":80"
		}
	}
	return hostPort, hostNoPort
}

// DefaultDialer is a dialer with all fields set to the default values.
var DefaultDialer = &Dialer{
	Proxy:            http.ProxyFromEnvironment,
	HandshakeTimeout: 45 * time.Second,
}

// nilDialer is dialer to use when receiver is nil.
var nilDialer = *DefaultDialer

// DialContext creates a new client connection. Use requestHeader to specify the
// origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies (Cookie).
// Use the response.Header to get the selected subprotocol
// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
//
// The context will be used in the request and in the Dialer.
//
// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
// non-nil *http.Response so that callers can handle redirects, authentication,
// etcetera. The response body may not contain the entire response and does not
// need to be closed by the application.
func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
	if d == nil {
		d = &nilDialer
	}

	challengeKey, err := generateChallengeKey()
	if err != nil {
		return nil, nil, err
	}

	u, err := url.Parse(urlStr)
	if err != nil {
		return nil, nil, err
	}

	switch u.Scheme {
	case "ws":
		u.Scheme = "http"
	case "wss":
		u.Scheme = "https"
	default:
		return nil, nil, errMalformedURL
	}

	if u.User != nil {
		// User name and password are not allowed in websocket URIs.
		return nil, nil, errMalformedURL
	}

	req := &http.Request{
		Method:     http.MethodGet,
		URL:        u,
		Proto:      "HTTP/1.1",
		ProtoMajor: 1,
		ProtoMinor: 1,
		Header:     make(http.Header),
		Host:       u.Host,
	}
	req = req.WithContext(ctx)

	// Set the cookies present in the cookie jar of the dialer
	if d.Jar != nil {
		for _, cookie := range d.Jar.Cookies(u) {
			req.AddCookie(cookie)
		}
	}

	// Set the request headers using the capitalization for names and values in
	// RFC examples. Although the capitalization shouldn't matter, there are
	// servers that depend on it. The Header.Set method is not used because the
	// method canonicalizes the header names.
	req.Header["Upgrade"] = []string{"websocket"}
	req.Header["Connection"] = []string{"Upgrade"}
	req.Header["Sec-WebSocket-Key"] = []string{challengeKey}
	req.Header["Sec-WebSocket-Version"] = []string{"13"}
	if len(d.Subprotocols) > 0 {
		req.Header["Sec-WebSocket-Protocol"] = []string{strings.Join(d.Subprotocols, ", ")}
	}
	for k, vs := range requestHeader {
		switch {
		case k == "Host":
			if len(vs) > 0 {
				req.Host = vs[0]
			}
		case k == "Upgrade" ||
			k == "Connection" ||
			k == "Sec-Websocket-Key" ||
			k == "Sec-Websocket-Version" ||
			k == "Sec-Websocket-Extensions" ||
			(k == "Sec-Websocket-Protocol" && len(d.Subprotocols) > 0):
			return nil, nil, errors.New("websocket: duplicate header not allowed: " + k)
		case k == "Sec-Websocket-Protocol":
			req.Header["Sec-WebSocket-Protocol"] = vs
		default:
			req.Header[k] = vs
		}
	}

	if d.EnableCompression {
		req.Header["Sec-WebSocket-Extensions"] = []string{"permessage-deflate; server_no_context_takeover; client_no_context_takeover"}
	}

	if d.HandshakeTimeout != 0 {
		var cancel func()
		ctx, cancel = context.WithTimeout(ctx, d.HandshakeTimeout)
		defer cancel()
	}

	var proxyURL *url.URL
	if d.Proxy != nil {
		proxyURL, err = d.Proxy(req)
		if err != nil {
			return nil, nil, err
		}
	}
	netDial, err := d.netDialFn(ctx, proxyURL, u)
	if err != nil {
		return nil, nil, err
	}

	hostPort, hostNoPort := hostPortNoPort(u)
	trace := httptrace.ContextClientTrace(ctx)
	if trace != nil && trace.GetConn != nil {
		trace.GetConn(hostPort)
	}

	netConn, err := netDial(ctx, "tcp", hostPort)
	if err != nil {
		return nil, nil, err
	}
	if trace != nil && trace.GotConn != nil {
		trace.GotConn(httptrace.GotConnInfo{
			Conn: netConn,
		})
	}

	// Close the network connection when returning an error. The variable
	// netConn is set to nil before the success return at the end of the
	// function.
	defer func() {
		if netConn != nil {
			// It's safe to ignore the error from Close() because this code is
			// only executed when returning a more important error to the
			// application.
			_ = netConn.Close()
		}
	}()

	// Do TLS handshake over established connection if a proxy exists.
	if proxyURL != nil && u.Scheme == "https" {

		cfg := cloneTLSConfig(d.TLSClientConfig)
		if cfg.ServerName == "" {
			cfg.ServerName = hostNoPort
		}
		tlsConn := tls.Client(netConn, cfg)
		netConn = tlsConn

		if trace != nil && trace.TLSHandshakeStart != nil {
			trace.TLSHandshakeStart()
		}
		err := doHandshake(ctx, tlsConn, cfg)
		if trace != nil && trace.TLSHandshakeDone != nil {
			trace.TLSHandshakeDone(tlsConn.ConnectionState(), err)
		}

		if err != nil {
			return nil, nil, err
		}
	}

	conn := newConn(netConn, false, d.ReadBufferSize, d.WriteBufferSize, d.WriteBufferPool, nil, nil)

	if err := req.Write(netConn); err != nil {
		return nil, nil, err
	}

	if trace != nil && trace.GotFirstResponseByte != nil {
		if peek, err := conn.br.Peek(1); err == nil && len(peek) == 1 {
			trace.GotFirstResponseByte()
		}
	}

	resp, err := http.ReadResponse(conn.br, req)
	if err != nil {
		if d.TLSClientConfig != nil {
			for _, proto := range d.TLSClientConfig.NextProtos {
				if proto != "http/1.1" {
					return nil, nil, fmt.Errorf(
						"websocket: protocol %q was given but is not supported;"+
							"sharing tls.Config with net/http Transport can cause this error: %w",
						proto, err,
					)
				}
			}
		}
		return nil, nil, err
	}

	if d.Jar != nil {
		if rc := resp.Cookies(); len(rc) > 0 {
			d.Jar.SetCookies(u, rc)
		}
	}

	if resp.StatusCode != 101 ||
		!tokenListContainsValue(resp.Header, "Upgrade", "websocket") ||
		!tokenListContainsValue(resp.Header, "Connection", "upgrade") ||
		resp.Header.Get("Sec-Websocket-Accept") != computeAcceptKey(challengeKey) {
		// Before closing the network connection on return from this
		// function, slurp up some of the response to aid application
		// debugging.
		buf := make([]byte, 1024)
		n, _ := io.ReadFull(resp.Body, buf)
		resp.Body = io.NopCloser(bytes.NewReader(buf[:n]))
		return nil, resp, ErrBadHandshake
	}

	for _, ext := range parseExtensions(resp.Header) {
		if ext[""] != "permessage-deflate" {
			continue
		}
		_, snct := ext["server_no_context_takeover"]
		_, cnct := ext["client_no_context_takeover"]
		if !snct || !cnct {
			return nil, resp, errInvalidCompression
		}
		conn.newCompressionWriter = compressNoContextTakeover
		conn.newDecompressionReader = decompressNoContextTakeover
		break
	}

	resp.Body = io.NopCloser(bytes.NewReader([]byte{}))
	conn.subprotocol = resp.Header.Get("Sec-Websocket-Protocol")

	if err := netConn.SetDeadline(time.Time{}); err != nil {
		return nil, resp, err
	}

	// Success! Set netConn to nil to stop the deferred function above from
	// closing the network connection.
	netConn = nil

	return conn, resp, nil
}

// Returns the dial function to establish the connection to either the backend
// server or the proxy (if it exists). If the dialed entity is HTTPS, then the
// returned dial function *also* performs the TLS handshake to the dialed entity.
// NOTE: If a proxy exists, it is possible for a second TLS handshake to be
// necessary over the established connection.
func (d *Dialer) netDialFn(ctx context.Context, proxyURL *url.URL, backendURL *url.URL) (netDialerFunc, error) {
	var netDial netDialerFunc
	if proxyURL != nil {
		netDial = d.netDialFromURL(proxyURL)
	} else {
		netDial = d.netDialFromURL(backendURL)
	}
	// If needed, wrap the dial function to set the connection deadline.
	if deadline, ok := ctx.Deadline(); ok {
		netDial = netDialWithDeadline(netDial, deadline)
	}
	// Proxy dialing is wrapped to implement CONNECT method and possibly proxy auth.
	if proxyURL != nil {
		return proxyFromURL(proxyURL, netDial)
	}
	return netDial, nil
}

// Returns function to create the connection depending on the Dialer's
// custom dialing functions and the passed URL of entity connecting to.
func (d *Dialer) netDialFromURL(u *url.URL) netDialerFunc {
	var netDial netDialerFunc
	switch {
	case d.NetDialContext != nil:
		netDial = d.NetDialContext
	case d.NetDial != nil:
		netDial = func(ctx context.Context, net, addr string) (net.Conn, error) {
			return d.NetDial(net, addr)
		}
	default:
		netDial = (&net.Dialer{}).DialContext
	}
	// If dialed entity is HTTPS, then either use custom TLS dialing function (if exists)
	// or wrap the previously computed "netDial" to use TLS config for handshake.
	if u.Scheme == "https" {
		if d.NetDialTLSContext != nil {
			netDial = d.NetDialTLSContext
		} else {
			netDial = netDialWithTLSHandshake(netDial, d.TLSClientConfig, u)
		}
	}
	return netDial
}

// Returns wrapped "netDial" function, performing TLS handshake after connecting.
func netDialWithTLSHandshake(netDial netDialerFunc, tlsConfig *tls.Config, u *url.URL) netDialerFunc {
	return func(ctx context.Context, unused, addr string) (net.Conn, error) {
		hostPort, hostNoPort := hostPortNoPort(u)
		trace := httptrace.ContextClientTrace(ctx)
		if trace != nil && trace.GetConn != nil {
			trace.GetConn(hostPort)
		}
		// Creates TCP connection to addr using passed "netDial" function.
		conn, err := netDial(ctx, "tcp", addr)
		if err != nil {
			return nil, err
		}
		cfg := cloneTLSConfig(tlsConfig)
		if cfg.ServerName == "" {
			cfg.ServerName = hostNoPort
		}
		tlsConn := tls.Client(conn, cfg)
		// Do the TLS handshake using TLSConfig over the wrapped connection.
		if trace != nil && trace.TLSHandshakeStart != nil {
			trace.TLSHandshakeStart()
		}
		err = doHandshake(ctx, tlsConn, cfg)
		if trace != nil && trace.TLSHandshakeDone != nil {
			trace.TLSHandshakeDone(tlsConn.ConnectionState(), err)
		}
		if err != nil {
			tlsConn.Close()
			return nil, err
		}
		return tlsConn, nil
	}
}

// Returns wrapped "netDial" function, setting passed deadline.
func netDialWithDeadline(netDial netDialerFunc, deadline time.Time) netDialerFunc {
	return func(ctx context.Context, network, addr string) (net.Conn, error) {
		c, err := netDial(ctx, network, addr)
		if err != nil {
			return nil, err
		}
		err = c.SetDeadline(deadline)
		if err != nil {
			c.Close()
			return nil, err
		}
		return c, nil
	}
}

func cloneTLSConfig(cfg *tls.Config) *tls.Config {
	if cfg == nil {
		return &tls.Config{}
	}
	return cfg.Clone()
}

func doHandshake(ctx context.Context, tlsConn *tls.Conn, cfg *tls.Config) error {
	if err := tlsConn.HandshakeContext(ctx); err != nil {
		return err
	}
	if !cfg.InsecureSkipVerify {
		if err := tlsConn.VerifyHostname(cfg.ServerName); err != nil {
			return err
		}
	}
	return nil
}


================================================
FILE: client_proxy_server_test.go
================================================
// Copyright 2025 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"context"
	"crypto/rand"
	"crypto/tls"
	"crypto/x509"
	"errors"
	"io"
	"net"
	"net/http"
	"net/http/httptest"
	"net/url"
	"strings"
	"sync/atomic"
	"testing"
)

// These test cases use a websocket client (Dialer)/proxy/websocket server (Upgrader)
// to validate the cases where a proxy is an intermediary between a websocket client
// and server. The test cases usually 1) create a websocket server which echoes any
// data received back to the client, 2) a basic duplex streaming proxy, and 3) a
// websocket client which sends random data to the server through the proxy,
// validating any subsequent data received is the same as the data sent. The various
// permutations include the proxy and backend schemes (HTTP or HTTPS), as well as
// the custom dial functions (e.g NetDialContext, NetDial) set on the Dialer.

const (
	subprotocolV1 = "subprotocol-version-1"
	subprotocolV2 = "subprotocol-version-2"
)

// Permutation 1
//
//	Backend: HTTP
//	Proxy:   HTTP
func TestHTTPProxyAndBackend(t *testing.T) {
	websocketTLS := false
	proxyTLS := false
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Dial the websocket server through the proxy server.
	dialer := Dialer{
		Proxy:        http.ProxyURL(proxyServerURL),
		Subprotocols: []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 2
//
//	Backend: HTTP
//	Proxy:   HTTP
//	DialFn:  NetDial (dials proxy)
func TestHTTPProxyWithNetDial(t *testing.T) {
	websocketTLS := false
	proxyTLS := false
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Dial the websocket server through the proxy server.
	var netDialCalled atomic.Int64
	dialer := Dialer{
		NetDial: func(network, addr string) (net.Conn, error) {
			netDialCalled.Add(1)
			return (&net.Dialer{}).DialContext(context.Background(), network, addr)
		},
		Proxy:        http.ProxyURL(proxyServerURL),
		Subprotocols: []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), netDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 3
//
//	Backend: HTTP
//	Proxy:   HTTP
//	DialFn:  NetDialContext (dials proxy)
func TestHTTPProxyWithNetDialContext(t *testing.T) {
	websocketTLS := false
	proxyTLS := false
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Dial the websocket server through the proxy server.
	var netDialCalled atomic.Int64
	dialer := Dialer{
		NetDialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
			netDialCalled.Add(1)
			return (&net.Dialer{}).DialContext(ctx, network, addr)
		},
		Proxy:        http.ProxyURL(proxyServerURL),
		Subprotocols: []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), netDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 4
//
//	Backend:    HTTPS
//	Proxy:      HTTP
//	DialFn:     NetDialTLSConfig (set but *ignored*)
//	TLS Config: set (used for backend TLS)
func TestHTTPProxyWithHTTPSBackend(t *testing.T) {
	websocketTLS := true
	proxyTLS := false
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	var netDialTLSCalled atomic.Int64
	dialer := Dialer{
		Proxy: http.ProxyURL(proxyServerURL),
		// This function should be ignored, because an HTTP proxy exists
		// and the backend TLS handshake should use TLSClientConfig.
		NetDialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
			netDialTLSCalled.Add(1)
			return (&net.Dialer{}).DialContext(ctx, network, addr)
		},
		// Used for the backend server TLS handshake.
		TLSClientConfig: tlsConfig(websocketTLS, proxyTLS),
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if numTLSDials := netDialTLSCalled.Load(); numTLSDials > 0 {
		t.Errorf("NetDialTLS should have been ignored")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 5
//
//	Backend:    HTTPS
//	Proxy:      HTTPS
//	TLS Config: set (used for both proxy and backend TLS)
func TestHTTPSProxyAndBackend(t *testing.T) {
	websocketTLS := true
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	dialer := Dialer{
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(websocketTLS, proxyTLS),
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 6
//
//	Backend:    HTTPS
//	Proxy:      HTTPS
//	DialFn:     NetDial (used to dial proxy)
//	TLS Config: set (used for both proxy and backend TLS)
func TestHTTPSProxyUsingNetDial(t *testing.T) {
	websocketTLS := true
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	var netDialCalled atomic.Int64
	dialer := Dialer{
		NetDial: func(network, addr string) (net.Conn, error) {
			netDialCalled.Add(1)
			return (&net.Dialer{}).DialContext(context.Background(), network, addr)
		},
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(websocketTLS, proxyTLS),
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), netDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 7
//
//	Backend:    HTTPS
//	Proxy:      HTTPS
//	DialFn:     NetDialContext (used to dial proxy)
//	TLS Config: set (used for both proxy and backend TLS)
func TestHTTPSProxyUsingNetDialContext(t *testing.T) {
	websocketTLS := true
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	var netDialCalled atomic.Int64
	dialer := Dialer{
		NetDialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
			netDialCalled.Add(1)
			return (&net.Dialer{}).DialContext(ctx, network, addr)
		},
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(websocketTLS, proxyTLS),
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), netDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 8
//
//	Backend:    HTTPS
//	Proxy:      HTTPS
//	DialFn:     NetDialTLSContext (used for proxy TLS)
//	TLS Config: set (used for backend TLS)
func TestHTTPSProxyUsingNetDialTLSContext(t *testing.T) {
	websocketTLS := true
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Configure the proxy dialing function which dials the proxy and
	// performs the TLS handshake.
	var proxyDialCalled atomic.Int64
	proxyCerts := x509.NewCertPool()
	proxyCerts.AppendCertsFromPEM(proxyServerCert)
	proxyTLSConfig := &tls.Config{RootCAs: proxyCerts}
	proxyDial := func(ctx context.Context, network, addr string) (net.Conn, error) {
		proxyDialCalled.Add(1)
		return tls.Dial(network, addr, proxyTLSConfig)
	}
	// Configure the backend webscocket TLS configuration (handshake occurs
	// over the previously created proxy connection).
	websocketCerts := x509.NewCertPool()
	websocketCerts.AppendCertsFromPEM(websocketServerCert)
	websocketTLSConfig := &tls.Config{RootCAs: websocketCerts}
	dialer := Dialer{
		Proxy: http.ProxyURL(proxyServerURL),
		// Dial and TLS handshake function to proxy.
		NetDialTLSContext: proxyDial,
		// Used for second TLS handshake to backend server over previously
		// established proxy connection.
		TLSClientConfig: websocketTLSConfig,
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), proxyDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 9
//
//	Backend:    HTTP
//	Proxy:      HTTPS
//	TLS Config: set (used for proxy TLS)
func TestHTTPSProxyHTTPBackend(t *testing.T) {
	websocketTLS := false
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	dialer := Dialer{
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(websocketTLS, proxyTLS),
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

// Permutation 10
//
//	Backend:    HTTP
//	Proxy:      HTTPS
//	DialFn:     NetDialTLSContext (used for proxy TLS)
//	TLS Config: set (ignored)
func TestHTTPSProxyUsingNetDialTLSContextWithHTTPBackend(t *testing.T) {
	websocketTLS := false
	proxyTLS := true
	// Start the websocket server, which echoes data back to sender.
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Start the proxy server.
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	var proxyDialCalled atomic.Int64
	dialer := Dialer{
		NetDialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
			proxyDialCalled.Add(1)
			return tls.Dial(network, addr, tlsConfig(websocketTLS, proxyTLS))
		},
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: &tls.Config{}, // Misconfigured, but ignored.
		Subprotocols:    []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	// Send, receive, and validate random data over websocket connection.
	sendReceiveData(t, wsClient)
	if e, a := int64(1), proxyDialCalled.Load(); e != a {
		t.Errorf("netDial not called")
	}
	// Validate the proxy server was called.
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy not called")
	}
}

func TestTLSValidationErrors(t *testing.T) {
	// Both websocket and proxy servers are started with TLS.
	websocketTLS := true
	proxyTLS := true
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	proxyServer, proxyServerURL, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Dialer without proxy CA cert fails TLS verification.
	tlsError := "tls: failed to verify certificate"
	dialer := Dialer{
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(true, false),
		Subprotocols:    []string{subprotocolV1},
	}
	_, _, err = dialer.Dial(websocketURL.String(), nil)
	if err == nil {
		t.Errorf("expected proxy TLS verification error did not arrive")
	} else if !strings.Contains(err.Error(), tlsError) {
		t.Errorf("expected proxy TLS error (%s), got (%s)", err.Error(), tlsError)
	}
	// Validate the proxy handler was *NOT* called (because proxy
	// server TLS validation failed).
	if e, a := int64(0), proxyServer.numCalls(); e != a {
		t.Errorf("proxy should not have been called")
	}
	// Dialer without websocket CA cert fails TLS verification.
	dialer = Dialer{
		Proxy:           http.ProxyURL(proxyServerURL),
		TLSClientConfig: tlsConfig(false, true),
		Subprotocols:    []string{subprotocolV1},
	}
	_, _, err = dialer.Dial(websocketURL.String(), nil)
	if err == nil {
		t.Errorf("expected websocket TLS verification error did not arrive")
	} else if !strings.Contains(err.Error(), tlsError) {
		t.Errorf("expected websocket TLS error (%s), got (%s)", err.Error(), tlsError)
	}
	// Validate the proxy server *was* called (but subsequent
	// websocket server failed TLS validation).
	if e, a := int64(1), proxyServer.numCalls(); e != a {
		t.Errorf("proxy have been called")
	}
}

func TestProxyFnErrorIsPropagated(t *testing.T) {
	websocketServer, websocketURL, err := newWebsocketServer(false)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	// Create a Dialer where Proxy function always returns an error.
	proxyURLError := errors.New("proxy URL generation error")
	dialer := Dialer{
		Proxy: func(r *http.Request) (*url.URL, error) {
			return nil, proxyURLError
		},
		Subprotocols: []string{subprotocolV1},
	}
	// Proxy URL generation error should halt request and be propagated.
	_, _, err = dialer.Dial(websocketURL.String(), nil)
	if err == nil {
		t.Fatalf("expected websocket dial error, received none")
	} else if !errors.Is(proxyURLError, err) {
		t.Fatalf("expected error (%s), got (%s)", proxyURLError, err)
	}
}

func TestProxyFnNilMeansNoProxy(t *testing.T) {
	// Both websocket and proxy servers are started.
	websocketTLS := false
	proxyTLS := false
	websocketServer, websocketURL, err := newWebsocketServer(websocketTLS)
	defer websocketServer.Close()
	if err != nil {
		t.Fatalf("error starting websocket server: %v", err)
	}
	proxyServer, _, err := newProxyServer(proxyTLS)
	defer proxyServer.Close()
	if err != nil {
		t.Fatalf("error starting proxy server: %v", err)
	}
	// Dialer created with Proxy URL generation function returning nil
	// proxy URL, which continues with backend server connection without
	// proxying.
	dialer := Dialer{
		Proxy: func(r *http.Request) (*url.URL, error) {
			return nil, nil
		},
		Subprotocols: []string{subprotocolV1},
	}
	wsClient, _, err := dialer.Dial(websocketURL.String(), nil)
	if err != nil {
		t.Fatalf("websocket dial error: %v", err)
	}
	sendReceiveData(t, wsClient)
	// Validate the proxy handler was *NOT* called (because proxy
	// URL generation returned nil).
	if e, a := int64(0), proxyServer.numCalls(); e != a {
		t.Errorf("proxy should not have been called")
	}
}

// "counter" interface can be implemented by a server to keep track
// of the number of times a handler was called, as well as "Close".
type counter interface {
	increment()
	numCalls() int64
	closer
}

type closer interface {
	Close()
}

// testServer implements "counter" interface.
type testServer struct {
	server     *httptest.Server
	numHandled atomic.Int64
}

func (ts *testServer) numCalls() int64 {
	return ts.numHandled.Load()
}

func (ts *testServer) increment() {
	ts.numHandled.Add(1)
}

func (ts *testServer) Close() {
	if ts.server != nil {
		ts.server.Close()
	}
}

// websocketEchoHandler upgrades the connection associated with the request, and
// echoes binary messages read off the websocket connection back to the client.
var websocketEchoHandler = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
	upgrader := Upgrader{
		CheckOrigin: func(r *http.Request) bool {
			return true // Accepting all requests
		},
		Subprotocols: []string{
			subprotocolV1,
			subprotocolV2,
		},
	}
	wsConn, err := upgrader.Upgrade(w, req, nil)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
	defer wsConn.Close()
	for {
		writer, err := wsConn.NextWriter(BinaryMessage)
		if err != nil {
			break
		}
		messageType, reader, err := wsConn.NextReader()
		if err != nil {
			break
		}
		if messageType != BinaryMessage {
			http.Error(w, "websocket reader not binary message type",
				http.StatusInternalServerError)
		}
		_, err = io.Copy(writer, reader)
		if err != nil {
			http.Error(w, "websocket server io copy error",
				http.StatusInternalServerError)
		}
	}
})

// Returns a test backend websocket server as well as the URL pointing
// to the server, or an error if one occurred. Sets up a TLS endpoint
// on the server if the passed "tlsServer" is true.
// func newWebsocketServer(tlsServer bool) (*httptest.Server, *url.URL, error) {
func newWebsocketServer(tlsServer bool) (closer, *url.URL, error) {
	// Start the websocket server, which echoes data back to sender.
	websocketServer := httptest.NewUnstartedServer(websocketEchoHandler)
	if tlsServer {
		websocketKeyPair, err := tls.X509KeyPair(websocketServerCert, websocketServerKey)
		if err != nil {
			return nil, nil, err
		}
		websocketServer.TLS = &tls.Config{
			Certificates: []tls.Certificate{websocketKeyPair},
		}
		websocketServer.StartTLS()
	} else {
		websocketServer.Start()
	}
	websocketURL, err := url.Parse(websocketServer.URL)
	if err != nil {
		return nil, nil, err
	}
	if tlsServer {
		websocketURL.Scheme = "wss"
	} else {
		websocketURL.Scheme = "ws"
	}
	return websocketServer, websocketURL, nil
}

// proxyHandler creates a full duplex streaming connection between the client
// (hijacking the http request connection), and an "upstream" dialed connection
// to the "Host". Creates two goroutines to copy between connections in each direction.
var proxyHandler = http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
	// Validate the CONNECT method.
	if req.Method != http.MethodConnect {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	// Dial upstream server.
	upstream, err := (&net.Dialer{}).DialContext(req.Context(), "tcp", req.URL.Host)
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer upstream.Close()
	// Return 200 OK to client.
	w.WriteHeader(http.StatusOK)
	// Hijack client connection.
	client, _, err := w.(http.Hijacker).Hijack()
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer client.Close()
	// Create duplex streaming between client and upstream connections.
	done := make(chan struct{}, 2)
	go func() {
		_, _ = io.Copy(upstream, client)
		done <- struct{}{}
	}()
	go func() {
		_, _ = io.Copy(client, upstream)
		done <- struct{}{}
	}()
	<-done
})

// Returns a new test HTTP server, as well as the URL to that server, or
// an error if one occurred. numProxyCalls keeps track of the number of
// times the proxy handler was called with this server.
func newProxyServer(tlsServer bool) (counter, *url.URL, error) {
	// Start the proxy server, keeping track of how many times the handler is called.
	ts := &testServer{}
	proxyServer := httptest.NewUnstartedServer(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		ts.increment()
		proxyHandler.ServeHTTP(w, req)
	}))
	if tlsServer {
		proxyKeyPair, err := tls.X509KeyPair(proxyServerCert, proxyServerKey)
		if err != nil {
			return nil, nil, err
		}
		proxyServer.TLS = &tls.Config{
			Certificates: []tls.Certificate{proxyKeyPair},
		}
		proxyServer.StartTLS()
	} else {
		proxyServer.Start()
	}
	proxyURL, err := url.Parse(proxyServer.URL)
	if err != nil {
		return nil, nil, err
	}
	return ts, proxyURL, nil
}

// Returns the TLS config with the RootCAs cert pool set. If
// neither websocket nor proxy server uses TLS, returns nil.
func tlsConfig(websocketTLS bool, proxyTLS bool) *tls.Config {
	if !websocketTLS && !proxyTLS {
		return nil
	}
	certPool := x509.NewCertPool()
	tlsConfig := &tls.Config{
		RootCAs: certPool,
	}
	if websocketTLS {
		tlsConfig.RootCAs.AppendCertsFromPEM(websocketServerCert)
	}
	if proxyTLS {
		tlsConfig.RootCAs.AppendCertsFromPEM(proxyServerCert)
	}
	return tlsConfig
}

// Sends, receives, and validates random data sent and received
// over the passed websocket connection.
const randomDataSize = 128 * 1024

func sendReceiveData(t *testing.T, wsConn *Conn) {
	// Create the random data.
	randomData := make([]byte, randomDataSize)
	if _, err := rand.Read(randomData); err != nil {
		t.Errorf("unexpected error reading random data: %v", err)
	}
	// Send the random data.
	err := wsConn.WriteMessage(BinaryMessage, randomData)
	if err != nil {
		t.Errorf("websocket write error: %v", err)
	}
	// Read from the websocket connection, and validate the
	// read data is the same as the previously sent data.
	_, received, err := wsConn.ReadMessage()
	if !bytes.Equal(randomData, received) {
		t.Errorf("unexpected data received: %d bytes sent, %d bytes received",
			len(received), len(randomData))
	}
}

// proxyServerCert was generated from crypto/tls/generate_cert.go with the following command:
//
//	go run generate_cert.go  --rsa-bits 2048 --host 127.0.0.1,::1,example.com --ca --start-date "Jan 1 00:00:00 1970" --duration=1000000h
//
// proxyServerCert is a self-signed.
var proxyServerCert = []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)

// proxyServerKey is the private key for proxyServerCert.
var proxyServerKey = []byte(`-----BEGIN RSA PRIVATE KEY-----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-----END RSA PRIVATE KEY-----
`)

// websocketServerCert is self-signed.
var websocketServerCert = []byte(`-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----`)

// websocketServerKey is the private key for websocketServerCert.
var websocketServerKey = []byte(`-----BEGIN PRIVATE KEY-----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-----END PRIVATE KEY-----
`)


================================================
FILE: client_server_test.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"bytes"
	"context"
	"crypto/tls"
	"crypto/x509"
	"encoding/base64"
	"encoding/binary"
	"errors"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"net/http/cookiejar"
	"net/http/httptest"
	"net/http/httptrace"
	"net/url"
	"reflect"
	"strings"
	"sync"
	"testing"
	"time"
)

var cstUpgrader = Upgrader{
	Subprotocols:      []string{"p0", "p1"},
	ReadBufferSize:    1024,
	WriteBufferSize:   1024,
	EnableCompression: true,
	Error: func(w http.ResponseWriter, r *http.Request, status int, reason error) {
		http.Error(w, reason.Error(), status)
	},
}

var cstDialer = Dialer{
	Subprotocols:     []string{"p1", "p2"},
	ReadBufferSize:   1024,
	WriteBufferSize:  1024,
	HandshakeTimeout: 30 * time.Second,
}

type cstHandler struct {
	*testing.T
	s *cstServer
}

type cstServer struct {
	URL    string
	Server *httptest.Server
	wg     sync.WaitGroup
}

const (
	cstPath       = "/a/b"
	cstRawQuery   = "x=y"
	cstRequestURI = cstPath + "?" + cstRawQuery
)

func (s *cstServer) Close() {
	s.Server.Close()
	// Wait for handler functions to complete.
	s.wg.Wait()
}

func newServer(t *testing.T) *cstServer {
	var s cstServer
	s.Server = httptest.NewServer(cstHandler{T: t, s: &s})
	s.Server.URL += cstRequestURI
	s.URL = makeWsProto(s.Server.URL)
	return &s
}

func newTLSServer(t *testing.T) *cstServer {
	var s cstServer
	s.Server = httptest.NewTLSServer(cstHandler{T: t, s: &s})
	s.Server.URL += cstRequestURI
	s.URL = makeWsProto(s.Server.URL)
	return &s
}

func (t cstHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Because tests wait for a response from a server, we are guaranteed that
	// the wait group count is incremented before the test waits on the group
	// in the call to (*cstServer).Close().
	t.s.wg.Add(1)
	defer t.s.wg.Done()

	if r.URL.Path != cstPath {
		t.Logf("path=%v, want %v", r.URL.Path, cstPath)
		http.Error(w, "bad path", http.StatusBadRequest)
		return
	}
	if r.URL.RawQuery != cstRawQuery {
		t.Logf("query=%v, want %v", r.URL.RawQuery, cstRawQuery)
		http.Error(w, "bad path", http.StatusBadRequest)
		return
	}
	subprotos := Subprotocols(r)
	if !reflect.DeepEqual(subprotos, cstDialer.Subprotocols) {
		t.Logf("subprotols=%v, want %v", subprotos, cstDialer.Subprotocols)
		http.Error(w, "bad protocol", http.StatusBadRequest)
		return
	}
	ws, err := cstUpgrader.Upgrade(w, r, http.Header{"Set-Cookie": {"sessionID=1234"}})
	if err != nil {
		t.Logf("Upgrade: %v", err)
		return
	}
	defer ws.Close()

	if ws.Subprotocol() != "p1" {
		t.Logf("Subprotocol() = %s, want p1", ws.Subprotocol())
		ws.Close()
		return
	}
	op, rd, err := ws.NextReader()
	if err != nil {
		t.Logf("NextReader: %v", err)
		return
	}
	wr, err := ws.NextWriter(op)
	if err != nil {
		t.Logf("NextWriter: %v", err)
		return
	}
	if _, err = io.Copy(wr, rd); err != nil {
		t.Logf("NextWriter: %v", err)
		return
	}
	if err := wr.Close(); err != nil {
		t.Logf("Close: %v", err)
		return
	}
}

func makeWsProto(s string) string {
	return "ws" + strings.TrimPrefix(s, "http")
}

func sendRecv(t *testing.T, ws *Conn) {
	const message = "Hello World!"
	if err := ws.SetWriteDeadline(time.Now().Add(time.Second)); err != nil {
		t.Fatalf("SetWriteDeadline: %v", err)
	}
	if err := ws.WriteMessage(TextMessage, []byte(message)); err != nil {
		t.Fatalf("WriteMessage: %v", err)
	}
	if err := ws.SetReadDeadline(time.Now().Add(time.Second)); err != nil {
		t.Fatalf("SetReadDeadline: %v", err)
	}
	_, p, err := ws.ReadMessage()
	if err != nil {
		t.Fatalf("ReadMessage: %v", err)
	}
	if string(p) != message {
		t.Fatalf("message=%s, want %s", p, message)
	}
}

func TestProxyDial(t *testing.T) {

	s := newServer(t)
	defer s.Close()

	surl, _ := url.Parse(s.Server.URL)

	cstDialer := cstDialer // make local copy for modification on next line.
	cstDialer.Proxy = http.ProxyURL(surl)

	connect := false
	origHandler := s.Server.Config.Handler

	// Capture the request Host header.
	s.Server.Config.Handler = http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			if r.Method == http.MethodConnect {
				connect = true
				w.WriteHeader(http.StatusOK)
				return
			}

			if !connect {
				t.Log("connect not received")
				http.Error(w, "connect not received", http.StatusMethodNotAllowed)
				return
			}
			origHandler.ServeHTTP(w, r)
		})

	ws, _, err := cstDialer.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestProxyAuthorizationDial(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	surl, _ := url.Parse(s.Server.URL)
	surl.User = url.UserPassword("username", "password")

	cstDialer := cstDialer // make local copy for modification on next line.
	cstDialer.Proxy = http.ProxyURL(surl)

	connect := false
	origHandler := s.Server.Config.Handler

	// Capture the request Host header.
	s.Server.Config.Handler = http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			proxyAuth := r.Header.Get("Proxy-Authorization")
			expectedProxyAuth := "Basic " + base64.StdEncoding.EncodeToString([]byte("username:password"))
			if r.Method == http.MethodConnect && proxyAuth == expectedProxyAuth {
				connect = true
				w.WriteHeader(http.StatusOK)
				return
			}

			if !connect {
				t.Log("connect with proxy authorization not received")
				http.Error(w, "connect with proxy authorization not received", http.StatusMethodNotAllowed)
				return
			}
			origHandler.ServeHTTP(w, r)
		})

	ws, _, err := cstDialer.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestDial(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	ws, _, err := cstDialer.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestDialCookieJar(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	jar, _ := cookiejar.New(nil)
	d := cstDialer
	d.Jar = jar

	u, _ := url.Parse(s.URL)

	switch u.Scheme {
	case "ws":
		u.Scheme = "http"
	case "wss":
		u.Scheme = "https"
	}

	cookies := []*http.Cookie{{Name: "gorilla", Value: "ws", Path: "/"}}
	d.Jar.SetCookies(u, cookies)

	ws, _, err := d.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()

	var gorilla string
	var sessionID string
	for _, c := range d.Jar.Cookies(u) {
		if c.Name == "gorilla" {
			gorilla = c.Value
		}

		if c.Name == "sessionID" {
			sessionID = c.Value
		}
	}
	if gorilla != "ws" {
		t.Error("Cookie not present in jar.")
	}

	if sessionID != "1234" {
		t.Error("Set-Cookie not received from the server.")
	}

	sendRecv(t, ws)
}

func rootCAs(t *testing.T, s *httptest.Server) *x509.CertPool {
	certs := x509.NewCertPool()
	for _, c := range s.TLS.Certificates {
		roots, err := x509.ParseCertificates(c.Certificate[len(c.Certificate)-1])
		if err != nil {
			t.Fatalf("error parsing server's root cert: %v", err)
		}
		for _, root := range roots {
			certs.AddCert(root)
		}
	}
	return certs
}

func TestDialTLS(t *testing.T) {
	s := newTLSServer(t)
	defer s.Close()

	d := cstDialer
	d.TLSClientConfig = &tls.Config{RootCAs: rootCAs(t, s.Server)}
	ws, _, err := d.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestDialTimeout(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	d := cstDialer
	d.HandshakeTimeout = -1
	ws, _, err := d.Dial(s.URL, nil)
	if err == nil {
		ws.Close()
		t.Fatalf("Dial: nil")
	}
}

// requireDeadlineNetConn fails the current test when Read or Write are called
// with no deadline.
type requireDeadlineNetConn struct {
	t                  *testing.T
	c                  net.Conn
	readDeadlineIsSet  bool
	writeDeadlineIsSet bool
}

func (c *requireDeadlineNetConn) SetDeadline(t time.Time) error {
	c.writeDeadlineIsSet = !t.Equal(time.Time{})
	c.readDeadlineIsSet = c.writeDeadlineIsSet
	return c.c.SetDeadline(t)
}

func (c *requireDeadlineNetConn) SetReadDeadline(t time.Time) error {
	c.readDeadlineIsSet = !t.Equal(time.Time{})
	return c.c.SetDeadline(t)
}

func (c *requireDeadlineNetConn) SetWriteDeadline(t time.Time) error {
	c.writeDeadlineIsSet = !t.Equal(time.Time{})
	return c.c.SetDeadline(t)
}

func (c *requireDeadlineNetConn) Write(p []byte) (int, error) {
	if !c.writeDeadlineIsSet {
		c.t.Fatalf("write with no deadline")
	}
	return c.c.Write(p)
}

func (c *requireDeadlineNetConn) Read(p []byte) (int, error) {
	if !c.readDeadlineIsSet {
		c.t.Fatalf("read with no deadline")
	}
	return c.c.Read(p)
}

func (c *requireDeadlineNetConn) Close() error         { return c.c.Close() }
func (c *requireDeadlineNetConn) LocalAddr() net.Addr  { return c.c.LocalAddr() }
func (c *requireDeadlineNetConn) RemoteAddr() net.Addr { return c.c.RemoteAddr() }

func TestHandshakeTimeout(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	d := cstDialer
	d.NetDial = func(n, a string) (net.Conn, error) {
		c, err := net.Dial(n, a)
		return &requireDeadlineNetConn{c: c, t: t}, err
	}
	ws, _, err := d.Dial(s.URL, nil)
	if err != nil {
		t.Fatal("Dial:", err)
	}
	ws.Close()
}

func TestHandshakeTimeoutInContext(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	d := cstDialer
	d.HandshakeTimeout = 0
	d.NetDialContext = func(ctx context.Context, n, a string) (net.Conn, error) {
		netDialer := &net.Dialer{}
		c, err := netDialer.DialContext(ctx, n, a)
		return &requireDeadlineNetConn{c: c, t: t}, err
	}

	ctx, cancel := context.WithDeadline(context.Background(), time.Now().Add(30*time.Second))
	defer cancel()
	ws, _, err := d.DialContext(ctx, s.URL, nil)
	if err != nil {
		t.Fatal("Dial:", err)
	}
	ws.Close()
}

func TestDialBadScheme(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	ws, _, err := cstDialer.Dial(s.Server.URL, nil)
	if err == nil {
		ws.Close()
		t.Fatalf("Dial: nil")
	}
}

func TestDialBadOrigin(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	ws, resp, err := cstDialer.Dial(s.URL, http.Header{"Origin": {"bad"}})
	if err == nil {
		ws.Close()
		t.Fatalf("Dial: nil")
	}
	if resp == nil {
		t.Fatalf("resp=nil, err=%v", err)
	}
	if resp.StatusCode != http.StatusForbidden {
		t.Fatalf("status=%d, want %d", resp.StatusCode, http.StatusForbidden)
	}
}

func TestDialBadHeader(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	for _, k := range []string{"Upgrade",
		"Connection",
		"Sec-Websocket-Key",
		"Sec-Websocket-Version",
		"Sec-Websocket-Protocol"} {
		h := http.Header{}
		h.Set(k, "bad")
		ws, _, err := cstDialer.Dial(s.URL, http.Header{"Origin": {"bad"}})
		if err == nil {
			ws.Close()
			t.Errorf("Dial with header %s returned nil", k)
		}
	}
}

func TestBadMethod(t *testing.T) {
	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ws, err := cstUpgrader.Upgrade(w, r, nil)
		if err == nil {
			t.Errorf("handshake succeeded, expect fail")
			ws.Close()
		}
	}))
	defer s.Close()

	req, err := http.NewRequest(http.MethodPost, s.URL, strings.NewReader(""))
	if err != nil {
		t.Fatalf("NewRequest returned error %v", err)
	}
	req.Header.Set("Connection", "upgrade")
	req.Header.Set("Upgrade", "websocket")
	req.Header.Set("Sec-Websocket-Version", "13")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Do returned error %v", err)
	}
	resp.Body.Close()
	if resp.StatusCode != http.StatusMethodNotAllowed {
		t.Errorf("Status = %d, want %d", resp.StatusCode, http.StatusMethodNotAllowed)
	}
}

func TestNoUpgrade(t *testing.T) {
	t.Parallel()
	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		ws, err := cstUpgrader.Upgrade(w, r, nil)
		if err == nil {
			t.Errorf("handshake succeeded, expect fail")
			ws.Close()
		}
	}))
	defer s.Close()

	req, err := http.NewRequest(http.MethodGet, s.URL, strings.NewReader(""))
	if err != nil {
		t.Fatalf("NewRequest returned error %v", err)
	}
	req.Header.Set("Connection", "upgrade")
	req.Header.Set("Sec-Websocket-Version", "13")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		t.Fatalf("Do returned error %v", err)
	}
	resp.Body.Close()
	if u := resp.Header.Get("Upgrade"); u != "websocket" {
		t.Errorf("Upgrade response header is %q, want %q", u, "websocket")
	}
	if resp.StatusCode != http.StatusUpgradeRequired {
		t.Errorf("Status = %d, want %d", resp.StatusCode, http.StatusUpgradeRequired)
	}
}

func TestDialExtraTokensInRespHeaders(t *testing.T) {
	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		challengeKey := r.Header.Get("Sec-Websocket-Key")
		w.Header().Set("Upgrade", "foo, websocket")
		w.Header().Set("Connection", "upgrade, keep-alive")
		w.Header().Set("Sec-Websocket-Accept", computeAcceptKey(challengeKey))
		w.WriteHeader(101)
	}))
	defer s.Close()

	ws, _, err := cstDialer.Dial(makeWsProto(s.URL), nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
}

func TestHandshake(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	ws, resp, err := cstDialer.Dial(s.URL, http.Header{"Origin": {s.URL}})
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()

	var sessionID string
	for _, c := range resp.Cookies() {
		if c.Name == "sessionID" {
			sessionID = c.Value
		}
	}
	if sessionID != "1234" {
		t.Error("Set-Cookie not received from the server.")
	}

	if ws.Subprotocol() != "p1" {
		t.Errorf("ws.Subprotocol() = %s, want p1", ws.Subprotocol())
	}
	sendRecv(t, ws)
}

func TestRespOnBadHandshake(t *testing.T) {
	const expectedStatus = http.StatusGone
	const expectedBody = "This is the response body."

	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(expectedStatus)
		_, _ = io.WriteString(w, expectedBody)
	}))
	defer s.Close()

	ws, resp, err := cstDialer.Dial(makeWsProto(s.URL), nil)
	if err == nil {
		ws.Close()
		t.Fatalf("Dial: nil")
	}

	if resp == nil {
		t.Fatalf("resp=nil, err=%v", err)
	}

	if resp.StatusCode != expectedStatus {
		t.Errorf("resp.StatusCode=%d, want %d", resp.StatusCode, expectedStatus)
	}

	p, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatalf("ReadFull(resp.Body) returned error %v", err)
	}

	if string(p) != expectedBody {
		t.Errorf("resp.Body=%s, want %s", p, expectedBody)
	}
}

type testLogWriter struct {
	t *testing.T
}

func (w testLogWriter) Write(p []byte) (int, error) {
	w.t.Logf("%s", p)
	return len(p), nil
}

// TestHost tests handling of host names and confirms that it matches net/http.
func TestHost(t *testing.T) {

	upgrader := Upgrader{}
	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if IsWebSocketUpgrade(r) {
			c, err := upgrader.Upgrade(w, r, http.Header{"X-Test-Host": {r.Host}})
			if err != nil {
				t.Fatal(err)
			}
			c.Close()
		} else {
			w.Header().Set("X-Test-Host", r.Host)
		}
	})

	server := httptest.NewServer(handler)
	defer server.Close()

	tlsServer := httptest.NewTLSServer(handler)
	defer tlsServer.Close()

	addrs := map[*httptest.Server]string{server: server.Listener.Addr().String(), tlsServer: tlsServer.Listener.Addr().String()}
	wsProtos := map[*httptest.Server]string{server: "ws://", tlsServer: "wss://"}
	httpProtos := map[*httptest.Server]string{server: "http://", tlsServer: "https://"}

	// Avoid log noise from net/http server by logging to testing.T
	server.Config.ErrorLog = log.New(testLogWriter{t}, "", 0)
	tlsServer.Config.ErrorLog = server.Config.ErrorLog

	cas := rootCAs(t, tlsServer)

	tests := []struct {
		fail               bool             // true if dial / get should fail
		server             *httptest.Server // server to use
		url                string           // host for request URI
		header             string           // optional request host header
		tls                string           // optional host for tls ServerName
		wantAddr           string           // expected host for dial
		wantHeader         string           // expected request header on server
		insecureSkipVerify bool
	}{
		{
			server:     server,
			url:        addrs[server],
			wantAddr:   addrs[server],
			wantHeader: addrs[server],
		},
		{
			server:     tlsServer,
			url:        addrs[tlsServer],
			wantAddr:   addrs[tlsServer],
			wantHeader: addrs[tlsServer],
		},

		{
			server:     server,
			url:        addrs[server],
			header:     "badhost.com",
			wantAddr:   addrs[server],
			wantHeader: "badhost.com",
		},
		{
			server:     tlsServer,
			url:        addrs[tlsServer],
			header:     "badhost.com",
			wantAddr:   addrs[tlsServer],
			wantHeader: "badhost.com",
		},

		{
			server:     server,
			url:        "example.com",
			header:     "badhost.com",
			wantAddr:   "example.com:80",
			wantHeader: "badhost.com",
		},
		{
			server:     tlsServer,
			url:        "example.com",
			header:     "badhost.com",
			wantAddr:   "example.com:443",
			wantHeader: "badhost.com",
		},

		{
			server:     server,
			url:        "badhost.com",
			header:     "example.com",
			wantAddr:   "badhost.com:80",
			wantHeader: "example.com",
		},
		{
			fail:     true,
			server:   tlsServer,
			url:      "badhost.com",
			header:   "example.com",
			wantAddr: "badhost.com:443",
		},
		{
			server:             tlsServer,
			url:                "badhost.com",
			insecureSkipVerify: true,
			wantAddr:           "badhost.com:443",
			wantHeader:         "badhost.com",
		},
		{
			server:     tlsServer,
			url:        "badhost.com",
			tls:        "example.com",
			wantAddr:   "badhost.com:443",
			wantHeader: "badhost.com",
		},
	}

	for i, tt := range tests {

		tls := &tls.Config{
			RootCAs:            cas,
			ServerName:         tt.tls,
			InsecureSkipVerify: tt.insecureSkipVerify,
		}

		var gotAddr string
		dialer := Dialer{
			NetDial: func(network, addr string) (net.Conn, error) {
				gotAddr = addr
				return net.Dial(network, addrs[tt.server])
			},
			TLSClientConfig: tls,
		}

		// Test websocket dial

		h := http.Header{}
		if tt.header != "" {
			h.Set("Host", tt.header)
		}
		c, resp, err := dialer.Dial(wsProtos[tt.server]+tt.url+"/", h)
		if err == nil {
			c.Close()
		}

		check := func(protos map[*httptest.Server]string) {
			name := fmt.Sprintf("%d: %s%s/ header[Host]=%q, tls.ServerName=%q", i+1, protos[tt.server], tt.url, tt.header, tt.tls)
			if gotAddr != tt.wantAddr {
				t.Errorf("%s: got addr %s, want %s", name, gotAddr, tt.wantAddr)
			}
			switch {
			case tt.fail && err == nil:
				t.Errorf("%s: unexpected success", name)
			case !tt.fail && err != nil:
				t.Errorf("%s: unexpected error %v", name, err)
			case !tt.fail && err == nil:
				if gotHost := resp.Header.Get("X-Test-Host"); gotHost != tt.wantHeader {
					t.Errorf("%s: got host %s, want %s", name, gotHost, tt.wantHeader)
				}
			}
		}

		check(wsProtos)

		// Confirm that net/http has same result

		transport := &http.Transport{
			Dial:            dialer.NetDial,
			TLSClientConfig: dialer.TLSClientConfig,
		}
		req, _ := http.NewRequest(http.MethodGet, httpProtos[tt.server]+tt.url+"/", nil)
		if tt.header != "" {
			req.Host = tt.header
		}
		client := &http.Client{Transport: transport}
		resp, err = client.Do(req)
		if err == nil {
			resp.Body.Close()
		}
		transport.CloseIdleConnections()
		check(httpProtos)
	}
}

func TestDialCompression(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	dialer := cstDialer
	dialer.EnableCompression = true
	ws, _, err := dialer.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestSocksProxyDial(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	proxyListener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen failed: %v", err)
	}
	defer proxyListener.Close()
	go func() {
		c1, err := proxyListener.Accept()
		if err != nil {
			t.Errorf("proxy accept failed: %v", err)
			return
		}
		defer c1.Close()

		_ = c1.SetDeadline(time.Now().Add(30 * time.Second))

		buf := make([]byte, 32)
		if _, err := io.ReadFull(c1, buf[:3]); err != nil {
			t.Errorf("read failed: %v", err)
			return
		}
		if want := []byte{5, 1, 0}; !bytes.Equal(want, buf[:len(want)]) {
			t.Errorf("read %x, want %x", buf[:len(want)], want)
		}
		if _, err := c1.Write([]byte{5, 0}); err != nil {
			t.Errorf("write failed: %v", err)
			return
		}
		if _, err := io.ReadFull(c1, buf[:10]); err != nil {
			t.Errorf("read failed: %v", err)
			return
		}
		if want := []byte{5, 1, 0, 1}; !bytes.Equal(want, buf[:len(want)]) {
			t.Errorf("read %x, want %x", buf[:len(want)], want)
			return
		}
		buf[1] = 0
		if _, err := c1.Write(buf[:10]); err != nil {
			t.Errorf("write failed: %v", err)
			return
		}

		ip := net.IP(buf[4:8])
		port := binary.BigEndian.Uint16(buf[8:10])

		c2, err := net.DialTCP("tcp", nil, &net.TCPAddr{IP: ip, Port: int(port)})
		if err != nil {
			t.Errorf("dial failed; %v", err)
			return
		}
		defer c2.Close()
		done := make(chan struct{})
		go func() {
			_, _ = io.Copy(c1, c2)
			close(done)
		}()
		_, _ = io.Copy(c2, c1)
		<-done
	}()

	purl, err := url.Parse("socks5://" + proxyListener.Addr().String())
	if err != nil {
		t.Fatalf("parse failed: %v", err)
	}

	cstDialer := cstDialer // make local copy for modification on next line.
	cstDialer.Proxy = http.ProxyURL(purl)

	ws, _, err := cstDialer.Dial(s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}
	defer ws.Close()
	sendRecv(t, ws)
}

func TestTracingDialWithContext(t *testing.T) {

	var headersWrote, requestWrote, getConn, gotConn, connectDone, gotFirstResponseByte bool
	trace := &httptrace.ClientTrace{
		WroteHeaders: func() {
			headersWrote = true
		},
		WroteRequest: func(httptrace.WroteRequestInfo) {
			requestWrote = true
		},
		GetConn: func(hostPort string) {
			getConn = true
		},
		GotConn: func(info httptrace.GotConnInfo) {
			gotConn = true
		},
		ConnectDone: func(network, addr string, err error) {
			connectDone = true
		},
		GotFirstResponseByte: func() {
			gotFirstResponseByte = true
		},
	}
	ctx := httptrace.WithClientTrace(context.Background(), trace)

	s := newTLSServer(t)
	defer s.Close()

	d := cstDialer
	d.TLSClientConfig = &tls.Config{RootCAs: rootCAs(t, s.Server)}

	ws, _, err := d.DialContext(ctx, s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}

	if !headersWrote {
		t.Fatal("Headers was not written")
	}
	if !requestWrote {
		t.Fatal("Request was not written")
	}
	if !getConn {
		t.Fatal("getConn was not called")
	}
	if !gotConn {
		t.Fatal("gotConn was not called")
	}
	if !connectDone {
		t.Fatal("connectDone was not called")
	}
	if !gotFirstResponseByte {
		t.Fatal("GotFirstResponseByte was not called")
	}

	defer ws.Close()
	sendRecv(t, ws)
}

func TestEmptyTracingDialWithContext(t *testing.T) {

	trace := &httptrace.ClientTrace{}
	ctx := httptrace.WithClientTrace(context.Background(), trace)

	s := newTLSServer(t)
	defer s.Close()

	d := cstDialer
	d.TLSClientConfig = &tls.Config{RootCAs: rootCAs(t, s.Server)}

	ws, _, err := d.DialContext(ctx, s.URL, nil)
	if err != nil {
		t.Fatalf("Dial: %v", err)
	}

	defer ws.Close()
	sendRecv(t, ws)
}

// TestNetDialConnect tests selection of dial method between NetDial, NetDialContext, NetDialTLS or NetDialTLSContext
func TestNetDialConnect(t *testing.T) {

	upgrader := Upgrader{}
	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if IsWebSocketUpgrade(r) {
			c, err := upgrader.Upgrade(w, r, http.Header{"X-Test-Host": {r.Host}})
			if err != nil {
				t.Fatal(err)
			}
			c.Close()
		} else {
			w.Header().Set("X-Test-Host", r.Host)
		}
	})

	server := httptest.NewServer(handler)
	defer server.Close()

	tlsServer := httptest.NewTLSServer(handler)
	defer tlsServer.Close()

	testUrls := map[*httptest.Server]string{
		server:    "ws://" + server.Listener.Addr().String() + "/",
		tlsServer: "wss://" + tlsServer.Listener.Addr().String() + "/",
	}

	cas := rootCAs(t, tlsServer)
	tlsConfig := &tls.Config{
		RootCAs:            cas,
		ServerName:         "example.com",
		InsecureSkipVerify: false,
	}

	tests := []struct {
		name              string
		server            *httptest.Server // server to use
		netDial           func(network, addr string) (net.Conn, error)
		netDialContext    func(ctx context.Context, network, addr string) (net.Conn, error)
		netDialTLSContext func(ctx context.Context, network, addr string) (net.Conn, error)
		tlsClientConfig   *tls.Config
	}{

		{
			name:   "HTTP server, all NetDial* defined, shall use NetDialContext",
			server: server,
			netDial: func(network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDial should not be called")
			},
			netDialContext: func(_ context.Context, network, addr string) (net.Conn, error) {
				return net.Dial(network, addr)
			},
			netDialTLSContext: func(_ context.Context, network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDialTLSContext should not be called")
			},
			tlsClientConfig: nil,
		},
		{
			name:              "HTTP server, all NetDial* undefined",
			server:            server,
			netDial:           nil,
			netDialContext:    nil,
			netDialTLSContext: nil,
			tlsClientConfig:   nil,
		},
		{
			name:   "HTTP server, NetDialContext undefined, shall fallback to NetDial",
			server: server,
			netDial: func(network, addr string) (net.Conn, error) {
				return net.Dial(network, addr)
			},
			netDialContext: nil,
			netDialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDialTLSContext should not be called")
			},
			tlsClientConfig: nil,
		},
		{
			name:   "HTTPS server, all NetDial* defined, shall use NetDialTLSContext",
			server: tlsServer,
			netDial: func(network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDial should not be called")
			},
			netDialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDialContext should not be called")
			},
			netDialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				netConn, err := net.Dial(network, addr)
				if err != nil {
					return nil, err
				}
				tlsConn := tls.Client(netConn, tlsConfig)
				err = tlsConn.Handshake()
				if err != nil {
					return nil, err
				}
				return tlsConn, nil
			},
			tlsClientConfig: nil,
		},
		{
			name:   "HTTPS server, NetDialTLSContext undefined, shall fallback to NetDialContext and do handshake",
			server: tlsServer,
			netDial: func(network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDial should not be called")
			},
			netDialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return net.Dial(network, addr)
			},
			netDialTLSContext: nil,
			tlsClientConfig:   tlsConfig,
		},
		{
			name:   "HTTPS server, NetDialTLSContext and NetDialContext undefined, shall fallback to NetDial and do handshake",
			server: tlsServer,
			netDial: func(network, addr string) (net.Conn, error) {
				return net.Dial(network, addr)
			},
			netDialContext:    nil,
			netDialTLSContext: nil,
			tlsClientConfig:   tlsConfig,
		},
		{
			name:              "HTTPS server, all NetDial* undefined",
			server:            tlsServer,
			netDial:           nil,
			netDialContext:    nil,
			netDialTLSContext: nil,
			tlsClientConfig:   tlsConfig,
		},
		{
			name:   "HTTPS server, all NetDialTLSContext defined, dummy TlsClientConfig defined, shall not do handshake",
			server: tlsServer,
			netDial: func(network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDial should not be called")
			},
			netDialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return nil, errors.New("NetDialContext should not be called")
			},
			netDialTLSContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				netConn, err := net.Dial(network, addr)
				if err != nil {
					return nil, err
				}
				tlsConn := tls.Client(netConn, tlsConfig)
				err = tlsConn.Handshake()
				if err != nil {
					return nil, err
				}
				return tlsConn, nil
			},
			tlsClientConfig: &tls.Config{
				RootCAs:            nil,
				ServerName:         "badserver.com",
				InsecureSkipVerify: false,
			},
		},
	}

	for _, tc := range tests {
		dialer := Dialer{
			NetDial:           tc.netDial,
			NetDialContext:    tc.netDialContext,
			NetDialTLSContext: tc.netDialTLSContext,
			TLSClientConfig:   tc.tlsClientConfig,
		}

		// Test websocket dial
		c, _, err := dialer.Dial(testUrls[tc.server], nil)
		if err != nil {
			t.Errorf("FAILED %s, err: %s", tc.name, err.Error())
		} else {
			c.Close()
		}
	}
}
func TestNextProtos(t *testing.T) {
	ts := httptest.NewUnstartedServer(
		http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {}),
	)
	ts.EnableHTTP2 = true
	ts.StartTLS()
	defer ts.Close()

	d := Dialer{
		TLSClientConfig: ts.Client().Transport.(*http.Transport).TLSClientConfig,
	}

	r, err := ts.Client().Get(ts.URL)
	if err != nil {
		t.Fatalf("Get: %v", err)
	}
	r.Body.Close()

	// Asserts that Dialer.TLSClientConfig.NextProtos contains "h2"
	// after the Client.Get call from net/http above.
	var containsHTTP2 bool = false
	for _, proto := range d.TLSClientConfig.NextProtos {
		if proto == "h2" {
			containsHTTP2 = true
		}
	}
	if !containsHTTP2 {
		t.Fatalf("Dialer.TLSClientConfig.NextProtos does not contain \"h2\"")
	}

	_, _, err = d.Dial(makeWsProto(ts.URL), nil)
	if err == nil {
		t.Fatalf("Dial succeeded, expect fail ")
	}
}

type dataBeforeHandshakeResponseWriter struct {
	http.ResponseWriter
}

type dataBeforeHandshakeConnection struct {
	net.Conn
	io.Reader
}

func (c *dataBeforeHandshakeConnection) Read(p []byte) (int, error) {
	return c.Reader.Read(p)
}

func (w dataBeforeHandshakeResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
	// Example single-frame masked text message from section 5.7 of the RFC.
	message := []byte{0x81, 0x85, 0x37, 0xfa, 0x21, 0x3d, 0x7f, 0x9f, 0x4d, 0x51, 0x58}
	n := len(message) / 2

	c, rw, err := http.NewResponseController(w.ResponseWriter).Hijack()
	if rw != nil {
		// Load first part of message into bufio.Reader. If the websocket
		// connection reads more than n bytes from the bufio.Reader, then the
		// test will fail with an unexpected EOF error.
		rw.Reader.Reset(bytes.NewReader(message[:n]))
		rw.Reader.Peek(n)
	}
	if c != nil {
		// Inject second part of message before data read from the network connection.
		c = &dataBeforeHandshakeConnection{
			Conn:   c,
			Reader: io.MultiReader(bytes.NewReader(message[n:]), c),
		}
	}
	return c, rw, err
}

func TestDataReceivedBeforeHandshake(t *testing.T) {
	s := newServer(t)
	defer s.Close()

	origHandler := s.Server.Config.Handler
	s.Server.Config.Handler = http.HandlerFunc(
		func(w http.ResponseWriter, r *http.Request) {
			origHandler.ServeHTTP(dataBeforeHandshakeResponseWriter{w}, r)
		})

	for _, readBufferSize := range []int{0, 1024} {
		t.Run(fmt.Sprintf("ReadBufferSize=%d", readBufferSize), func(t *testing.T) {
			dialer := cstDialer
			dialer.ReadBufferSize = readBufferSize
			ws, _, err := cstDialer.Dial(s.URL, nil)
			if err != nil {
				t.Fatalf("Dial: %v", err)
			}
			defer ws.Close()
			_, m, err := ws.ReadMessage()
			if err != nil || string(m) != "Hello" {
				t.Fatalf("ReadMessage() = %q, %v, want \"Hello\", nil", m, err)
			}
		})
	}
}


================================================
FILE: client_test.go
================================================
// Copyright 2014 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"net/url"
	"testing"
)

var hostPortNoPortTests = []struct {
	u                    *url.URL
	hostPort, hostNoPort string
}{
	{&url.URL{Scheme: "ws", Host: "example.com"}, "example.com:80", "example.com"},
	{&url.URL{Scheme: "wss", Host: "example.com"}, "example.com:443", "example.com"},
	{&url.URL{Scheme: "ws", Host: "example.com:7777"}, "example.com:7777", "example.com"},
	{&url.URL{Scheme: "wss", Host: "example.com:7777"}, "example.com:7777", "example.com"},
}

func TestHostPortNoPort(t *testing.T) {
	for _, tt := range hostPortNoPortTests {
		hostPort, hostNoPort := hostPortNoPort(tt.u)
		if hostPort != tt.hostPort {
			t.Errorf("hostPortNoPort(%v) returned hostPort %q, want %q", tt.u, hostPort, tt.hostPort)
		}
		if hostNoPort != tt.hostNoPort {
			t.Errorf("hostPortNoPort(%v) returned hostNoPort %q, want %q", tt.u, hostNoPort, tt.hostNoPort)
		}
	}
}


================================================
FILE: compression.go
================================================
// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"compress/flate"
	"errors"
	"io"
	"strings"
	"sync"
)

const (
	minCompressionLevel     = -2 // flate.HuffmanOnly not defined in Go < 1.6
	maxCompressionLevel     = flate.BestCompression
	defaultCompressionLevel = 1
)

var (
	flateWriterPools [maxCompressionLevel - minCompressionLevel + 1]sync.Pool
	flateReaderPool  = sync.Pool{New: func() interface{} {
		return flate.NewReader(nil)
	}}
)

func decompressNoContextTakeover(r io.Reader) io.ReadCloser {
	const tail =
	// Add four bytes as specified in RFC
	"\x00\x00\xff\xff" +
		// Add final block to squelch unexpected EOF error from flate reader.
		"\x01\x00\x00\xff\xff"

	fr, _ := flateReaderPool.Get().(io.ReadCloser)
	mr := io.MultiReader(r, strings.NewReader(tail))
	if err := fr.(flate.Resetter).Reset(mr, nil); err != nil {
		// Reset never fails, but handle error in case that changes.
		fr = flate.NewReader(mr)
	}
	return &flateReadWrapper{fr}
}

func isValidCompressionLevel(level int) bool {
	return minCompressionLevel <= level && level <= maxCompressionLevel
}

func compressNoContextTakeover(w io.WriteCloser, level int) io.WriteCloser {
	p := &flateWriterPools[level-minCompressionLevel]
	tw := &truncWriter{w: w}
	fw, _ := p.Get().(*flate.Writer)
	if fw == nil {
		fw, _ = flate.NewWriter(tw, level)
	} else {
		fw.Reset(tw)
	}
	return &flateWriteWrapper{fw: fw, tw: tw, p: p}
}

// truncWriter is an io.Writer that writes all but the last four bytes of the
// stream to another io.Writer.
type truncWriter struct {
	w io.WriteCloser
	n int
	p [4]byte
}

func (w *truncWriter) Write(p []byte) (int, error) {
	n := 0

	// fill buffer first for simplicity.
	if w.n < len(w.p) {
		n = copy(w.p[w.n:], p)
		p = p[n:]
		w.n += n
		if len(p) == 0 {
			return n, nil
		}
	}

	m := len(p)
	if m > len(w.p) {
		m = len(w.p)
	}

	if nn, err := w.w.Write(w.p[:m]); err != nil {
		return n + nn, err
	}

	copy(w.p[:], w.p[m:])
	copy(w.p[len(w.p)-m:], p[len(p)-m:])
	nn, err := w.w.Write(p[:len(p)-m])
	return n + nn, err
}

type flateWriteWrapper struct {
	fw *flate.Writer
	tw *truncWriter
	p  *sync.Pool
}

func (w *flateWriteWrapper) Write(p []byte) (int, error) {
	if w.fw == nil {
		return 0, errWriteClosed
	}
	return w.fw.Write(p)
}

func (w *flateWriteWrapper) Close() error {
	if w.fw == nil {
		return errWriteClosed
	}
	err1 := w.fw.Flush()
	w.p.Put(w.fw)
	w.fw = nil
	if w.tw.p != [4]byte{0, 0, 0xff, 0xff} {
		return errors.New("websocket: internal error, unexpected bytes at end of flate stream")
	}
	err2 := w.tw.w.Close()
	if err1 != nil {
		return err1
	}
	return err2
}

type flateReadWrapper struct {
	fr io.ReadCloser
}

func (r *flateReadWrapper) Read(p []byte) (int, error) {
	if r.fr == nil {
		return 0, io.ErrClosedPipe
	}
	n, err := r.fr.Read(p)
	if err == io.EOF {
		// Preemptively place the reader back in the pool. This helps with
		// scenarios where the application does not call NextReader() soon after
		// this final read.
		r.Close()
	}
	return n, err
}

func (r *flateReadWrapper) Close() error {
	if r.fr == nil {
		return io.ErrClosedPipe
	}
	err := r.fr.Close()
	flateReaderPool.Put(r.fr)
	r.fr = nil
	return err
}


================================================
FILE: compression_test.go
================================================
package websocket

import (
	"bytes"
	"fmt"
	"io"
	"testing"
)

type nopCloser struct{ io.Writer }

func (nopCloser) Close() error { return nil }

func TestTruncWriter(t *testing.T) {
	const data = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijlkmnopqrstuvwxyz987654321"
	for n := 1; n <= 10; n++ {
		var b bytes.Buffer
		w := &truncWriter{w: nopCloser{&b}}
		p := []byte(data)
		for len(p) > 0 {
			m := len(p)
			if m > n {
				m = n
			}
			_, _ = w.Write(p[:m])
			p = p[m:]
		}
		if b.String() != data[:len(data)-len(w.p)] {
			t.Errorf("%d: %q", n, b.String())
		}
	}
}

func textMessages(num int) [][]byte {
	messages := make([][]byte, num)
	for i := 0; i < num; i++ {
		msg := fmt.Sprintf("planet: %d, country: %d, city: %d, street: %d", i, i, i, i)
		messages[i] = []byte(msg)
	}
	return messages
}

func BenchmarkWriteNoCompression(b *testing.B) {
	w := io.Discard
	c := newTestConn(nil, w, false)
	messages := textMessages(100)
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = c.WriteMessage(TextMessage, messages[i%len(messages)])
	}
	b.ReportAllocs()
}

func BenchmarkWriteWithCompression(b *testing.B) {
	w := io.Discard
	c := newTestConn(nil, w, false)
	messages := textMessages(100)
	c.enableWriteCompression = true
	c.newCompressionWriter = compressNoContextTakeover
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_ = c.WriteMessage(TextMessage, messages[i%len(messages)])
	}
	b.ReportAllocs()
}

func TestValidCompressionLevel(t *testing.T) {
	c := newTestConn(nil, nil, false)
	for _, level := range []int{minCompressionLevel - 1, maxCompressionLevel + 1} {
		if err := c.SetCompressionLevel(level); err == nil {
			t.Errorf("no error for level %d", level)
		}
	}
	for _, level := range []int{minCompressionLevel, maxCompressionLevel} {
		if err := c.SetCompressionLevel(level); err != nil {
			t.Errorf("error for level %d", level)
		}
	}
}


================================================
FILE: conn.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"crypto/rand"
	"encoding/binary"
	"errors"
	"io"
	"net"
	"strconv"
	"strings"
	"sync"
	"time"
	"unicode/utf8"
)

const (
	// Frame header byte 0 bits from Section 5.2 of RFC 6455
	finalBit = 1 << 7
	rsv1Bit  = 1 << 6
	rsv2Bit  = 1 << 5
	rsv3Bit  = 1 << 4

	// Frame header byte 1 bits from Section 5.2 of RFC 6455
	maskBit = 1 << 7

	maxFrameHeaderSize         = 2 + 8 + 4 // Fixed header + length + mask
	maxControlFramePayloadSize = 125

	writeWait = time.Second

	defaultReadBufferSize  = 4096
	defaultWriteBufferSize = 4096

	continuationFrame = 0
	noFrame           = -1
)

// Close codes defined in RFC 6455, section 11.7.
const (
	CloseNormalClosure           = 1000
	CloseGoingAway               = 1001
	CloseProtocolError           = 1002
	CloseUnsupportedData         = 1003
	CloseNoStatusReceived        = 1005
	CloseAbnormalClosure         = 1006
	CloseInvalidFramePayloadData = 1007
	ClosePolicyViolation         = 1008
	CloseMessageTooBig           = 1009
	CloseMandatoryExtension      = 1010
	CloseInternalServerErr       = 1011
	CloseServiceRestart          = 1012
	CloseTryAgainLater           = 1013
	CloseTLSHandshake            = 1015
)

// The message types are defined in RFC 6455, section 11.8.
const (
	// TextMessage denotes a text data message. The text message payload is
	// interpreted as UTF-8 encoded text data.
	TextMessage = 1

	// BinaryMessage denotes a binary data message.
	BinaryMessage = 2

	// CloseMessage denotes a close control message. The optional message
	// payload contains a numeric code and text. Use the FormatCloseMessage
	// function to format a close message payload.
	CloseMessage = 8

	// PingMessage denotes a ping control message. The optional message payload
	// is UTF-8 encoded text.
	PingMessage = 9

	// PongMessage denotes a pong control message. The optional message payload
	// is UTF-8 encoded text.
	PongMessage = 10
)

// ErrCloseSent is returned when the application writes a message to the
// connection after sending a close message.
var ErrCloseSent = errors.New("websocket: close sent")

// ErrReadLimit is returned when reading a message that is larger than the
// read limit set for the connection.
var ErrReadLimit = errors.New("websocket: read limit exceeded")

// netError satisfies the net Error interface.
type netError struct {
	msg       string
	temporary bool
	timeout   bool
}

func (e *netError) Error() string   { return e.msg }
func (e *netError) Temporary() bool { return e.temporary }
func (e *netError) Timeout() bool   { return e.timeout }

// CloseError represents a close message.
type CloseError struct {
	// Code is defined in RFC 6455, section 11.7.
	Code int

	// Text is the optional text payload.
	Text string
}

func (e *CloseError) Error() string {
	s := []byte("websocket: close ")
	s = strconv.AppendInt(s, int64(e.Code), 10)
	switch e.Code {
	case CloseNormalClosure:
		s = append(s, " (normal)"...)
	case CloseGoingAway:
		s = append(s, " (going away)"...)
	case CloseProtocolError:
		s = append(s, " (protocol error)"...)
	case CloseUnsupportedData:
		s = append(s, " (unsupported data)"...)
	case CloseNoStatusReceived:
		s = append(s, " (no status)"...)
	case CloseAbnormalClosure:
		s = append(s, " (abnormal closure)"...)
	case CloseInvalidFramePayloadData:
		s = append(s, " (invalid payload data)"...)
	case ClosePolicyViolation:
		s = append(s, " (policy violation)"...)
	case CloseMessageTooBig:
		s = append(s, " (message too big)"...)
	case CloseMandatoryExtension:
		s = append(s, " (mandatory extension missing)"...)
	case CloseInternalServerErr:
		s = append(s, " (internal server error)"...)
	case CloseTLSHandshake:
		s = append(s, " (TLS handshake error)"...)
	}
	if e.Text != "" {
		s = append(s, ": "...)
		s = append(s, e.Text...)
	}
	return string(s)
}

// IsCloseError returns boolean indicating whether the error is a *CloseError
// with one of the specified codes.
func IsCloseError(err error, codes ...int) bool {
	if e, ok := err.(*CloseError); ok {
		for _, code := range codes {
			if e.Code == code {
				return true
			}
		}
	}
	return false
}

// IsUnexpectedCloseError returns boolean indicating whether the error is a
// *CloseError with a code not in the list of expected codes.
func IsUnexpectedCloseError(err error, expectedCodes ...int) bool {
	if e, ok := err.(*CloseError); ok {
		for _, code := range expectedCodes {
			if e.Code == code {
				return false
			}
		}
		return true
	}
	return false
}

var (
	errWriteTimeout        = &netError{msg: "websocket: write timeout", timeout: true, temporary: true}
	errUnexpectedEOF       = &CloseError{Code: CloseAbnormalClosure, Text: io.ErrUnexpectedEOF.Error()}
	errBadWriteOpCode      = errors.New("websocket: bad write message type")
	errWriteClosed         = errors.New("websocket: write closed")
	errInvalidControlFrame = errors.New("websocket: invalid control frame")
)

// maskRand is an io.Reader for generating mask bytes. The reader is initialized
// to crypto/rand Reader. Tests swap the reader to a math/rand reader for
// reproducible results.
var maskRand = rand.Reader

// newMaskKey returns a new 32 bit value for masking client frames.
func newMaskKey() [4]byte {
	var k [4]byte
	_, _ = io.ReadFull(maskRand, k[:])
	return k
}

func isControl(frameType int) bool {
	return frameType == CloseMessage || frameType == PingMessage || frameType == PongMessage
}

func isData(frameType int) bool {
	return frameType == TextMessage || frameType == BinaryMessage
}

var validReceivedCloseCodes = map[int]bool{
	// see http://www.iana.org/assignments/websocket/websocket.xhtml#close-code-number

	CloseNormalClosure:           true,
	CloseGoingAway:               true,
	CloseProtocolError:           true,
	CloseUnsupportedData:         true,
	CloseNoStatusReceived:        false,
	CloseAbnormalClosure:         false,
	CloseInvalidFramePayloadData: true,
	ClosePolicyViolation:         true,
	CloseMessageTooBig:           true,
	CloseMandatoryExtension:      true,
	CloseInternalServerErr:       true,
	CloseServiceRestart:          true,
	CloseTryAgainLater:           true,
	CloseTLSHandshake:            false,
}

func isValidReceivedCloseCode(code int) bool {
	return validReceivedCloseCodes[code] || (code >= 3000 && code <= 4999)
}

// BufferPool represents a pool of buffers. The *sync.Pool type satisfies this
// interface.  The type of the value stored in a pool is not specified.
type BufferPool interface {
	// Get gets a value from the pool or returns nil if the pool is empty.
	Get() interface{}
	// Put adds a value to the pool.
	Put(interface{})
}

// writePoolData is the type added to the write buffer pool. This wrapper is
// used to prevent applications from peeking at and depending on the values
// added to the pool.
type writePoolData struct{ buf []byte }

// The Conn type represents a WebSocket connection.
type Conn struct {
	conn        net.Conn
	isServer    bool
	subprotocol string

	// Write fields
	mu            chan struct{} // used as mutex to protect write to conn
	writeBuf      []byte        // frame is constructed in this buffer.
	writePool     BufferPool
	writeBufSize  int
	writeDeadline time.Time
	writer        io.WriteCloser // the current writer returned to the application
	isWriting     bool           // for best-effort concurrent write detection

	writeErrMu sync.Mutex
	writeErr   error

	enableWriteCompression bool
	compressionLevel       int
	newCompressionWriter   func(io.WriteCloser, int) io.WriteCloser

	// Read fields
	reader  io.ReadCloser // the current reader returned to the application
	readErr error
	br      *bufio.Reader
	// bytes remaining in current frame.
	// set setReadRemaining to safely update this value and prevent overflow
	readRemaining int64
	readFinal     bool  // true the current message has more frames.
	readLength    int64 // Message size.
	readLimit     int64 // Maximum message size.
	readMaskPos   int
	readMaskKey   [4]byte
	handlePong    func(string) error
	handlePing    func(string) error
	handleClose   func(int, string) error
	readErrCount  int
	messageReader *messageReader // the current low-level reader

	readDecompress         bool // whether last read frame had RSV1 set
	newDecompressionReader func(io.Reader) io.ReadCloser
}

func newConn(conn net.Conn, isServer bool, readBufferSize, writeBufferSize int, writeBufferPool BufferPool, br *bufio.Reader, writeBuf []byte) *Conn {

	if br == nil {
		if readBufferSize == 0 {
			readBufferSize = defaultReadBufferSize
		} else if readBufferSize < maxControlFramePayloadSize {
			// must be large enough for control frame
			readBufferSize = maxControlFramePayloadSize
		}
		br = bufio.NewReaderSize(conn, readBufferSize)
	}

	if writeBufferSize <= 0 {
		writeBufferSize = defaultWriteBufferSize
	}
	writeBufferSize += maxFrameHeaderSize

	if writeBuf == nil && writeBufferPool == nil {
		writeBuf = make([]byte, writeBufferSize)
	}

	mu := make(chan struct{}, 1)
	mu <- struct{}{}
	c := &Conn{
		isServer:               isServer,
		br:                     br,
		conn:                   conn,
		mu:                     mu,
		readFinal:              true,
		writeBuf:               writeBuf,
		writePool:              writeBufferPool,
		writeBufSize:           writeBufferSize,
		enableWriteCompression: true,
		compressionLevel:       defaultCompressionLevel,
	}
	c.SetCloseHandler(nil)
	c.SetPingHandler(nil)
	c.SetPongHandler(nil)
	return c
}

// setReadRemaining tracks the number of bytes remaining on the connection. If n
// overflows, an ErrReadLimit is returned.
func (c *Conn) setReadRemaining(n int64) error {
	if n < 0 {
		return ErrReadLimit
	}

	c.readRemaining = n
	return nil
}

// Subprotocol returns the negotiated protocol for the connection.
func (c *Conn) Subprotocol() string {
	return c.subprotocol
}

// Close closes the underlying network connection without sending or waiting
// for a close message.
func (c *Conn) Close() error {
	return c.conn.Close()
}

// LocalAddr returns the local network address.
func (c *Conn) LocalAddr() net.Addr {
	return c.conn.LocalAddr()
}

// RemoteAddr returns the remote network address.
func (c *Conn) RemoteAddr() net.Addr {
	return c.conn.RemoteAddr()
}

// Write methods

func (c *Conn) writeFatal(err error) error {
	c.writeErrMu.Lock()
	if c.writeErr == nil {
		c.writeErr = err
	}
	c.writeErrMu.Unlock()
	return err
}

func (c *Conn) read(n int) ([]byte, error) {
	p, err := c.br.Peek(n)
	if err == io.EOF {
		err = errUnexpectedEOF
	}
	// Discard is guaranteed to succeed because the number of bytes to discard
	// is less than or equal to the number of bytes buffered.
	_, _ = c.br.Discard(len(p))
	return p, err
}

func (c *Conn) write(frameType int, deadline time.Time, buf0, buf1 []byte) error {
	<-c.mu
	defer func() { c.mu <- struct{}{} }()

	c.writeErrMu.Lock()
	err := c.writeErr
	c.writeErrMu.Unlock()
	if err != nil {
		return err
	}

	if err := c.conn.SetWriteDeadline(deadline); err != nil {
		return c.writeFatal(err)
	}
	if len(buf1) == 0 {
		_, err = c.conn.Write(buf0)
	} else {
		err = c.writeBufs(buf0, buf1)
	}
	if err != nil {
		return c.writeFatal(err)
	}
	if frameType == CloseMessage {
		_ = c.writeFatal(ErrCloseSent)
	}
	return nil
}

func (c *Conn) writeBufs(bufs ...[]byte) error {
	b := net.Buffers(bufs)
	_, err := b.WriteTo(c.conn)
	return err
}

// WriteControl writes a control message with the given deadline. The allowed
// message types are CloseMessage, PingMessage and PongMessage.
func (c *Conn) WriteControl(messageType int, data []byte, deadline time.Time) error {
	if !isControl(messageType) {
		return errBadWriteOpCode
	}
	if len(data) > maxControlFramePayloadSize {
		return errInvalidControlFrame
	}

	b0 := byte(messageType) | finalBit
	b1 := byte(len(data))
	if !c.isServer {
		b1 |= maskBit
	}

	buf := make([]byte, 0, maxFrameHeaderSize+maxControlFramePayloadSize)
	buf = append(buf, b0, b1)

	if c.isServer {
		buf = append(buf, data...)
	} else {
		key := newMaskKey()
		buf = append(buf, key[:]...)
		buf = append(buf, data...)
		maskBytes(key, 0, buf[6:])
	}

	if deadline.IsZero() {
		// No timeout for zero time.
		<-c.mu
	} else {
		d := time.Until(deadline)
		if d < 0 {
			return errWriteTimeout
		}
		select {
		case <-c.mu:
		default:
			timer := time.NewTimer(d)
			select {
			case <-c.mu:
				timer.Stop()
			case <-timer.C:
				return errWriteTimeout
			}
		}
	}

	defer func() { c.mu <- struct{}{} }()

	c.writeErrMu.Lock()
	err := c.writeErr
	c.writeErrMu.Unlock()
	if err != nil {
		return err
	}

	if err := c.conn.SetWriteDeadline(deadline); err != nil {
		return c.writeFatal(err)
	}
	if _, err = c.conn.Write(buf); err != nil {
		return c.writeFatal(err)
	}
	if messageType == CloseMessage {
		_ = c.writeFatal(ErrCloseSent)
	}
	return err
}

// beginMessage prepares a connection and message writer for a new message.
func (c *Conn) beginMessage(mw *messageWriter, messageType int) error {
	// Close previous writer if not already closed by the application. It's
	// probably better to return an error in this situation, but we cannot
	// change this without breaking existing applications.
	if c.writer != nil {
		c.writer.Close()
		c.writer = nil
	}

	if !isControl(messageType) && !isData(messageType) {
		return errBadWriteOpCode
	}

	c.writeErrMu.Lock()
	err := c.writeErr
	c.writeErrMu.Unlock()
	if err != nil {
		return err
	}

	mw.c = c
	mw.frameType = messageType
	mw.pos = maxFrameHeaderSize

	if c.writeBuf == nil {
		wpd, ok := c.writePool.Get().(writePoolData)
		if ok {
			c.writeBuf = wpd.buf
		} else {
			c.writeBuf = make([]byte, c.writeBufSize)
		}
	}
	return nil
}

// NextWriter returns a writer for the next message to send. The writer's Close
// method flushes the complete message to the network.
//
// There can be at most one open writer on a connection. NextWriter closes the
// previous writer if the application has not already done so.
//
// All message types (TextMessage, BinaryMessage, CloseMessage, PingMessage and
// PongMessage) are supported.
func (c *Conn) NextWriter(messageType int) (io.WriteCloser, error) {
	var mw messageWriter
	if err := c.beginMessage(&mw, messageType); err != nil {
		return nil, err
	}
	c.writer = &mw
	if c.newCompressionWriter != nil && c.enableWriteCompression && isData(messageType) {
		w := c.newCompressionWriter(c.writer, c.compressionLevel)
		mw.compress = true
		c.writer = w
	}
	return c.writer, nil
}

type messageWriter struct {
	c         *Conn
	compress  bool // whether next call to flushFrame should set RSV1
	pos       int  // end of data in writeBuf.
	frameType int  // type of the current frame.
	err       error
}

func (w *messageWriter) endMessage(err error) error {
	if w.err != nil {
		return err
	}
	c := w.c
	w.err = err
	c.writer = nil
	if c.writePool != nil {
		c.writePool.Put(writePoolData{buf: c.writeBuf})
		c.writeBuf = nil
	}
	return err
}

// flushFrame writes buffered data and extra as a frame to the network. The
// final argument indicates that this is the last frame in the message.
func (w *messageWriter) flushFrame(final bool, extra []byte) error {
	c := w.c
	length := w.pos - maxFrameHeaderSize + len(extra)

	// Check for invalid control frames.
	if isControl(w.frameType) &&
		(!final || length > maxControlFramePayloadSize) {
		return w.endMessage(errInvalidControlFrame)
	}

	b0 := byte(w.frameType)
	if final {
		b0 |= finalBit
	}
	if w.compress {
		b0 |= rsv1Bit
	}
	w.compress = false

	b1 := byte(0)
	if !c.isServer {
		b1 |= maskBit
	}

	// Assume that the frame starts at beginning of c.writeBuf.
	framePos := 0
	if c.isServer {
		// Adjust up if mask not included in the header.
		framePos = 4
	}

	switch {
	case length >= 65536:
		c.writeBuf[framePos] = b0
		c.writeBuf[framePos+1] = b1 | 127
		binary.BigEndian.PutUint64(c.writeBuf[framePos+2:], uint64(length))
	case length > 125:
		framePos += 6
		c.writeBuf[framePos] = b0
		c.writeBuf[framePos+1] = b1 | 126
		binary.BigEndian.PutUint16(c.writeBuf[framePos+2:], uint16(length))
	default:
		framePos += 8
		c.writeBuf[framePos] = b0
		c.writeBuf[framePos+1] = b1 | byte(length)
	}

	if !c.isServer {
		key := newMaskKey()
		copy(c.writeBuf[maxFrameHeaderSize-4:], key[:])
		maskBytes(key, 0, c.writeBuf[maxFrameHeaderSize:w.pos])
		if len(extra) > 0 {
			return w.endMessage(c.writeFatal(errors.New("websocket: internal error, extra used in client mode")))
		}
	}

	// Write the buffers to the connection with best-effort detection of
	// concurrent writes. See the concurrency section in the package
	// documentation for more info.

	if c.isWriting {
		panic("concurrent write to websocket connection")
	}
	c.isWriting = true

	err := c.write(w.frameType, c.writeDeadline, c.writeBuf[framePos:w.pos], extra)

	if !c.isWriting {
		panic("concurrent write to websocket connection")
	}
	c.isWriting = false

	if err != nil {
		return w.endMessage(err)
	}

	if final {
		_ = w.endMessage(errWriteClosed)
		return nil
	}

	// Setup for next frame.
	w.pos = maxFrameHeaderSize
	w.frameType = continuationFrame
	return nil
}

func (w *messageWriter) ncopy(max int) (int, error) {
	n := len(w.c.writeBuf) - w.pos
	if n <= 0 {
		if err := w.flushFrame(false, nil); err != nil {
			return 0, err
		}
		n = len(w.c.writeBuf) - w.pos
	}
	if n > max {
		n = max
	}
	return n, nil
}

func (w *messageWriter) Write(p []byte) (int, error) {
	if w.err != nil {
		return 0, w.err
	}

	if len(p) > 2*len(w.c.writeBuf) && w.c.isServer {
		// Don't buffer large messages.
		err := w.flushFrame(false, p)
		if err != nil {
			return 0, err
		}
		return len(p), nil
	}

	nn := len(p)
	for len(p) > 0 {
		n, err := w.ncopy(len(p))
		if err != nil {
			return 0, err
		}
		copy(w.c.writeBuf[w.pos:], p[:n])
		w.pos += n
		p = p[n:]
	}
	return nn, nil
}

func (w *messageWriter) WriteString(p string) (int, error) {
	if w.err != nil {
		return 0, w.err
	}

	nn := len(p)
	for len(p) > 0 {
		n, err := w.ncopy(len(p))
		if err != nil {
			return 0, err
		}
		copy(w.c.writeBuf[w.pos:], p[:n])
		w.pos += n
		p = p[n:]
	}
	return nn, nil
}

func (w *messageWriter) ReadFrom(r io.Reader) (nn int64, err error) {
	if w.err != nil {
		return 0, w.err
	}
	for {
		if w.pos == len(w.c.writeBuf) {
			err = w.flushFrame(false, nil)
			if err != nil {
				break
			}
		}
		var n int
		n, err = r.Read(w.c.writeBuf[w.pos:])
		w.pos += n
		nn += int64(n)
		if err != nil {
			if err == io.EOF {
				err = nil
			}
			break
		}
	}
	return nn, err
}

func (w *messageWriter) Close() error {
	if w.err != nil {
		return w.err
	}
	return w.flushFrame(true, nil)
}

// WritePreparedMessage writes prepared message into connection.
func (c *Conn) WritePreparedMessage(pm *PreparedMessage) error {
	frameType, frameData, err := pm.frame(prepareKey{
		isServer:         c.isServer,
		compress:         c.newCompressionWriter != nil && c.enableWriteCompression && isData(pm.messageType),
		compressionLevel: c.compressionLevel,
	})
	if err != nil {
		return err
	}
	if c.isWriting {
		panic("concurrent write to websocket connection")
	}
	c.isWriting = true
	err = c.write(frameType, c.writeDeadline, frameData, nil)
	if !c.isWriting {
		panic("concurrent write to websocket connection")
	}
	c.isWriting = false
	return err
}

// WriteMessage is a helper method for getting a writer using NextWriter,
// writing the message and closing the writer.
func (c *Conn) WriteMessage(messageType int, data []byte) error {

	if c.isServer && (c.newCompressionWriter == nil || !c.enableWriteCompression) {
		// Fast path with no allocations and single frame.

		var mw messageWriter
		if err := c.beginMessage(&mw, messageType); err != nil {
			return err
		}
		n := copy(c.writeBuf[mw.pos:], data)
		mw.pos += n
		data = data[n:]
		return mw.flushFrame(true, data)
	}

	w, err := c.NextWriter(messageType)
	if err != nil {
		return err
	}
	if _, err = w.Write(data); err != nil {
		return err
	}
	return w.Close()
}

// SetWriteDeadline sets the write deadline on the underlying network
// connection. After a write has timed out, the websocket state is corrupt and
// all future writes will return an error. A zero value for t means writes will
// not time out.
func (c *Conn) SetWriteDeadline(t time.Time) error {
	c.writeDeadline = t
	return nil
}

// Read methods

func (c *Conn) advanceFrame() (int, error) {
	// 1. Skip remainder of previous frame.

	if c.readRemaining > 0 {
		if _, err := io.CopyN(io.Discard, c.br, c.readRemaining); err != nil {
			return noFrame, err
		}
	}

	// 2. Read and parse first two bytes of frame header.
	// To aid debugging, collect and report all errors in the first two bytes
	// of the header.

	var errors []string

	p, err := c.read(2)
	if err != nil {
		return noFrame, err
	}

	frameType := int(p[0] & 0xf)
	final := p[0]&finalBit != 0
	rsv1 := p[0]&rsv1Bit != 0
	rsv2 := p[0]&rsv2Bit != 0
	rsv3 := p[0]&rsv3Bit != 0
	mask := p[1]&maskBit != 0
	_ = c.setReadRemaining(int64(p[1] & 0x7f)) // will not fail because argument is >= 0

	c.readDecompress = false
	if rsv1 {
		if c.newDecompressionReader != nil {
			c.readDecompress = true
		} else {
			errors = append(errors, "RSV1 set")
		}
	}

	if rsv2 {
		errors = append(errors, "RSV2 set")
	}

	if rsv3 {
		errors = append(errors, "RSV3 set")
	}

	switch frameType {
	case CloseMessage, PingMessage, PongMessage:
		if c.readRemaining > maxControlFramePayloadSize {
			errors = append(errors, "len > 125 for control")
		}
		if !final {
			errors = append(errors, "FIN not set on control")
		}
	case TextMessage, BinaryMessage:
		if !c.readFinal {
			errors = append(errors, "data before FIN")
		}
		c.readFinal = final
	case continuationFrame:
		if c.readFinal {
			errors = append(errors, "continuation after FIN")
		}
		c.readFinal = final
	default:
		errors = append(errors, "bad opcode "+strconv.Itoa(frameType))
	}

	if mask != c.isServer {
		errors = append(errors, "bad MASK")
	}

	if len(errors) > 0 {
		return noFrame, c.handleProtocolError(strings.Join(errors, ", "))
	}

	// 3. Read and parse frame length as per
	// https://tools.ietf.org/html/rfc6455#section-5.2
	//
	// The length of the "Payload data", in bytes: if 0-125, that is the payload
	// length.
	// - If 126, the following 2 bytes interpreted as a 16-bit unsigned
	// integer are the payload length.
	// - If 127, the following 8 bytes interpreted as
	// a 64-bit unsigned integer (the most significant bit MUST be 0) are the
	// payload length. Multibyte length quantities are expressed in network byte
	// order.

	switch c.readRemaining {
	case 126:
		p, err := c.read(2)
		if err != nil {
			return noFrame, err
		}

		if err := c.setReadRemaining(int64(binary.BigEndian.Uint16(p))); err != nil {
			return noFrame, err
		}
	case 127:
		p, err := c.read(8)
		if err != nil {
			return noFrame, err
		}

		if err := c.setReadRemaining(int64(binary.BigEndian.Uint64(p))); err != nil {
			return noFrame, err
		}
	}

	// 4. Handle frame masking.

	if mask {
		c.readMaskPos = 0
		p, err := c.read(len(c.readMaskKey))
		if err != nil {
			return noFrame, err
		}
		copy(c.readMaskKey[:], p)
	}

	// 5. For text and binary messages, enforce read limit and return.

	if frameType == continuationFrame || frameType == TextMessage || frameType == BinaryMessage {

		c.readLength += c.readRemaining
		// Don't allow readLength to overflow in the presence of a large readRemaining
		// counter.
		if c.readLength < 0 {
			return noFrame, ErrReadLimit
		}

		if c.readLimit > 0 && c.readLength > c.readLimit {
			// Make a best effort to send a close message describing the problem.
			_ = c.WriteControl(CloseMessage, FormatCloseMessage(CloseMessageTooBig, ""), time.Now().Add(writeWait))
			return noFrame, ErrReadLimit
		}

		return frameType, nil
	}

	// 6. Read control frame payload.

	var payload []byte
	if c.readRemaining > 0 {
		payload, err = c.read(int(c.readRemaining))
		_ = c.setReadRemaining(0) // will not fail because argument is >= 0
		if err != nil {
			return noFrame, err
		}
		if c.isServer {
			maskBytes(c.readMaskKey, 0, payload)
		}
	}

	// 7. Process control frame payload.

	switch frameType {
	case PongMessage:
		if err := c.handlePong(string(payload)); err != nil {
			return noFrame, err
		}
	case PingMessage:
		if err := c.handlePing(string(payload)); err != nil {
			return noFrame, err
		}
	case CloseMessage:
		closeCode := CloseNoStatusReceived
		closeText := ""
		if len(payload) >= 2 {
			closeCode = int(binary.BigEndian.Uint16(payload))
			if !isValidReceivedCloseCode(closeCode) {
				return noFrame, c.handleProtocolError("bad close code " + strconv.Itoa(closeCode))
			}
			closeText = string(payload[2:])
			if !utf8.ValidString(closeText) {
				return noFrame, c.handleProtocolError("invalid utf8 payload in close frame")
			}
		}
		if err := c.handleClose(closeCode, closeText); err != nil {
			return noFrame, err
		}
		return noFrame, &CloseError{Code: closeCode, Text: closeText}
	}

	return frameType, nil
}

func (c *Conn) handleProtocolError(message string) error {
	data := FormatCloseMessage(CloseProtocolError, message)
	if len(data) > maxControlFramePayloadSize {
		data = data[:maxControlFramePayloadSize]
	}
	// Make a best effor to send a close message describing the problem.
	_ = c.WriteControl(CloseMessage, data, time.Now().Add(writeWait))
	return errors.New("websocket: " + message)
}

// NextReader returns the next data message received from the peer. The
// returned messageType is either TextMessage or BinaryMessage.
//
// There can be at most one open reader on a connection. NextReader discards
// the previous message if the application has not already consumed it.
//
// Applications must break out of the application's read loop when this method
// returns a non-nil error value. Errors returned from this method are
// permanent. Once this method returns a non-nil error, all subsequent calls to
// this method return the same error.
func (c *Conn) NextReader() (messageType int, r io.Reader, err error) {
	// Close previous reader, only relevant for decompression.
	if c.reader != nil {
		c.reader.Close()
		c.reader = nil
	}

	c.messageReader = nil
	c.readLength = 0

	for c.readErr == nil {
		frameType, err := c.advanceFrame()
		if err != nil {
			c.readErr = err
			break
		}

		if frameType == TextMessage || frameType == BinaryMessage {
			c.messageReader = &messageReader{c}
			c.reader = c.messageReader
			if c.readDecompress {
				c.reader = c.newDecompressionReader(c.reader)
			}
			return frameType, c.reader, nil
		}
	}

	// Applications that do handle the error returned from this method spin in
	// tight loop on connection failure. To help application developers detect
	// this error, panic on repeated reads to the failed connection.
	c.readErrCount++
	if c.readErrCount >= 1000 {
		panic("repeated read on failed websocket connection")
	}

	return noFrame, nil, c.readErr
}

type messageReader struct{ c *Conn }

func (r *messageReader) Read(b []byte) (int, error) {
	c := r.c
	if c.messageReader != r {
		return 0, io.EOF
	}

	for c.readErr == nil {

		if c.readRemaining > 0 {
			if int64(len(b)) > c.readRemaining {
				b = b[:c.readRemaining]
			}
			n, err := c.br.Read(b)
			c.readErr = err
			if c.isServer {
				c.readMaskPos = maskBytes(c.readMaskKey, c.readMaskPos, b[:n])
			}
			rem := c.readRemaining
			rem -= int64(n)
			_ = c.setReadRemaining(rem) // rem is guaranteed to be >= 0
			if c.readRemaining > 0 && c.readErr == io.EOF {
				c.readErr = errUnexpectedEOF
			}
			return n, c.readErr
		}

		if c.readFinal {
			c.messageReader = nil
			return 0, io.EOF
		}

		frameType, err := c.advanceFrame()
		switch {
		case err != nil:
			c.readErr = err
		case frameType == TextMessage || frameType == BinaryMessage:
			c.readErr = errors.New("websocket: internal error, unexpected text or binary in Reader")
		}
	}

	err := c.readErr
	if err == io.EOF && c.messageReader == r {
		err = errUnexpectedEOF
	}
	return 0, err
}

func (r *messageReader) Close() error {
	return nil
}

// ReadMessage is a helper method for getting a reader using NextReader and
// reading from that reader to a buffer.
func (c *Conn) ReadMessage() (messageType int, p []byte, err error) {
	var r io.Reader
	messageType, r, err = c.NextReader()
	if err != nil {
		return messageType, nil, err
	}
	p, err = io.ReadAll(r)
	return messageType, p, err
}

// SetReadDeadline sets the read deadline on the underlying network connection.
// After a read has timed out, the websocket connection state is corrupt and
// all future reads will return an error. A zero value for t means reads will
// not time out.
func (c *Conn) SetReadDeadline(t time.Time) error {
	return c.conn.SetReadDeadline(t)
}

// SetReadLimit sets the maximum size in bytes for a message read from the peer. If a
// message exceeds the limit, the connection sends a close message to the peer
// and returns ErrReadLimit to the application.
func (c *Conn) SetReadLimit(limit int64) {
	c.readLimit = limit
}

// CloseHandler returns the current close handler
func (c *Conn) CloseHandler() func(code int, text string) error {
	return c.handleClose
}

// SetCloseHandler sets the handler for close messages received from the peer.
// The code argument to h is the received close code or CloseNoStatusReceived
// if the close message is empty. The default close handler sends a close
// message back to the peer.
//
// The handler function is called from the NextReader, ReadMessage and message
// reader Read methods. The application must read the connection to process
// close messages as described in the section on Control Messages above.
//
// The connection read methods return a CloseError when a close message is
// received. Most applications should handle close messages as part of their
// normal error handling. Applications should only set a close handler when the
// application must perform some action before sending a close message back to
// the peer.
func (c *Conn) SetCloseHandler(h func(code int, text string) error) {
	if h == nil {
		h = func(code int, text string) error {
			message := FormatCloseMessage(code, "")
			// Make a best effor to send the close message.
			_ = c.WriteControl(CloseMessage, message, time.Now().Add(writeWait))
			return nil
		}
	}
	c.handleClose = h
}

// PingHandler returns the current ping handler
func (c *Conn) PingHandler() func(appData string) error {
	return c.handlePing
}

// SetPingHandler sets the handler for ping messages received from the peer.
// The appData argument to h is the PING message application data. The default
// ping handler sends a pong to the peer.
//
// The handler function is called from the NextReader, ReadMessage and message
// reader Read methods. The application must read the connection to process
// ping messages as described in the section on Control Messages above.
func (c *Conn) SetPingHandler(h func(appData string) error) {
	if h == nil {
		h = func(message string) error {
			// Make a best effort to send the pong message.
			_ = c.WriteControl(PongMessage, []byte(message), time.Now().Add(writeWait))
			return nil
		}
	}
	c.handlePing = h
}

// PongHandler returns the current pong handler
func (c *Conn) PongHandler() func(appData string) error {
	return c.handlePong
}

// SetPongHandler sets the handler for pong messages received from the peer.
// The appData argument to h is the PONG message application data. The default
// pong handler does nothing.
//
// The handler function is called from the NextReader, ReadMessage and message
// reader Read methods. The application must read the connection to process
// pong messages as described in the section on Control Messages above.
func (c *Conn) SetPongHandler(h func(appData string) error) {
	if h == nil {
		h = func(string) error { return nil }
	}
	c.handlePong = h
}

// NetConn returns the underlying connection that is wrapped by c.
// Note that writing to or reading from this connection directly will corrupt the
// WebSocket connection.
func (c *Conn) NetConn() net.Conn {
	return c.conn
}

// UnderlyingConn returns the internal net.Conn. This can be used to further
// modifications to connection specific flags.
// Deprecated: Use the NetConn method.
func (c *Conn) UnderlyingConn() net.Conn {
	return c.conn
}

// EnableWriteCompression enables and disables write compression of
// subsequent text and binary messages. This function is a noop if
// compression was not negotiated with the peer.
func (c *Conn) EnableWriteCompression(enable bool) {
	c.enableWriteCompression = enable
}

// SetCompressionLevel sets the flate compression level for subsequent text and
// binary messages. This function is a noop if compression was not negotiated
// with the peer. See the compress/flate package for a description of
// compression levels.
func (c *Conn) SetCompressionLevel(level int) error {
	if !isValidCompressionLevel(level) {
		return errors.New("websocket: invalid compression level")
	}
	c.compressionLevel = level
	return nil
}

// FormatCloseMessage formats closeCode and text as a WebSocket close message.
// An empty message is returned for code CloseNoStatusReceived.
func FormatCloseMessage(closeCode int, text string) []byte {
	if closeCode == CloseNoStatusReceived {
		// Return empty message because it's illegal to send
		// CloseNoStatusReceived. Return non-nil value in case application
		// checks for nil.
		return []byte{}
	}
	buf := make([]byte, 2+len(text))
	binary.BigEndian.PutUint16(buf, uint16(closeCode))
	copy(buf[2:], text)
	return buf
}


================================================
FILE: conn_broadcast_test.go
================================================
// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"io"
	"sync/atomic"
	"testing"
)

// broadcastBench allows to run broadcast benchmarks.
// In every broadcast benchmark we create many connections, then send the same
// message into every connection and wait for all writes complete. This emulates
// an application where many connections listen to the same data - i.e. PUB/SUB
// scenarios with many subscribers in one channel.
type broadcastBench struct {
	w           io.Writer
	closeCh     chan struct{}
	doneCh      chan struct{}
	count       int32
	conns       []*broadcastConn
	compression bool
	usePrepared bool
}

type broadcastMessage struct {
	payload  []byte
	prepared *PreparedMessage
}

type broadcastConn struct {
	conn  *Conn
	msgCh chan *broadcastMessage
}

func newBroadcastConn(c *Conn) *broadcastConn {
	return &broadcastConn{
		conn:  c,
		msgCh: make(chan *broadcastMessage, 1),
	}
}

func newBroadcastBench(usePrepared, compression bool) *broadcastBench {
	bench := &broadcastBench{
		w:           io.Discard,
		doneCh:      make(chan struct{}),
		closeCh:     make(chan struct{}),
		usePrepared: usePrepared,
		compression: compression,
	}
	bench.makeConns(10000)
	return bench
}

func (b *broadcastBench) makeConns(numConns int) {
	conns := make([]*broadcastConn, numConns)

	for i := 0; i < numConns; i++ {
		c := newTestConn(nil, b.w, true)
		if b.compression {
			c.enableWriteCompression = true
			c.newCompressionWriter = compressNoContextTakeover
		}
		conns[i] = newBroadcastConn(c)
		go func(c *broadcastConn) {
			for {
				select {
				case msg := <-c.msgCh:
					if msg.prepared != nil {
						_ = c.conn.WritePreparedMessage(msg.prepared)
					} else {
						_ = c.conn.WriteMessage(TextMessage, msg.payload)
					}
					val := atomic.AddInt32(&b.count, 1)
					if val%int32(numConns) == 0 {
						b.doneCh <- struct{}{}
					}
				case <-b.closeCh:
					return
				}
			}
		}(conns[i])
	}
	b.conns = conns
}

func (b *broadcastBench) close() {
	close(b.closeCh)
}

func (b *broadcastBench) broadcastOnce(msg *broadcastMessage) {
	for _, c := range b.conns {
		c.msgCh <- msg
	}
	<-b.doneCh
}

func BenchmarkBroadcast(b *testing.B) {
	benchmarks := []struct {
		name        string
		usePrepared bool
		compression bool
	}{
		{"NoCompression", false, false},
		{"Compression", false, true},
		{"NoCompressionPrepared", true, false},
		{"CompressionPrepared", true, true},
	}
	payload := textMessages(1)[0]
	for _, bm := range benchmarks {
		b.Run(bm.name, func(b *testing.B) {
			bench := newBroadcastBench(bm.usePrepared, bm.compression)
			defer bench.close()
			b.ResetTimer()
			for i := 0; i < b.N; i++ {
				message := &broadcastMessage{
					payload: payload,
				}
				if bench.usePrepared {
					pm, _ := NewPreparedMessage(TextMessage, message.payload)
					message.prepared = pm
				}
				bench.broadcastOnce(message)
			}
			b.ReportAllocs()
		})
	}
}


================================================
FILE: conn_test.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"io"
	"net"
	"reflect"
	"sync"
	"testing"
	"testing/iotest"
	"time"
)

var _ net.Error = errWriteTimeout

type fakeNetConn struct {
	io.Reader
	io.Writer
}

func (c fakeNetConn) Close() error                       { return nil }
func (c fakeNetConn) LocalAddr() net.Addr                { return localAddr }
func (c fakeNetConn) RemoteAddr() net.Addr               { return remoteAddr }
func (c fakeNetConn) SetDeadline(t time.Time) error      { return nil }
func (c fakeNetConn) SetReadDeadline(t time.Time) error  { return nil }
func (c fakeNetConn) SetWriteDeadline(t time.Time) error { return nil }

type fakeAddr int

var (
	localAddr  = fakeAddr(1)
	remoteAddr = fakeAddr(2)
)

func (a fakeAddr) Network() string {
	return "net"
}

func (a fakeAddr) String() string {
	return "str"
}

// newTestConn creates a connection backed by a fake network connection using
// default values for buffering.
func newTestConn(r io.Reader, w io.Writer, isServer bool) *Conn {
	return newConn(fakeNetConn{Reader: r, Writer: w}, isServer, 1024, 1024, nil, nil, nil)
}

func TestFraming(t *testing.T) {
	frameSizes := []int{
		0, 1, 2, 124, 125, 126, 127, 128, 129, 65534, 65535,
		// 65536, 65537
	}
	var readChunkers = []struct {
		name string
		f    func(io.Reader) io.Reader
	}{
		{"half", iotest.HalfReader},
		{"one", iotest.OneByteReader},
		{"asis", func(r io.Reader) io.Reader { return r }},
	}
	writeBuf := make([]byte, 65537)
	for i := range writeBuf {
		writeBuf[i] = byte(i)
	}
	var writers = []struct {
		name string
		f    func(w io.Writer, n int) (int, error)
	}{
		{"iocopy", func(w io.Writer, n int) (int, error) {
			nn, err := io.Copy(w, bytes.NewReader(writeBuf[:n]))
			return int(nn), err
		}},
		{"write", func(w io.Writer, n int) (int, error) {
			return w.Write(writeBuf[:n])
		}},
		{"string", func(w io.Writer, n int) (int, error) {
			return io.WriteString(w, string(writeBuf[:n]))
		}},
	}

	for _, compress := range []bool{false, true} {
		for _, isServer := range []bool{true, false} {
			for _, chunker := range readChunkers {

				var connBuf bytes.Buffer
				wc := newTestConn(nil, &connBuf, isServer)
				rc := newTestConn(chunker.f(&connBuf), nil, !isServer)
				if compress {
					wc.newCompressionWriter = compressNoContextTakeover
					rc.newDecompressionReader = decompressNoContextTakeover
				}
				for _, n := range frameSizes {
					for _, writer := range writers {
						name := fmt.Sprintf("z:%v, s:%v, r:%s, n:%d w:%s", compress, isServer, chunker.name, n, writer.name)

						w, err := wc.NextWriter(TextMessage)
						if err != nil {
							t.Errorf("%s: wc.NextWriter() returned %v", name, err)
							continue
						}
						nn, err := writer.f(w, n)
						if err != nil || nn != n {
							t.Errorf("%s: w.Write(writeBuf[:n]) returned %d, %v", name, nn, err)
							continue
						}
						err = w.Close()
						if err != nil {
							t.Errorf("%s: w.Close() returned %v", name, err)
							continue
						}

						opCode, r, err := rc.NextReader()
						if err != nil || opCode != TextMessage {
							t.Errorf("%s: NextReader() returned %d, r, %v", name, opCode, err)
							continue
						}

						t.Logf("frame size: %d", n)
						rbuf, err := io.ReadAll(r)
						if err != nil {
							t.Errorf("%s: ReadFull() returned rbuf, %v", name, err)
							continue
						}

						if len(rbuf) != n {
							t.Errorf("%s: len(rbuf) is %d, want %d", name, len(rbuf), n)
							continue
						}

						for i, b := range rbuf {
							if byte(i) != b {
								t.Errorf("%s: bad byte at offset %d", name, i)
								break
							}
						}
					}
				}
			}
		}
	}
}

func TestWriteControlDeadline(t *testing.T) {
	t.Parallel()
	message := []byte("hello")
	var connBuf bytes.Buffer
	c := newTestConn(nil, &connBuf, true)
	if err := c.WriteControl(PongMessage, message, time.Time{}); err != nil {
		t.Errorf("WriteControl(..., zero deadline) = %v, want nil", err)
	}
	if err := c.WriteControl(PongMessage, message, time.Now().Add(time.Second)); err != nil {
		t.Errorf("WriteControl(..., future deadline) = %v, want nil", err)
	}
	if err := c.WriteControl(PongMessage, message, time.Now().Add(-time.Second)); err == nil {
		t.Errorf("WriteControl(..., past deadline) = nil, want timeout error")
	}
}

func TestConcurrencyWriteControl(t *testing.T) {
	const message = "this is a ping/pong messsage"
	loop := 10
	workers := 10
	for i := 0; i < loop; i++ {
		var connBuf bytes.Buffer

		wg := sync.WaitGroup{}
		wc := newTestConn(nil, &connBuf, true)

		for i := 0; i < workers; i++ {
			wg.Add(1)
			go func() {
				defer wg.Done()
				if err := wc.WriteControl(PongMessage, []byte(message), time.Now().Add(time.Second)); err != nil {
					t.Errorf("concurrently wc.WriteControl() returned %v", err)
				}
			}()
		}

		wg.Wait()
		wc.Close()
	}
}

func TestControl(t *testing.T) {
	const message = "this is a ping/pong message"
	for _, isServer := range []bool{true, false} {
		for _, isWriteControl := range []bool{true, false} {
			name := fmt.Sprintf("s:%v, wc:%v", isServer, isWriteControl)
			var connBuf bytes.Buffer
			wc := newTestConn(nil, &connBuf, isServer)
			rc := newTestConn(&connBuf, nil, !isServer)
			if isWriteControl {
				_ = wc.WriteControl(PongMessage, []byte(message), time.Now().Add(time.Second))
			} else {
				w, err := wc.NextWriter(PongMessage)
				if err != nil {
					t.Errorf("%s: wc.NextWriter() returned %v", name, err)
					continue
				}
				if _, err := w.Write([]byte(message)); err != nil {
					t.Errorf("%s: w.Write() returned %v", name, err)
					continue
				}
				if err := w.Close(); err != nil {
					t.Errorf("%s: w.Close() returned %v", name, err)
					continue
				}
				var actualMessage string
				rc.SetPongHandler(func(s string) error { actualMessage = s; return nil })
				_, _, _ = rc.NextReader()
				if actualMessage != message {
					t.Errorf("%s: pong=%q, want %q", name, actualMessage, message)
					continue
				}
			}
		}
	}
}

// simpleBufferPool is an implementation of BufferPool for TestWriteBufferPool.
type simpleBufferPool struct {
	v interface{}
}

func (p *simpleBufferPool) Get() interface{} {
	v := p.v
	p.v = nil
	return v
}

func (p *simpleBufferPool) Put(v interface{}) {
	p.v = v
}

func TestWriteBufferPool(t *testing.T) {
	const message = "Now is the time for all good people to come to the aid of the party."

	var buf bytes.Buffer
	var pool simpleBufferPool
	rc := newTestConn(&buf, nil, false)

	// Specify writeBufferSize smaller than message size to ensure that pooling
	// works with fragmented messages.
	wc := newConn(fakeNetConn{Writer: &buf}, true, 1024, len(message)-1, &pool, nil, nil)

	if wc.writeBuf != nil {
		t.Fatal("writeBuf not nil after create")
	}

	// Part 1: test NextWriter/Write/Close

	w, err := wc.NextWriter(TextMessage)
	if err != nil {
		t.Fatalf("wc.NextWriter() returned %v", err)
	}

	if wc.writeBuf == nil {
		t.Fatal("writeBuf is nil after NextWriter")
	}

	writeBufAddr := &wc.writeBuf[0]

	if _, err := io.WriteString(w, message); err != nil {
		t.Fatalf("io.WriteString(w, message) returned %v", err)
	}

	if err := w.Close(); err != nil {
		t.Fatalf("w.Close() returned %v", err)
	}

	if wc.writeBuf != nil {
		t.Fatal("writeBuf not nil after w.Close()")
	}

	if wpd, ok := pool.v.(writePoolData); !ok || len(wpd.buf) == 0 || &wpd.buf[0] != writeBufAddr {
		t.Fatal("writeBuf not returned to pool")
	}

	opCode, p, err := rc.ReadMessage()
	if opCode != TextMessage || err != nil {
		t.Fatalf("ReadMessage() returned %d, p, %v", opCode, err)
	}

	if s := string(p); s != message {
		t.Fatalf("message is %s, want %s", s, message)
	}

	// Part 2: Test WriteMessage.

	if err := wc.WriteMessage(TextMessage, []byte(message)); err != nil {
		t.Fatalf("wc.WriteMessage() returned %v", err)
	}

	if wc.writeBuf != nil {
		t.Fatal("writeBuf not nil after wc.WriteMessage()")
	}

	if wpd, ok := pool.v.(writePoolData); !ok || len(wpd.buf) == 0 || &wpd.buf[0] != writeBufAddr {
		t.Fatal("writeBuf not returned to pool after WriteMessage")
	}

	opCode, p, err = rc.ReadMessage()
	if opCode != TextMessage || err != nil {
		t.Fatalf("ReadMessage() returned %d, p, %v", opCode, err)
	}

	if s := string(p); s != message {
		t.Fatalf("message is %s, want %s", s, message)
	}
}

// TestWriteBufferPoolSync ensures that *sync.Pool works as a buffer pool.
func TestWriteBufferPoolSync(t *testing.T) {
	var buf bytes.Buffer
	var pool sync.Pool
	wc := newConn(fakeNetConn{Writer: &buf}, true, 1024, 1024, &pool, nil, nil)
	rc := newTestConn(&buf, nil, false)

	const message = "Hello World!"
	for i := 0; i < 3; i++ {
		if err := wc.WriteMessage(TextMessage, []byte(message)); err != nil {
			t.Fatalf("wc.WriteMessage() returned %v", err)
		}
		opCode, p, err := rc.ReadMessage()
		if opCode != TextMessage || err != nil {
			t.Fatalf("ReadMessage() returned %d, p, %v", opCode, err)
		}
		if s := string(p); s != message {
			t.Fatalf("message is %s, want %s", s, message)
		}
	}
}

// errorWriter is an io.Writer than returns an error on all writes.
type errorWriter struct{}

func (ew errorWriter) Write(p []byte) (int, error) { return 0, errors.New("error") }

// TestWriteBufferPoolError ensures that buffer is returned to pool after error
// on write.
func TestWriteBufferPoolError(t *testing.T) {

	// Part 1: Test NextWriter/Write/Close

	var pool simpleBufferPool
	wc := newConn(fakeNetConn{Writer: errorWriter{}}, true, 1024, 1024, &pool, nil, nil)

	w, err := wc.NextWriter(TextMessage)
	if err != nil {
		t.Fatalf("wc.NextWriter() returned %v", err)
	}

	if wc.writeBuf == nil {
		t.Fatal("writeBuf is nil after NextWriter")
	}

	writeBufAddr := &wc.writeBuf[0]

	if _, err := io.WriteString(w, "Hello"); err != nil {
		t.Fatalf("io.WriteString(w, message) returned %v", err)
	}

	if err := w.Close(); err == nil {
		t.Fatalf("w.Close() did not return error")
	}

	if wpd, ok := pool.v.(writePoolData); !ok || len(wpd.buf) == 0 || &wpd.buf[0] != writeBufAddr {
		t.Fatal("writeBuf not returned to pool")
	}

	// Part 2: Test WriteMessage

	wc = newConn(fakeNetConn{Writer: errorWriter{}}, true, 1024, 1024, &pool, nil, nil)

	if err := wc.WriteMessage(TextMessage, []byte("Hello")); err == nil {
		t.Fatalf("wc.WriteMessage did not return error")
	}

	if wpd, ok := pool.v.(writePoolData); !ok || len(wpd.buf) == 0 || &wpd.buf[0] != writeBufAddr {
		t.Fatal("writeBuf not returned to pool")
	}
}

func TestCloseFrameBeforeFinalMessageFrame(t *testing.T) {
	const bufSize = 512

	expectedErr := &CloseError{Code: CloseNormalClosure, Text: "hello"}

	var b1, b2 bytes.Buffer
	wc := newConn(&fakeNetConn{Reader: nil, Writer: &b1}, false, 1024, bufSize, nil, nil, nil)
	rc := newTestConn(&b1, &b2, true)

	w, _ := wc.NextWriter(BinaryMessage)
	_, _ = w.Write(make([]byte, bufSize+bufSize/2))
	_ = wc.WriteControl(CloseMessage, FormatCloseMessage(expectedErr.Code, expectedErr.Text), time.Now().Add(10*time.Second))
	w.Close()

	op, r, err := rc.NextReader()
	if op != BinaryMessage || err != nil {
		t.Fatalf("NextReader() returned %d, %v", op, err)
	}
	_, err = io.Copy(io.Discard, r)
	if !reflect.DeepEqual(err, expectedErr) {
		t.Fatalf("io.Copy() returned %v, want %v", err, expectedErr)
	}
	_, _, err = rc.NextReader()
	if !reflect.DeepEqual(err, expectedErr) {
		t.Fatalf("NextReader() returned %v, want %v", err, expectedErr)
	}
}

func TestEOFWithinFrame(t *testing.T) {
	const bufSize = 64

	for n := 0; ; n++ {
		var b bytes.Buffer
		wc := newTestConn(nil, &b, false)
		rc := newTestConn(&b, nil, true)

		w, _ := wc.NextWriter(BinaryMessage)
		_, _ = w.Write(make([]byte, bufSize))
		w.Close()

		if n >= b.Len() {
			break
		}
		b.Truncate(n)

		op, r, err := rc.NextReader()
		if err == errUnexpectedEOF {
			continue
		}
		if op != BinaryMessage || err != nil {
			t.Fatalf("%d: NextReader() returned %d, %v", n, op, err)
		}
		_, err = io.Copy(io.Discard, r)
		if err != errUnexpectedEOF {
			t.Fatalf("%d: io.Copy() returned %v, want %v", n, err, errUnexpectedEOF)
		}
		_, _, err = rc.NextReader()
		if err != errUnexpectedEOF {
			t.Fatalf("%d: NextReader() returned %v, want %v", n, err, errUnexpectedEOF)
		}
	}
}

func TestEOFBeforeFinalFrame(t *testing.T) {
	const bufSize = 512

	var b1, b2 bytes.Buffer
	wc := newConn(&fakeNetConn{Writer: &b1}, false, 1024, bufSize, nil, nil, nil)
	rc := newTestConn(&b1, &b2, true)

	w, _ := wc.NextWriter(BinaryMessage)
	_, _ = w.Write(make([]byte, bufSize+bufSize/2))

	op, r, err := rc.NextReader()
	if op != BinaryMessage || err != nil {
		t.Fatalf("NextReader() returned %d, %v", op, err)
	}
	_, err = io.Copy(io.Discard, r)
	if err != errUnexpectedEOF {
		t.Fatalf("io.Copy() returned %v, want %v", err, errUnexpectedEOF)
	}
	_, _, err = rc.NextReader()
	if err != errUnexpectedEOF {
		t.Fatalf("NextReader() returned %v, want %v", err, errUnexpectedEOF)
	}
}

func TestWriteAfterMessageWriterClose(t *testing.T) {
	wc := newTestConn(nil, &bytes.Buffer{}, false)
	w, _ := wc.NextWriter(BinaryMessage)
	_, _ = io.WriteString(w, "hello")
	if err := w.Close(); err != nil {
		t.Fatalf("unexpected error closing message writer, %v", err)
	}

	if _, err := io.WriteString(w, "world"); err == nil {
		t.Fatalf("no error writing after close")
	}

	w, _ = wc.NextWriter(BinaryMessage)
	_, _ = io.WriteString(w, "hello")

	// close w by getting next writer
	_, err := wc.NextWriter(BinaryMessage)
	if err != nil {
		t.Fatalf("unexpected error getting next writer, %v", err)
	}

	if _, err := io.WriteString(w, "world"); err == nil {
		t.Fatalf("no error writing after close")
	}
}

func TestReadLimit(t *testing.T) {
	t.Run("Test ReadLimit is enforced", func(t *testing.T) {
		const readLimit = 512
		message := make([]byte, readLimit+1)

		var b1, b2 bytes.Buffer
		wc := newConn(&fakeNetConn{Writer: &b1}, false, 1024, readLimit-2, nil, nil, nil)
		rc := newTestConn(&b1, &b2, true)
		rc.SetReadLimit(readLimit)

		// Send message at the limit with interleaved pong.
		w, _ := wc.NextWriter(BinaryMessage)
		_, _ = w.Write(message[:readLimit-1])
		_ = wc.WriteControl(PongMessage, []byte("this is a pong"), time.Now().Add(10*time.Second))
		_, _ = w.Write(message[:1])
		w.Close()

		// Send message larger than the limit.
		_ = wc.WriteMessage(BinaryMessage, message[:readLimit+1])

		op, _, err := rc.NextReader()
		if op != BinaryMessage || err != nil {
			t.Fatalf("1: NextReader() returned %d, %v", op, err)
		}
		op, r, err := rc.NextReader()
		if op != BinaryMessage || err != nil {
			t.Fatalf("2: NextReader() returned %d, %v", op, err)
		}
		_, err = io.Copy(io.Discard, r)
		if err != ErrReadLimit {
			t.Fatalf("io.Copy() returned %v", err)
		}
	})

	t.Run("Test that ReadLimit cannot be overflowed", func(t *testing.T) {
		const readLimit = 1

		var b1, b2 bytes.Buffer
		rc := newTestConn(&b1, &b2, true)
		rc.SetReadLimit(readLimit)

		// First, send a non-final binary message
		b1.Write([]byte("\x02\x81"))

		// Mask key
		b1.Write([]byte("\x00\x00\x00\x00"))

		// First payload
		b1.Write([]byte("A"))

		// Next, send a negative-length, non-final continuation frame
		b1.Write([]byte("\x00\xFF\x80\x00\x00\x00\x00\x00\x00\x00"))

		// Mask key
		b1.Write([]byte("\x00\x00\x00\x00"))

		// Next, send a too long, final continuation frame
		b1.Write([]byte("\x80\xFF\x00\x00\x00\x00\x00\x00\x00\x05"))

		// Mask key
		b1.Write([]byte("\x00\x00\x00\x00"))

		// Too-long payload
		b1.Write([]byte("BCDEF"))

		op, r, err := rc.NextReader()
		if op != BinaryMessage || err != nil {
			t.Fatalf("1: NextReader() returned %d, %v", op, err)
		}

		var buf [10]byte
		var read int
		n, err := r.Read(buf[:])
		if err != nil && err != ErrReadLimit {
			t.Fatalf("unexpected error testing read limit: %v", err)
		}
		read += n

		n, err = r.Read(buf[:])
		if err != nil && err != ErrReadLimit {
			t.Fatalf("unexpected error testing read limit: %v", err)
		}
		read += n

		if err == nil && read > readLimit {
			t.Fatalf("read limit exceeded: limit %d, read %d", readLimit, read)
		}
	})
}

func TestAddrs(t *testing.T) {
	c := newTestConn(nil, nil, true)
	if c.LocalAddr() != localAddr {
		t.Errorf("LocalAddr = %v, want %v", c.LocalAddr(), localAddr)
	}
	if c.RemoteAddr() != remoteAddr {
		t.Errorf("RemoteAddr = %v, want %v", c.RemoteAddr(), remoteAddr)
	}
}

func TestDeprecatedUnderlyingConn(t *testing.T) {
	var b1, b2 bytes.Buffer
	fc := fakeNetConn{Reader: &b1, Writer: &b2}
	c := newConn(fc, true, 1024, 1024, nil, nil, nil)
	ul := c.UnderlyingConn()
	if ul != fc {
		t.Fatalf("Underlying conn is not what it should be.")
	}
}

func TestNetConn(t *testing.T) {
	var b1, b2 bytes.Buffer
	fc := fakeNetConn{Reader: &b1, Writer: &b2}
	c := newConn(fc, true, 1024, 1024, nil, nil, nil)
	ul := c.NetConn()
	if ul != fc {
		t.Fatalf("Underlying conn is not what it should be.")
	}
}

func TestBufioReadBytes(t *testing.T) {
	// Test calling bufio.ReadBytes for value longer than read buffer size.

	m := make([]byte, 512)
	m[len(m)-1] = '\n'

	var b1, b2 bytes.Buffer
	wc := newConn(fakeNetConn{Writer: &b1}, false, len(m)+64, len(m)+64, nil, nil, nil)
	rc := newConn(fakeNetConn{Reader: &b1, Writer: &b2}, true, len(m)-64, len(m)-64, nil, nil, nil)

	w, _ := wc.NextWriter(BinaryMessage)
	_, _ = w.Write(m)
	w.Close()

	op, r, err := rc.NextReader()
	if op != BinaryMessage || err != nil {
		t.Fatalf("NextReader() returned %d, %v", op, err)
	}

	br := bufio.NewReader(r)
	p, err := br.ReadBytes('\n')
	if err != nil {
		t.Fatalf("ReadBytes() returned %v", err)
	}
	if len(p) != len(m) {
		t.Fatalf("read returned %d bytes, want %d bytes", len(p), len(m))
	}
}

var closeErrorTests = []struct {
	err   error
	codes []int
	ok    bool
}{
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNormalClosure}, true},
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNoStatusReceived}, false},
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNoStatusReceived, CloseNormalClosure}, true},
	{errors.New("hello"), []int{CloseNormalClosure}, false},
}

func TestCloseError(t *testing.T) {
	for _, tt := range closeErrorTests {
		ok := IsCloseError(tt.err, tt.codes...)
		if ok != tt.ok {
			t.Errorf("IsCloseError(%#v, %#v) returned %v, want %v", tt.err, tt.codes, ok, tt.ok)
		}
	}
}

var unexpectedCloseErrorTests = []struct {
	err   error
	codes []int
	ok    bool
}{
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNormalClosure}, false},
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNoStatusReceived}, true},
	{&CloseError{Code: CloseNormalClosure}, []int{CloseNoStatusReceived, CloseNormalClosure}, false},
	{errors.New("hello"), []int{CloseNormalClosure}, false},
}

func TestUnexpectedCloseErrors(t *testing.T) {
	for _, tt := range unexpectedCloseErrorTests {
		ok := IsUnexpectedCloseError(tt.err, tt.codes...)
		if ok != tt.ok {
			t.Errorf("IsUnexpectedCloseError(%#v, %#v) returned %v, want %v", tt.err, tt.codes, ok, tt.ok)
		}
	}
}

type blockingWriter struct {
	c1, c2 chan struct{}
}

func (w blockingWriter) Write(p []byte) (int, error) {
	// Allow main to continue
	close(w.c1)
	// Wait for panic in main
	<-w.c2
	return len(p), nil
}

func TestConcurrentWritePanic(t *testing.T) {
	w := blockingWriter{make(chan struct{}), make(chan struct{})}
	c := newTestConn(nil, w, false)
	go func() {
		_ = c.WriteMessage(TextMessage, []byte{})
	}()

	// wait for goroutine to block in write.
	<-w.c1

	defer func() {
		close(w.c2)
		if v := recover(); v != nil {
			return
		}
	}()

	_ = c.WriteMessage(TextMessage, []byte{})
	t.Fatal("should not get here")
}

type failingReader struct{}

func (r failingReader) Read(p []byte) (int, error) {
	return 0, io.EOF
}

func TestFailedConnectionReadPanic(t *testing.T) {
	c := newTestConn(failingReader{}, nil, false)

	defer func() {
		if v := recover(); v != nil {
			return
		}
	}()

	for i := 0; i < 20000; i++ {
		_, _, _ = c.ReadMessage()
	}
	t.Fatal("should not get here")
}


================================================
FILE: doc.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package websocket implements the WebSocket protocol defined in RFC 6455.
//
// Overview
//
// The Conn type represents a WebSocket connection. A server application calls
// the Upgrader.Upgrade method from an HTTP request handler to get a *Conn:
//
//  var upgrader = websocket.Upgrader{
//      ReadBufferSize:  1024,
//      WriteBufferSize: 1024,
//  }
//
//  func handler(w http.ResponseWriter, r *http.Request) {
//      conn, err := upgrader.Upgrade(w, r, nil)
//      if err != nil {
//          log.Println(err)
//          return
//      }
//      ... Use conn to send and receive messages.
//  }
//
// Call the connection's WriteMessage and ReadMessage methods to send and
// receive messages as a slice of bytes. This snippet of code shows how to echo
// messages using these methods:
//
//  for {
//      messageType, p, err := conn.ReadMessage()
//      if err != nil {
//          log.Println(err)
//          return
//      }
//      if err := conn.WriteMessage(messageType, p); err != nil {
//          log.Println(err)
//          return
//      }
//  }
//
// In above snippet of code, p is a []byte and messageType is an int with value
// websocket.BinaryMessage or websocket.TextMessage.
//
// An application can also send and receive messages using the io.WriteCloser
// and io.Reader interfaces. To send a message, call the connection NextWriter
// method to get an io.WriteCloser, write the message to the writer and close
// the writer when done. To receive a message, call the connection NextReader
// method to get an io.Reader and read until io.EOF is returned. This snippet
// shows how to echo messages using the NextWriter and NextReader methods:
//
//  for {
//      messageType, r, err := conn.NextReader()
//      if err != nil {
//          return
//      }
//      w, err := conn.NextWriter(messageType)
//      if err != nil {
//          return err
//      }
//      if _, err := io.Copy(w, r); err != nil {
//          return err
//      }
//      if err := w.Close(); err != nil {
//          return err
//      }
//  }
//
// Data Messages
//
// The WebSocket protocol distinguishes between text and binary data messages.
// Text messages are interpreted as UTF-8 encoded text. The interpretation of
// binary messages is left to the application.
//
// This package uses the TextMessage and BinaryMessage integer constants to
// identify the two data message types. The ReadMessage and NextReader methods
// return the type of the received message. The messageType argument to the
// WriteMessage and NextWriter methods specifies the type of a sent message.
//
// It is the application's responsibility to ensure that text messages are
// valid UTF-8 encoded text.
//
// Control Messages
//
// The WebSocket protocol defines three types of control messages: close, ping
// and pong. Call the connection WriteControl, WriteMessage or NextWriter
// methods to send a control message to the peer.
//
// Connections handle received close messages by calling the handler function
// set with the SetCloseHandler method and by returning a *CloseError from the
// NextReader, ReadMessage or the message Read method. The default close
// handler sends a close message to the peer.
//
// Connections handle received ping messages by calling the handler function
// set with the SetPingHandler method. The default ping handler sends a pong
// message to the peer.
//
// Connections handle received pong messages by calling the handler function
// set with the SetPongHandler method. The default pong handler does nothing.
// If an application sends ping messages, then the application should set a
// pong handler to receive the corresponding pong.
//
// The control message handler functions are called from the NextReader,
// ReadMessage and message reader Read methods. The default close and ping
// handlers can block these methods for a short time when the handler writes to
// the connection.
//
// The application must read the connection to process close, ping and pong
// messages sent from the peer. If the application is not otherwise interested
// in messages from the peer, then the application should start a goroutine to
// read and discard messages from the peer. A simple example is:
//
//  func readLoop(c *websocket.Conn) {
//      for {
//          if _, _, err := c.NextReader(); err != nil {
//              c.Close()
//              break
//          }
//      }
//  }
//
// Concurrency
//
// Connections support one concurrent reader and one concurrent writer.
//
// Applications are responsible for ensuring that no more than one goroutine
// calls the write methods (NextWriter, SetWriteDeadline, WriteMessage,
// WriteJSON, EnableWriteCompression, SetCompressionLevel) concurrently and
// that no more than one goroutine calls the read methods (NextReader,
// SetReadDeadline, ReadMessage, ReadJSON, SetPongHandler, SetPingHandler)
// concurrently.
//
// The Close and WriteControl methods can be called concurrently with all other
// methods.
//
// Origin Considerations
//
// Web browsers allow Javascript applications to open a WebSocket connection to
// any host. It's up to the server to enforce an origin policy using the Origin
// request header sent by the browser.
//
// The Upgrader calls the function specified in the CheckOrigin field to check
// the origin. If the CheckOrigin function returns false, then the Upgrade
// method fails the WebSocket handshake with HTTP status 403.
//
// If the CheckOrigin field is nil, then the Upgrader uses a safe default: fail
// the handshake if the Origin request header is present and the Origin host is
// not equal to the Host request header.
//
// The deprecated package-level Upgrade function does not perform origin
// checking. The application is responsible for checking the Origin header
// before calling the Upgrade function.
//
// Buffers
//
// Connections buffer network input and output to reduce the number
// of system calls when reading or writing messages.
//
// Write buffers are also used for constructing WebSocket frames. See RFC 6455,
// Section 5 for a discussion of message framing. A WebSocket frame header is
// written to the network each time a write buffer is flushed to the network.
// Decreasing the size of the write buffer can increase the amount of framing
// overhead on the connection.
//
// The buffer sizes in bytes are specified by the ReadBufferSize and
// WriteBufferSize fields in the Dialer and Upgrader. The Dialer uses a default
// size of 4096 when a buffer size field is set to zero. The Upgrader reuses
// buffers created by the HTTP server when a buffer size field is set to zero.
// The HTTP server buffers have a size of 4096 at the time of this writing.
//
// The buffer sizes do not limit the size of a message that can be read or
// written by a connection.
//
// Buffers are held for the lifetime of the connection by default. If the
// Dialer or Upgrader WriteBufferPool field is set, then a connection holds the
// write buffer only when writing a message.
//
// Applications should tune the buffer sizes to balance memory use and
// performance. Increasing the buffer size uses more memory, but can reduce the
// number of system calls to read or write the network. In the case of writing,
// increasing the buffer size can reduce the number of frame headers written to
// the network.
//
// Some guidelines for setting buffer parameters are:
//
// Limit the buffer sizes to the maximum expected message size. Buffers larger
// than the largest message do not provide any benefit.
//
// Depending on the distribution of message sizes, setting the buffer size to
// a value less than the maximum expected message size can greatly reduce memory
// use with a small impact on performance. Here's an example: If 99% of the
// messages are smaller than 256 bytes and the maximum message size is 512
// bytes, then a buffer size of 256 bytes will result in 1.01 more system calls
// than a buffer size of 512 bytes. The memory savings is 50%.
//
// A write buffer pool is useful when the application has a modest number
// writes over a large number of connections. when buffers are pooled, a larger
// buffer size has a reduced impact on total memory use and has the benefit of
// reducing system calls and frame overhead.
//
// Compression EXPERIMENTAL
//
// Per message compression extensions (RFC 7692) are experimentally supported
// by this package in a limited capacity. Setting the EnableCompression option
// to true in Dialer or Upgrader will attempt to negotiate per message deflate
// support.
//
//  var upgrader = websocket.Upgrader{
//      EnableCompression: true,
//  }
//
// If compression was successfully negotiated with the connection's peer, any
// message received in compressed form will be automatically decompressed.
// All Read methods will return uncompressed bytes.
//
// Per message compression of messages written to a connection can be enabled
// or disabled by calling the corresponding Conn method:
//
//  conn.EnableWriteCompression(false)
//
// Currently this package does not support compression with "context takeover".
// This means that messages must be compressed and decompressed in isolation,
// without retaining sliding window or dictionary state across messages. For
// more details refer to RFC 7692.
//
// Use of compression is experimental and may result in decreased performance.
package websocket


================================================
FILE: example_test.go
================================================
// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket_test

import (
	"log"
	"net/http"
	"testing"

	"github.com/gorilla/websocket"
)

var (
	c   *websocket.Conn
	req *http.Request
)

// The websocket.IsUnexpectedCloseError function is useful for identifying
// application and protocol errors.
//
// This server application works with a client application running in the
// browser. The client application does not explicitly close the websocket. The
// only expected close message from the client has the code
// websocket.CloseGoingAway. All other close messages are likely the
// result of an application or protocol error and are logged to aid debugging.
func ExampleIsUnexpectedCloseError() {
	for {
		messageType, p, err := c.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway) {
				log.Printf("error: %v, user-agent: %v", err, req.Header.Get("User-Agent"))
			}
			return
		}
		processMessage(messageType, p)
	}
}

func processMessage(mt int, p []byte) {}

// TestX prevents godoc from showing this entire file in the example. Remove
// this function when a second example is added.
func TestX(t *testing.T) {}


================================================
FILE: examples/autobahn/README.md
================================================
# Test Server

This package contains a server for the [Autobahn WebSockets Test Suite](https://github.com/crossbario/autobahn-testsuite).

To test the server, run

    go run server.go

and start the client test driver

    mkdir -p reports
    docker run -it --rm \
        -v ${PWD}/config:/config \
        -v ${PWD}/reports:/reports \
        crossbario/autobahn-testsuite \
        wstest -m fuzzingclient -s /config/fuzzingclient.json

When the client completes, it writes a report to reports/index.html.


================================================
FILE: examples/autobahn/config/fuzzingclient.json
================================================
{
  "cases": ["*"],
  "exclude-cases": [],
  "exclude-agent-cases": {},
  "outdir": "/reports",
  "options": {"failByDrop": false},
  "servers": [
    {
      "agent": "ReadAllWriteMessage",
      "url": "ws://host.docker.internal:9000/m"
    },
    {
      "agent": "ReadAllWritePreparedMessage",
      "url": "ws://host.docker.internal:9000/p"
    },
    {
      "agent": "CopyFull",
      "url": "ws://host.docker.internal:9000/f"
    },
    {
      "agent": "ReadAllWrite",
      "url": "ws://host.docker.internal:9000/r"
    },
    {
      "agent": "CopyWriterOnly",
      "url": "ws://host.docker.internal:9000/c"
    }
  ]
}


================================================
FILE: examples/autobahn/server.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Command server is a test server for the Autobahn WebSockets Test Suite.
package main

import (
	"errors"
	"flag"
	"io"
	"log"
	"net/http"
	"time"
	"unicode/utf8"

	"github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:    4096,
	WriteBufferSize:   4096,
	EnableCompression: true,
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
}

// echoCopy echoes messages from the client using io.Copy.
func echoCopy(w http.ResponseWriter, r *http.Request, writerOnly bool) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println("Upgrade:", err)
		return
	}
	defer conn.Close()
	for {
		mt, r, err := conn.NextReader()
		if err != nil {
			if err != io.EOF {
				log.Println("NextReader:", err)
			}
			return
		}
		if mt == websocket.TextMessage {
			r = &validator{r: r}
		}
		w, err := conn.NextWriter(mt)
		if err != nil {
			log.Println("NextWriter:", err)
			return
		}
		if mt == websocket.TextMessage {
			r = &validator{r: r}
		}
		if writerOnly {
			_, err = io.Copy(struct{ io.Writer }{w}, r)
		} else {
			_, err = io.Copy(w, r)
		}
		if err != nil {
			if err == errInvalidUTF8 {
				conn.WriteControl(websocket.CloseMessage,
					websocket.FormatCloseMessage(websocket.CloseInvalidFramePayloadData, ""),
					time.Time{})
			}
			log.Println("Copy:", err)
			return
		}
		err = w.Close()
		if err != nil {
			log.Println("Close:", err)
			return
		}
	}
}

func echoCopyWriterOnly(w http.ResponseWriter, r *http.Request) {
	echoCopy(w, r, true)
}

func echoCopyFull(w http.ResponseWriter, r *http.Request) {
	echoCopy(w, r, false)
}

// echoReadAll echoes messages from the client by reading the entire message
// with io.ReadAll.
func echoReadAll(w http.ResponseWriter, r *http.Request, writeMessage, writePrepared bool) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println("Upgrade:", err)
		return
	}
	defer conn.Close()
	for {
		mt, b, err := conn.ReadMessage()
		if err != nil {
			if err != io.EOF {
				log.Println("NextReader:", err)
			}
			return
		}
		if mt == websocket.TextMessage {
			if !utf8.Valid(b) {
				conn.WriteControl(websocket.CloseMessage,
					websocket.FormatCloseMessage(websocket.CloseInvalidFramePayloadData, ""),
					time.Time{})
				log.Println("ReadAll: invalid utf8")
			}
		}
		if writeMessage {
			if !writePrepared {
				err = conn.WriteMessage(mt, b)
				if err != nil {
					log.Println("WriteMessage:", err)
				}
			} else {
				pm, err := websocket.NewPreparedMessage(mt, b)
				if err != nil {
					log.Println("NewPreparedMessage:", err)
					return
				}
				err = conn.WritePreparedMessage(pm)
				if err != nil {
					log.Println("WritePreparedMessage:", err)
				}
			}
		} else {
			w, err := conn.NextWriter(mt)
			if err != nil {
				log.Println("NextWriter:", err)
				return
			}
			if _, err := w.Write(b); err != nil {
				log.Println("Writer:", err)
				return
			}
			if err := w.Close(); err != nil {
				log.Println("Close:", err)
				return
			}
		}
	}
}

func echoReadAllWriter(w http.ResponseWriter, r *http.Request) {
	echoReadAll(w, r, false, false)
}

func echoReadAllWriteMessage(w http.ResponseWriter, r *http.Request) {
	echoReadAll(w, r, true, false)
}

func echoReadAllWritePreparedMessage(w http.ResponseWriter, r *http.Request) {
	echoReadAll(w, r, true, true)
}

func serveHome(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.Error(w, "Not found.", http.StatusNotFound)
		return
	}
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	io.WriteString(w, "<html><body>Echo Server</body></html>")
}

var addr = flag.String("addr", ":9000", "http service address")

func main() {
	flag.Parse()
	http.HandleFunc("/", serveHome)
	http.HandleFunc("/c", echoCopyWriterOnly)
	http.HandleFunc("/f", echoCopyFull)
	http.HandleFunc("/r", echoReadAllWriter)
	http.HandleFunc("/m", echoReadAllWriteMessage)
	http.HandleFunc("/p", echoReadAllWritePreparedMessage)
	err := http.ListenAndServe(*addr, nil)
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}

type validator struct {
	state int
	x     rune
	r     io.Reader
}

var errInvalidUTF8 = errors.New("invalid utf8")

func (r *validator) Read(p []byte) (int, error) {
	n, err := r.r.Read(p)
	state := r.state
	x := r.x
	for _, b := range p[:n] {
		state, x = decode(state, x, b)
		if state == utf8Reject {
			break
		}
	}
	r.state = state
	r.x = x
	if state == utf8Reject || (err == io.EOF && state != utf8Accept) {
		return n, errInvalidUTF8
	}
	return n, err
}

// UTF-8 decoder from http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
//
// Copyright (c) 2008-2009 Bjoern Hoehrmann <bjoern@hoehrmann.de>
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
var utf8d = [...]byte{
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 00..1f
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 20..3f
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 40..5f
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 60..7f
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, // 80..9f
	7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, // a0..bf
	8, 8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, // c0..df
	0xa, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x3, 0x4, 0x3, 0x3, // e0..ef
	0xb, 0x6, 0x6, 0x6, 0x5, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, 0x8, // f0..ff
	0x0, 0x1, 0x2, 0x3, 0x5, 0x8, 0x7, 0x1, 0x1, 0x1, 0x4, 0x6, 0x1, 0x1, 0x1, 0x1, // s0..s0
	1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 1, 1, 1, 1, // s1..s2
	1, 2, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, // s3..s4
	1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, // s5..s6
	1, 3, 1, 1, 1, 1, 1, 3, 1, 3, 1, 1, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, // s7..s8
}

const (
	utf8Accept = 0
	utf8Reject = 1
)

func decode(state int, x rune, b byte) (int, rune) {
	t := utf8d[b]
	if state != utf8Accept {
		x = rune(b&0x3f) | (x << 6)
	} else {
		x = rune((0xff >> t) & b)
	}
	state = int(utf8d[256+state*16+int(t)])
	return state, x
}


================================================
FILE: examples/chat/README.md
================================================
# Chat Example

This application shows how to use the
[websocket](https://github.com/gorilla/websocket) package to implement a simple
web chat application.

## Running the example

The example requires a working Go development environment. The [Getting
Started](http://golang.org/doc/install) page describes how to install the
development environment.

Once you have Go up and running, you can download, build and run the example
using the following commands.

    $ go get github.com/gorilla/websocket
    $ cd `go list -f '{{.Dir}}' github.com/gorilla/websocket/examples/chat`
    $ go run *.go

To use the chat example, open http://localhost:8080/ in your browser.

## Server

The server application defines two types, `Client` and `Hub`. The server
creates an instance of the `Client` type for each websocket connection. A
`Client` acts as an intermediary between the websocket connection and a single
instance of the `Hub` type. The `Hub` maintains a set of registered clients and
broadcasts messages to the clients.

The application runs one goroutine for the `Hub` and two goroutines for each
`Client`. The goroutines communicate with each other using channels. The `Hub`
has channels for registering clients, unregistering clients and broadcasting
messages. A `Client` has a buffered channel of outbound messages. One of the
client's goroutines reads messages from this channel and writes the messages to
the websocket. The other client goroutine reads messages from the websocket and
sends them to the hub.

### Hub 

The code for the `Hub` type is in
[hub.go](https://github.com/gorilla/websocket/blob/main/examples/chat/hub.go).
The application's `main` function starts the hub's `run` method as a goroutine.
Clients send requests to the hub using the `register`, `unregister` and
`broadcast` channels.

The hub registers clients by adding the client pointer as a key in the
`clients` map. The map value is always true.

The unregister code is a little more complicated. In addition to deleting the
client pointer from the `clients` map, the hub closes the clients's `send`
channel to signal the client that no more messages will be sent to the client.

The hub handles messages by looping over the registered clients and sending the
message to the client's `send` channel. If the client's `send` buffer is full,
then the hub assumes that the client is dead or stuck. In this case, the hub
unregisters the client and closes the websocket.

### Client

The code for the `Client` type is in [client.go](https://github.com/gorilla/websocket/blob/main/examples/chat/client.go).

The `serveWs` function is registered by the application's `main` function as
an HTTP handler. The handler upgrades the HTTP connection to the WebSocket
protocol, creates a client, registers the client with the hub and schedules the
client to be unregistered using a defer statement.

Next, the HTTP handler starts the client's `writePump` method as a goroutine.
This method transfers messages from the client's send channel to the websocket
connection. The writer method exits when the channel is closed by the hub or
there's an error writing to the websocket connection.

Finally, the HTTP handler calls the client's `readPump` method. This method
transfers inbound messages from the websocket to the hub.

WebSocket connections [support one concurrent reader and one concurrent
writer](https://godoc.org/github.com/gorilla/websocket#hdr-Concurrency). The
application ensures that these concurrency requirements are met by executing
all reads from the `readPump` goroutine and all writes from the `writePump`
goroutine.

To improve efficiency under high load, the `writePump` function coalesces
pending chat messages in the `send` channel to a single WebSocket message. This
reduces the number of system calls and the amount of data sent over the
network.

## Frontend

The frontend code is in [home.html](https://github.com/gorilla/websocket/blob/main/examples/chat/home.html).

On document load, the script checks for websocket functionality in the browser.
If websocket functionality is available, then the script opens a connection to
the server and registers a callback to handle messages from the server. The
callback appends the message to the chat log using the appendLog function.

To allow the user to manually scroll through the chat log without interruption
from new messages, the `appendLog` function checks the scroll position before
adding new content. If the chat log is scrolled to the bottom, then the
function scrolls new content into view after adding the content. Otherwise, the
scroll position is not changed.

The form handler writes the user input to the websocket and clears the input
field.


================================================
FILE: examples/chat/client.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"log"
	"net/http"
	"time"

	"github.com/gorilla/websocket"
)

const (
	// Time allowed to write a message to the peer.
	writeWait = 10 * time.Second

	// Time allowed to read the next pong message from the peer.
	pongWait = 60 * time.Second

	// Send pings to peer with this period. Must be less than pongWait.
	pingPeriod = (pongWait * 9) / 10

	// Maximum message size allowed from peer.
	maxMessageSize = 512
)

var (
	newline = []byte{'\n'}
	space   = []byte{' '}
)

var upgrader = websocket.Upgrader{
	ReadBufferSize:  1024,
	WriteBufferSize: 1024,
}

// Client is a middleman between the websocket connection and the hub.
type Client struct {
	hub *Hub

	// The websocket connection.
	conn *websocket.Conn

	// Buffered channel of outbound messages.
	send chan []byte
}

// readPump pumps messages from the websocket connection to the hub.
//
// The application runs readPump in a per-connection goroutine. The application
// ensures that there is at most one reader on a connection by executing all
// reads from this goroutine.
func (c *Client) readPump() {
	defer func() {
		c.hub.unregister <- c
		c.conn.Close()
	}()
	c.conn.SetReadLimit(maxMessageSize)
	c.conn.SetReadDeadline(time.Now().Add(pongWait))
	c.conn.SetPongHandler(func(string) error { c.conn.SetReadDeadline(time.Now().Add(pongWait)); return nil })
	for {
		_, message, err := c.conn.ReadMessage()
		if err != nil {
			if websocket.IsUnexpectedCloseError(err, websocket.CloseGoingAway, websocket.CloseAbnormalClosure) {
				log.Printf("error: %v", err)
			}
			break
		}
		message = bytes.TrimSpace(bytes.Replace(message, newline, space, -1))
		c.hub.broadcast <- message
	}
}

// writePump pumps messages from the hub to the websocket connection.
//
// A goroutine running writePump is started for each connection. The
// application ensures that there is at most one writer to a connection by
// executing all writes from this goroutine.
func (c *Client) writePump() {
	ticker := time.NewTicker(pingPeriod)
	defer func() {
		ticker.Stop()
		c.conn.Close()
	}()
	for {
		select {
		case message, ok := <-c.send:
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if !ok {
				// The hub closed the channel.
				c.conn.WriteMessage(websocket.CloseMessage, []byte{})
				return
			}

			w, err := c.conn.NextWriter(websocket.TextMessage)
			if err != nil {
				return
			}
			w.Write(message)

			// Add queued chat messages to the current websocket message.
			n := len(c.send)
			for i := 0; i < n; i++ {
				w.Write(newline)
				w.Write(<-c.send)
			}

			if err := w.Close(); err != nil {
				return
			}
		case <-ticker.C:
			c.conn.SetWriteDeadline(time.Now().Add(writeWait))
			if err := c.conn.WriteMessage(websocket.PingMessage, nil); err != nil {
				return
			}
		}
	}
}

// serveWs handles websocket requests from the peer.
func serveWs(hub *Hub, w http.ResponseWriter, r *http.Request) {
	conn, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println(err)
		return
	}
	client := &Client{hub: hub, conn: conn, send: make(chan []byte, 256)}
	client.hub.register <- client

	// Allow collection of memory referenced by the caller by doing all work in
	// new goroutines.
	go client.writePump()
	go client.readPump()
}


================================================
FILE: examples/chat/home.html
================================================
<!DOCTYPE html>
<html lang="en">
<head>
<title>Chat Example</title>
<script type="text/javascript">
window.onload = function () {
    var conn;
    var msg = document.getElementById("msg");
    var log = document.getElementById("log");

    function appendLog(item) {
        var doScroll = log.scrollTop > log.scrollHeight - log.clientHeight - 1;
        log.appendChild(item);
        if (doScroll) {
            log.scrollTop = log.scrollHeight - log.clientHeight;
        }
    }

    document.getElementById("form").onsubmit = function () {
        if (!conn) {
            return false;
        }
        if (!msg.value) {
            return false;
        }
        conn.send(msg.value);
        msg.value = "";
        return false;
    };

    if (window["WebSocket"]) {
        conn = new WebSocket("ws://" + document.location.host + "/ws");
        conn.onclose = function (evt) {
            var item = document.createElement("div");
            item.innerHTML = "<b>Connection closed.</b>";
            appendLog(item);
        };
        conn.onmessage = function (evt) {
            var messages = evt.data.split('\n');
            for (var i = 0; i < messages.length; i++) {
                var item = document.createElement("div");
                item.innerText = messages[i];
                appendLog(item);
            }
        };
    } else {
        var item = document.createElement("div");
        item.innerHTML = "<b>Your browser does not support WebSockets.</b>";
        appendLog(item);
    }
};
</script>
<style type="text/css">
html {
    overflow: hidden;
}

body {
    overflow: hidden;
    padding: 0;
    margin: 0;
    width: 100%;
    height: 100%;
    background: gray;
}

#log {
    background: white;
    margin: 0;
    padding: 0.5em 0.5em 0.5em 0.5em;
    position: absolute;
    top: 0.5em;
    left: 0.5em;
    right: 0.5em;
    bottom: 3em;
    overflow: auto;
}

#form {
    padding: 0 0.5em 0 0.5em;
    margin: 0;
    position: absolute;
    bottom: 1em;
    left: 0px;
    width: 100%;
    overflow: hidden;
}

</style>
</head>
<body>
<div id="log"></div>
<form id="form">
    <input type="submit" value="Send" />
    <input type="text" id="msg" size="64" autofocus />
</form>
</body>
</html>


================================================
FILE: examples/chat/hub.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

// Hub maintains the set of active clients and broadcasts messages to the
// clients.
type Hub struct {
	// Registered clients.
	clients map[*Client]bool

	// Inbound messages from the clients.
	broadcast chan []byte

	// Register requests from the clients.
	register chan *Client

	// Unregister requests from clients.
	unregister chan *Client
}

func newHub() *Hub {
	return &Hub{
		broadcast:  make(chan []byte),
		register:   make(chan *Client),
		unregister: make(chan *Client),
		clients:    make(map[*Client]bool),
	}
}

func (h *Hub) run() {
	for {
		select {
		case client := <-h.register:
			h.clients[client] = true
		case client := <-h.unregister:
			if _, ok := h.clients[client]; ok {
				delete(h.clients, client)
				close(client.send)
			}
		case message := <-h.broadcast:
			for client := range h.clients {
				select {
				case client.send <- message:
				default:
					close(client.send)
					delete(h.clients, client)
				}
			}
		}
	}
}


================================================
FILE: examples/chat/main.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"flag"
	"log"
	"net/http"
)

var addr = flag.String("addr", ":8080", "http service address")

func serveHome(w http.ResponseWriter, r *http.Request) {
	log.Println(r.URL)
	if r.URL.Path != "/" {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	http.ServeFile(w, r, "home.html")
}

func main() {
	flag.Parse()
	hub := newHub()
	go hub.run()
	http.HandleFunc("/", serveHome)
	http.HandleFunc("/ws", func(w http.ResponseWriter, r *http.Request) {
		serveWs(hub, w, r)
	})
	err := http.ListenAndServe(*addr, nil)
	if err != nil {
		log.Fatal("ListenAndServe: ", err)
	}
}


================================================
FILE: examples/command/README.md
================================================
# Command example

This example connects a websocket connection to stdin and stdout of a command.
Received messages are written to stdin followed by a `\n`. Each line read from
standard out is sent as a message to the client.

    $ go get github.com/gorilla/websocket
    $ cd `go list -f '{{.Dir}}' github.com/gorilla/websocket/examples/command`
    $ go run main.go <command and arguments to run>
    # Open http://localhost:8080/ .

Try the following commands.

    # Echo sent messages to the output area.
    $ go run main.go cat

    # Run a shell.Try sending "ls" and "cat main.go".
    $ go run main.go sh



================================================
FILE: examples/command/home.html
================================================
<!DOCTYPE html>
<html lang="en">
<head>
<title>Command Example</title>
<script type="text/javascript">
window.onload = function () {
    var conn;
    var msg = document.getElementById("msg");
    var log = document.getElementById("log");

    function appendLog(item) {
        var doScroll = log.scrollTop > log.scrollHeight - log.clientHeight - 1;
        log.appendChild(item);
        if (doScroll) {
            log.scrollTop = log.scrollHeight - log.clientHeight;
        }
    }

    document.getElementById("form").onsubmit = function () {
        if (!conn) {
            return false;
        }
        if (!msg.value) {
            return false;
        }
        conn.send(msg.value);
        msg.value = "";
        return false;
    };

    if (window["WebSocket"]) {
        conn = new WebSocket("ws://" + document.location.host + "/ws");
        conn.onclose = function (evt) {
            var item = document.createElement("div");
            item.innerHTML = "<b>Connection closed.</b>";
            appendLog(item);
        };
        conn.onmessage = function (evt) {
            var messages = evt.data.split('\n');
            for (var i = 0; i < messages.length; i++) {
                var item = document.createElement("div");
                item.innerText = messages[i];
                appendLog(item);
            }
        };
    } else {
        var item = document.createElement("div");
        item.innerHTML = "<b>Your browser does not support WebSockets.</b>";
        appendLog(item);
    }
};
</script>
<style type="text/css">
html {
    overflow: hidden;
}

body {
    overflow: hidden;
    padding: 0;
    margin: 0;
    width: 100%;
    height: 100%;
    background: gray;
}

#log {
    background: white;
    margin: 0;
    padding: 0.5em 0.5em 0.5em 0.5em;
    position: absolute;
    top: 0.5em;
    left: 0.5em;
    right: 0.5em;
    bottom: 3em;
    overflow: auto;
}

#log pre {
  margin: 0;
}

#form {
    padding: 0 0.5em 0 0.5em;
    margin: 0;
    position: absolute;
    bottom: 1em;
    left: 0px;
    width: 100%;
    overflow: hidden;
}

</style>
</head>
<body>
<div id="log"></div>
<form id="form">
    <input type="submit" value="Send" />
    <input type="text" id="msg" size="64"/>
</form>
</body>
</html>


================================================
FILE: examples/command/main.go
================================================
// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bufio"
	"flag"
	"io"
	"log"
	"net/http"
	"os"
	"os/exec"
	"time"

	"github.com/gorilla/websocket"
)

var (
	addr    = flag.String("addr", "127.0.0.1:8080", "http service address")
	cmdPath string
)

const (
	// Time allowed to write a message to the peer.
	writeWait = 10 * time.Second

	// Maximum message size allowed from peer.
	maxMessageSize = 8192

	// Time allowed to read the next pong message from the peer.
	pongWait = 60 * time.Second

	// Send pings to peer with this period. Must be less than pongWait.
	pingPeriod = (pongWait * 9) / 10

	// Time to wait before force close on connection.
	closeGracePeriod = 10 * time.Second
)

func pumpStdin(ws *websocket.Conn, w io.Writer) {
	defer ws.Close()
	ws.SetReadLimit(maxMessageSize)
	ws.SetReadDeadline(time.Now().Add(pongWait))
	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
	for {
		_, message, err := ws.ReadMessage()
		if err != nil {
			break
		}
		message = append(message, '\n')
		if _, err := w.Write(message); err != nil {
			break
		}
	}
}

func pumpStdout(ws *websocket.Conn, r io.Reader, done chan struct{}) {
	defer func() {
	}()
	s := bufio.NewScanner(r)
	for s.Scan() {
		ws.SetWriteDeadline(time.Now().Add(writeWait))
		if err := ws.WriteMessage(websocket.TextMessage, s.Bytes()); err != nil {
			ws.Close()
			break
		}
	}
	if s.Err() != nil {
		log.Println("scan:", s.Err())
	}
	close(done)

	ws.SetWriteDeadline(time.Now().Add(writeWait))
	ws.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
	time.Sleep(closeGracePeriod)
	ws.Close()
}

func ping(ws *websocket.Conn, done chan struct{}) {
	ticker := time.NewTicker(pingPeriod)
	defer ticker.Stop()
	for {
		select {
		case <-ticker.C:
			if err := ws.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(writeWait)); err != nil {
				log.Println("ping:", err)
			}
		case <-done:
			return
		}
	}
}

func internalError(ws *websocket.Conn, msg string, err error) {
	log.Println(msg, err)
	ws.WriteMessage(websocket.TextMessage, []byte("Internal server error."))
}

var upgrader = websocket.Upgrader{}

func serveWs(w http.ResponseWriter, r *http.Request) {
	ws, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Println("upgrade:", err)
		return
	}

	defer ws.Close()

	outr, outw, err := os.Pipe()
	if err != nil {
		internalError(ws, "stdout:", err)
		return
	}
	defer outr.Close()
	defer outw.Close()

	inr, inw, err := os.Pipe()
	if err != nil {
		internalError(ws, "stdin:", err)
		return
	}
	defer inr.Close()
	defer inw.Close()

	proc, err := os.StartProcess(cmdPath, flag.Args(), &os.ProcAttr{
		Files: []*os.File{inr, outw, outw},
	})
	if err != nil {
		internalError(ws, "start:", err)
		return
	}

	inr.Close()
	outw.Close()

	stdoutDone := make(chan struct{})
	go pumpStdout(ws, outr, stdoutDone)
	go ping(ws, stdoutDone)

	pumpStdin(ws, inw)

	// Some commands will exit when stdin is closed.
	inw.Close()

	// Other commands need a bonk on the head.
	if err := proc.Signal(os.Interrupt); err != nil {
		log.Println("inter:", err)
	}

	select {
	case <-stdoutDone:
	case <-time.After(time.Second):
		// A bigger bonk on the head.
		if err := proc.Signal(os.Kill); err != nil {
			log.Println("term:", err)
		}
		<-stdoutDone
	}

	if _, err := proc.Wait(); err != nil {
		log.Println("wait:", err)
	}
}

func serveHome(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	http.ServeFile(w, r, "home.html")
}

func main() {
	flag.Parse()
	if len(flag.Args()) < 1 {
		log.Fatal("must specify at least one argument")
	}
	var err error
	cmdPath, err = exec.LookPath(flag.Args()[0])
	if err != nil {
		log.Fatal(err)
	}
	http.HandleFunc("/", serveHome)
	http.HandleFunc("/ws", serveWs)
	log.Fatal(http.ListenAndServe(*addr, nil))
}


================================================
FILE: examples/echo/README.md
================================================
# Client and server example

This example shows a simple client and server.

The server echoes messages sent to it. The client sends a message every second
and prints all messages received.

To run the example, start the server:

    $ go run server.go

Next, start the client:

    $ go run client.go

The server includes a simple web client. To use the client, open
http://127.0.0.1:8080 in the browser and follow the instructions on the page.


================================================
FILE: examples/echo/client.go
================================================
// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore
// +build ignore

package main

import (
	"flag"
	"log"
	"net/url"
	"os"
	"os/signal"
	"time"

	"github.com/gorilla/websocket"
)

var addr = flag.String("addr", "localhost:8080", "http service address")

func main() {
	flag.Parse()
	log.SetFlags(0)

	interrupt := make(chan os.Signal, 1)
	signal.Notify(interrupt, os.Interrupt)

	u := url.URL{Scheme: "ws", Host: *addr, Path: "/echo"}
	log.Printf("connecting to %s", u.String())

	c, _, err := websocket.DefaultDialer.Dial(u.String(), nil)
	if err != nil {
		log.Fatal("dial:", err)
	}
	defer c.Close()

	done := make(chan struct{})

	go func() {
		defer close(done)
		for {
			_, message, err := c.ReadMessage()
			if err != nil {
				log.Println("read:", err)
				return
			}
			log.Printf("recv: %s", message)
		}
	}()

	ticker := time.NewTicker(time.Second)
	defer ticker.Stop()

	for {
		select {
		case <-done:
			return
		case t := <-ticker.C:
			err := c.WriteMessage(websocket.TextMessage, []byte(t.String()))
			if err != nil {
				log.Println("write:", err)
				return
			}
		case <-interrupt:
			log.Println("interrupt")

			// Cleanly close the connection by sending a close message and then
			// waiting (with timeout) for the server to close the connection.
			err := c.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
			if err != nil {
				log.Println("write close:", err)
				return
			}
			select {
			case <-done:
			case <-time.After(time.Second):
			}
			return
		}
	}
}


================================================
FILE: examples/echo/server.go
================================================
// Copyright 2015 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore
// +build ignore

package main

import (
	"flag"
	"html/template"
	"log"
	"net/http"

	"github.com/gorilla/websocket"
)

var addr = flag.String("addr", "localhost:8080", "http service address")

var upgrader = websocket.Upgrader{} // use default options

func echo(w http.ResponseWriter, r *http.Request) {
	c, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Print("upgrade:", err)
		return
	}
	defer c.Close()
	for {
		mt, message, err := c.ReadMessage()
		if err != nil {
			log.Println("read:", err)
			break
		}
		log.Printf("recv: %s", message)
		err = c.WriteMessage(mt, message)
		if err != nil {
			log.Println("write:", err)
			break
		}
	}
}

func home(w http.ResponseWriter, r *http.Request) {
	homeTemplate.Execute(w, "ws://"+r.Host+"/echo")
}

func main() {
	flag.Parse()
	log.SetFlags(0)
	http.HandleFunc("/echo", echo)
	http.HandleFunc("/", home)
	log.Fatal(http.ListenAndServe(*addr, nil))
}

var homeTemplate = template.Must(template.New("").Parse(`
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script>  
window.addEventListener("load", function(evt) {

    var output = document.getElementById("output");
    var input = document.getElementById("input");
    var ws;

    var print = function(message) {
        var d = document.createElement("div");
        d.textContent = message;
        output.appendChild(d);
        output.scroll(0, output.scrollHeight);
    };

    document.getElementById("open").onclick = function(evt) {
        if (ws) {
            return false;
        }
        ws = new WebSocket("{{.}}");
        ws.onopen = function(evt) {
            print("OPEN");
        }
        ws.onclose = function(evt) {
            print("CLOSE");
            ws = null;
        }
        ws.onmessage = function(evt) {
            print("RESPONSE: " + evt.data);
        }
        ws.onerror = function(evt) {
            print("ERROR: " + evt.data);
        }
        return false;
    };

    document.getElementById("send").onclick = function(evt) {
        if (!ws) {
            return false;
        }
        print("SEND: " + input.value);
        ws.send(input.value);
        return false;
    };

    document.getElementById("close").onclick = function(evt) {
        if (!ws) {
            return false;
        }
        ws.close();
        return false;
    };

});
</script>
</head>
<body>
<table>
<tr><td valign="top" width="50%">
<p>Click "Open" to create a connection to the server, 
"Send" to send a message to the server and "Close" to close the connection. 
You can change the message and send multiple times.
<p>
<form>
<button id="open">Open</button>
<button id="close">Close</button>
<p><input id="input" type="text" value="Hello world!">
<button id="send">Send</button>
</form>
</td><td valign="top" width="50%">
<div id="output" style="max-height: 70vh;overflow-y: scroll;"></div>
</td></tr></table>
</body>
</html>
`))


================================================
FILE: examples/filewatch/README.md
================================================
# File Watch example.

This example sends a file to the browser client for display whenever the file is modified.

    $ go get github.com/gorilla/websocket
    $ cd `go list -f '{{.Dir}}' github.com/gorilla/websocket/examples/filewatch`
    $ go run main.go <name of file to watch>
    # Open http://localhost:8080/ .
    # Modify the file to see it update in the browser.


================================================
FILE: examples/filewatch/main.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"flag"
	"html/template"
	"log"
	"net/http"
	"os"
	"strconv"
	"time"

	"github.com/gorilla/websocket"
)

const (
	// Time allowed to write the file to the client.
	writeWait = 10 * time.Second

	// Time allowed to read the next pong message from the client.
	pongWait = 60 * time.Second

	// Send pings to client with this period. Must be less than pongWait.
	pingPeriod = (pongWait * 9) / 10

	// Poll file for changes with this period.
	filePeriod = 10 * time.Second
)

var (
	addr      = flag.String("addr", ":8080", "http service address")
	homeTempl = template.Must(template.New("").Parse(homeHTML))
	filename  string
	upgrader  = websocket.Upgrader{
		ReadBufferSize:  1024,
		WriteBufferSize: 1024,
	}
)

func readFileIfModified(lastMod time.Time) ([]byte, time.Time, error) {
	fi, err := os.Stat(filename)
	if err != nil {
		return nil, lastMod, err
	}
	if !fi.ModTime().After(lastMod) {
		return nil, lastMod, nil
	}
	p, err := os.ReadFile(filename)
	if err != nil {
		return nil, fi.ModTime(), err
	}
	return p, fi.ModTime(), nil
}

func reader(ws *websocket.Conn) {
	defer ws.Close()
	ws.SetReadLimit(512)
	ws.SetReadDeadline(time.Now().Add(pongWait))
	ws.SetPongHandler(func(string) error { ws.SetReadDeadline(time.Now().Add(pongWait)); return nil })
	for {
		_, _, err := ws.ReadMessage()
		if err != nil {
			break
		}
	}
}

func writer(ws *websocket.Conn, lastMod time.Time) {
	lastError := ""
	pingTicker := time.NewTicker(pingPeriod)
	fileTicker := time.NewTicker(filePeriod)
	defer func() {
		pingTicker.Stop()
		fileTicker.Stop()
		ws.Close()
	}()
	for {
		select {
		case <-fileTicker.C:
			var p []byte
			var err error

			p, lastMod, err = readFileIfModified(lastMod)

			if err != nil {
				if s := err.Error(); s != lastError {
					lastError = s
					p = []byte(lastError)
				}
			} else {
				lastError = ""
			}

			if p != nil {
				ws.SetWriteDeadline(time.Now().Add(writeWait))
				if err := ws.WriteMessage(websocket.TextMessage, p); err != nil {
					return
				}
			}
		case <-pingTicker.C:
			ws.SetWriteDeadline(time.Now().Add(writeWait))
			if err := ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
				return
			}
		}
	}
}

func serveWs(w http.ResponseWriter, r *http.Request) {
	ws, err := upgrader.Upgrade(w, r, nil)
	if err != nil {
		if _, ok := err.(websocket.HandshakeError); !ok {
			log.Println(err)
		}
		return
	}

	var lastMod time.Time
	if n, err := strconv.ParseInt(r.FormValue("lastMod"), 16, 64); err == nil {
		lastMod = time.Unix(0, n)
	}

	go writer(ws, lastMod)
	reader(ws)
}

func serveHome(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path != "/" {
		http.Error(w, "Not found", http.StatusNotFound)
		return
	}
	if r.Method != http.MethodGet {
		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
		return
	}
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	p, lastMod, err := readFileIfModified(time.Time{})
	if err != nil {
		p = []byte(err.Error())
		lastMod = time.Unix(0, 0)
	}
	var v = struct {
		Host    string
		Data    string
		LastMod string
	}{
		r.Host,
		string(p),
		strconv.FormatInt(lastMod.UnixNano(), 16),
	}
	homeTempl.Execute(w, &v)
}

func main() {
	flag.Parse()
	if flag.NArg() != 1 {
		log.Fatal("filename not specified")
	}
	filename = flag.Args()[0]
	http.HandleFunc("/", serveHome)
	http.HandleFunc("/ws", serveWs)
	if err := http.ListenAndServe(*addr, nil); err != nil {
		log.Fatal(err)
	}
}

const homeHTML = `<!DOCTYPE html>
<html lang="en">
    <head>
        <title>WebSocket Example</title>
    </head>
    <body>
        <pre id="fileData">{{.Data}}</pre>
        <script type="text/javascript">
            (function() {
                var data = document.getElementById("fileData");
                var conn = new WebSocket("ws://{{.Host}}/ws?lastMod={{.LastMod}}");
                conn.onclose = function(evt) {
                    data.textContent = 'Connection closed';
                }
                conn.onmessage = function(evt) {
                    console.log('file updated');
                    data.textContent = evt.data;
                }
            })();
        </script>
    </body>
</html>
`


================================================
FILE: go.mod
================================================
module github.com/gorilla/websocket

go 1.20

retract (
    v1.5.2 // tag accidentally overwritten
)

require golang.org/x/net v0.26.0


================================================
FILE: go.sum
================================================
golang.org/x/net v0.26.0 h1:soB7SVo0PWrY4vPW/+ay0jKDNScG2X9wFeYlXIvJsOQ=
golang.org/x/net v0.26.0/go.mod h1:5YKkiSynbBIh3p6iOc/vibscux0x38BZDkn8sCUPxHE=


================================================
FILE: join.go
================================================
// Copyright 2019 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"io"
	"strings"
)

// JoinMessages concatenates received messages to create a single io.Reader.
// The string term is appended to each message. The returned reader does not
// support concurrent calls to the Read method.
func JoinMessages(c *Conn, term string) io.Reader {
	return &joinReader{c: c, term: term}
}

type joinReader struct {
	c    *Conn
	term string
	r    io.Reader
}

func (r *joinReader) Read(p []byte) (int, error) {
	if r.r == nil {
		var err error
		_, r.r, err = r.c.NextReader()
		if err != nil {
			return 0, err
		}
		if r.term != "" {
			r.r = io.MultiReader(r.r, strings.NewReader(r.term))
		}
	}
	n, err := r.r.Read(p)
	if err == io.EOF {
		err = nil
		r.r = nil
	}
	return n, err
}


================================================
FILE: join_test.go
================================================
// Copyright 2019 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"io"
	"strings"
	"testing"
)

func TestJoinMessages(t *testing.T) {
	messages := []string{"a", "bc", "def", "ghij", "klmno", "0", "12", "345", "6789"}
	for _, readChunk := range []int{1, 2, 3, 4, 5, 6, 7} {
		for _, term := range []string{"", ","} {
			var connBuf bytes.Buffer
			wc := newTestConn(nil, &connBuf, true)
			rc := newTestConn(&connBuf, nil, false)
			for _, m := range messages {
				_ = wc.WriteMessage(BinaryMessage, []byte(m))
			}

			var result bytes.Buffer
			_, err := io.CopyBuffer(&result, JoinMessages(rc, term), make([]byte, readChunk))
			if IsUnexpectedCloseError(err, CloseAbnormalClosure) {
				t.Errorf("readChunk=%d, term=%q: unexpected error %v", readChunk, term, err)
			}
			want := strings.Join(messages, term) + term
			if result.String() != want {
				t.Errorf("readChunk=%d, term=%q, got %q, want %q", readChunk, term, result.String(), want)
			}
		}
	}
}


================================================
FILE: json.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"encoding/json"
	"io"
)

// WriteJSON writes the JSON encoding of v as a message.
//
// Deprecated: Use c.WriteJSON instead.
func WriteJSON(c *Conn, v interface{}) error {
	return c.WriteJSON(v)
}

// WriteJSON writes the JSON encoding of v as a message.
//
// See the documentation for encoding/json Marshal for details about the
// conversion of Go values to JSON.
func (c *Conn) WriteJSON(v interface{}) error {
	w, err := c.NextWriter(TextMessage)
	if err != nil {
		return err
	}
	err1 := json.NewEncoder(w).Encode(v)
	err2 := w.Close()
	if err1 != nil {
		return err1
	}
	return err2
}

// ReadJSON reads the next JSON-encoded message from the connection and stores
// it in the value pointed to by v.
//
// Deprecated: Use c.ReadJSON instead.
func ReadJSON(c *Conn, v interface{}) error {
	return c.ReadJSON(v)
}

// ReadJSON reads the next JSON-encoded message from the connection and stores
// it in the value pointed to by v.
//
// See the documentation for the encoding/json Unmarshal function for details
// about the conversion of JSON to a Go value.
func (c *Conn) ReadJSON(v interface{}) error {
	_, r, err := c.NextReader()
	if err != nil {
		return err
	}
	err = json.NewDecoder(r).Decode(v)
	if err == io.EOF {
		// One value is expected in the message.
		err = io.ErrUnexpectedEOF
	}
	return err
}


================================================
FILE: json_test.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"encoding/json"
	"io"
	"reflect"
	"testing"
)

func TestJSON(t *testing.T) {
	var buf bytes.Buffer
	wc := newTestConn(nil, &buf, true)
	rc := newTestConn(&buf, nil, false)

	var actual, expect struct {
		A int
		B string
	}
	expect.A = 1
	expect.B = "hello"

	if err := wc.WriteJSON(&expect); err != nil {
		t.Fatal("write", err)
	}

	if err := rc.ReadJSON(&actual); err != nil {
		t.Fatal("read", err)
	}

	if !reflect.DeepEqual(&actual, &expect) {
		t.Fatal("equal", actual, expect)
	}
}

func TestPartialJSONRead(t *testing.T) {
	var buf0, buf1 bytes.Buffer
	wc := newTestConn(nil, &buf0, true)
	rc := newTestConn(&buf0, &buf1, false)

	var v struct {
		A int
		B string
	}
	v.A = 1
	v.B = "hello"

	messageCount := 0

	// Partial JSON values.

	data, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	for i := len(data) - 1; i >= 0; i-- {
		if err := wc.WriteMessage(TextMessage, data[:i]); err != nil {
			t.Fatal(err)
		}
		messageCount++
	}

	// Whitespace.

	if err := wc.WriteMessage(TextMessage, []byte(" ")); err != nil {
		t.Fatal(err)
	}
	messageCount++

	// Close.

	if err := wc.WriteMessage(CloseMessage, FormatCloseMessage(CloseNormalClosure, "")); err != nil {
		t.Fatal(err)
	}

	for i := 0; i < messageCount; i++ {
		err := rc.ReadJSON(&v)
		if err != io.ErrUnexpectedEOF {
			t.Error("read", i, err)
		}
	}

	err = rc.ReadJSON(&v)
	if _, ok := err.(*CloseError); !ok {
		t.Error("final", err)
	}
}

func TestDeprecatedJSON(t *testing.T) {
	var buf bytes.Buffer
	wc := newTestConn(nil, &buf, true)
	rc := newTestConn(&buf, nil, false)

	var actual, expect struct {
		A int
		B string
	}
	expect.A = 1
	expect.B = "hello"

	if err := WriteJSON(wc, &expect); err != nil {
		t.Fatal("write", err)
	}

	if err := ReadJSON(rc, &actual); err != nil {
		t.Fatal("read", err)
	}

	if !reflect.DeepEqual(&actual, &expect) {
		t.Fatal("equal", actual, expect)
	}
}


================================================
FILE: mask.go
================================================
// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
// this source code is governed by a BSD-style license that can be found in the
// LICENSE file.

//go:build !appengine
// +build !appengine

package websocket

import "unsafe"

const wordSize = int(unsafe.Sizeof(uintptr(0)))

func maskBytes(key [4]byte, pos int, b []byte) int {
	// Mask one byte at a time for small buffers.
	if len(b) < 2*wordSize {
		for i := range b {
			b[i] ^= key[pos&3]
			pos++
		}
		return pos & 3
	}

	// Mask one byte at a time to word boundary.
	if n := int(uintptr(unsafe.Pointer(&b[0]))) % wordSize; n != 0 {
		n = wordSize - n
		for i := range b[:n] {
			b[i] ^= key[pos&3]
			pos++
		}
		b = b[n:]
	}

	// Create aligned word size key.
	var k [wordSize]byte
	for i := range k {
		k[i] = key[(pos+i)&3]
	}
	kw := *(*uintptr)(unsafe.Pointer(&k))

	// Mask one word at a time.
	n := (len(b) / wordSize) * wordSize
	for i := 0; i < n; i += wordSize {
		*(*uintptr)(unsafe.Pointer(uintptr(unsafe.Pointer(&b[0])) + uintptr(i))) ^= kw
	}

	// Mask one byte at a time for remaining bytes.
	b = b[n:]
	for i := range b {
		b[i] ^= key[pos&3]
		pos++
	}

	return pos & 3
}


================================================
FILE: mask_safe.go
================================================
// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
// this source code is governed by a BSD-style license that can be found in the
// LICENSE file.

//go:build appengine
// +build appengine

package websocket

func maskBytes(key [4]byte, pos int, b []byte) int {
	for i := range b {
		b[i] ^= key[pos&3]
		pos++
	}
	return pos & 3
}


================================================
FILE: mask_test.go
================================================
// Copyright 2016 The Gorilla WebSocket Authors. All rights reserved.  Use of
// this source code is governed by a BSD-style license that can be found in the
// LICENSE file.

// !appengine

package websocket

import (
	"fmt"
	"testing"
)

func maskBytesByByte(key [4]byte, pos int, b []byte) int {
	for i := range b {
		b[i] ^= key[pos&3]
		pos++
	}
	return pos & 3
}

func notzero(b []byte) int {
	for i := range b {
		if b[i] != 0 {
			return i
		}
	}
	return -1
}

func TestMaskBytes(t *testing.T) {
	key := [4]byte{1, 2, 3, 4}
	for size := 1; size <= 1024; size++ {
		for align := 0; align < wordSize; align++ {
			for pos := 0; pos < 4; pos++ {
				b := make([]byte, size+align)[align:]
				maskBytes(key, pos, b)
				maskBytesByByte(key, pos, b)
				if i := notzero(b); i >= 0 {
					t.Errorf("size:%d, align:%d, pos:%d, offset:%d", size, align, pos, i)
				}
			}
		}
	}
}

func BenchmarkMaskBytes(b *testing.B) {
	for _, size := range []int{2, 4, 8, 16, 32, 512, 1024} {
		b.Run(fmt.Sprintf("size-%d", size), func(b *testing.B) {
			for _, align := range []int{wordSize / 2} {
				b.Run(fmt.Sprintf("align-%d", align), func(b *testing.B) {
					for _, fn := range []struct {
						name string
						fn   func(key [4]byte, pos int, b []byte) int
					}{
						{"byte", maskBytesByByte},
						{"word", maskBytes},
					} {
						b.Run(fn.name, func(b *testing.B) {
							key := newMaskKey()
							data := make([]byte, size+align)[align:]
							for i := 0; i < b.N; i++ {
								fn.fn(key, 0, data)
							}
							b.SetBytes(int64(len(data)))
						})
					}
				})
			}
		})
	}
}


================================================
FILE: prepared.go
================================================
// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"net"
	"sync"
	"time"
)

// PreparedMessage caches on the wire representations of a message payload.
// Use PreparedMessage to efficiently send a message payload to multiple
// connections. PreparedMessage is especially useful when compression is used
// because the CPU and memory expensive compression operation can be executed
// once for a given set of compression options.
type PreparedMessage struct {
	messageType int
	data        []byte
	mu          sync.Mutex
	frames      map[prepareKey]*preparedFrame
}

// prepareKey defines a unique set of options to cache prepared frames in PreparedMessage.
type prepareKey struct {
	isServer         bool
	compress         bool
	compressionLevel int
}

// preparedFrame contains data in wire representation.
type preparedFrame struct {
	once sync.Once
	data []byte
}

// NewPreparedMessage returns an initialized PreparedMessage. You can then send
// it to connection using WritePreparedMessage method. Valid wire
// representation will be calculated lazily only once for a set of current
// connection options.
func NewPreparedMessage(messageType int, data []byte) (*PreparedMessage, error) {
	pm := &PreparedMessage{
		messageType: messageType,
		frames:      make(map[prepareKey]*preparedFrame),
		data:        data,
	}

	// Prepare a plain server frame.
	_, frameData, err := pm.frame(prepareKey{isServer: true, compress: false})
	if err != nil {
		return nil, err
	}

	// To protect against caller modifying the data argument, remember the data
	// copied to the plain server frame.
	pm.data = frameData[len(frameData)-len(data):]
	return pm, nil
}

func (pm *PreparedMessage) frame(key prepareKey) (int, []byte, error) {
	pm.mu.Lock()
	frame, ok := pm.frames[key]
	if !ok {
		frame = &preparedFrame{}
		pm.frames[key] = frame
	}
	pm.mu.Unlock()

	var err error
	frame.once.Do(func() {
		// Prepare a frame using a 'fake' connection.
		// TODO: Refactor code in conn.go to allow more direct construction of
		// the frame.
		mu := make(chan struct{}, 1)
		mu <- struct{}{}
		var nc prepareConn
		c := &Conn{
			conn:                   &nc,
			mu:                     mu,
			isServer:               key.isServer,
			compressionLevel:       key.compressionLevel,
			enableWriteCompression: true,
			writeBuf:               make([]byte, defaultWriteBufferSize+maxFrameHeaderSize),
		}
		if key.compress {
			c.newCompressionWriter = compressNoContextTakeover
		}
		err = c.WriteMessage(pm.messageType, pm.data)
		frame.data = nc.buf.Bytes()
	})
	return pm.messageType, frame.data, err
}

type prepareConn struct {
	buf bytes.Buffer
	net.Conn
}

func (pc *prepareConn) Write(p []byte) (int, error)        { return pc.buf.Write(p) }
func (pc *prepareConn) SetWriteDeadline(t time.Time) error { return nil }


================================================
FILE: prepared_test.go
================================================
// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bytes"
	"compress/flate"
	"math/rand"
	"testing"
)

var preparedMessageTests = []struct {
	messageType            int
	isServer               bool
	enableWriteCompression bool
	compressionLevel       int
}{
	// Server
	{TextMessage, true, false, flate.BestSpeed},
	{TextMessage, true, true, flate.BestSpeed},
	{TextMessage, true, true, flate.BestCompression},
	{PingMessage, true, false, flate.BestSpeed},
	{PingMessage, true, true, flate.BestSpeed},

	// Client
	{TextMessage, false, false, flate.BestSpeed},
	{TextMessage, false, true, flate.BestSpeed},
	{TextMessage, false, true, flate.BestCompression},
	{PingMessage, false, false, flate.BestSpeed},
	{PingMessage, false, true, flate.BestSpeed},
}

func TestPreparedMessage(t *testing.T) {
	testRand := rand.New(rand.NewSource(99))
	prevMaskRand := maskRand
	maskRand = testRand
	defer func() { maskRand = prevMaskRand }()

	for _, tt := range preparedMessageTests {
		var data = []byte("this is a test")
		var buf bytes.Buffer
		c := newTestConn(nil, &buf, tt.isServer)
		if tt.enableWriteCompression {
			c.newCompressionWriter = compressNoContextTakeover
		}
		if err := c.SetCompressionLevel(tt.compressionLevel); err != nil {
			t.Fatal(err)
		}

		// Seed random number generator for consistent frame mask.
		testRand.Seed(1234)

		if err := c.WriteMessage(tt.messageType, data); err != nil {
			t.Fatal(err)
		}
		want := buf.String()

		pm, err := NewPreparedMessage(tt.messageType, data)
		if err != nil {
			t.Fatal(err)
		}

		// Scribble on data to ensure that NewPreparedMessage takes a snapshot.
		copy(data, "hello world")

		// Seed random number generator for consistent frame mask.
		testRand.Seed(1234)

		buf.Reset()
		if err := c.WritePreparedMessage(pm); err != nil {
			t.Fatal(err)
		}
		got := buf.String()

		if got != want {
			t.Errorf("write message != prepared message for %+v", tt)
		}
	}
}


================================================
FILE: proxy.go
================================================
// Copyright 2017 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"bytes"
	"context"
	"encoding/base64"
	"errors"
	"net"
	"net/http"
	"net/url"
	"strings"

	"golang.org/x/net/proxy"
)

type netDialerFunc func(ctx context.Context, network, addr string) (net.Conn, error)

func (fn netDialerFunc) Dial(network, addr string) (net.Conn, error) {
	return fn(context.Background(), network, addr)
}

func (fn netDialerFunc) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
	return fn(ctx, network, addr)
}

func proxyFromURL(proxyURL *url.URL, forwardDial netDialerFunc) (netDialerFunc, error) {
	if proxyURL.Scheme == "http" || proxyURL.Scheme == "https" {
		return (&httpProxyDialer{proxyURL: proxyURL, forwardDial: forwardDial}).DialContext, nil
	}
	dialer, err := proxy.FromURL(proxyURL, forwardDial)
	if err != nil {
		return nil, err
	}
	if d, ok := dialer.(proxy.ContextDialer); ok {
		return d.DialContext, nil
	}
	return func(ctx context.Context, net, addr string) (net.Conn, error) {
		return dialer.Dial(net, addr)
	}, nil
}

type httpProxyDialer struct {
	proxyURL    *url.URL
	forwardDial netDialerFunc
}

func (hpd *httpProxyDialer) DialContext(ctx context.Context, network string, addr string) (net.Conn, error) {
	hostPort, _ := hostPortNoPort(hpd.proxyURL)
	conn, err := hpd.forwardDial(ctx, network, hostPort)
	if err != nil {
		return nil, err
	}

	connectHeader := make(http.Header)
	if user := hpd.proxyURL.User; user != nil {
		proxyUser := user.Username()
		if proxyPassword, passwordSet := user.Password(); passwordSet {
			credential := base64.StdEncoding.EncodeToString([]byte(proxyUser + ":" + proxyPassword))
			connectHeader.Set("Proxy-Authorization", "Basic "+credential)
		}
	}
	connectReq := &http.Request{
		Method: http.MethodConnect,
		URL:    &url.URL{Opaque: addr},
		Host:   addr,
		Header: connectHeader,
	}

	if err := connectReq.Write(conn); err != nil {
		conn.Close()
		return nil, err
	}

	// Read response. It's OK to use and discard buffered reader here because
	// the remote server does not speak until spoken to.
	br := bufio.NewReader(conn)
	resp, err := http.ReadResponse(br, connectReq)
	if err != nil {
		conn.Close()
		return nil, err
	}

	// Close the response body to silence false positives from linters. Reset
	// the buffered reader first to ensure that Close() does not read from
	// conn.
	// Note: Applications must call resp.Body.Close() on a response returned
	// http.ReadResponse to inspect trailers or read another response from the
	// buffered reader. The call to resp.Body.Close() does not release
	// resources.
	br.Reset(bytes.NewReader(nil))
	_ = resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		_ = conn.Close()
		f := strings.SplitN(resp.Status, " ", 2)
		return nil, errors.New(f[1])
	}
	return conn, nil
}


================================================
FILE: server.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"net"
	"net/http"
	"net/url"
	"strings"
	"time"
)

// HandshakeError describes an error with the handshake from the peer.
type HandshakeError struct {
	message string
}

func (e HandshakeError) Error() string { return e.message }

// Upgrader specifies parameters for upgrading an HTTP connection to a
// WebSocket connection.
//
// It is safe to call Upgrader's methods concurrently.
type Upgrader struct {
	// HandshakeTimeout specifies the duration for the handshake to complete.
	HandshakeTimeout time.Duration

	// ReadBufferSize and WriteBufferSize specify I/O buffer sizes in bytes. If a buffer
	// size is zero, then buffers allocated by the HTTP server are used. The
	// I/O buffer sizes do not limit the size of the messages that can be sent
	// or received.
	ReadBufferSize, WriteBufferSize int

	// WriteBufferPool is a pool of buffers for write operations. If the value
	// is not set, then write buffers are allocated to the connection for the
	// lifetime of the connection.
	//
	// A pool is most useful when the application has a modest volume of writes
	// across a large number of connections.
	//
	// Applications should use a single pool for each unique value of
	// WriteBufferSize.
	WriteBufferPool BufferPool

	// Subprotocols specifies the server's supported protocols in order of
	// preference. If this field is not nil, then the Upgrade method negotiates a
	// subprotocol by selecting the first match in this list with a protocol
	// requested by the client. If there's no match, then no protocol is
	// negotiated (the Sec-Websocket-Protocol header is not included in the
	// handshake response).
	Subprotocols []string

	// Error specifies the function for generating HTTP error responses. If Error
	// is nil, then http.Error is used to generate the HTTP response.
	Error func(w http.ResponseWriter, r *http.Request, status int, reason error)

	// CheckOrigin returns true if the request Origin header is acceptable. If
	// CheckOrigin is nil, then a safe default is used: return false if the
	// Origin request header is present and the origin host is not equal to
	// request Host header.
	//
	// A CheckOrigin function should carefully validate the request origin to
	// prevent cross-site request forgery.
	CheckOrigin func(r *http.Request) bool

	// EnableCompression specify if the server should attempt to negotiate per
	// message compression (RFC 7692). Setting this value to true does not
	// guarantee that compression will be supported. Currently only "no context
	// takeover" modes are supported.
	EnableCompression bool
}

func (u *Upgrader) returnError(w http.ResponseWriter, r *http.Request, status int, reason string) (*Conn, error) {
	err := HandshakeError{reason}
	if u.Error != nil {
		u.Error(w, r, status, err)
	} else {
		w.Header().Set("Sec-Websocket-Version", "13")
		http.Error(w, http.StatusText(status), status)
	}
	return nil, err
}

// checkSameOrigin returns true if the origin is not set or is equal to the request host.
func checkSameOrigin(r *http.Request) bool {
	origin := r.Header["Origin"]
	if len(origin) == 0 {
		return true
	}
	u, err := url.Parse(origin[0])
	if err != nil {
		return false
	}
	return equalASCIIFold(u.Host, r.Host)
}

func (u *Upgrader) selectSubprotocol(r *http.Request, responseHeader http.Header) string {
	if u.Subprotocols != nil {
		clientProtocols := Subprotocols(r)
		for _, clientProtocol := range clientProtocols {
			for _, serverProtocol := range u.Subprotocols {
				if clientProtocol == serverProtocol {
					return clientProtocol
				}
			}
		}
	} else if responseHeader != nil {
		return responseHeader.Get("Sec-Websocket-Protocol")
	}
	return ""
}

// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
//
// The responseHeader is included in the response to the client's upgrade
// request. Use the responseHeader to specify cookies (Set-Cookie). To specify
// subprotocols supported by the server, set Upgrader.Subprotocols directly.
//
// If the upgrade fails, then Upgrade replies to the client with an HTTP error
// response.
func (u *Upgrader) Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header) (*Conn, error) {
	const badHandshake = "websocket: the client is not using the websocket protocol: "

	if !tokenListContainsValue(r.Header, "Connection", "upgrade") {
		return u.returnError(w, r, http.StatusBadRequest, badHandshake+"'upgrade' token not found in 'Connection' header")
	}

	if !tokenListContainsValue(r.Header, "Upgrade", "websocket") {
		w.Header().Set("Upgrade", "websocket")
		return u.returnError(w, r, http.StatusUpgradeRequired, badHandshake+"'websocket' token not found in 'Upgrade' header")
	}

	if r.Method != http.MethodGet {
		return u.returnError(w, r, http.StatusMethodNotAllowed, badHandshake+"request method is not GET")
	}

	if !tokenListContainsValue(r.Header, "Sec-Websocket-Version", "13") {
		return u.returnError(w, r, http.StatusBadRequest, "websocket: unsupported version: 13 not found in 'Sec-Websocket-Version' header")
	}

	if _, ok := responseHeader["Sec-Websocket-Extensions"]; ok {
		return u.returnError(w, r, http.StatusInternalServerError, "websocket: application specific 'Sec-WebSocket-Extensions' headers are unsupported")
	}

	checkOrigin := u.CheckOrigin
	if checkOrigin == nil {
		checkOrigin = checkSameOrigin
	}
	if !checkOrigin(r) {
		return u.returnError(w, r, http.StatusForbidden, "websocket: request origin not allowed by Upgrader.CheckOrigin")
	}

	challengeKey := r.Header.Get("Sec-Websocket-Key")
	if !isValidChallengeKey(challengeKey) {
		return u.returnError(w, r, http.StatusBadRequest, "websocket: not a websocket handshake: 'Sec-WebSocket-Key' header must be Base64 encoded value of 16-byte in length")
	}

	subprotocol := u.selectSubprotocol(r, responseHeader)

	// Negotiate PMCE
	var compress bool
	if u.EnableCompression {
		for _, ext := range parseExtensions(r.Header) {
			if ext[""] != "permessage-deflate" {
				continue
			}
			compress = true
			break
		}
	}

	netConn, brw, err := http.NewResponseController(w).Hijack()
	if err != nil {
		return u.returnError(w, r, http.StatusInternalServerError,
			"websocket: hijack: "+err.Error())
	}

	// Close the network connection when returning an error. The variable
	// netConn is set to nil before the success return at the end of the
	// function.
	defer func() {
		if netConn != nil {
			// It's safe to ignore the error from Close() because this code is
			// only executed when returning a more important error to the
			// application.
			_ = netConn.Close()
		}
	}()

	var br *bufio.Reader
	if u.ReadBufferSize == 0 && brw.Reader.Size() > 256 {
		// Use hijacked buffered reader as the connection reader.
		br = brw.Reader
	} else if brw.Reader.Buffered() > 0 {
		// Wrap the network connection to read buffered data in brw.Reader
		// before reading from the network connection. This should be rare
		// because a client must not send message data before receiving the
		// handshake response.
		netConn = &brNetConn{br: brw.Reader, Conn: netConn}
	}

	buf := brw.Writer.AvailableBuffer()

	var writeBuf []byte
	if u.WriteBufferPool == nil && u.WriteBufferSize == 0 && len(buf) >= maxFrameHeaderSize+256 {
		// Reuse hijacked write buffer as connection buffer.
		writeBuf = buf
	}

	c := newConn(netConn, true, u.ReadBufferSize, u.WriteBufferSize, u.WriteBufferPool, br, writeBuf)
	c.subprotocol = subprotocol

	if compress {
		c.newCompressionWriter = compressNoContextTakeover
		c.newDecompressionReader = decompressNoContextTakeover
	}

	// Use larger of hijacked buffer and connection write buffer for header.
	p := buf
	if len(c.writeBuf) > len(p) {
		p = c.writeBuf
	}
	p = p[:0]

	p = append(p, "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: "...)
	p = append(p, computeAcceptKey(challengeKey)...)
	p = append(p, "\r\n"...)
	if c.subprotocol != "" {
		p = append(p, "Sec-WebSocket-Protocol: "...)
		p = append(p, c.subprotocol...)
		p = append(p, "\r\n"...)
	}
	if compress {
		p = append(p, "Sec-WebSocket-Extensions: permessage-deflate; server_no_context_takeover; client_no_context_takeover\r\n"...)
	}
	for k, vs := range responseHeader {
		if k == "Sec-Websocket-Protocol" {
			continue
		}
		for _, v := range vs {
			p = append(p, k...)
			p = append(p, ": "...)
			for i := 0; i < len(v); i++ {
				b := v[i]
				if b <= 31 {
					// prevent response splitting.
					b = ' '
				}
				p = append(p, b)
			}
			p = append(p, "\r\n"...)
		}
	}
	p = append(p, "\r\n"...)

	if u.HandshakeTimeout > 0 {
		if err := netConn.SetWriteDeadline(time.Now().Add(u.HandshakeTimeout)); err != nil {
			return nil, err
		}
	} else {
		// Clear deadlines set by HTTP server.
		if err := netConn.SetDeadline(time.Time{}); err != nil {
			return nil, err
		}
	}

	if _, err = netConn.Write(p); err != nil {
		return nil, err
	}
	if u.HandshakeTimeout > 0 {
		if err := netConn.SetWriteDeadline(time.Time{}); err != nil {
			return nil, err
		}
	}

	// Success! Set netConn to nil to stop the deferred function above from
	// closing the network connection.
	netConn = nil

	return c, nil
}

// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
//
// Deprecated: Use websocket.Upgrader instead.
//
// Upgrade does not perform origin checking. The application is responsible for
// checking the Origin header before calling Upgrade. An example implementation
// of the same origin policy check is:
//
//	if req.Header.Get("Origin") != "http://"+req.Host {
//		http.Error(w, "Origin not allowed", http.StatusForbidden)
//		return
//	}
//
// If the endpoint supports subprotocols, then the application is responsible
// for negotiating the protocol used on the connection. Use the Subprotocols()
// function to get the subprotocols requested by the client. Use the
// Sec-Websocket-Protocol response header to specify the subprotocol selected
// by the application.
//
// The responseHeader is included in the response to the client's upgrade
// request. Use the responseHeader to specify cookies (Set-Cookie) and the
// negotiated subprotocol (Sec-Websocket-Protocol).
//
// The connection buffers IO to the underlying network connection. The
// readBufSize and writeBufSize parameters specify the size of the buffers to
// use. Messages can be larger than the buffers.
//
// If the request is not a valid WebSocket handshake, then Upgrade returns an
// error of type HandshakeError. Applications should handle this error by
// replying to the client with an HTTP error response.
func Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header, readBufSize, writeBufSize int) (*Conn, error) {
	u := Upgrader{ReadBufferSize: readBufSize, WriteBufferSize: writeBufSize}
	u.Error = func(w http.ResponseWriter, r *http.Request, status int, reason error) {
		// don't return errors to maintain backwards compatibility
	}
	u.CheckOrigin = func(r *http.Request) bool {
		// allow all connections by default
		return true
	}
	return u.Upgrade(w, r, responseHeader)
}

// Subprotocols returns the subprotocols requested by the client in the
// Sec-Websocket-Protocol header.
func Subprotocols(r *http.Request) []string {
	h := strings.TrimSpace(r.Header.Get("Sec-Websocket-Protocol"))
	if h == "" {
		return nil
	}
	protocols := strings.Split(h, ",")
	for i := range protocols {
		protocols[i] = strings.TrimSpace(protocols[i])
	}
	return protocols
}

// IsWebSocketUpgrade returns true if the client requested upgrade to the
// WebSocket protocol.
func IsWebSocketUpgrade(r *http.Request) bool {
	return tokenListContainsValue(r.Header, "Connection", "upgrade") &&
		tokenListContainsValue(r.Header, "Upgrade", "websocket")
}

type brNetConn struct {
	br *bufio.Reader
	net.Conn
}

func (b *brNetConn) Read(p []byte) (n int, err error) {
	if b.br != nil {
		// Limit read to buferred data.
		if n := b.br.Buffered(); len(p) > n {
			p = p[:n]
		}
		n, err = b.br.Read(p)
		if b.br.Buffered() == 0 {
			b.br = nil
		}
		return n, err
	}
	return b.Conn.Read(p)
}

// NetConn returns the underlying connection that is wrapped by b.
func (b *brNetConn) NetConn() net.Conn {
	return b.Conn
}



================================================
FILE: server_test.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"bufio"
	"bytes"
	"errors"
	"net"
	"net/http"
	"net/http/httptest"
	"reflect"
	"strings"
	"testing"
)

var subprotocolTests = []struct {
	h         string
	protocols []string
}{
	{"", nil},
	{"foo", []string{"foo"}},
	{"foo,bar", []string{"foo", "bar"}},
	{"foo, bar", []string{"foo", "bar"}},
	{" foo, bar", []string{"foo", "bar"}},
	{" foo, bar ", []string{"foo", "bar"}},
}

func TestSubprotocols(t *testing.T) {
	for _, st := range subprotocolTests {
		r := http.Request{Header: http.Header{"Sec-Websocket-Protocol": {st.h}}}
		protocols := Subprotocols(&r)
		if !reflect.DeepEqual(st.protocols, protocols) {
			t.Errorf("SubProtocols(%q) returned %#v, want %#v", st.h, protocols, st.protocols)
		}
	}
}

var isWebSocketUpgradeTests = []struct {
	ok bool
	h  http.Header
}{
	{false, http.Header{"Upgrade": {"websocket"}}},
	{false, http.Header{"Connection": {"upgrade"}}},
	{true, http.Header{"Connection": {"upgRade"}, "Upgrade": {"WebSocket"}}},
}

func TestIsWebSocketUpgrade(t *testing.T) {
	for _, tt := range isWebSocketUpgradeTests {
		ok := IsWebSocketUpgrade(&http.Request{Header: tt.h})
		if tt.ok != ok {
			t.Errorf("IsWebSocketUpgrade(%v) returned %v, want %v", tt.h, ok, tt.ok)
		}
	}
}

func TestSubProtocolSelection(t *testing.T) {
	upgrader := Upgrader{
		Subprotocols: []string{"foo", "bar", "baz"},
	}

	r := http.Request{Header: http.Header{"Sec-Websocket-Protocol": {"foo", "bar"}}}
	s := upgrader.selectSubprotocol(&r, nil)
	if s != "foo" {
		t.Errorf("Upgrader.selectSubprotocol returned %v, want %v", s, "foo")
	}

	r = http.Request{Header: http.Header{"Sec-Websocket-Protocol": {"bar", "foo"}}}
	s = upgrader.selectSubprotocol(&r, nil)
	if s != "bar" {
		t.Errorf("Upgrader.selectSubprotocol returned %v, want %v", s, "bar")
	}

	r = http.Request{Header: http.Header{"Sec-Websocket-Protocol": {"baz"}}}
	s = upgrader.selectSubprotocol(&r, nil)
	if s != "baz" {
		t.Errorf("Upgrader.selectSubprotocol returned %v, want %v", s, "baz")
	}

	r = http.Request{Header: http.Header{"Sec-Websocket-Protocol": {"quux"}}}
	s = upgrader.selectSubprotocol(&r, nil)
	if s != "" {
		t.Errorf("Upgrader.selectSubprotocol returned %v, want %v", s, "empty string")
	}
}

var checkSameOriginTests = []struct {
	ok bool
	r  *http.Request
}{
	{false, &http.Request{Host: "example.org", Header: map[string][]string{"Origin": {"https://other.org"}}}},
	{true, &http.Request{Host: "example.org", Header: map[string][]string{"Origin": {"https://example.org"}}}},
	{true, &http.Request{Host: "Example.org", Header: map[string][]string{"Origin": {"https://example.org"}}}},
}

func TestCheckSameOrigin(t *testing.T) {
	for _, tt := range checkSameOriginTests {
		ok := checkSameOrigin(tt.r)
		if tt.ok != ok {
			t.Errorf("checkSameOrigin(%+v) returned %v, want %v", tt.r, ok, tt.ok)
		}
	}
}

type reuseTestResponseWriter struct {
	brw *bufio.ReadWriter
	http.ResponseWriter
}

func (resp *reuseTestResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
	return fakeNetConn{strings.NewReader(""), &bytes.Buffer{}}, resp.brw, nil
}

var bufioReuseTests = []struct {
	n     int
	reuse bool
}{
	{4096, true},
	{128, false},
}

func xTestBufioReuse(t *testing.T) {
	for i, tt := range bufioReuseTests {
		br := bufio.NewReaderSize(strings.NewReader(""), tt.n)
		bw := bufio.NewWriterSize(&bytes.Buffer{}, tt.n)
		resp := &reuseTestResponseWriter{
			brw: bufio.NewReadWriter(br, bw),
		}
		upgrader := Upgrader{}
		c, err := upgrader.Upgrade(resp, &http.Request{
			Method: http.MethodGet,
			Header: http.Header{
				"Upgrade":               []string{"websocket"},
				"Connection":            []string{"upgrade"},
				"Sec-Websocket-Key":     []string{"dGhlIHNhbXBsZSBub25jZQ=="},
				"Sec-Websocket-Version": []string{"13"},
			}}, nil)
		if err != nil {
			t.Fatal(err)
		}
		if reuse := c.br == br; reuse != tt.reuse {
			t.Errorf("%d: buffered reader reuse=%v, want %v", i, reuse, tt.reuse)
		}
		writeBuf := bw.AvailableBuffer()
		if reuse := &c.writeBuf[0] == &writeBuf[0]; reuse != tt.reuse {
			t.Errorf("%d: write buffer reuse=%v, want %v", i, reuse, tt.reuse)
		}
	}
}

func TestHijack_NotSupported(t *testing.T) {
	t.Parallel()

	req := httptest.NewRequest(http.MethodGet, "http://example.com", nil)
	req.Header.Set("Upgrade", "websocket")
	req.Header.Set("Connection", "upgrade")
	req.Header.Set("Sec-Websocket-Key", "dGhlIHNhbXBsZSBub25jZQ==")
	req.Header.Set("Sec-Websocket-Version", "13")

	recorder := httptest.NewRecorder()

	upgrader := Upgrader{}
	_, err := upgrader.Upgrade(recorder, req, nil)

	if want := (HandshakeError{}); !errors.As(err, &want) || recorder.Code != http.StatusInternalServerError {
		t.Errorf("want %T and status_code=%d", want, http.StatusInternalServerError)
		t.Fatalf("got err=%T and status_code=%d", err, recorder.Code)
	}
}


================================================
FILE: util.go
================================================
// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"crypto/rand"
	"crypto/sha1"
	"encoding/base64"
	"io"
	"net/http"
	"strings"
	"unicode/utf8"
)

var keyGUID = []byte("258EAFA5-E914-47DA-95CA-C5AB0DC85B11")

func computeAcceptKey(challengeKey string) string {
	h := sha1.New()
	h.Write([]byte(challengeKey))
	h.Write(keyGUID)
	return base64.StdEncoding.EncodeToString(h.Sum(nil))
}

func generateChallengeKey() (string, error) {
	p := make([]byte, 16)
	if _, err := io.ReadFull(rand.Reader, p); err != nil {
		return "", err
	}
	return base64.StdEncoding.EncodeToString(p), nil
}

// Token octets per RFC 2616.
var isTokenOctet = [256]bool{
	'!':  true,
	'#':  true,
	'$':  true,
	'%':  true,
	'&':  true,
	'\'': true,
	'*':  true,
	'+':  true,
	'-':  true,
	'.':  true,
	'0':  true,
	'1':  true,
	'2':  true,
	'3':  true,
	'4':  true,
	'5':  true,
	'6':  true,
	'7':  true,
	'8':  true,
	'9':  true,
	'A':  true,
	'B':  true,
	'C':  true,
	'D':  true,
	'E':  true,
	'F':  true,
	'G':  true,
	'H':  true,
	'I':  true,
	'J':  true,
	'K':  true,
	'L':  true,
	'M':  true,
	'N':  true,
	'O':  true,
	'P':  true,
	'Q':  true,
	'R':  true,
	'S':  true,
	'T':  true,
	'U':  true,
	'W':  true,
	'V':  true,
	'X':  true,
	'Y':  true,
	'Z':  true,
	'^':  true,
	'_':  true,
	'`':  true,
	'a':  true,
	'b':  true,
	'c':  true,
	'd':  true,
	'e':  true,
	'f':  true,
	'g':  true,
	'h':  true,
	'i':  true,
	'j':  true,
	'k':  true,
	'l':  true,
	'm':  true,
	'n':  true,
	'o':  true,
	'p':  true,
	'q':  true,
	'r':  true,
	's':  true,
	't':  true,
	'u':  true,
	'v':  true,
	'w':  true,
	'x':  true,
	'y':  true,
	'z':  true,
	'|':  true,
	'~':  true,
}

// skipSpace returns a slice of the string s with all leading RFC 2616 linear
// whitespace removed.
func skipSpace(s string) (rest string) {
	i := 0
	for ; i < len(s); i++ {
		if b := s[i]; b != ' ' && b != '\t' {
			break
		}
	}
	return s[i:]
}

// nextToken returns the leading RFC 2616 token of s and the string following
// the token.
func nextToken(s string) (token, rest string) {
	i := 0
	for ; i < len(s); i++ {
		if !isTokenOctet[s[i]] {
			break
		}
	}
	return s[:i], s[i:]
}

// nextTokenOrQuoted returns the leading token or quoted string per RFC 2616
// and the string following the token or quoted string.
func nextTokenOrQuoted(s string) (value string, rest string) {
	if !strings.HasPrefix(s, "\"") {
		return nextToken(s)
	}
	s = s[1:]
	for i := 0; i < len(s); i++ {
		switch s[i] {
		case '"':
			return s[:i], s[i+1:]
		case '\\':
			p := make([]byte, len(s)-1)
			j := copy(p, s[:i])
			escape := true
			for i = i + 1; i < len(s); i++ {
				b := s[i]
				switch {
				case escape:
					escape = false
					p[j] = b
					j++
				case b == '\\':
					escape = true
				case b == '"':
					return string(p[:j]), s[i+1:]
				default:
					p[j] = b
					j++
				}
			}
			return "", ""
		}
	}
	return "", ""
}

// equalASCIIFold returns true if s is equal to t with ASCII case folding as
// defined in RFC 4790.
func equalASCIIFold(s, t string) bool {
	for s != "" && t != "" {
		sr, size := utf8.DecodeRuneInString(s)
		s = s[size:]
		tr, size := utf8.DecodeRuneInString(t)
		t = t[size:]
		if sr == tr {
			continue
		}
		if 'A' <= sr && sr <= 'Z' {
			sr = sr + 'a' - 'A'
		}
		if 'A' <= tr && tr <= 'Z' {
			tr = tr + 'a' - 'A'
		}
		if sr != tr {
			return false
		}
	}
	return s == t
}

// tokenListContainsValue returns true if the 1#token header with the given
// name contains a token equal to value with ASCII case folding.
func tokenListContainsValue(header http.Header, name string, value string) bool {
headers:
	for _, s := range header[name] {
		for {
			var t string
			t, s = nextToken(skipSpace(s))
			if t == "" {
				continue headers
			}
			s = skipSpace(s)
			if s != "" && s[0] != ',' {
				continue headers
			}
			if equalASCIIFold(t, value) {
				return true
			}
			if s == "" {
				continue headers
			}
			s = s[1:]
		}
	}
	return false
}

// parseExtensions parses WebSocket extensions from a header.
func parseExtensions(header http.Header) []map[string]string {
	// From RFC 6455:
	//
	//  Sec-WebSocket-Extensions = extension-list
	//  extension-list = 1#extension
	//  extension = extension-token *( ";" extension-param )
	//  extension-token = registered-token
	//  registered-token = token
	//  extension-param = token [ "=" (token | quoted-string) ]
	//     ;When using the quoted-string syntax variant, the value
	//     ;after quoted-string unescaping MUST conform to the
	//     ;'token' ABNF.

	var result []map[string]string
headers:
	for _, s := range header["Sec-Websocket-Extensions"] {
		for {
			var t string
			t, s = nextToken(skipSpace(s))
			if t == "" {
				continue headers
			}
			ext := map[string]string{"": t}
			for {
				s = skipSpace(s)
				if !strings.HasPrefix(s, ";") {
					break
				}
				var k string
				k, s = nextToken(skipSpace(s[1:]))
				if k == "" {
					continue headers
				}
				s = skipSpace(s)
				var v string
				if strings.HasPrefix(s, "=") {
					v, s = nextTokenOrQuoted(skipSpace(s[1:]))
					s = skipSpace(s)
				}
				if s != "" && s[0] != ',' && s[0] != ';' {
					continue headers
				}
				ext[k] = v
			}
			if s != "" && s[0] != ',' {
				continue headers
			}
			result = append(result, ext)
			if s == "" {
				continue headers
			}
			s = s[1:]
		}
	}
	return result
}

// isValidChallengeKey checks if the argument meets RFC6455 specification.
func isValidChallengeKey(s string) bool {
	// From RFC6455:
	//
	// A |Sec-WebSocket-Key| header field with a base64-encoded (see
	// Section 4 of [RFC4648]) value that, when decoded, is 16 bytes in
	// length.

	if s == "" {
		return false
	}
	decoded, err := base64.StdEncoding.DecodeString(s)
	return err == nil && len(decoded) == 16
}


================================================
FILE: util_test.go
================================================
// Copyright 2014 The Gorilla WebSocket Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package websocket

import (
	"net/http"
	"reflect"
	"testing"
)

var equalASCIIFoldTests = []struct {
	t, s string
	eq   bool
}{
	{"WebSocket", "websocket", true},
	{"websocket", "WebSocket", true},
	{"Öyster", "öyster", false},
	{"WebSocket", "WetSocket", false},
}

func TestEqualASCIIFold(t *testing.T) {
	for _, tt := range equalASCIIFoldTests {
		eq := equalASCIIFold(tt.s, tt.t)
		if eq != tt.eq {
			t.Errorf("equalASCIIFold(%q, %q) = %v, want %v", tt.s, tt.t, eq, tt.eq)
		}
	}
}

var tokenListContainsValueTests = []struct {
	value string
	ok    bool
}{
	{"WebSocket", true},
	{"WEBSOCKET", true},
	{"websocket", true},
	{"websockets", false},
	{"x websocket", false},
	{"websocket x", false},
	{"other,websocket,more", true},
	{"other, websocket, more", true},
}

func TestTokenListContainsValue(t *testing.T) {
	for _, tt := range tokenListContainsValueTests {
		h := http.Header{"Upgrade": {tt.value}}
		ok := tokenListContainsValue(h, "Upgrade", "websocket")
		if ok != tt.ok {
			t.Errorf("tokenListContainsValue(h, n, %q) = %v, want %v", tt.value, ok, tt.ok)
		}
	}
}

var isValidChallengeKeyTests = []struct {
	key string
	ok  bool
}{
	{"dGhlIHNhbXBsZSBub25jZQ==", true},
	{"", false},
	{"InvalidKey", false},
	{"WHQ4eXhscUtKYjBvOGN3WEdtOEQ=", false},
}

func TestIsValidChallengeKey(t *testing.T) {
	for _, tt := range isValidChallengeKeyTests {
		ok := isValidChallengeKey(tt.key)
		if ok != tt.ok {
			t.Errorf("isValidChallengeKey returns %v, want %v", ok, tt.ok)
		}
	}
}

var parseExtensionTests = []struct {
	value      string
	extensions []map[string]string
}{
	{`foo`, []map[string]string{{"": "foo"}}},
	{`foo, bar; baz=2`, []map[string]string{
		{"": "foo"},
		{"": "bar", "baz": "2"}}},
	{`foo; bar="b,a;z"`, []map[string]string{
		{"": "foo", "bar": "b,a;z"}}},
	{`foo , bar; baz = 2`, []map[string]string{
		{"": "foo"},
		{"": "bar", "baz": "2"}}},
	{`foo, bar; baz=2 junk`, []map[string]string{
		{"": "foo"}}},
	{`foo junk, bar; baz=2 junk`, nil},
	{`mux; max-channels=4; flow-control, deflate-stream`, []map[string]string{
		{"": "mux", "max-channels": "4", "flow-control": ""},
		{"": "deflate-stream"}}},
	{`permessage-foo; x="10"`, []map[string]string{
		{"": "permessage-foo", "x": "10"}}},
	{`permessage-foo; use_y, permessage-foo`, []map[string]string{
		{"": "permessage-foo", "use_y": ""},
		{"": "permessage-foo"}}},
	{`permessage-deflate; client_max_window_bits; server_max_window_bits=10 , permessage-deflate; client_max_window_bits`, []map[string]string{
		{"": "permessage-deflate", "client_max_window_bits": "", "server_max_window_bits": "10"},
		{"": "permessage-deflate", "client_max_window_bits": ""}}},
	{"permessage-deflate; server_no_context_takeover; client_max_window_bits=15", []map[string]string{
		{"": "permessage-deflate", "server_no_context_takeover": "", "client_max_window_bits": "15"},
	}},
}

func TestParseExtensions(t *testing.T) {
	for _, tt := range parseExtensionTests {
		h := http.Header{http.CanonicalHeaderKey("Sec-WebSocket-Extensions"): {tt.value}}
		extensions := parseExtensions(h)
		if !reflect.DeepEqual(extensions, tt.extensions) {
			t.Errorf("parseExtensions(%q)\n    = %v,\nwant %v", tt.value, extensions, tt.extensions)
		}
	}
}