snapshot of https://github.com/gorilla/websocket.git (main, 2026-09-15; blobs > 131072B omitted)

.circleci/config.yml

@@ -0,0 +1,70 @@
+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"]

.github/release-drafter.yml

@@ -0,0 +1,7 @@
+# Config for https://github.com/apps/release-drafter
+template: |
+  
+  <summary of changes here>
+  
+  ## CHANGELOG
+  $CHANGES

.gitignore

@@ -0,0 +1,25 @@
+# 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

AUTHORS

@@ -0,0 +1,9 @@
+# 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>
+

LICENSE

@@ -0,0 +1,22 @@
+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.

README.md

@@ -0,0 +1,32 @@
+# 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).

client.go

@@ -0,0 +1,517 @@
+// 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
+}

client_proxy_server_test.go

@@ -0,0 +1,911 @@
+// 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-----
+`)

client_test.go

@@ -0,0 +1,32 @@
+// 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)
+		}
+	}
+}

compression.go

@@ -0,0 +1,152 @@
+// 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
+}

compression_test.go

@@ -0,0 +1,79 @@
+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)
+		}
+	}
+}

conn_broadcast_test.go

@@ -0,0 +1,130 @@
+// 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()
+		})
+	}
+}

conn_test.go

@@ -0,0 +1,746 @@
+// 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")
+}

doc.go

@@ -0,0 +1,227 @@
+// 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

example_test.go

@@ -0,0 +1,45 @@
+// 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) {}

examples/autobahn/README.md

@@ -0,0 +1,18 @@
+# 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.

examples/autobahn/config/fuzzingclient.json

@@ -0,0 +1,29 @@
+{
+  "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"
+    }
+  ]
+}

examples/autobahn/server.go

@@ -0,0 +1,265 @@
+// 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
+}

examples/chat/README.md

@@ -0,0 +1,102 @@
+# 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.

examples/chat/client.go

@@ -0,0 +1,137 @@
+// 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()
+}

examples/chat/home.html

@@ -0,0 +1,98 @@
+<!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>

examples/chat/hub.go

@@ -0,0 +1,53 @@
+// 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)
+				}
+			}
+		}
+	}
+}

examples/chat/main.go

@@ -0,0 +1,40 @@
+// 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)
+	}
+}

examples/command/README.md

@@ -0,0 +1,19 @@
+# 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
+

examples/command/home.html

@@ -0,0 +1,102 @@
+<!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>

examples/command/main.go

@@ -0,0 +1,193 @@
+// 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))
+}

examples/echo/README.md

@@ -0,0 +1,17 @@
+# 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.

examples/echo/client.go

@@ -0,0 +1,83 @@
+// 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
+		}
+	}
+}

examples/echo/server.go

@@ -0,0 +1,135 @@
+// 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>
+`))

examples/filewatch/README.md

@@ -0,0 +1,9 @@
+# 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.

examples/filewatch/main.go

@@ -0,0 +1,192 @@
+// 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>
+`

go.mod

@@ -0,0 +1,9 @@
+module github.com/gorilla/websocket
+
+go 1.20
+
+retract (
+    v1.5.2 // tag accidentally overwritten
+)
+
+require golang.org/x/net v0.26.0

go.sum

@@ -0,0 +1,2 @@
+golang.org/x/net v0.26.0 h1:soB7SVo0PWrY4vPW/+ay0jKDNScG2X9wFeYlXIvJsOQ=
+golang.org/x/net v0.26.0/go.mod h1:5YKkiSynbBIh3p6iOc/vibscux0x38BZDkn8sCUPxHE=

join.go

@@ -0,0 +1,42 @@
+// 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
+}

join_test.go

@@ -0,0 +1,36 @@
+// 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)
+			}
+		}
+	}
+}

json.go

@@ -0,0 +1,60 @@
+// 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
+}

json_test.go

@@ -0,0 +1,116 @@
+// 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)
+	}
+}

mask.go

@@ -0,0 +1,55 @@
+// 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
+}

mask_safe.go

@@ -0,0 +1,16 @@
+// 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
+}

mask_test.go

@@ -0,0 +1,72 @@
+// 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)))
+						})
+					}
+				})
+			}
+		})
+	}
+}

prepared.go

@@ -0,0 +1,102 @@
+// 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 }

prepared_test.go

@@ -0,0 +1,81 @@
+// 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)
+		}
+	}
+}

proxy.go

@@ -0,0 +1,104 @@
+// 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
+}

server.go

@@ -0,0 +1,373 @@
+// 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
+}
+

server_test.go

@@ -0,0 +1,171 @@
+// 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)
+	}
+}

util.go

@@ -0,0 +1,298 @@
+// 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
+}

util_test.go

@@ -0,0 +1,115 @@
+// 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)
+		}
+	}
+}