261 lines
8.3 KiB
Go
261 lines
8.3 KiB
Go
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// Copyright 2013 The Gorilla WebSocket Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package websocket
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import (
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"bufio"
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"errors"
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"net"
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"net/http"
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"net/url"
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"strings"
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"time"
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)
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// HandshakeError describes an error with the handshake from the peer.
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type HandshakeError struct {
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message string
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}
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func (e HandshakeError) Error() string { return e.message }
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// Upgrader specifies parameters for upgrading an HTTP connection to a
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// WebSocket connection.
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type Upgrader struct {
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// HandshakeTimeout specifies the duration for the handshake to complete.
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HandshakeTimeout time.Duration
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// ReadBufferSize and WriteBufferSize specify I/O buffer sizes. If a buffer
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// size is zero, then a default value of 4096 is used. The I/O buffer sizes
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// do not limit the size of the messages that can be sent or received.
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ReadBufferSize, WriteBufferSize int
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// Subprotocols specifies the server's supported protocols in order of
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// preference. If this field is set, then the Upgrade method negotiates a
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// subprotocol by selecting the first match in this list with a protocol
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// requested by the client.
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Subprotocols []string
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// Error specifies the function for generating HTTP error responses. If Error
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// is nil, then http.Error is used to generate the HTTP response.
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Error func(w http.ResponseWriter, r *http.Request, status int, reason error)
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// CheckOrigin returns true if the request Origin header is acceptable. If
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// CheckOrigin is nil, the host in the Origin header must not be set or
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// must match the host of the request.
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CheckOrigin func(r *http.Request) bool
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}
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func (u *Upgrader) returnError(w http.ResponseWriter, r *http.Request, status int, reason string) (*Conn, error) {
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err := HandshakeError{reason}
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if u.Error != nil {
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u.Error(w, r, status, err)
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} else {
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http.Error(w, http.StatusText(status), status)
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}
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return nil, err
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}
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// checkSameOrigin returns true if the origin is not set or is equal to the request host.
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func checkSameOrigin(r *http.Request) bool {
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origin := r.Header["Origin"]
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if len(origin) == 0 {
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return true
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}
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u, err := url.Parse(origin[0])
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if err != nil {
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return false
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}
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return u.Host == r.Host
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}
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func (u *Upgrader) selectSubprotocol(r *http.Request, responseHeader http.Header) string {
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if u.Subprotocols != nil {
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clientProtocols := Subprotocols(r)
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for _, serverProtocol := range u.Subprotocols {
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for _, clientProtocol := range clientProtocols {
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if clientProtocol == serverProtocol {
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return clientProtocol
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}
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}
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}
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} else if responseHeader != nil {
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return responseHeader.Get("Sec-Websocket-Protocol")
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}
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return ""
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}
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// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
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//
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// The responseHeader is included in the response to the client's upgrade
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// request. Use the responseHeader to specify cookies (Set-Cookie) and the
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// application negotiated subprotocol (Sec-Websocket-Protocol).
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//
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// If the upgrade fails, then Upgrade replies to the client with an HTTP error
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// response.
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func (u *Upgrader) Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header) (*Conn, error) {
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if r.Method != "GET" {
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return u.returnError(w, r, http.StatusMethodNotAllowed, "websocket: method not GET")
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}
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if values := r.Header["Sec-Websocket-Version"]; len(values) == 0 || values[0] != "13" {
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return u.returnError(w, r, http.StatusBadRequest, "websocket: version != 13")
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}
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if !tokenListContainsValue(r.Header, "Connection", "upgrade") {
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return u.returnError(w, r, http.StatusBadRequest, "websocket: could not find connection header with token 'upgrade'")
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}
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if !tokenListContainsValue(r.Header, "Upgrade", "websocket") {
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return u.returnError(w, r, http.StatusBadRequest, "websocket: could not find upgrade header with token 'websocket'")
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}
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checkOrigin := u.CheckOrigin
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if checkOrigin == nil {
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checkOrigin = checkSameOrigin
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}
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if !checkOrigin(r) {
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return u.returnError(w, r, http.StatusForbidden, "websocket: origin not allowed")
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}
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challengeKey := r.Header.Get("Sec-Websocket-Key")
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if challengeKey == "" {
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return u.returnError(w, r, http.StatusBadRequest, "websocket: key missing or blank")
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}
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subprotocol := u.selectSubprotocol(r, responseHeader)
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var (
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netConn net.Conn
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br *bufio.Reader
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err error
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)
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h, ok := w.(http.Hijacker)
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if !ok {
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return u.returnError(w, r, http.StatusInternalServerError, "websocket: response does not implement http.Hijacker")
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}
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var rw *bufio.ReadWriter
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netConn, rw, err = h.Hijack()
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if err != nil {
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return u.returnError(w, r, http.StatusInternalServerError, err.Error())
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}
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br = rw.Reader
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if br.Buffered() > 0 {
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netConn.Close()
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return nil, errors.New("websocket: client sent data before handshake is complete")
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}
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c := newConn(netConn, true, u.ReadBufferSize, u.WriteBufferSize)
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c.subprotocol = subprotocol
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p := c.writeBuf[:0]
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p = append(p, "HTTP/1.1 101 Switching Protocols\r\nUpgrade: websocket\r\nConnection: Upgrade\r\nSec-WebSocket-Accept: "...)
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p = append(p, computeAcceptKey(challengeKey)...)
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p = append(p, "\r\n"...)
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if c.subprotocol != "" {
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p = append(p, "Sec-Websocket-Protocol: "...)
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p = append(p, c.subprotocol...)
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p = append(p, "\r\n"...)
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}
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for k, vs := range responseHeader {
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if k == "Sec-Websocket-Protocol" {
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continue
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}
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for _, v := range vs {
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p = append(p, k...)
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p = append(p, ": "...)
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for i := 0; i < len(v); i++ {
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b := v[i]
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if b <= 31 {
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// prevent response splitting.
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b = ' '
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}
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p = append(p, b)
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}
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p = append(p, "\r\n"...)
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}
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}
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p = append(p, "\r\n"...)
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// Clear deadlines set by HTTP server.
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netConn.SetDeadline(time.Time{})
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if u.HandshakeTimeout > 0 {
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netConn.SetWriteDeadline(time.Now().Add(u.HandshakeTimeout))
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}
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if _, err = netConn.Write(p); err != nil {
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netConn.Close()
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return nil, err
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}
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if u.HandshakeTimeout > 0 {
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netConn.SetWriteDeadline(time.Time{})
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}
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return c, nil
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}
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// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
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//
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// This function is deprecated, use websocket.Upgrader instead.
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//
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// The application is responsible for checking the request origin before
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// calling Upgrade. An example implementation of the same origin policy is:
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//
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// if req.Header.Get("Origin") != "http://"+req.Host {
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// http.Error(w, "Origin not allowed", 403)
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// return
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// }
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//
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// If the endpoint supports subprotocols, then the application is responsible
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// for negotiating the protocol used on the connection. Use the Subprotocols()
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// function to get the subprotocols requested by the client. Use the
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// Sec-Websocket-Protocol response header to specify the subprotocol selected
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// by the application.
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//
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// The responseHeader is included in the response to the client's upgrade
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// request. Use the responseHeader to specify cookies (Set-Cookie) and the
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// negotiated subprotocol (Sec-Websocket-Protocol).
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//
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// The connection buffers IO to the underlying network connection. The
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// readBufSize and writeBufSize parameters specify the size of the buffers to
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// use. Messages can be larger than the buffers.
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//
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// If the request is not a valid WebSocket handshake, then Upgrade returns an
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// error of type HandshakeError. Applications should handle this error by
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// replying to the client with an HTTP error response.
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func Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header, readBufSize, writeBufSize int) (*Conn, error) {
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u := Upgrader{ReadBufferSize: readBufSize, WriteBufferSize: writeBufSize}
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u.Error = func(w http.ResponseWriter, r *http.Request, status int, reason error) {
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// don't return errors to maintain backwards compatibility
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}
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u.CheckOrigin = func(r *http.Request) bool {
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// allow all connections by default
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return true
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}
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return u.Upgrade(w, r, responseHeader)
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}
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// Subprotocols returns the subprotocols requested by the client in the
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// Sec-Websocket-Protocol header.
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func Subprotocols(r *http.Request) []string {
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h := strings.TrimSpace(r.Header.Get("Sec-Websocket-Protocol"))
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if h == "" {
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return nil
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}
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protocols := strings.Split(h, ",")
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for i := range protocols {
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protocols[i] = strings.TrimSpace(protocols[i])
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}
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return protocols
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}
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// IsWebSocketUpgrade returns true if the client requested upgrade to the
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// WebSocket protocol.
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func IsWebSocketUpgrade(r *http.Request) bool {
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return tokenListContainsValue(r.Header, "Connection", "upgrade") &&
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tokenListContainsValue(r.Header, "Upgrade", "websocket")
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}
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