mirror of https://github.com/gorilla/websocket.git
129 lines
3.6 KiB
Go
129 lines
3.6 KiB
Go
// Copyright 2013 Gary Burd. 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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"strings"
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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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// Upgrade upgrades the HTTP server connection to the WebSocket protocol.
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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 WebSocket subprotocols, then the application is
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// responsible for selecting a subprotocol that is acceptable to the client and
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// echoing that value back to the client. Use the Subprotocols function to get
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// the list of protocols specified by the client. Use the
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// Sec-Websocket-Protocol response header to echo the selected protocol back to
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// the client.
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//
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// Appilcations can set cookies by adding a Set-Cookie header to the response
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// header.
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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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if values := r.Header["Sec-Websocket-Version"]; len(values) == 0 || values[0] != "13" {
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return nil, HandshakeError{"websocket: version != 13"}
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}
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if !tokenListContainsValue(r.Header, "Connection", "upgrade") {
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return nil, HandshakeError{"websocket: connection header != upgrade"}
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}
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if !tokenListContainsValue(r.Header, "Upgrade", "websocket") {
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return nil, HandshakeError{"websocket: upgrade != websocket"}
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}
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var challengeKey string
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values := r.Header["Sec-Websocket-Key"]
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if len(values) == 0 || values[0] == "" {
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return nil, HandshakeError{"websocket: key missing or blank"}
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}
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challengeKey = values[0]
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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 nil, errors.New("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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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, readBufSize, writeBufSize)
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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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for k, vs := range responseHeader {
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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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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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return c, nil
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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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