mirror of https://github.com/gorilla/websocket.git
185 lines
5.0 KiB
Go
185 lines
5.0 KiB
Go
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// Copyright 2013 Gary Burd. All rights reserved.
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// Copyright 2014 Joachim Bauch. 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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"time"
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)
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const (
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DEFAULT_READ_BUFFER_SIZE = 4096
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DEFAULT_WRITE_BUFFER_SIZE = 4096
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)
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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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// Input and output buffer sizes. If the buffer size is zero, then
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// default values will be used.
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ReadBufferSize, WriteBufferSize int
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// Subprotocols specifies the server's supported protocols. If Subprotocols
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// is nil, then Upgrade does not negotiate a subprotocol.
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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.
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// If CheckOrigin is nil, then no origin check is done.
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CheckOrigin func(r *http.Request) bool
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}
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// Return an error depending on settings on the Upgrader
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func (u *Upgrader) returnError(w http.ResponseWriter, r *http.Request, status int, reason error) {
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if u.Error != nil {
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u.Error(w, r, status, reason)
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} else {
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http.Error(w, reason.Error(), status)
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}
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}
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// Check if the passed subprotocol is supported by the server
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func (u *Upgrader) hasSubprotocol(subprotocol string) bool {
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if u.Subprotocols == nil {
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return false
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}
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for _, s := range u.Subprotocols {
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if s == subprotocol {
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return true
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}
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}
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return false
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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).
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//
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// The connection buffers IO to the underlying network connection.
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// 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. Depending on settings on the Upgrader,
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// an error message already has been returned to the caller.
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func (u *Upgrader) Upgrade(w http.ResponseWriter, r *http.Request, responseHeader http.Header) (*Conn, error) {
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if values := r.Header["Sec-Websocket-Version"]; len(values) == 0 || values[0] != "13" {
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err := HandshakeError{"websocket: version != 13"}
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u.returnError(w, r, http.StatusBadRequest, err)
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return nil, err
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}
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if !tokenListContainsValue(r.Header, "Connection", "upgrade") {
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err := HandshakeError{"websocket: connection header != upgrade"}
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u.returnError(w, r, http.StatusBadRequest, err)
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return nil, err
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}
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if !tokenListContainsValue(r.Header, "Upgrade", "websocket") {
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err := HandshakeError{"websocket: upgrade != websocket"}
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u.returnError(w, r, http.StatusBadRequest, err)
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return nil, err
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}
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if u.CheckOrigin != nil && !u.CheckOrigin(r) {
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err := HandshakeError{"websocket: origin not allowed"}
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u.returnError(w, r, http.StatusForbidden, err)
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return nil, err
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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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err := HandshakeError{"websocket: key missing or blank"}
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u.returnError(w, r, http.StatusBadRequest, err)
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return nil, err
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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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readBufSize := u.ReadBufferSize
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if readBufSize == 0 {
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readBufSize = DEFAULT_READ_BUFFER_SIZE
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}
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writeBufSize := u.WriteBufferSize
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if writeBufSize == 0 {
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writeBufSize = DEFAULT_WRITE_BUFFER_SIZE
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}
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c := newConn(netConn, true, readBufSize, writeBufSize)
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if u.Subprotocols != nil {
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for _, proto := range Subprotocols(r) {
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if u.hasSubprotocol(proto) {
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c.subprotocol = proto
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break
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}
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}
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}
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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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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 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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return c, nil
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}
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