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client.go
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client.go
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// Copyright 2013 Gary Burd. 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 (
"errors"
"net"
"net/http"
"net/url"
"strings"
)
// ErrBadHandshake is returned when the server response to opening handshake is
// invalid.
var ErrBadHandshake = errors.New("websocket: bad handshake")
// 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 (Set-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.
func NewClient(netConn net.Conn, u *url.URL, requestHeader http.Header, readBufSize, writeBufSize int) (c *Conn, response *http.Response, err error) {
challengeKey, err := generateChallengeKey()
if err != nil {
return nil, nil, err
}
acceptKey := computeAcceptKey(challengeKey)
c = newConn(netConn, false, readBufSize, writeBufSize)
p := c.writeBuf[:0]
p = append(p, "GET "...)
p = append(p, u.RequestURI()...)
p = append(p, " HTTP/1.1\r\nHost: "...)
p = append(p, u.Host...)
p = append(p, "\r\nUpgrade: websocket\r\nConnection: upgrade\r\nSec-WebSocket-Version: 13\r\nSec-WebSocket-Key: "...)
p = append(p, challengeKey...)
p = append(p, "\r\n"...)
for k, vs := range requestHeader {
for _, v := range vs {
p = append(p, k...)
p = append(p, ": "...)
p = append(p, v...)
p = append(p, "\r\n"...)
}
}
p = append(p, "\r\n"...)
if _, err := netConn.Write(p); err != nil {
return nil, nil, err
}
resp, err := http.ReadResponse(c.br, &http.Request{Method: "GET", URL: u})
if err != nil {
return nil, nil, err
}
if resp.StatusCode != 101 ||
!strings.EqualFold(resp.Header.Get("Upgrade"), "websocket") ||
!strings.EqualFold(resp.Header.Get("Connection"), "upgrade") ||
resp.Header.Get("Sec-Websocket-Accept") != acceptKey {
return nil, resp, ErrBadHandshake
}
return c, resp, nil
}