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// 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"
"io"
"io/ioutil"
"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.
type Dialer struct {
// NetDial specifies the dial function for creating TCP connections. If
// NetDial is nil, net.Dial is used.
NetDial func(network, addr string) (net.Conn, error)
// NetDialContext specifies the dial function for creating TCP connections. If
// NetDialContext is nil, net.DialContext is used.
NetDialContext 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.
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: "GET",
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()
}
// Get network dial function.
var netDial func(network, add string) (net.Conn, error)
if d.NetDialContext != nil {
netDial = func(network, addr string) (net.Conn, error) {
return d.NetDialContext(ctx, network, addr)
}
} else if d.NetDial != nil {
netDial = d.NetDial
} else {
netDialer := &net.Dialer{}
netDial = func(network, addr string) (net.Conn, error) {
return netDialer.DialContext(ctx, network, addr)
}
}
// If needed, wrap the dial function to set the connection deadline.
if deadline, ok := ctx.Deadline(); ok {
forwardDial := netDial
netDial = func(network, addr string) (net.Conn, error) {
c, err := forwardDial(network, addr)
if err != nil {
return nil, err
}
err = c.SetDeadline(deadline)
if err != nil {
c.Close()
return nil, err
}
return c, nil
}
}
// If needed, wrap the dial function to connect through a proxy.
if d.Proxy != nil {
proxyURL, err := d.Proxy(req)
if err != nil {
return nil, nil, err
}
if proxyURL != nil {
dialer, err := proxy_FromURL(proxyURL, netDialerFunc(netDial))
if err != nil {
return nil, nil, err
}
netDial = dialer.Dial
}
}
hostPort, hostNoPort := hostPortNoPort(u)
trace := httptrace.ContextClientTrace(ctx)
if trace != nil && trace.GetConn != nil {
trace.GetConn(hostPort)
}
netConn, err := netDial("tcp", hostPort)
if trace != nil && trace.GotConn != nil {
trace.GotConn(httptrace.GotConnInfo{
Conn: netConn,
})
}
if err != nil {
return nil, nil, err
}
defer func() {
if netConn != nil {
netConn.Close()
}
}()
if u.Scheme == "https" {
cfg := cloneTLSConfig(d.TLSClientConfig)
if cfg.ServerName == "" {
cfg.ServerName = hostNoPort
}
tlsConn := tls.Client(netConn, cfg)
netConn = tlsConn
var err error
if trace != nil {
err = doHandshakeWithTrace(trace, tlsConn, cfg)
} else {
err = doHandshake(tlsConn, cfg)
}
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 {
return nil, nil, err
}
if d.Jar != nil {
if rc := resp.Cookies(); len(rc) > 0 {
d.Jar.SetCookies(u, rc)
}
}
if resp.StatusCode != 101 ||
!strings.EqualFold(resp.Header.Get("Upgrade"), "websocket") ||
!strings.EqualFold(resp.Header.Get("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 = ioutil.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 = ioutil.NopCloser(bytes.NewReader([]byte{}))
conn.subprotocol = resp.Header.Get("Sec-Websocket-Protocol")
netConn.SetDeadline(time.Time{})
netConn = nil // to avoid close in defer.
return conn, resp, nil
}
func doHandshake(tlsConn *tls.Conn, cfg *tls.Config) error {
if err := tlsConn.Handshake(); err != nil {
return err
}
if !cfg.InsecureSkipVerify {
if err := tlsConn.VerifyHostname(cfg.ServerName); err != nil {
return err
}
}
return nil
}