396 lines
11 KiB
Go
396 lines
11 KiB
Go
// 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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"bytes"
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"context"
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"crypto/tls"
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"errors"
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"io"
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"io/ioutil"
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"net"
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"net/http"
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"net/http/httptrace"
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"net/url"
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"strings"
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"time"
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)
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// ErrBadHandshake is returned when the server response to opening handshake is
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// invalid.
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var ErrBadHandshake = errors.New("websocket: bad handshake")
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var errInvalidCompression = errors.New("websocket: invalid compression negotiation")
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// NewClient creates a new client connection using the given net connection.
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// The URL u specifies the host and request URI. Use requestHeader to specify
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// the origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies
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// (Cookie). Use the response.Header to get the selected subprotocol
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// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
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//
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// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
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// non-nil *http.Response so that callers can handle redirects, authentication,
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// etc.
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//
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// Deprecated: Use Dialer instead.
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func NewClient(netConn net.Conn, u *url.URL, requestHeader http.Header, readBufSize, writeBufSize int) (c *Conn, response *http.Response, err error) {
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d := Dialer{
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ReadBufferSize: readBufSize,
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WriteBufferSize: writeBufSize,
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NetDial: func(net, addr string) (net.Conn, error) {
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return netConn, nil
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},
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}
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return d.Dial(u.String(), requestHeader)
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}
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// A Dialer contains options for connecting to WebSocket server.
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type Dialer struct {
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// NetDial specifies the dial function for creating TCP connections. If
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// NetDial is nil, net.Dial is used.
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NetDial func(network, addr string) (net.Conn, error)
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// NetDialContext specifies the dial function for creating TCP connections. If
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// NetDialContext is nil, net.DialContext is used.
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NetDialContext func(ctx context.Context, network, addr string) (net.Conn, error)
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// Proxy specifies a function to return a proxy for a given
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// Request. If the function returns a non-nil error, the
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// request is aborted with the provided error.
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// If Proxy is nil or returns a nil *URL, no proxy is used.
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Proxy func(*http.Request) (*url.URL, error)
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// TLSClientConfig specifies the TLS configuration to use with tls.Client.
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// If nil, the default configuration is used.
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TLSClientConfig *tls.Config
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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 in bytes. If a buffer
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// size is zero, then a useful default size 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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// WriteBufferPool is a pool of buffers for write operations. If the value
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// is not set, then write buffers are allocated to the connection for the
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// lifetime of the connection.
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//
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// A pool is most useful when the application has a modest volume of writes
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// across a large number of connections.
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//
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// Applications should use a single pool for each unique value of
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// WriteBufferSize.
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WriteBufferPool BufferPool
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// Subprotocols specifies the client's requested subprotocols.
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Subprotocols []string
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// EnableCompression specifies if the client should attempt to negotiate
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// per message compression (RFC 7692). Setting this value to true does not
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// guarantee that compression will be supported. Currently only "no context
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// takeover" modes are supported.
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EnableCompression bool
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// Jar specifies the cookie jar.
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// If Jar is nil, cookies are not sent in requests and ignored
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// in responses.
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Jar http.CookieJar
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}
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// Dial creates a new client connection by calling DialContext with a background context.
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func (d *Dialer) Dial(urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
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return d.DialContext(context.Background(), urlStr, requestHeader)
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}
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var errMalformedURL = errors.New("malformed ws or wss URL")
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func hostPortNoPort(u *url.URL) (hostPort, hostNoPort string) {
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hostPort = u.Host
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hostNoPort = u.Host
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if i := strings.LastIndex(u.Host, ":"); i > strings.LastIndex(u.Host, "]") {
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hostNoPort = hostNoPort[:i]
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} else {
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switch u.Scheme {
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case "wss":
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hostPort += ":443"
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case "https":
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hostPort += ":443"
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default:
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hostPort += ":80"
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}
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}
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return hostPort, hostNoPort
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}
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// DefaultDialer is a dialer with all fields set to the default values.
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var DefaultDialer = &Dialer{
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Proxy: http.ProxyFromEnvironment,
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HandshakeTimeout: 45 * time.Second,
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}
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// nilDialer is dialer to use when receiver is nil.
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var nilDialer = *DefaultDialer
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// DialContext creates a new client connection. Use requestHeader to specify the
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// origin (Origin), subprotocols (Sec-WebSocket-Protocol) and cookies (Cookie).
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// Use the response.Header to get the selected subprotocol
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// (Sec-WebSocket-Protocol) and cookies (Set-Cookie).
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//
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// The context will be used in the request and in the Dialer.
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//
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// If the WebSocket handshake fails, ErrBadHandshake is returned along with a
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// non-nil *http.Response so that callers can handle redirects, authentication,
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// etcetera. The response body may not contain the entire response and does not
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// need to be closed by the application.
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func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader http.Header) (*Conn, *http.Response, error) {
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if d == nil {
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d = &nilDialer
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}
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challengeKey, err := generateChallengeKey()
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if err != nil {
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return nil, nil, err
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}
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u, err := url.Parse(urlStr)
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if err != nil {
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return nil, nil, err
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}
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switch u.Scheme {
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case "ws":
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u.Scheme = "http"
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case "wss":
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u.Scheme = "https"
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default:
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return nil, nil, errMalformedURL
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}
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if u.User != nil {
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// User name and password are not allowed in websocket URIs.
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return nil, nil, errMalformedURL
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}
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req := &http.Request{
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Method: "GET",
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URL: u,
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Proto: "HTTP/1.1",
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ProtoMajor: 1,
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ProtoMinor: 1,
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Header: make(http.Header),
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Host: u.Host,
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}
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req = req.WithContext(ctx)
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// Set the cookies present in the cookie jar of the dialer
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if d.Jar != nil {
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for _, cookie := range d.Jar.Cookies(u) {
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req.AddCookie(cookie)
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}
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}
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// Set the request headers using the capitalization for names and values in
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// RFC examples. Although the capitalization shouldn't matter, there are
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// servers that depend on it. The Header.Set method is not used because the
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// method canonicalizes the header names.
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req.Header["Upgrade"] = []string{"websocket"}
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req.Header["Connection"] = []string{"Upgrade"}
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req.Header["Sec-WebSocket-Key"] = []string{challengeKey}
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req.Header["Sec-WebSocket-Version"] = []string{"13"}
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if len(d.Subprotocols) > 0 {
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req.Header["Sec-WebSocket-Protocol"] = []string{strings.Join(d.Subprotocols, ", ")}
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}
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for k, vs := range requestHeader {
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switch {
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case k == "Host":
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if len(vs) > 0 {
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req.Host = vs[0]
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}
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case k == "Upgrade" ||
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k == "Connection" ||
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k == "Sec-Websocket-Key" ||
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k == "Sec-Websocket-Version" ||
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k == "Sec-Websocket-Extensions" ||
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(k == "Sec-Websocket-Protocol" && len(d.Subprotocols) > 0):
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return nil, nil, errors.New("websocket: duplicate header not allowed: " + k)
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case k == "Sec-Websocket-Protocol":
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req.Header["Sec-WebSocket-Protocol"] = vs
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default:
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req.Header[k] = vs
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}
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}
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if d.EnableCompression {
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req.Header["Sec-WebSocket-Extensions"] = []string{"permessage-deflate; server_no_context_takeover; client_no_context_takeover"}
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}
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if d.HandshakeTimeout != 0 {
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var cancel func()
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ctx, cancel = context.WithTimeout(ctx, d.HandshakeTimeout)
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defer cancel()
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}
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// Get network dial function.
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var netDial func(network, add string) (net.Conn, error)
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if d.NetDialContext != nil {
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netDial = func(network, addr string) (net.Conn, error) {
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return d.NetDialContext(ctx, network, addr)
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}
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} else if d.NetDial != nil {
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netDial = d.NetDial
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} else {
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netDialer := &net.Dialer{}
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netDial = func(network, addr string) (net.Conn, error) {
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return netDialer.DialContext(ctx, network, addr)
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}
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}
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// If needed, wrap the dial function to set the connection deadline.
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if deadline, ok := ctx.Deadline(); ok {
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forwardDial := netDial
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netDial = func(network, addr string) (net.Conn, error) {
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c, err := forwardDial(network, addr)
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if err != nil {
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return nil, err
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}
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err = c.SetDeadline(deadline)
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if err != nil {
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c.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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}
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// If needed, wrap the dial function to connect through a proxy.
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if d.Proxy != nil {
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proxyURL, err := d.Proxy(req)
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if err != nil {
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return nil, nil, err
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}
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if proxyURL != nil {
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dialer, err := proxy_FromURL(proxyURL, netDialerFunc(netDial))
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if err != nil {
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return nil, nil, err
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}
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netDial = dialer.Dial
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}
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}
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hostPort, hostNoPort := hostPortNoPort(u)
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trace := httptrace.ContextClientTrace(ctx)
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if trace != nil && trace.GetConn != nil {
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trace.GetConn(hostPort)
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}
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netConn, err := netDial("tcp", hostPort)
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if trace != nil && trace.GotConn != nil {
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trace.GotConn(httptrace.GotConnInfo{
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Conn: netConn,
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})
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}
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if err != nil {
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return nil, nil, err
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}
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defer func() {
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if netConn != nil {
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netConn.Close()
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}
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}()
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if u.Scheme == "https" {
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cfg := cloneTLSConfig(d.TLSClientConfig)
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if cfg.ServerName == "" {
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cfg.ServerName = hostNoPort
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}
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tlsConn := tls.Client(netConn, cfg)
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netConn = tlsConn
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var err error
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if trace != nil {
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err = doHandshakeWithTrace(trace, tlsConn, cfg)
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} else {
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err = doHandshake(tlsConn, cfg)
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}
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if err != nil {
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return nil, nil, err
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}
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}
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conn := newConn(netConn, false, d.ReadBufferSize, d.WriteBufferSize, d.WriteBufferPool, nil, nil)
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if err := req.Write(netConn); err != nil {
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return nil, nil, err
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}
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if trace != nil && trace.GotFirstResponseByte != nil {
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if peek, err := conn.br.Peek(1); err == nil && len(peek) == 1 {
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trace.GotFirstResponseByte()
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}
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}
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resp, err := http.ReadResponse(conn.br, req)
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if err != nil {
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return nil, nil, err
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}
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if d.Jar != nil {
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if rc := resp.Cookies(); len(rc) > 0 {
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d.Jar.SetCookies(u, rc)
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}
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}
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if resp.StatusCode != 101 ||
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!strings.EqualFold(resp.Header.Get("Upgrade"), "websocket") ||
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!strings.EqualFold(resp.Header.Get("Connection"), "upgrade") ||
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resp.Header.Get("Sec-Websocket-Accept") != computeAcceptKey(challengeKey) {
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// Before closing the network connection on return from this
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// function, slurp up some of the response to aid application
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// debugging.
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buf := make([]byte, 1024)
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n, _ := io.ReadFull(resp.Body, buf)
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resp.Body = ioutil.NopCloser(bytes.NewReader(buf[:n]))
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return nil, resp, ErrBadHandshake
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}
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for _, ext := range parseExtensions(resp.Header) {
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if ext[""] != "permessage-deflate" {
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continue
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}
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_, snct := ext["server_no_context_takeover"]
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_, cnct := ext["client_no_context_takeover"]
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if !snct || !cnct {
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return nil, resp, errInvalidCompression
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}
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conn.newCompressionWriter = compressNoContextTakeover
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conn.newDecompressionReader = decompressNoContextTakeover
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break
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}
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resp.Body = ioutil.NopCloser(bytes.NewReader([]byte{}))
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conn.subprotocol = resp.Header.Get("Sec-Websocket-Protocol")
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netConn.SetDeadline(time.Time{})
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netConn = nil // to avoid close in defer.
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return conn, resp, nil
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}
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func doHandshake(tlsConn *tls.Conn, cfg *tls.Config) error {
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if err := tlsConn.Handshake(); err != nil {
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return err
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}
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if !cfg.InsecureSkipVerify {
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if err := tlsConn.VerifyHostname(cfg.ServerName); err != nil {
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return err
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}
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}
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return nil
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}
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