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listener.go
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listener.go
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package tinywss
import (
"bytes"
"crypto/tls"
"errors"
"fmt"
"net"
"net/http"
"strings"
"sync"
"time"
"github.com/getlantern/ops"
)
// Configuration options for ListenAddr
type ListenOpts struct {
Addr string
CertFile string
KeyFile string
TLSConf *tls.Config
HandshakeTimeout time.Duration
Protocols []string // allowed protocols
// If provided, this listener is used instead of starting
// a TLS listener using the tls configuration specified.
// Addr, CertFile, KeyFile and TLSConf are ignored if this
// is given.
Listener net.Listener
// Multiplex options
KeepAliveInterval time.Duration
KeepAliveTimeout time.Duration
MaxFrameSize int
MaxReceiveBuffer int
}
// ListenAddr starts a tinywss server listening at the
// configured address.
func ListenAddr(opts *ListenOpts) (net.Listener, error) {
l, err := listenAddr(opts)
if err != nil {
return nil, err
}
if l.supportsProtocol(ProtocolMux) {
return wrapListenerSmux(l, opts)
} else {
return l, nil
}
}
func listenAddr(opts *ListenOpts) (*listener, error) {
handshakeTimeout := opts.HandshakeTimeout
if handshakeTimeout == 0 {
handshakeTimeout = defaultHandshakeTimeout
}
var err error
ll := opts.Listener
if ll == nil {
ll, err = newTLSListener(opts)
if err != nil {
return nil, err
}
} else if opts.Addr != "" {
return nil, fmt.Errorf("tinywss: cannot specify address and wrapped listener")
}
l := &listener{
connections: make(chan net.Conn, 1000),
closed: make(chan struct{}),
handshakeTimeout: handshakeTimeout,
innerListener: ll,
}
var protos []string
if len(opts.Protocols) > 0 {
protos = opts.Protocols
} else {
protos = defaultProtocols
}
l.protocols = make([]string, len(protos))
copy(l.protocols, protos)
l.srv = &http.Server{
Addr: opts.Addr,
Handler: http.HandlerFunc(l.handleRequest),
}
ops.Go(func() {
l.listen()
})
return l, nil
}
var _ net.Listener = &listener{}
type listener struct {
srv *http.Server
connections chan net.Conn
closed chan struct{}
mx sync.Mutex
innerListener net.Listener
protocols []string
handshakeTimeout time.Duration
}
func (l *listener) listen() {
err := l.srv.Serve(l.innerListener)
if err != http.ErrServerClosed {
log.Errorf("tinywss listener: %s", err)
}
l.Close()
}
// implements net.Listener.Accept
func (l *listener) Accept() (net.Conn, error) {
select {
case conn, ok := <-l.connections:
if !ok {
return nil, ErrListenerClosed
}
return conn, nil
case <-l.closed:
return nil, ErrListenerClosed
}
}
// implements net.Listener.Close
func (l *listener) Close() error {
l.mx.Lock()
defer l.mx.Unlock()
select {
case <-l.closed:
return nil
default:
close(l.closed)
return l.srv.Close()
}
}
// implements net.Listener.Addr
func (l *listener) Addr() net.Addr {
return l.innerListener.Addr()
}
func (l *listener) handleRequest(w http.ResponseWriter, r *http.Request) {
conn, err := l.upgrade(w, r)
if err != nil {
if conn != nil {
conn.Close()
}
if _, ok := err.(HandshakeError); ok {
log.Debugf("error upgrading request: %s", err)
} else {
log.Errorf("error upgrading request: %s", err)
}
return
}
l.connections <- conn
}
func (l *listener) upgrade(w http.ResponseWriter, r *http.Request) (net.Conn, error) {
if r.Method != "GET" {
sendError(w, http.StatusBadRequest)
return nil, handshakeErr("request method must be GET")
}
if !headerHasValue(r.Header, "Connection", "upgrade") {
sendError(w, http.StatusBadRequest)
return nil, handshakeErr("`Connection` header is missing or invalid")
}
if !headerHasValue(r.Header, "Upgrade", "websocket") {
sendError(w, http.StatusBadRequest)
return nil, handshakeErr("`Upgrade` header is missing or invalid")
}
wskey := r.Header.Get("Sec-Websocket-Key")
if wskey == "" {
sendError(w, http.StatusBadRequest)
return nil, handshakeErr("`Sec-WebSocket-Key' header is missing or invalid")
}
wsproto := r.Header.Get("Sec-Websocket-Protocol")
if !l.supportsProtocol(wsproto) {
sendError(w, http.StatusBadRequest)
return nil, handshakeErr(fmt.Sprintf("`Sec-WebSocket-Protocol' header is missing or invalid (%s)", wsproto))
}
h, ok := w.(http.Hijacker)
if !ok {
return nil, errors.New("response was not http.Hijacker")
}
conn, buf, err := h.Hijack()
if err != nil {
return nil, err
}
err = conn.SetDeadline(time.Time{})
if err != nil {
return conn, err
}
if buf.Reader.Buffered() > 0 {
return conn, handshakeErr("request payload before handshake")
}
hdr := make(http.Header, 0)
hdr.Set("Connection", "Upgrade")
hdr.Set("Upgrade", "websocket")
hdr.Set("Sec-WebSocket-Accept", acceptForKey(wskey))
hdr.Set("Sec-WebSocket-Protocol", wsproto)
res := bytes.NewBufferString("HTTP/1.1 101 Switching Protocols\r\n")
hdr.Write(res)
res.WriteString("\r\n")
if l.handshakeTimeout > 0 {
conn.SetWriteDeadline(time.Now().Add(l.handshakeTimeout))
}
if _, err = conn.Write(res.Bytes()); err != nil {
return conn, err
}
if l.handshakeTimeout > 0 {
conn.SetWriteDeadline(time.Time{})
}
return &WsConn{
Conn: conn,
protocol: wsproto,
headers: cloneHeaders(r.Header),
}, nil
}
func (l *listener) supportsProtocol(p string) bool {
for _, proto := range l.protocols {
if strings.EqualFold(proto, p) {
return true
}
}
return false
}
// default inner listener
func newTLSListener(opts *ListenOpts) (net.Listener, error) {
l, err := net.Listen("tcp", opts.Addr)
if err != nil {
return nil, err
}
var tlsConf *tls.Config
if opts.TLSConf == nil {
tlsConf = &tls.Config{}
} else {
tlsConf = opts.TLSConf.Clone()
}
if !strSliceContains(tlsConf.NextProtos, "http/1.1") {
tlsConf.NextProtos = append(tlsConf.NextProtos, "http/1.1")
}
hasCert := len(tlsConf.Certificates) > 0 || tlsConf.GetCertificate != nil
if !hasCert || opts.CertFile != "" || opts.KeyFile != "" {
var err error
tlsConf.Certificates = make([]tls.Certificate, 1)
tlsConf.Certificates[0], err = tls.LoadX509KeyPair(opts.CertFile, opts.KeyFile)
if err != nil {
return nil, err
}
}
tl := tls.NewListener(l, tlsConf)
return tl, nil
}