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server.go
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server.go
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package websocket
import (
"bufio"
"context"
"math/rand"
"net"
"net/http"
"strings"
"time"
"golang.org/x/net/websocket"
"github.com/faireal/trojan-go/common"
"github.com/faireal/trojan-go/config"
"github.com/faireal/trojan-go/log"
"github.com/faireal/trojan-go/redirector"
"github.com/faireal/trojan-go/tunnel"
)
// Fake response writer
// Websocket ServeHTTP method uses Hijack method to get the ReadWriter
type fakeHTTPResponseWriter struct {
http.Hijacker
http.ResponseWriter
ReadWriter *bufio.ReadWriter
Conn net.Conn
}
func (w *fakeHTTPResponseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
return w.Conn, w.ReadWriter, nil
}
type Server struct {
underlay tunnel.Server
hostname string
path string
enabled bool
redirAddr net.Addr
redir *redirector.Redirector
ctx context.Context
cancel context.CancelFunc
timeout time.Duration
}
func (s *Server) Close() error {
s.cancel()
return s.underlay.Close()
}
func (s *Server) AcceptConn(tunnel.Tunnel) (tunnel.Conn, error) {
conn, err := s.underlay.AcceptConn(&Tunnel{})
if err != nil {
return nil, common.NewError("websocket failed to accept connection from underlying server")
}
if !s.enabled {
s.redir.Redirect(&redirector.Redirection{
InboundConn: conn,
RedirectTo: s.redirAddr,
})
return nil, common.NewError("websocket is disabled. redirecting http request from " + conn.RemoteAddr().String())
}
rewindConn := common.NewRewindConn(conn)
rewindConn.SetBufferSize(512)
defer rewindConn.StopBuffering()
rw := bufio.NewReadWriter(bufio.NewReader(rewindConn), bufio.NewWriter(rewindConn))
req, err := http.ReadRequest(rw.Reader)
if err != nil {
log.Debug("invalid http request")
rewindConn.Rewind()
rewindConn.StopBuffering()
s.redir.Redirect(&redirector.Redirection{
InboundConn: rewindConn,
RedirectTo: s.redirAddr,
})
return nil, common.NewError("not a valid http request: " + conn.RemoteAddr().String()).Base(err)
}
if strings.ToLower(req.Header.Get("Upgrade")) != "websocket" || req.URL.Path != s.path {
log.Debug("invalid http websocket handshake request")
rewindConn.Rewind()
rewindConn.StopBuffering()
s.redir.Redirect(&redirector.Redirection{
InboundConn: rewindConn,
RedirectTo: s.redirAddr,
})
return nil, common.NewError("not a valid websocket handshake request: " + conn.RemoteAddr().String()).Base(err)
}
handshake := make(chan struct{})
url := "wss://" + s.hostname + s.path
origin := "https://" + s.hostname
wsConfig, err := websocket.NewConfig(url, origin)
if err != nil {
return nil, common.NewError("failed to create websocket config").Base(err)
}
var wsConn *websocket.Conn
ctx, cancel := context.WithCancel(s.ctx)
wsServer := websocket.Server{
Config: *wsConfig,
Handler: func(conn *websocket.Conn) {
wsConn = conn // store the websocket after handshaking
wsConn.PayloadType = websocket.BinaryFrame // treat it as a binary websocket
log.Debug("websocket obtained")
handshake <- struct{}{}
// this function SHOULD NOT return unless the connection is ended
// or the websocket will be closed by ServeHTTP method
<-ctx.Done()
log.Debug("websocket closed")
},
Handshake: func(wsConfig *websocket.Config, httpRequest *http.Request) error {
log.Debug("websocket url", httpRequest.URL, "origin", httpRequest.Header.Get("Origin"))
return nil
},
}
respWriter := &fakeHTTPResponseWriter{
Conn: conn,
ReadWriter: rw,
}
go wsServer.ServeHTTP(respWriter, req)
select {
case <-handshake:
case <-time.After(s.timeout):
}
if wsConn == nil {
cancel()
return nil, common.NewError("websocket failed to handshake")
}
return &InboundConn{
OutboundConn: OutboundConn{
tcpConn: conn,
Conn: wsConn,
},
ctx: ctx,
cancel: cancel,
}, nil
}
func (s *Server) AcceptPacket(tunnel.Tunnel) (tunnel.PacketConn, error) {
return nil, common.NewError("not supported")
}
func NewServer(ctx context.Context, underlay tunnel.Server) (*Server, error) {
cfg := config.FromContext(ctx, Name).(*Config)
if cfg.Websocket.Enabled {
if !strings.HasPrefix(cfg.Websocket.Path, "/") {
return nil, common.NewError("websocket path must start with \"/\"")
}
}
if cfg.RemoteHost == "" {
log.Warn("empty websocket redirection hostname")
cfg.RemoteHost = cfg.Websocket.Host
}
if cfg.RemotePort == 0 {
log.Warn("empty websocket redirection port")
cfg.RemotePort = 80
}
ctx, cancel := context.WithCancel(ctx)
log.Debug("websocket server created")
return &Server{
enabled: cfg.Websocket.Enabled,
hostname: cfg.Websocket.Host,
path: cfg.Websocket.Path,
ctx: ctx,
cancel: cancel,
underlay: underlay,
timeout: time.Second * time.Duration(rand.Intn(10)+5),
redir: redirector.NewRedirector(ctx),
redirAddr: tunnel.NewAddressFromHostPort("tcp", cfg.RemoteHost, cfg.RemotePort),
}, nil
}