func (ut *udpConnTrack) run() {
// connect to socks
var e error
for i := 0; i < 2; i++ {
ut.socksConn, e = dialLocalSocks(ut.localSocksAddr)
if e != nil {
log.Printf("fail to connect SOCKS proxy: %s", e)
} else {
// need to finish handshake in 1 mins
ut.socksConn.SetDeadline(time.Now().Add(time.Minute * 1))
break
}
}
if ut.socksConn == nil {
close(ut.socksClosed)
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
return
}
// create one UDP to recv/send packets
socksAddr := ut.socksConn.LocalAddr().(*net.TCPAddr)
udpBind, err := net.ListenUDP("udp", &net.UDPAddr{
IP: socksAddr.IP,
Port: 0,
Zone: socksAddr.Zone,
})
if err != nil {
log.Printf("error in binding local UDP: %s", err)
ut.socksConn.Close()
close(ut.socksClosed)
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
return
}
// socks request/reply
_, e = gosocks.WriteSocksRequest(ut.socksConn, &gosocks.SocksRequest{
Cmd: gosocks.SocksCmdUDPAssociate,
HostType: gosocks.SocksIPv4Host,
DstHost: "0.0.0.0",
DstPort: 0,
})
if e != nil {
log.Printf("error to send socks request: %s", e)
ut.socksConn.Close()
close(ut.socksClosed)
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
return
}
reply, e := gosocks.ReadSocksReply(ut.socksConn)
if e != nil {
log.Printf("error to read socks reply: %s", e)
ut.socksConn.Close()
close(ut.socksClosed)
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
return
}
if reply.Rep != gosocks.SocksSucceeded {
log.Printf("socks connect request fail, retcode: %d", reply.Rep)
ut.socksConn.Close()
close(ut.socksClosed)
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
return
}
relayAddr := gosocks.SocksAddrToNetAddr("udp", reply.BndHost, reply.BndPort).(*net.UDPAddr)
ut.socksConn.SetDeadline(time.Time{})
// monitor socks TCP connection
go gosocks.ConnMonitor(ut.socksConn, ut.socksClosed)
// read UDP packets from relay
quitUDP := make(chan bool)
chRelayUDP := make(chan *gosocks.UDPPacket)
go gosocks.UDPReader(udpBind, chRelayUDP, quitUDP)
for {
var t *time.Timer
if ut.t2s.isDNS(ut.remoteIP.String(), ut.remotePort) {
t = time.NewTimer(10 * time.Second)
} else {
t = time.NewTimer(2 * time.Minute)
}
select {
// pkt from relay
case pkt, ok := <-chRelayUDP:
if !ok {
ut.socksConn.Close()
udpBind.Close()
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
close(quitUDP)
return
}
if pkt.Addr.String() != relayAddr.String() {
continue
}
udpReq, err := gosocks.ParseUDPRequest(pkt.Data)
if err != nil {
log.Printf("error to parse UDP request from relay: %s", err)
continue
}
if udpReq.Frag != gosocks.SocksNoFragment {
continue
}
ut.send(udpReq.Data)
if ut.t2s.isDNS(ut.remoteIP.String(), ut.remotePort) {
// DNS-without-fragment only has one request-response
log.Printf("DNS session")
if ut.t2s.cache != nil {
ut.t2s.cache.store(udpReq.Data)
}
ut.socksConn.Close()
udpBind.Close()
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
close(quitUDP)
return
}
// pkt from tun
case pkt := <-ut.fromTunCh:
req := &gosocks.UDPRequest{
Frag: 0,
HostType: gosocks.SocksIPv4Host,
DstHost: pkt.ip.DstIP.String(),
DstPort: uint16(pkt.udp.DstPort),
Data: pkt.udp.Payload,
}
datagram := gosocks.PackUDPRequest(req)
_, err := udpBind.WriteToUDP(datagram, relayAddr)
releaseUDPPacket(pkt)
if err != nil {
log.Printf("error to send UDP packet to relay: %s", err)
ut.socksConn.Close()
udpBind.Close()
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
close(quitUDP)
return
}
case <-ut.socksClosed:
ut.socksConn.Close()
udpBind.Close()
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
close(quitUDP)
return
case <-t.C:
ut.socksConn.Close()
udpBind.Close()
close(ut.quitBySelf)
ut.t2s.clearUDPConnTrack(ut.id)
close(quitUDP)
return
case <-ut.quitByOther:
log.Printf("udpConnTrack quitByOther")
ut.socksConn.Close()
udpBind.Close()
close(quitUDP)
return
}
t.Stop()
}
}
func (tt *tcpConnTrack) tcpSocks2Tun(dstIP net.IP, dstPort uint16, conn net.Conn, readCh chan<- []byte, writeCh <-chan *tcpPacket, closeCh chan bool) {
_, e := gosocks.WriteSocksRequest(conn, &gosocks.SocksRequest{
Cmd: gosocks.SocksCmdConnect,
HostType: gosocks.SocksIPv4Host,
DstHost: dstIP.String(),
DstPort: dstPort,
})
if e != nil {
log.Printf("error to send socks request: %s", e)
conn.Close()
close(closeCh)
return
}
reply, e := gosocks.ReadSocksReply(conn)
if e != nil {
log.Printf("error to read socks reply: %s", e)
conn.Close()
close(closeCh)
return
}
if reply.Rep != gosocks.SocksSucceeded {
log.Printf("socks connect request fail, retcode: %d", reply.Rep)
conn.Close()
close(closeCh)
return
}
// writer
go func() {
loop:
for {
select {
case <-closeCh:
break loop
case pkt := <-writeCh:
conn.Write(pkt.tcp.Payload)
// increase window when processed
wnd := atomic.LoadInt32(&tt.recvWindow)
wnd += int32(len(pkt.tcp.Payload))
if wnd > int32(MAX_RECV_WINDOW) {
wnd = int32(MAX_RECV_WINDOW)
}
atomic.StoreInt32(&tt.recvWindow, wnd)
releaseTCPPacket(pkt)
}
}
}()
// reader
for {
var buf [MTU - 40]byte
// tt.sendWndCond.L.Lock()
var wnd int32
var cur int32
wnd = atomic.LoadInt32(&tt.sendWindow)
if wnd <= 0 {
for wnd <= 0 {
tt.sendWndCond.L.Lock()
tt.sendWndCond.Wait()
wnd = atomic.LoadInt32(&tt.sendWindow)
}
tt.sendWndCond.L.Unlock()
}
cur = wnd
if cur > MTU-40 {
cur = MTU - 40
}
// tt.sendWndCond.L.Unlock()
n, e := conn.Read(buf[:cur])
if e != nil {
log.Printf("error to read from socks: %s", e)
conn.Close()
break
} else {
b := make([]byte, n)
copy(b, buf[:n])
readCh <- b
// tt.sendWndCond.L.Lock()
nxt := wnd - int32(n)
if nxt < 0 {
nxt = 0
}
// if sendWindow does not equal to wnd, it is already updated by a
// received pkt from TUN
atomic.CompareAndSwapInt32(&tt.sendWindow, wnd, nxt)
// tt.sendWndCond.L.Unlock()
}
}
close(closeCh)
}