[client] Refactor/iface pkg (#2646)

Refactor the flat code structure

client/iface/bind/bind.go

@@ -0,0 +1,142 @@
+package bind
+
+import (
+	"fmt"
+	"net"
+	"runtime"
+	"sync"
+
+	"github.com/pion/stun/v2"
+	"github.com/pion/transport/v3"
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/net/ipv4"
+	wgConn "golang.zx2c4.com/wireguard/conn"
+)
+
+type receiverCreator struct {
+	iceBind *ICEBind
+}
+
+func (rc receiverCreator) CreateIPv4ReceiverFn(msgPool *sync.Pool, pc *ipv4.PacketConn, conn *net.UDPConn) wgConn.ReceiveFunc {
+	return rc.iceBind.createIPv4ReceiverFn(msgPool, pc, conn)
+}
+
+type ICEBind struct {
+	*wgConn.StdNetBind
+
+	muUDPMux sync.Mutex
+
+	transportNet transport.Net
+	udpMux       *UniversalUDPMuxDefault
+
+	filterFn FilterFn
+}
+
+func NewICEBind(transportNet transport.Net, filterFn FilterFn) *ICEBind {
+	ib := &ICEBind{
+		transportNet: transportNet,
+		filterFn:     filterFn,
+	}
+
+	rc := receiverCreator{
+		ib,
+	}
+	ib.StdNetBind = wgConn.NewStdNetBindWithReceiverCreator(rc)
+	return ib
+}
+
+// GetICEMux returns the ICE UDPMux that was created and used by ICEBind
+func (s *ICEBind) GetICEMux() (*UniversalUDPMuxDefault, error) {
+	s.muUDPMux.Lock()
+	defer s.muUDPMux.Unlock()
+	if s.udpMux == nil {
+		return nil, fmt.Errorf("ICEBind has not been initialized yet")
+	}
+
+	return s.udpMux, nil
+}
+
+func (s *ICEBind) createIPv4ReceiverFn(ipv4MsgsPool *sync.Pool, pc *ipv4.PacketConn, conn *net.UDPConn) wgConn.ReceiveFunc {
+	s.muUDPMux.Lock()
+	defer s.muUDPMux.Unlock()
+
+	s.udpMux = NewUniversalUDPMuxDefault(
+		UniversalUDPMuxParams{
+			UDPConn:  conn,
+			Net:      s.transportNet,
+			FilterFn: s.filterFn,
+		},
+	)
+	return func(bufs [][]byte, sizes []int, eps []wgConn.Endpoint) (n int, err error) {
+		msgs := ipv4MsgsPool.Get().(*[]ipv4.Message)
+		defer ipv4MsgsPool.Put(msgs)
+		for i := range bufs {
+			(*msgs)[i].Buffers[0] = bufs[i]
+		}
+		var numMsgs int
+		if runtime.GOOS == "linux" {
+			numMsgs, err = pc.ReadBatch(*msgs, 0)
+			if err != nil {
+				return 0, err
+			}
+		} else {
+			msg := &(*msgs)[0]
+			msg.N, msg.NN, _, msg.Addr, err = conn.ReadMsgUDP(msg.Buffers[0], msg.OOB)
+			if err != nil {
+				return 0, err
+			}
+			numMsgs = 1
+		}
+		for i := 0; i < numMsgs; i++ {
+			msg := &(*msgs)[i]
+
+			// todo: handle err
+			ok, _ := s.filterOutStunMessages(msg.Buffers, msg.N, msg.Addr)
+			if ok {
+				sizes[i] = 0
+			} else {
+				sizes[i] = msg.N
+			}
+
+			addrPort := msg.Addr.(*net.UDPAddr).AddrPort()
+			ep := &wgConn.StdNetEndpoint{AddrPort: addrPort} // TODO: remove allocation
+			wgConn.GetSrcFromControl(msg.OOB[:msg.NN], ep)
+			eps[i] = ep
+		}
+		return numMsgs, nil
+	}
+}
+
+func (s *ICEBind) filterOutStunMessages(buffers [][]byte, n int, addr net.Addr) (bool, error) {
+	for i := range buffers {
+		if !stun.IsMessage(buffers[i]) {
+			continue
+		}
+
+		msg, err := s.parseSTUNMessage(buffers[i][:n])
+		if err != nil {
+			buffers[i] = []byte{}
+			return true, err
+		}
+
+		muxErr := s.udpMux.HandleSTUNMessage(msg, addr)
+		if muxErr != nil {
+			log.Warnf("failed to handle STUN packet")
+		}
+
+		buffers[i] = []byte{}
+		return true, nil
+	}
+	return false, nil
+}
+
+func (s *ICEBind) parseSTUNMessage(raw []byte) (*stun.Message, error) {
+	msg := &stun.Message{
+		Raw: raw,
+	}
+	if err := msg.Decode(); err != nil {
+		return nil, err
+	}
+
+	return msg, nil
+}