Bind init

iface/bind/bind.go

@@ -0,0 +1,174 @@
+package bind
+
+import (
+	"errors"
+	"fmt"
+	"github.com/pion/stun"
+	log "github.com/sirupsen/logrus"
+	"golang.zx2c4.com/wireguard/conn"
+	"net"
+	"net/netip"
+	"sync"
+	"syscall"
+)
+
+type ICEBind struct {
+	sharedConn net.PacketConn
+	udpMux     *UniversalUDPMuxDefault
+
+	mu sync.Mutex // protects following fields
+}
+
+func (b *ICEBind) GetICEMux() (*UniversalUDPMuxDefault, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+	if b.udpMux == nil {
+		return nil, fmt.Errorf("ICEBind has not been initialized yet")
+	}
+
+	return b.udpMux, nil
+}
+
+func (b *ICEBind) Open(uport uint16) ([]conn.ReceiveFunc, uint16, error) {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	if b.sharedConn != nil {
+		return nil, 0, conn.ErrBindAlreadyOpen
+	}
+
+	port := int(uport)
+	ipv4Conn, port, err := listenNet("udp4", port)
+	if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
+		return nil, 0, err
+	}
+	b.sharedConn = ipv4Conn
+	b.udpMux = NewUniversalUDPMuxDefault(UniversalUDPMuxParams{UDPConn: b.sharedConn})
+
+	portAddr1, err := netip.ParseAddrPort(ipv4Conn.LocalAddr().String())
+	if err != nil {
+		return nil, 0, err
+	}
+
+	log.Infof("opened ICEBind on %s", ipv4Conn.LocalAddr().String())
+
+	return []conn.ReceiveFunc{
+			b.makeReceiveIPv4(b.sharedConn),
+		},
+		portAddr1.Port(), nil
+}
+
+func listenNet(network string, port int) (*net.UDPConn, int, error) {
+	conn, err := net.ListenUDP(network, &net.UDPAddr{Port: port})
+	if err != nil {
+		return nil, 0, err
+	}
+
+	// Retrieve port.
+	laddr := conn.LocalAddr()
+	uaddr, err := net.ResolveUDPAddr(
+		laddr.Network(),
+		laddr.String(),
+	)
+	if err != nil {
+		return nil, 0, err
+	}
+	return conn, uaddr.Port, nil
+}
+
+func parseSTUNMessage(raw []byte) (*stun.Message, error) {
+	msg := &stun.Message{
+		Raw: append([]byte{}, raw...),
+	}
+	if err := msg.Decode(); err != nil {
+		return nil, err
+	}
+
+	return msg, nil
+}
+
+func (b *ICEBind) makeReceiveIPv4(c net.PacketConn) conn.ReceiveFunc {
+	return func(buff []byte) (int, conn.Endpoint, error) {
+		n, endpoint, err := c.ReadFrom(buff)
+		if err != nil {
+			return 0, nil, err
+		}
+		e, err := netip.ParseAddrPort(endpoint.String())
+		if err != nil {
+			return 0, nil, err
+		}
+		if !stun.IsMessage(buff[:20]) {
+			// WireGuard traffic
+			return n, (*conn.StdNetEndpoint)(&net.UDPAddr{
+				IP:   e.Addr().AsSlice(),
+				Port: int(e.Port()),
+				Zone: e.Addr().Zone(),
+			}), nil
+		}
+
+		msg, err := parseSTUNMessage(buff[:n])
+		if err != nil {
+			return 0, nil, err
+		}
+
+		err = b.udpMux.HandleSTUNMessage(msg, endpoint)
+		if err != nil {
+			return 0, nil, err
+		}
+		if err != nil {
+			log.Warnf("failed to handle packet")
+		}
+
+		// discard packets because they are STUN related
+		return 0, nil, nil //todo proper return
+	}
+}
+
+func (b *ICEBind) Close() error {
+	b.mu.Lock()
+	defer b.mu.Unlock()
+
+	var err1, err2 error
+	if b.sharedConn != nil {
+		c := b.sharedConn
+		b.sharedConn = nil
+		err1 = c.Close()
+	}
+
+	if b.udpMux != nil {
+		m := b.udpMux
+		b.udpMux = nil
+		err2 = m.Close()
+	}
+
+	if err1 != nil {
+		return err1
+	}
+
+	return err2
+}
+
+// SetMark sets the mark for each packet sent through this Bind.
+// This mark is passed to the kernel as the socket option SO_MARK.
+func (b *ICEBind) SetMark(mark uint32) error {
+	return nil
+}
+
+func (b *ICEBind) Send(buff []byte, endpoint conn.Endpoint) error {
+	nend, ok := endpoint.(*conn.StdNetEndpoint)
+	if !ok {
+		return conn.ErrWrongEndpointType
+	}
+	_, err := b.sharedConn.WriteTo(buff, (*net.UDPAddr)(nend))
+	return err
+}
+
+// ParseEndpoint creates a new endpoint from a string.
+func (b *ICEBind) ParseEndpoint(s string) (ep conn.Endpoint, err error) {
+	e, err := netip.ParseAddrPort(s)
+	return (*conn.StdNetEndpoint)(&net.UDPAddr{
+		IP:   e.Addr().AsSlice(),
+		Port: int(e.Port()),
+		Zone: e.Addr().Zone(),
+	}), err
+}