Make TCPMux IPv4/IPv6 aware

TCPMux before would create one internal connection per ufrag. This could
cause remote IPv6 traffic to be dispatched to a local IPv4 handler (or
the inverse). The ice.Agent would then discard the traffic since a
candidate pair must be the same IP version.

This commit now creates two connections per ufrag. When requesting a
connection for a ufrag the user must specify if they want IPv4 or IPv6.

Relates to pion/webrtc#2125
Relates to pion/webrtc#1356

gather.go

@@ -177,7 +177,7 @@ func (a *Agent) gatherCandidatesLocal(ctx context.Context, networkTypes []Networ
 			case tcp:
 				// Handle ICE TCP passive mode
 				a.log.Debugf("GetConn by ufrag: %s\n", a.localUfrag)
-				conn, err = a.tcpMux.GetConnByUfrag(a.localUfrag)
+				conn, err = a.tcpMux.GetConnByUfrag(a.localUfrag, mappedIP.To4() == nil)
 				if err != nil {
 					if !errors.Is(err, ErrTCPMuxNotInitialized) {
 						a.log.Warnf("error getting tcp conn by ufrag: %s %s %s\n", network, ip, a.localUfrag)

tcp_mux.go

@@ -19,7 +19,7 @@ import (
 // 2. allow mocking in tests.
 type TCPMux interface {
 	io.Closer
-	GetConnByUfrag(ufrag string) (net.PacketConn, error)
+	GetConnByUfrag(ufrag string, isIPv6 bool) (net.PacketConn, error)
 	RemoveConnByUfrag(ufrag string)
 }
 
@@ -36,7 +36,7 @@ func (m *invalidTCPMux) Close() error {
 }
 
 // GetConnByUfrag implements TCPMux interface.
-func (m *invalidTCPMux) GetConnByUfrag(ufrag string) (net.PacketConn, error) {
+func (m *invalidTCPMux) GetConnByUfrag(ufrag string, isIPv6 bool) (net.PacketConn, error) {
 	return nil, ErrTCPMuxNotInitialized
 }
 
@@ -49,8 +49,8 @@ type TCPMuxDefault struct {
 	params *TCPMuxParams
 	closed bool
 
-	// conns is a map of all tcpPacketConns indexed by ufrag
-	conns map[string]*tcpPacketConn
+	// connsIPv4 and connsIPv6 are maps of all tcpPacketConns indexed by ufrag
+	connsIPv4, connsIPv6 map[string]*tcpPacketConn
 
 	mu sync.Mutex
 	wg sync.WaitGroup
@@ -72,7 +72,8 @@ func NewTCPMuxDefault(params TCPMuxParams) *TCPMuxDefault {
 	m := &TCPMuxDefault{
 		params: &params,
 
-		conns: map[string]*tcpPacketConn{},
+		connsIPv4: map[string]*tcpPacketConn{},
+		connsIPv6: map[string]*tcpPacketConn{},
 	}
 
 	m.wg.Add(1)
@@ -109,33 +110,33 @@ func (m *TCPMuxDefault) LocalAddr() net.Addr {
 }
 
 // GetConnByUfrag retrieves an existing or creates a new net.PacketConn.
-func (m *TCPMuxDefault) GetConnByUfrag(ufrag string) (net.PacketConn, error) {
+func (m *TCPMuxDefault) GetConnByUfrag(ufrag string, isIPv6 bool) (net.PacketConn, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
 	if m.closed {
 		return nil, io.ErrClosedPipe
 	}
 
-	conn, ok := m.conns[ufrag]
-
-	if ok {
+	if conn, ok := m.getConn(ufrag, isIPv6); ok {
 		return conn, nil
-		// return nil, fmt.Errorf("duplicate ufrag %v", ufrag)
 	}
 
-	conn = m.createConn(ufrag, m.LocalAddr())
-
-	return conn, nil
+	return m.createConn(ufrag, m.LocalAddr(), isIPv6), nil
 }
 
-func (m *TCPMuxDefault) createConn(ufrag string, localAddr net.Addr) *tcpPacketConn {
+func (m *TCPMuxDefault) createConn(ufrag string, localAddr net.Addr, isIPv6 bool) *tcpPacketConn {
 	conn := newTCPPacketConn(tcpPacketParams{
 		ReadBuffer: m.params.ReadBufferSize,
 		LocalAddr:  localAddr,
 		Logger:     m.params.Logger,
 	})
-	m.conns[ufrag] = conn
+
+	if isIPv6 {
+		m.connsIPv6[ufrag] = conn
+	} else {
+		m.connsIPv4[ufrag] = conn
+	}
 
 	m.wg.Add(1)
 	go func() {
@@ -199,9 +200,17 @@ func (m *TCPMuxDefault) handleConn(conn net.Conn) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	packetConn, ok := m.conns[ufrag]
+	host, _, err := net.SplitHostPort(conn.RemoteAddr().String())
+	if err != nil {
+		m.closeAndLogError(conn)
+		m.params.Logger.Warnf("Failed to get host in STUN message from %s to %s\n", conn.RemoteAddr(), conn.LocalAddr())
+		return
+	}
+
+	isIPv6 := net.ParseIP(host).To4() == nil
+	packetConn, ok := m.getConn(ufrag, isIPv6)
 	if !ok {
-		packetConn = m.createConn(ufrag, conn.LocalAddr())
+		packetConn = m.createConn(ufrag, conn.LocalAddr(), isIPv6)
 	}
 
 	if err := packetConn.AddConn(conn, buf); err != nil {
@@ -216,10 +225,15 @@ func (m *TCPMuxDefault) Close() error {
 	m.mu.Lock()
 	m.closed = true
 
-	for _, conn := range m.conns {
+	for _, conn := range m.connsIPv4 {
 		m.closeAndLogError(conn)
 	}
-	m.conns = map[string]*tcpPacketConn{}
+	for _, conn := range m.connsIPv6 {
+		m.closeAndLogError(conn)
+	}
+
+	m.connsIPv4 = map[string]*tcpPacketConn{}
+	m.connsIPv6 = map[string]*tcpPacketConn{}
 
 	err := m.params.Listener.Close()
 
@@ -235,12 +249,27 @@ func (m *TCPMuxDefault) RemoveConnByUfrag(ufrag string) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 
-	if conn, ok := m.conns[ufrag]; ok {
+	if conn, ok := m.connsIPv4[ufrag]; ok {
+		m.closeAndLogError(conn)
+		delete(m.connsIPv4, ufrag)
+	}
+
+	if conn, ok := m.connsIPv6[ufrag]; ok {
 		m.closeAndLogError(conn)
-		delete(m.conns, ufrag)
+		delete(m.connsIPv6, ufrag)
 	}
 }
 
+func (m *TCPMuxDefault) getConn(ufrag string, isIPv6 bool) (val *tcpPacketConn, ok bool) {
+	if isIPv6 {
+		val, ok = m.connsIPv6[ufrag]
+	} else {
+		val, ok = m.connsIPv4[ufrag]
+	}
+
+	return
+}
+
 const streamingPacketHeaderLen = 2
 
 // readStreamingPacket reads 1 packet from stream

tcp_mux_test.go

@@ -55,7 +55,7 @@ func TestTCPMux_Recv(t *testing.T) {
 	n, err := writeStreamingPacket(conn, msg.Raw)
 	require.NoError(t, err, "error writing tcp stun packet")
 
-	pktConn, err := tcpMux.GetConnByUfrag("myufrag")
+	pktConn, err := tcpMux.GetConnByUfrag("myufrag", false)
 	require.NoError(t, err, "error retrieving muxed connection for ufrag")
 	defer func() {
 		_ = pktConn.Close()
@@ -90,12 +90,12 @@ func TestTCPMux_NoDeadlockWhenClosingUnusedPacketConn(t *testing.T) {
 		ReadBufferSize: 20,
 	})
 
-	_, err = tcpMux.GetConnByUfrag("test")
+	_, err = tcpMux.GetConnByUfrag("test", false)
 	require.NoError(t, err, "error getting conn by ufrag")
 
 	require.NoError(t, tcpMux.Close(), "error closing tcpMux")
 
-	conn, err := tcpMux.GetConnByUfrag("test")
+	conn, err := tcpMux.GetConnByUfrag("test", false)
 	assert.Nil(t, conn, "should receive nil because mux is closed")
 	assert.Equal(t, io.ErrClosedPipe, err, "should receive error because mux is closed")
 }