Single port handling via UDPMux

Allows for ICE to handle connections on a single UDP port

README.md

@@ -62,6 +62,7 @@ Check out the **[contributing wiki](https://github.com/pion/webrtc/wiki/Contribu
 * [Assad Obaid](https://github.com/assadobaid)
 * [Antoine Baché](https://github.com/Antonito)
 * [Will Forcey](https://github.com/wawesomeNOGUI)
+* [David Zhao](https://github.com/davidzhao)
 
 ### License
 MIT License - see [LICENSE](LICENSE) for full text

agent.go

@@ -123,6 +123,7 @@ type Agent struct {
 
 	net    *vnet.Net
 	tcpMux TCPMux
+	udpMux UDPMux
 
 	interfaceFilter func(string) bool
 
@@ -314,6 +315,7 @@ func NewAgent(config *AgentConfig) (*Agent, error) { //nolint:gocognit
 	if a.tcpMux == nil {
 		a.tcpMux = newInvalidTCPMux()
 	}
+	a.udpMux = config.UDPMux
 
 	if a.net == nil {
 		a.net = vnet.NewNet(nil)
@@ -897,6 +899,9 @@ func (a *Agent) Close() error {
 	a.err.Store(ErrClosed)
 
 	a.tcpMux.RemoveConnByUfrag(a.localUfrag)
+	if a.udpMux != nil {
+		a.udpMux.RemoveConnByUfrag(a.localUfrag)
+	}
 
 	close(a.done)
 

agent_config.go

@@ -145,6 +145,11 @@ type AgentConfig struct {
 	// experimental and the API might change in the future.
 	TCPMux TCPMux
 
+	// UDPMux is used for multiplexing multiple incoming UDP connections on a single port
+	// when this is set, the agent ignores PortMin and PortMax configurations and will
+	// defer to UDPMux for incoming connections
+	UDPMux UDPMux
+
 	// Proxy Dialer is a dialer that should be implemented by the user based on golang.org/x/net/proxy
 	// dial interface in order to support corporate proxies
 	ProxyDialer proxy.Dialer

agent_udpmux_test.go

@@ -0,0 +1,67 @@
+// +build !js
+
+package ice
+
+import (
+	"testing"
+
+	"github.com/pion/logging"
+	"github.com/pion/transport/test"
+	"github.com/stretchr/testify/require"
+)
+
+// TestMuxAgent is an end to end test over UDP mux, ensuring two agents could connect over mux
+func TestMuxAgent(t *testing.T) {
+	report := test.CheckRoutines(t)
+	defer report()
+	loggerFactory := logging.NewDefaultLoggerFactory()
+
+	udpMux := NewUDPMuxDefault(UDPMuxParams{
+		Logger:         loggerFactory.NewLogger("ice"),
+		ReadBufferSize: 20,
+	})
+	muxPort := 7686
+	require.NoError(t, udpMux.Start(muxPort))
+
+	muxedA, err := NewAgent(&AgentConfig{
+		UDPMux:         udpMux,
+		CandidateTypes: []CandidateType{CandidateTypeHost},
+		NetworkTypes:   supportedNetworkTypes(),
+	})
+	require.NoError(t, err)
+
+	a, err := NewAgent(&AgentConfig{
+		CandidateTypes: []CandidateType{CandidateTypeHost},
+		NetworkTypes:   supportedNetworkTypes(),
+	})
+	require.NoError(t, err)
+
+	conn, muxedConn := connect(a, muxedA)
+
+	pair := muxedA.getSelectedPair()
+	require.NotNil(t, pair)
+	require.Equal(t, muxPort, pair.Local.Port())
+
+	// send a packet to Mux
+	data := []byte("hello world")
+	_, err = conn.Write(data)
+	require.NoError(t, err)
+
+	buffer := make([]byte, 1024)
+	n, err := muxedConn.Read(buffer)
+	require.NoError(t, err)
+	require.Equal(t, data, buffer[:n])
+
+	// send a packet from Mux
+	_, err = muxedConn.Write(data)
+	require.NoError(t, err)
+
+	n, err = conn.Read(buffer)
+	require.NoError(t, err)
+	require.Equal(t, data, buffer[:n])
+
+	// close it down
+	require.NoError(t, conn.Close())
+	require.NoError(t, muxedConn.Close())
+	require.NoError(t, udpMux.Close())
+}

errors.go

@@ -109,6 +109,9 @@ var (
 	// ErrTCPRemoteAddrAlreadyExists indicates we already have the connection with same remote addr.
 	ErrTCPRemoteAddrAlreadyExists = errors.New("conn with same remote addr already exists")
 
+	// ErrMuxNotStarted indicates the Mux has not been started prior to use
+	ErrMuxNotStarted = errors.New("mux must be started first")
+
 	errSendPacket                    = errors.New("failed to send packet")
 	errAttributeTooShortICECandidate = errors.New("attribute not long enough to be ICE candidate")
 	errParseComponent                = errors.New("could not parse component")

gather.go

@@ -164,7 +164,6 @@ func (a *Agent) gatherCandidatesLocal(ctx context.Context, networkTypes []Networ
 			switch network {
 			case tcp:
 				// Handle ICE TCP passive mode
-
 				a.log.Debugf("GetConn by ufrag: %s\n", a.localUfrag)
 				conn, err = a.tcpMux.GetConnByUfrag(a.localUfrag)
 				if err != nil {
@@ -178,10 +177,18 @@ func (a *Agent) gatherCandidatesLocal(ctx context.Context, networkTypes []Networ
 				// is there a way to verify that the listen address is even
 				// accessible from the current interface.
 			case udp:
-				conn, err = listenUDPInPortRange(a.net, a.log, int(a.portmax), int(a.portmin), network, &net.UDPAddr{IP: ip, Port: 0})
-				if err != nil {
-					a.log.Warnf("could not listen %s %s\n", network, ip)
-					continue
+				if a.udpMux != nil {
+					conn, err = a.udpMux.GetConnByUfrag(a.localUfrag)
+					if err != nil {
+						a.log.Warnf("could not get udp muxed connection: %v\n", err)
+						continue
+					}
+				} else {
+					conn, err = listenUDPInPortRange(a.net, a.log, int(a.portmax), int(a.portmin), network, &net.UDPAddr{IP: ip, Port: 0})
+					if err != nil {
+						a.log.Warnf("could not listen %s %s\n", network, ip)
+						continue
+					}
 				}
 
 				port = conn.LocalAddr().(*net.UDPAddr).Port

go.mod

@@ -4,6 +4,7 @@ go 1.13
 
 require (
 	github.com/google/uuid v1.2.0
+	github.com/kr/pretty v0.1.0 // indirect
 	github.com/pion/dtls/v2 v2.0.9
 	github.com/pion/logging v0.2.2
 	github.com/pion/mdns v0.0.5
@@ -13,4 +14,5 @@ require (
 	github.com/pion/turn/v2 v2.0.5
 	github.com/stretchr/testify v1.7.0
 	golang.org/x/net v0.0.0-20210331212208-0fccb6fa2b5c
+	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
 )

go.sum

@@ -2,6 +2,11 @@ github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/google/uuid v1.2.0 h1:qJYtXnJRWmpe7m/3XlyhrsLrEURqHRM2kxzoxXqyUDs=
 github.com/google/uuid v1.2.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
+github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
+github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
+github.com/kr/text v0.1.0 h1:45sCR5RtlFHMR4UwH9sdQ5TC8v0qDQCHnXt+kaKSTVE=
+github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/pion/dtls/v2 v2.0.9 h1:7Ow+V++YSZQMYzggI0P9vLJz/hUFcffsfGMfT/Qy+u8=
 github.com/pion/dtls/v2 v2.0.9/go.mod h1:O0Wr7si/Zj5/EBFlDzDd6UtVxx25CE1r7XM7BQKYQho=
 github.com/pion/logging v0.2.2 h1:M9+AIj/+pxNsDfAT64+MAVgJO0rsyLnoJKCqf//DoeY=
@@ -50,7 +55,8 @@ golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
+gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

tcp_mux.go

@@ -23,9 +23,8 @@ type TCPMux interface {
 	RemoveConnByUfrag(ufrag string)
 }
 
-// invalidTCPMux is an implementation of TCPMux that always returns ErroTCPMuxNotInitialized.
-type invalidTCPMux struct {
-}
+// invalidTCPMux is an implementation of TCPMux that always returns ErrTCPMuxNotInitialized.
+type invalidTCPMux struct{}
 
 func newInvalidTCPMux() *invalidTCPMux {
 	return &invalidTCPMux{}