udp: fix reading two streams with same port and different multicast IP (#2133) (#2332)

Fixes #2133

go.mod

@@ -7,7 +7,7 @@ require (
 	github.com/abema/go-mp4 v0.13.0
 	github.com/alecthomas/kong v0.8.0
 	github.com/bluenviron/gohlslib v1.0.2
-	github.com/bluenviron/gortsplib/v4 v4.0.1
+	github.com/bluenviron/gortsplib/v4 v4.0.2-0.20230911215322-4ede58cda208
 	github.com/bluenviron/mediacommon v1.1.1
 	github.com/datarhei/gosrt v0.5.4
 	github.com/fsnotify/fsnotify v1.6.0
@@ -25,7 +25,6 @@ require (
 	github.com/pion/webrtc/v3 v3.2.19
 	github.com/stretchr/testify v1.8.4
 	golang.org/x/crypto v0.13.0
-	golang.org/x/net v0.15.0
 	golang.org/x/term v0.12.0
 	gopkg.in/yaml.v2 v2.4.0
 )
@@ -66,6 +65,7 @@ require (
 	github.com/ugorji/go/codec v1.2.11 // indirect
 	github.com/xo/terminfo v0.0.0-20210125001918-ca9a967f8778 // indirect
 	golang.org/x/arch v0.3.0 // indirect
+	golang.org/x/net v0.15.0 // indirect
 	golang.org/x/sys v0.12.0 // indirect
 	golang.org/x/text v0.13.0 // indirect
 	google.golang.org/protobuf v1.30.0 // indirect

go.sum

@@ -14,8 +14,8 @@ github.com/benburkert/openpgp v0.0.0-20160410205803-c2471f86866c h1:8XZeJrs4+ZYh
 github.com/benburkert/openpgp v0.0.0-20160410205803-c2471f86866c/go.mod h1:x1vxHcL/9AVzuk5HOloOEPrtJY0MaalYr78afXZ+pWI=
 github.com/bluenviron/gohlslib v1.0.2 h1:LDA/CubL525e9rLWw+G/9GbFS6iXwozmOg8KJBT4qF4=
 github.com/bluenviron/gohlslib v1.0.2/go.mod h1:oam0wsI2XqcHLTG6NM8HRvxAQsa3hIA0MLRiTOE7CB8=
-github.com/bluenviron/gortsplib/v4 v4.0.1 h1:6Ng9fRW40tHnOx/kDqO6gIrSZocdvfHTp6mjdnkWlEU=
-github.com/bluenviron/gortsplib/v4 v4.0.1/go.mod h1:bfw1TZzHt6NsuKgQxrfrb8w0NnYMvNvqZ1jgjQk5qaU=
+github.com/bluenviron/gortsplib/v4 v4.0.2-0.20230911215322-4ede58cda208 h1:w1aishvJ4U2TuM1SsFmWoKuFNogqhla3eh2Qn6AyRtE=
+github.com/bluenviron/gortsplib/v4 v4.0.2-0.20230911215322-4ede58cda208/go.mod h1:l6LO4TlHC3YdLIbEn89GeeSgzHaJlpAFF7NLZ7h4A+A=
 github.com/bluenviron/mediacommon v1.1.1 h1:cGFy5hnLBeiTrpPyEOf23En+E86r3s99tudlQHY9eEA=
 github.com/bluenviron/mediacommon v1.1.1/go.mod h1:/vlOVSebDwzdRtQONOKLua0fOSJg1tUDHpP+h9a0uqM=
 github.com/bytedance/sonic v1.5.0/go.mod h1:ED5hyg4y6t3/9Ku1R6dU/4KyJ48DZ4jPhfY1O2AihPM=

internal/core/udp_source.go

@@ -8,8 +8,8 @@ import (
 
 	"github.com/bluenviron/gortsplib/v4/pkg/description"
 	"github.com/bluenviron/gortsplib/v4/pkg/format"
+	"github.com/bluenviron/gortsplib/v4/pkg/multicast"
 	"github.com/bluenviron/mediacommon/pkg/formats/mpegts"
-	"golang.org/x/net/ipv4"
 
 	"github.com/bluenviron/mediamtx/internal/conf"
 	"github.com/bluenviron/mediamtx/internal/logger"
@@ -18,34 +18,10 @@ import (
 )
 
 const (
-	multicastTTL = 16
-	udpMTU       = 1472
+	// same size as GStreamer's rtspsrc
+	udpKernelReadBufferSize = 0x80000
 )
 
-func joinMulticastGroupOnAtLeastOneInterface(p *ipv4.PacketConn, listenIP net.IP) error {
-	intfs, err := net.Interfaces()
-	if err != nil {
-		return err
-	}
-
-	success := false
-
-	for _, intf := range intfs {
-		if (intf.Flags & net.FlagMulticast) != 0 {
-			err := p.JoinGroup(&intf, &net.UDPAddr{IP: listenIP})
-			if err == nil {
-				success = true
-			}
-		}
-	}
-
-	if !success {
-		return fmt.Errorf("unable to activate multicast on any network interface")
-	}
-
-	return nil
-}
-
 type packetConnReader struct {
 	net.PacketConn
 }
@@ -61,6 +37,11 @@ func (r *packetConnReader) Read(p []byte) (int, error) {
 	return n, err
 }
 
+type packetConn interface {
+	net.PacketConn
+	SetReadBuffer(int) error
+}
+
 type udpSourceParent interface {
 	logger.Writer
 	setReady(req pathSourceStaticSetReadyReq) pathSourceStaticSetReadyRes
@@ -97,24 +78,26 @@ func (s *udpSource) run(ctx context.Context, cnf *conf.PathConf, _ chan *conf.Pa
 		return err
 	}
 
-	pc, err := net.ListenPacket(restrictNetwork("udp", addr.String()))
-	if err != nil {
-		return err
-	}
-	defer pc.Close()
-
-	if addr.IP.IsMulticast() {
-		p := ipv4.NewPacketConn(pc)
+	var pc packetConn
 
-		err = p.SetMulticastTTL(multicastTTL)
+	if ip4 := addr.IP.To4(); ip4 != nil && addr.IP.IsMulticast() {
+		pc, err = multicast.NewMultiConn(hostPort, net.ListenPacket)
 		if err != nil {
 			return err
 		}
-
-		err = joinMulticastGroupOnAtLeastOneInterface(p, addr.IP)
+	} else {
+		tmp, err := net.ListenPacket(restrictNetwork("udp", addr.String()))
 		if err != nil {
 			return err
 		}
+		pc = tmp.(*net.UDPConn)
+	}
+
+	defer pc.Close()
+
+	err = pc.SetReadBuffer(udpKernelReadBufferSize)
+	if err != nil {
+		return err
 	}
 
 	readerErr := make(chan error)