udp: support using domain names instead of IPs (#2150)

internal/conf/path.go

@@ -200,16 +200,11 @@ func (pconf *PathConf) check(conf *Conf, name string) error {
 			return fmt.Errorf("a path with a regular expression (or path 'all') cannot have a HLS source. use another path")
 		}
 
-		host, _, err := net.SplitHostPort(pconf.Source[len("udp://"):])
+		_, _, err := net.SplitHostPort(pconf.Source[len("udp://"):])
 		if err != nil {
 			return fmt.Errorf("'%s' is not a valid UDP URL", pconf.Source)
 		}
 
-		ip := net.ParseIP(host)
-		if ip == nil {
-			return fmt.Errorf("'%s' is not a valid IP", host)
-		}
-
 	case strings.HasPrefix(pconf.Source, "srt://"):
 		if pconf.Regexp != nil {
 			return fmt.Errorf("a path with a regular expression (or path 'all') cannot have a SRT source. use another path")

internal/core/udp_source.go

@@ -92,16 +92,18 @@ func (s *udpSource) run(ctx context.Context, cnf *conf.PathConf, _ chan *conf.Pa
 
 	hostPort := cnf.Source[len("udp://"):]
 
-	pc, err := net.ListenPacket(restrictNetwork("udp", hostPort))
+	addr, err := net.ResolveUDPAddr("udp", hostPort)
+	if err != nil {
+		return err
+	}
+
+	pc, err := net.ListenPacket(restrictNetwork("udp", addr.String()))
 	if err != nil {
 		return err
 	}
 	defer pc.Close()
 
-	host, _, _ := net.SplitHostPort(hostPort)
-	ip := net.ParseIP(host)
-
-	if ip.IsMulticast() {
+	if addr.IP.IsMulticast() {
 		p := ipv4.NewPacketConn(pc)
 
 		err = p.SetMulticastTTL(multicastTTL)
@@ -109,7 +111,7 @@ func (s *udpSource) run(ctx context.Context, cnf *conf.PathConf, _ chan *conf.Pa
 			return err
 		}
 
-		err = joinMulticastGroupOnAtLeastOneInterface(p, ip)
+		err = joinMulticastGroupOnAtLeastOneInterface(p, addr.IP)
 		if err != nil {
 			return err
 		}

internal/core/udp_source_test.go

@@ -0,0 +1,86 @@
+package core
+
+import (
+	"bufio"
+	"net"
+	"testing"
+	"time"
+
+	"github.com/bluenviron/gortsplib/v3"
+	"github.com/bluenviron/gortsplib/v3/pkg/formats"
+	"github.com/bluenviron/gortsplib/v3/pkg/url"
+	"github.com/bluenviron/mediacommon/pkg/formats/mpegts"
+	"github.com/pion/rtp"
+	"github.com/stretchr/testify/require"
+)
+
+func TestUDPSource(t *testing.T) {
+	p, ok := newInstance("paths:\n" +
+		"  proxied:\n" +
+		"    source: udp://localhost:9999\n" +
+		"    sourceOnDemand: yes\n")
+	require.Equal(t, true, ok)
+	defer p.Close()
+
+	c := gortsplib.Client{}
+
+	u, err := url.Parse("rtsp://127.0.0.1:8554/proxied")
+	require.NoError(t, err)
+
+	err = c.Start(u.Scheme, u.Host)
+	require.NoError(t, err)
+	defer c.Close()
+
+	connected := make(chan struct{})
+	received := make(chan struct{})
+
+	go func() {
+		time.Sleep(200 * time.Millisecond)
+
+		conn, err := net.Dial("udp", "localhost:9999")
+		require.NoError(t, err)
+		defer conn.Close()
+
+		track := &mpegts.Track{
+			Codec: &mpegts.CodecH264{},
+		}
+
+		bw := bufio.NewWriter(conn)
+		w := mpegts.NewWriter(bw, []*mpegts.Track{track})
+		require.NoError(t, err)
+
+		err = w.WriteH26x(track, 0, 0, true, [][]byte{
+			{ // IDR
+				0x05, 1,
+			},
+		})
+		require.NoError(t, err)
+		bw.Flush()
+
+		<-connected
+
+		err = w.WriteH26x(track, 0, 0, true, [][]byte{{5, 2}})
+		require.NoError(t, err)
+		bw.Flush()
+	}()
+
+	medias, baseURL, _, err := c.Describe(u)
+	require.NoError(t, err)
+
+	var forma *formats.H264
+	medi := medias.FindFormat(&forma)
+
+	_, err = c.Setup(medi, baseURL, 0, 0)
+	require.NoError(t, err)
+
+	c.OnPacketRTP(medi, forma, func(pkt *rtp.Packet) {
+		require.Equal(t, []byte{5, 1}, pkt.Payload)
+		close(received)
+	})
+
+	_, err = c.Play(nil)
+	require.NoError(t, err)
+
+	close(connected)
+	<-received
+}