support routing ULPFEC group definitions

pkg/description/session.go

@@ -2,6 +2,7 @@ package description
 
 import (
 	"fmt"
+	"strings"
 
 	psdp "github.com/pion/sdp/v3"
 
@@ -36,15 +37,21 @@ func hasMediaWithID(medias []*Media, id string) bool {
 	return false
 }
 
+// SessionFECGroup is a FEC group.
+type SessionFECGroup []string
+
 // Session is the description of a RTSP stream.
 type Session struct {
-	// base URL of the stream (read only).
+	// Base URL of the stream (read only).
 	BaseURL *url.URL
 
-	// title of the stream (optional).
+	// Title of the stream (optional).
 	Title string
 
-	// available media streams.
+	// FEC groups (RFC5109).
+	FECGroups []SessionFECGroup
+
+	// Media streams.
 	Medias []*Media
 }
 
@@ -87,6 +94,20 @@ func (d *Session) Unmarshal(ssd *sdp.SessionDescription) error {
 		return fmt.Errorf("media IDs sent partially")
 	}
 
+	for _, attr := range ssd.Attributes {
+		if attr.Key == "group" && strings.HasPrefix(attr.Value, "FEC ") {
+			group := SessionFECGroup(strings.Split(attr.Value[len("FEC "):], " "))
+
+			for _, id := range group {
+				if !hasMediaWithID(d.Medias, id) {
+					return fmt.Errorf("FEC group points to an invalid media ID: %v", id)
+				}
+			}
+
+			d.FECGroups = append(d.FECGroups, group)
+		}
+	}
+
 	return nil
 }
 
@@ -132,5 +153,12 @@ func (d Session) Marshal(multicast bool) ([]byte, error) {
 		sout.MediaDescriptions[i] = media.Marshal()
 	}
 
+	for _, group := range d.FECGroups {
+		sout.Attributes = append(sout.Attributes, psdp.Attribute{
+			Key:   "group",
+			Value: "FEC " + strings.Join(group, " "),
+		})
+	}
+
 	return sout.Marshal()
 }

pkg/description/session_test.go

@@ -629,6 +629,89 @@ var casesSession = []struct {
 			},
 		},
 	},
+	{
+		"ulpfec rfc5109",
+		"v=0\r\n" +
+			"o=adam 289083124 289083124 IN IP4 host.example.com\r\n" +
+			"s=ULP FEC Seminar\r\n" +
+			"t=0 0\r\n" +
+			"c=IN IP4 224.2.17.12/127\r\n" +
+			"a=group:FEC 1 2\r\n" +
+			"a=group:FEC 3 4\r\n" +
+			"m=audio 30000 RTP/AVP 0\r\n" +
+			"a=mid:1\r\n" +
+			"m=application 30002 RTP/AVP 100\r\n" +
+			"a=rtpmap:100 ulpfec/8000\r\n" +
+			"a=mid:2\r\n" +
+			"m=video 30004 RTP/AVP 31\r\n" +
+			"a=mid:3\r\n" +
+			"m=application 30004 RTP/AVP 101\r\n" +
+			"c=IN IP4 224.2.17.13/127\r\n" +
+			"a=rtpmap:101 ulpfec/8000\r\n" +
+			"a=mid:4\r\n",
+		"v=0\r\n" +
+			"o=- 0 0 IN IP4 127.0.0.1\r\n" +
+			"s=ULP FEC Seminar\r\n" +
+			"c=IN IP4 0.0.0.0\r\n" +
+			"t=0 0\r\n" +
+			"a=group:FEC 1 2\r\n" +
+			"a=group:FEC 3 4\r\n" +
+			"m=audio 0 RTP/AVP 0\r\n" +
+			"a=mid:1\r\n" +
+			"a=control\r\n" +
+			"a=rtpmap:0 PCMU/8000\r\n" +
+			"m=application 0 RTP/AVP 100\r\n" +
+			"a=mid:2\r\n" +
+			"a=control\r\n" +
+			"a=rtpmap:100 ulpfec/8000\r\n" +
+			"m=video 0 RTP/AVP 31\r\n" +
+			"a=mid:3\r\n" +
+			"a=control\r\n" +
+			"m=application 0 RTP/AVP 101\r\n" +
+			"a=mid:4\r\n" +
+			"a=control\r\n" +
+			"a=rtpmap:101 ulpfec/8000\r\n",
+		Session{
+			Title: "ULP FEC Seminar",
+			FECGroups: []SessionFECGroup{
+				{"1", "2"},
+				{"3", "4"},
+			},
+			Medias: []*Media{
+				{
+					ID:      "1",
+					Type:    MediaTypeAudio,
+					Formats: []format.Format{&format.G711{MULaw: true}},
+				},
+				{
+					ID:   "2",
+					Type: MediaTypeApplication,
+					Formats: []format.Format{&format.Generic{
+						PayloadTyp: 100,
+						RTPMa:      "ulpfec/8000",
+						ClockRat:   8000,
+					}},
+				},
+				{
+					ID:   "3",
+					Type: MediaTypeVideo,
+					Formats: []format.Format{&format.Generic{
+						PayloadTyp: 31,
+						ClockRat:   90000,
+					}},
+				},
+				{
+					ID:   "4",
+					Type: MediaTypeApplication,
+					Formats: []format.Format{&format.Generic{
+						PayloadTyp: 101,
+						RTPMa:      "ulpfec/8000",
+						ClockRat:   8000,
+					}},
+				},
+			},
+		},
+	},
 }
 
 func TestSessionUnmarshal(t *testing.T) {
@@ -735,6 +818,25 @@ func FuzzSessionUnmarshalErrors(f *testing.F) {
 		"m=audio 0 RTP/AVP/TCP 0\r\n" +
 		"a=mid:2\r\n")
 
+	f.Add("v=0\r\n" +
+		"o=adam 289083124 289083124 IN IP4 host.example.com\r\n" +
+		"s=ULP FEC Seminar\r\n" +
+		"t=0 0\r\n" +
+		"c=IN IP4 224.2.17.12/127\r\n" +
+		"a=group:FEC 1 2\r\n" +
+		"a=group:FEC 3 4\r\n" +
+		"m=audio 30000 RTP/AVP 0\r\n" +
+		"a=mid:1\r\n" +
+		"m=application 30002 RTP/AVP 100\r\n" +
+		"a=rtpmap:100 ulpfec/8000\r\n" +
+		"a=mid:2\r\n" +
+		"m=video 30004 RTP/AVP 31\r\n" +
+		"a=mid:3\r\n" +
+		"m=application 30004 RTP/AVP 101\r\n" +
+		"c=IN IP4 224.2.17.13/127\r\n" +
+		"a=rtpmap:101 ulpfec/8000\r\n" +
+		"a=mid:4\r\n")
+
 	f.Fuzz(func(t *testing.T, enc string) {
 		var sd sdp.SessionDescription
 		err := sd.Unmarshal([]byte(enc))

pkg/description/testdata/fuzz/FuzzSessionUnmarshalErrors/fb7e5db5b68fa760

@@ -0,0 +1,2 @@
+go test fuzz v1
+string("v=0\ns=0\na=group:FEC 0")

server_conn.go

@@ -27,17 +27,19 @@ func getSessionID(header base.Header) string {
 func serverSideDescription(d *description.Session, contentBase *url.URL) *description.Session {
 	out := &description.Session{
 		Title:     d.Title,
+		FECGroups: d.FECGroups,
 		Medias:    make([]*description.Media, len(d.Medias)),
 	}
 
 	for i, medi := range d.Medias {
 		mc := &description.Media{
 			Type: medi.Type,
+			ID:   medi.ID,
 			// Direction: skipped for the moment
-			Formats: medi.Formats,
 			// we have to use trackID=number in order to support clients
 			// like the Grandstream GXV3500.
 			Control: "trackID=" + strconv.FormatInt(int64(i), 10),
+			Formats: medi.Formats,
 		}
 
 		// always use the absolute URL of the track as control attribute, in order