feat(sdp): parse media direction attribute

sdp/offer.go

@@ -100,6 +100,7 @@ type MediaDesc struct {
 	Codecs         []CodecInfo
 	DTMFType       byte // set to 0 if there's no DTMF
 	CryptoProfiles []srtp.Profile
+	Direction      sdp.Direction
 }
 
 func appendCryptoProfiles(attrs []sdp.Attribute, profiles []srtp.Profile) []sdp.Attribute {
@@ -450,6 +451,19 @@ func ParseWith(s *media.CodecSet, data []byte) (*Description, error) {
 		return nil, err
 	}
 	offer.MediaDesc = *m
+
+	dir := sdp.DirectionSendRecv
+	for _, key := range []string{"sendrecv", "sendonly", "recvonly", "inactive"} {
+		if _, ok := offer.SDP.Attribute(key); ok {
+			dir, _ = sdp.NewDirection(key)
+			break
+		}
+	}
+	if m.Direction != 0 {
+		dir = m.Direction
+	}
+	offer.MediaDesc.Direction = dir
+
 	return offer, nil
 }
 
@@ -651,6 +665,12 @@ func ParseMediaWith(s *media.CodecSet, d *sdp.MediaDescription) (*MediaDesc, err
 				continue
 			}
 			out.CryptoProfiles = append(out.CryptoProfiles, *p)
+		case "sendrecv", "sendonly", "recvonly", "inactive":
+			dir, err := sdp.NewDirection(m.Key)
+			if err != nil {
+				continue
+			}
+			out.Direction = dir
 		}
 	}
 	for _, f := range d.MediaName.Formats {

sdp/offer_test.go

@@ -813,3 +813,69 @@ func TestSRTPIntegration(t *testing.T) {
 	packetMKI := extractMKIFromSRTPPacket(offerCaptured[0], len(offerMKI), authTagSize)
 	require.Equal(t, offerMKI, packetMKI, "MKI %v does not match expected value %v", packetMKI, offerMKI)
 }
+
+func TestParseDirection(t *testing.T) {
+	g := media.GlobalCodecs()
+
+	const head = `v=0
+o=- 1 1 IN IP4 203.0.113.5
+s=LiveKit
+c=IN IP4 203.0.113.5
+t=0 0
+`
+
+	tests := []struct {
+		name string
+		sdp  string
+		want sdp.Direction
+	}{
+		{
+			name: "media-level sendonly (hold)",
+			sdp: head + `m=audio 10000 RTP/AVP 0
+a=rtpmap:0 PCMU/8000
+a=sendonly
+`,
+			want: sdp.DirectionSendOnly,
+		},
+		{
+			name: "no attribute defaults to sendrecv",
+			sdp: head + `m=audio 10000 RTP/AVP 0
+a=rtpmap:0 PCMU/8000
+`,
+			want: sdp.DirectionSendRecv,
+		},
+		{
+			name: "session-level applies when media omits",
+			sdp: head + `a=sendonly
+m=audio 10000 RTP/AVP 0
+a=rtpmap:0 PCMU/8000
+`,
+			want: sdp.DirectionSendOnly,
+		},
+		{
+			name: "media overrides session",
+			sdp: head + `a=inactive
+m=audio 10000 RTP/AVP 0
+a=rtpmap:0 PCMU/8000
+a=sendonly
+`,
+			want: sdp.DirectionSendOnly,
+		},
+		{
+			name: "inactive media level",
+			sdp: head + `m=audio 10000 RTP/AVP 0
+a=rtpmap:0 PCMU/8000
+a=inactive
+`,
+			want: sdp.DirectionInactive,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			d, err := ParseWith(g, []byte(test.sdp))
+			require.NoError(t, err)
+			require.Equal(t, test.want, d.Direction)
+		})
+	}
+}