1455420 - WebRTC track msids are randomized after every renegotiation

Status: RESOLVED INVALID

(Firefox :: Untriaged, defect)

Description

[thomasmullendesign]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_3) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.181 Safari/537.36

Steps to reproduce:

Renegotiated a WebRTC connection and compared initial and new SDP offers.

No changes have been made to the streams with addTrack or addStream or otherwise. Note the streamID is the same. Chrome, Safari and Firefox 58.X.X do not exhibit this behaviour.



Actual results:

The track portion of the a=msid line in a WebRTC sdp changes between every renegotiation as of the recent Firefox 59 update. This is not in the specification as breaks track removal detection through SDP parsing.




Expected results:

The track portion should remain the same, like the stream portion does, for msids. Renegotiation shouldn't change the msid lines if nothing has been changed.

Here is a sample SDP the demonstrates the issue:

Initial negotiation SDP:
v=0
o=mozilla...THIS_IS_SDPARTA-59.0.2 4371461466401803386 0 IN IP4 0.0.0.0
s=-
t=0 0
a=sendrecv
a=fingerprint:sha-256 5C:F4:0B:EF:39:55:C3:15:04:E3:D2:F9:8C:46:10:4D:05:5F:44:22:A3:18:9E:17:1B:0F:43:41:10:2C:2D:D6
a=group:BUNDLE sdparta_0 sdparta_1 sdparta_2
a=ice-options:trickle
a=msid-semantic:WMS *
m=audio 9 UDP/TLS/RTP/SAVPF 109 9 0 8 101
c=IN IP4 0.0.0.0
a=sendrecv
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid
a=fmtp:109 maxplaybackrate=48000;stereo=1;useinbandfec=1
a=fmtp:101 0-15
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_0
a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {8e6e2468-3744-8c45-9119-309656ff53b6}
a=rtcp-mux
a=rtpmap:109 opus/48000/2
a=rtpmap:9 G722/8000/1
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=setup:actpass
a=ssrc:1635194633 cname:{013f7227-76fa-004d-ac4d-13d91e5064b5}
m=audio 0 UDP/TLS/RTP/SAVPF 109 9 0 8 101
c=IN IP4 0.0.0.0
a=bundle-only
a=sendrecv
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid
a=fmtp:109 maxplaybackrate=48000;stereo=1;useinbandfec=1
a=fmtp:101 0-15
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_1
a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {1aa3c2c3-9bba-4944-8940-a10a5992dd35}
a=rtcp-mux
a=rtpmap:109 opus/48000/2
a=rtpmap:9 G722/8000/1
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:101 telephone-event/8000
a=setup:actpass
a=ssrc:946241047 cname:{013f7227-76fa-004d-ac4d-13d91e5064b5}
m=application 9 DTLS/SCTP 5000
c=IN IP4 0.0.0.0
a=sendrecv
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_2
a=sctpmap:5000 webrtc-datachannel 256
a=setup:actpass
a=max-message-size:1073741823

Renegotiated SDP: 
v=0
o=mozilla...THIS_IS_SDPARTA-59.0.2 4371461466401803386 1 IN IP4 0.0.0.0
s=-
t=0 0
a=sendrecv
a=fingerprint:sha-256 5C:F4:0B:EF:39:55:C3:15:04:E3:D2:F9:8C:46:10:4D:05:5F:44:22:A3:18:9E:17:1B:0F:43:41:10:2C:2D:D6
a=group:BUNDLE sdparta_0 sdparta_1 sdparta_2
a=ice-options:trickle
a=msid-semantic:WMS *
m=audio 60011 UDP/TLS/RTP/SAVPF 109 101 0 8 9
c=IN IP4 192.168.1.112
a=candidate:0 1 UDP 2122252543 192.168.1.112 60011 typ host
a=candidate:4 1 TCP 2105524479 192.168.1.112 9 typ host tcptype active
a=sendrecv
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid
a=fmtp:109 maxplaybackrate=48000;stereo=1;useinbandfec=1
a=fmtp:101 0-15
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_0
a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {8e6e2468-3744-8c45-9119-309656ff53b6}
a=rtcp-mux
a=rtpmap:109 opus/48000/2
a=rtpmap:101 telephone-event/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:9 G722/8000/1
a=setup:actpass
a=ssrc:1635194633 cname:{013f7227-76fa-004d-ac4d-13d91e5064b5}
m=audio 0 UDP/TLS/RTP/SAVPF 109 101 0 8 9
c=IN IP4 0.0.0.0
a=bundle-only
a=sendrecv
a=extmap:1 urn:ietf:params:rtp-hdrext:ssrc-audio-level
a=extmap:2 urn:ietf:params:rtp-hdrext:sdes:mid
a=fmtp:109 maxplaybackrate=48000;stereo=1;useinbandfec=1
a=fmtp:101 0-15
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_1
a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {1aa3c2c3-9bba-4944-8940-a10a5992dd35}
a=rtcp-mux
a=rtpmap:109 opus/48000/2
a=rtpmap:101 telephone-event/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:9 G722/8000/1
a=setup:actpass
a=ssrc:946241047 cname:{013f7227-76fa-004d-ac4d-13d91e5064b5}
m=application 9 DTLS/SCTP 5000
c=IN IP4 0.0.0.0
a=sendrecv
a=ice-pwd:f48d90ebbe2452e1223f486c9d9da507
a=ice-ufrag:9d8d528d
a=mid:sdparta_2
a=sctpmap:5000 webrtc-datachannel 256
a=setup:actpass
a=max-message-size:1073741823

Offending lines:

a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {1aa3c2c3-9bba-4944-8940-a10a5992dd35}
a=msid:{e47880ed-4b38-6044-a4b8-a5fc549c59f5} {8e6e2468-3744-8c45-9119-309656ff53b6}