createOffer() is creating two different a=ice-ufrag lines, confusing media servers

[space88man]

Using pypi release and HEAD on master:

1. The SDP from createOffer() for a audio+video MediaPlayer has different ice-ufrag and ice-pwd lines for m=audio and m=video. This causes ICE failures.
2. aiortc stores the first pair in the Connection object. A media server (Kurento) uses the second pair to do ICE REQUEST, this leads to integrity check and username match failures.
3. Browser offers use the same ice-ufrag/ice-pwd attributes for both streams.
4. If aiortc does the answer SDP, it creates the same ice-ufrag/ice-pwd for both media streams.

Symptoms of this failure:

• ICE REQUEST/RESPONSE from aiortc to Kurento works (answer SDP has identical ice-ufrag/ice-pwd pairs)
• ICE REQUEST from Kurento to aiortc fails: ValueError due to integrity check; if you bypass integrity check in aioice, then ValueError due to mismatch username.

Would it be possible for aiortc to emulate browsers and reuse ice-ufrag/ice-pwd attributes in both media streams on offer?

The first ice-ufrag/ice-pwd pair is stored in the Connection and used to verify integrity and username. But the media server uses the second pair.

# SDP offer with different ice-ufrag ice-pwd

a=candidate:d3528481068ed87c99af586f1926906f 1 udp 2130706431 192.168.1.7 45836 typ host                                                                                                                                                                 
a=candidate:11b689b4112f791f3859a4d254e61e25 1 udp 2130706431 192.168.125.1 51993 typ host                                                                                                                                                               
a=candidate:4928f5caa10844d454e97e1af3038bee 1 udp 2130706431 192.168.122.1 32856 typ host                                                                                                                                                               
a=candidate:653e4b9fd74e9451ff76d5b7d540707e 1 udp 2130706431 192.168.81.5 45101 typ host                                                                                                                                                                
a=end-of-candidates                                                                                                                                                                                                                                      
a=ice-ufrag:zXsi                                                                                                                                                                                                                                         
a=ice-pwd:FtFO6ChcdyYcB1VXgSXY8Q                                                                                                                                                                                                                         
a=fingerprint:sha-256 53:C4:92:EF:11:C0:88:39:CB:33:B3:43:BE:9C:B0:ED:CB:6A:C0:8A:7C:7E:A2:3B:C2:22:6B:70:8B:B3:B8:18                                                                                                                                    
a=setup:actpass                                                                                                                                                                                                                                          
m=video 41338 UDP/TLS/RTP/SAVPF 97 98 99 100 101 102                                                                                                                                                                                                     
c=IN IP4 192.168.1.7                                                                                                                                                                                                                                     
a=sendrecv                                                                                                                                                                                                                                               
a=extmap:1 urn:ietf:params:rtp-hdrext:sdes:mid                                                                                                                                                                                                           
a=extmap:2 http://www.webrtc.org/experiments/rtp-hdrext/abs-send-time                                                                                                                                                                                    
a=mid:1                                                                                                                                                                                                                                                  
a=msid:96de37fb-5b3b-474d-adc3-7f215e73e542 9451c57b-7777-4445-b2bb-1eaf81037d61                                                                                                                                                                         
a=rtcp:9 IN IP4 0.0.0.0                                                                                                                                                                                                                                  
a=rtcp-mux                                                                                                                                                                                                                                               
a=ssrc-group:FID 1477349285 2207491607                                                                                                                                                                                                                   
a=ssrc:1477349285 cname:10db87c7-ea3f-4f1e-b7e3-23db3c535517                                                                                                                                                                                             
a=ssrc:2207491607 cname:10db87c7-ea3f-4f1e-b7e3-23db3c535517                                                                                                                                                                                             
a=rtpmap:97 VP8/90000                                                                                                                                                                                                                                    
a=rtcp-fb:97 nack                                                                                                                                                                                                                                        
a=rtcp-fb:97 nack pli                                                                                                                                                                                                                                    
a=rtcp-fb:97 goog-remb                                                                                                                                                                                                                                   
a=rtpmap:98 rtx/90000                                                                                                                                                                                                                                    
a=fmtp:98 apt=97                                                                                                                                                                                                                                         
a=rtpmap:99 H264/90000                                                                                                                                                                                                                                   
a=rtcp-fb:99 nack                                                                                                                                                                                                                                        
a=rtcp-fb:99 nack pli                                                                                                                                                                                                                                    
a=rtcp-fb:99 goog-remb                                                                                                                                                                                                                                   
a=fmtp:99 packetization-mode=1;level-asymmetry-allowed=1;profile-level-id=42001f                                                                                                                                                                         
a=rtpmap:100 rtx/90000                                                                                                                                                                                                                                   
a=fmtp:100 apt=99                                                                                                                                                                                                                                        
a=rtpmap:101 H264/90000                                                                                                                                                                                                                                  
a=rtcp-fb:101 nack                                                                                                                                                                                                                                       
a=rtcp-fb:101 nack pli                                                                                                                                                                                                                                   
a=rtcp-fb:101 goog-remb                                                                                                                                                                                                                                  
a=fmtp:101 packetization-mode=1;level-asymmetry-allowed=1;profile-level-id=42e01f                                                                                                                                                                        
a=rtpmap:102 rtx/90000                                                                                                                                                                                                                                   
a=fmtp:102 apt=101                                                                                                                                                                                                                                       
a=candidate:d3528481068ed87c99af586f1926906f 1 udp 2130706431 192.168.1.7 41338 typ host                                                                                                                                                                 
a=candidate:11b689b4112f791f3859a4d254e61e25 1 udp 2130706431 192.168.125.1 37361 typ host                                                                                                                                                               
a=candidate:4928f5caa10844d454e97e1af3038bee 1 udp 2130706431 192.168.122.1 50189 typ host                                                                                                                                                               
a=candidate:653e4b9fd74e9451ff76d5b7d540707e 1 udp 2130706431 192.168.81.5 43653 typ host                                                                                                                                                                
a=end-of-candidates                                                                                                                                                                                                                                      
a=ice-ufrag:E8CY                                                                                                            
a=ice-pwd:tdmBCyR8ZPw0JelU6Etjht                                                                                            
a=fingerprint:sha-256 53:C4:92:EF:11:C0:88:39:CB:33:B3:43:BE:9C:B0:ED:CB:6A:C0:8A:7C:7E:A2:3B:C2:22:6B:70:8B:B3:B8:18       
a=setup:actpass

See the closed issue #369 for more background. I wasn't clear about what was happening so the explanation there is bad but left for reference.

[space88man]

Test: between aiortc and Kurento I rewrote aiortc's offer SDP to reuse ice-ufrag/ice-pwd from m=audio.

This does indeed work and the two are able to exchange RTP.

[jlaine]

At first look I'd suggest looking for a fix on the kurento side, as it's perfectly legitimate to have ice-ufrag / ice-pwd at the media level, and not at the session level. Is the failure specific to kurento or are you able to reproduce it with aiortc vs a browser?

[jlaine]

No reply from submitter, closing

[kenaniah]

The Rust webrtc crate also complains about having different ice-ufrag values, viewing it as an error when the values differ.

@jlaine could you please reopen this issue?