TURN REST API: Error parsing API from Janus

[ehfd]

CC @fancycode

Issue number one: The TURN REST API capability provided by the signaling server is not well documented, when one must use TURN with Janus.

nextcloud-spreed-signaling/backend_server.go

Line 180 in 4e34e97

r.HandleFunc("/turn/credentials", b.setComonHeaders(b.getTurnCredentials)).Methods("GET")

Documentation should specify correctly that they should add the turn_rest_api option in Janus pointing to /turn/credentials for janus.jcfg in order to utilze turn_rest_api_key:

nat: {
    stun_server = "stun.myurl.invalid"
    stun_port = 3478
    full_trickle = true
    turn_rest_api = "http://localhost:8080/turn/credentials"
    turn_rest_api_key = "<REDACTED>"
}

Issue number two:

Directly accessing http://localhost:8080/turn/credentials?service=turn&api=<REDACTED>&key=<REDACTED>&username=example (same format as https://github.com/meetecho/janus-gateway/blob/dc8323741043a75537fb770d42ca37498a3d8947/src/turnrest.c#L140) results correctly in:

{"username":"1700000000:example","password":"<REDACTED>","ttl":86400,"uris":["turn:turn.myurl.invalid:3478?transport=udp","turn:turn.myurl.invalid:3478?transport=tcp"]}

But in Janus:

[ERR] [turnrest.c:janus_turnrest_request:198] Couldn't parse response: error on line 1: '[' or '{' expected near end of file
[WARN] [{REDACTED}] Failed to add some remote candidates (added 0, expected 1)

Therefore, the TURN REST API is not usable, possibly an empty response for some reason?

[fancycode]

If you increase the log level in Janus, you should see what was received:
https://github.com/meetecho/janus-gateway/blob/dc8323741043a75537fb770d42ca37498a3d8947/src/turnrest.c#L192-L194

[ehfd]

[5060505176029085] Peer advertised 'actpass' DTLS role, we'll be a DTLS client
[5060505176029085] There are 1 audio, 1 video and 1 data m-lines
[5060505176029085] Setting ICE locally: got OFFER
[5060505176029085] Creating ICE agent (ICE Full mode, controlled)
Sending request: http://localhost:8080/turn/credentials?service=turn&api={REDACTED}&key={REDACTED}&username=2103426825996819
Got 0 bytes from the TURN REST API server

[ERR] [turnrest.c:janus_turnrest_request:198] Couldn't parse response: error on line 1: '[' or '{' expected near end of file[5060505176029085] Adding 10.244.42.121 to the addresses to gather candidates for
[5060505176029085] Parsing m-line #0...
[5060505176029085] ICE ufrag (local):   vq7x

I modified nothing from the request with curl and wget to get the response from http://localhost:8080/turn/credentials?service=turn&api={REDACTED}&key={REDACTED}&username=2103426825996819 and received the adequate response:

{"username":"1737200889:2103426825996819","password":"{REDACTED}","ttl":86400,"uris":["{REDACTED}"]}

Even tried 127.0.0.1 instead of localhost with no avail...

[fancycode]

There is no code path that returns an empty response for the TURN endpoint, even in case of errors - so I'm a bit lost as to why Janus seems to receive 0 bytes. Which version of Janus and libcurl is this?

Could you configure the frontend webserver address of your signaling server in Janus and check the webserver log? Maybe this shows some more details.