[1.x] Streaming plugin recording capability has mutex issues

[evplatt]

What version of Janus is this happening on?
1.0.0

Have you tested a more recent version of Janus too?
N/A

Was this working before?
Unknown - first usage

Is there a gdb or libasan trace of the issue?
No

Additional context

For streaming recording start requests with 'media' key (not the "old method"), mountpoints_mutex is never unlocked after starting the recording. Suspect it should be unlocked prior to 'goto prepare_response'

For streaming recording stop requests with 'media' key (not the "old method"):

• source->rec_mutex attempts to lock twice, once before if(media) and once after, causing a lockup
• mountpoints_mutex is never unlocked after stopping the recording. Suspect it should be unlocked prior to 'goto prepare_response'

[atoppi]

Thanks for reporting @evplatt.

When starting recording it seems that both a mp ref decrease and mountpoints_mutex unlock are missing in this block

janus-gateway/src/plugins/janus_streaming.c

Lines 4680 to 4685 in 2009325

	}
	janus_mutex_unlock(&source->rec_mutex);
	/* Send a success response back */
	response = json_object();
	json_object_set_new(response, "streaming", json_string("ok"));
	goto prepare_response;

When stopping I can confirm the double source->rec_mutex locking

janus-gateway/src/plugins/janus_streaming.c

Lines 4782 to 4785 in 2009325

	janus_mutex_lock(&source->rec_mutex);
	if(media) {
	/* Iterate on all media to stop */
	janus_mutex_lock(&source->rec_mutex);

and also the missing unlock / unref

janus-gateway/src/plugins/janus_streaming.c

Lines 4811 to 4816 in 2009325

	}
	janus_mutex_unlock(&source->rec_mutex);
	/* Send a success response back */
	response = json_object();
	json_object_set_new(response, "streaming", json_string("ok"));
	goto prepare_response;

we'll work on a fix.

[lminiero]

Related to this, I fixed a couple of additional issues:

• there was still a crash when stopping a recording, and that was due to a dereference of stream->rc that could be NULL (not all streams may be recording, when we choose to stop it)
• there was also a problem when starting recordings using the legacy API, as the code was not really using the video and data properties when provided.

Both should be fixed in the commit above.