[libnice] 'Gathering' state not triggered for 'host' candidates

Juan Navarro juan.navarro at gmx.es
Thu Sep 21 18:54:01 UTC 2017


my local unit tests have been failing due to an issue with the change 
logic of the NiceAgent's component state NICE_COMPONENT_STATE_GATHERING:

This state is only notified through "component-state-changed" -or 
obtained through nice_agent_get_component_state()- when:
-> A new local candidate has been obtained,
-> AND the candidate is either Server Reflexive (STUN) or Relayed (TURN),
-> AND the NiceAgent component was in either DISCONNECTED or FAILED states.

Shouldn't it also change to that state even if only 'host' candidates 
are being gathered?

Relevant code

         if (nice_address_is_valid (&cand->server) &&
             (cand->type == NICE_CANDIDATE_TYPE_SERVER_REFLEXIVE ||
                 cand->type == NICE_CANDIDATE_TYPE_RELAYED)) {

           if (cand->component->state ==
               cand->component->state == NICE_COMPONENT_STATE_FAILED)
             agent_signal_component_state_change (agent,

In my failing test, I have two peers which gather local candidates and 
exchange them in order to check that a connection can be established. 
The signals "new-candidate-full" of each peer will trigger a call to the 
function "nice_agent_set_remote_candidates()" on the other peer.

Docs state that: "You must first call nice_agent_gather_candidates() 
[...] before calling nice_agent_set_remote_candidates()"

So, to prevent mistakes, before the actual call to 
"nice_agent_set_remote_candidates()", a security check is done by 
calling "nice_agent_get_component_state()" with the appropriate 
parameters, and ensuring that the result is one of 

specifically, the check ensures that the state is *not* any of

However, as you may imagine already, the state is DISCONNECTED during 
the test, even if both peers have already gathered multiple local 
candidates (of type 'host').

As far as I understand, the component state should change to GATHERING 
as soon as the first local candidate is found, regardless of it being 
type "host" or any other. Is there some spec I'm forgetting/not 
understanding about this?

Kind regards,

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