diff options
| -rw-r--r-- | agent/conncheck.c | 30 |
1 files changed, 26 insertions, 4 deletions
diff --git a/agent/conncheck.c b/agent/conncheck.c index 4b785b5..88d2534 100644 --- a/agent/conncheck.c +++ b/agent/conncheck.c @@ -591,7 +591,6 @@ priv_conn_recheck_on_timeout (NiceAgent *agent, CandidateCheckPair *p) */ nice_debug ("Agent %p : pair %p was cancelled, " "triggering a new connection check", agent, p); - p->recheck_on_timeout = FALSE; priv_add_pair_to_triggered_check_queue (agent, p); return TRUE; } @@ -2650,9 +2649,32 @@ int conn_check_send (NiceAgent *agent, CandidateCheckPair *pair) if (nice_socket_is_reliable(pair->sockptr)) { stun_timer_start_reliable(&pair->timer, agent->stun_reliable_timeout); } else { - stun_timer_start (&pair->timer, - priv_compute_conncheck_timer (agent, stream), - agent->stun_max_retransmissions); + StunTimer *timer = &pair->timer; + + if (pair->recheck_on_timeout) + /* The pair recheck on timeout can easily cause repetitive rechecks in + * a ping-pong effect, if both peers with the same behaviour try to + * check the same pair almost simultaneously, and if the network rtt + * is greater than the initial timer rto. The reply to the initial + * stun request may arrive after the in-progress conncheck + * cancellation (described in RFC 5245, sect 7.2.1.4). Cancellation + * creates a new stun request, and forgets the initial one. + * The conncheck timer is restarted with the same initial value, + * so the same situation happens again later. + * + * We choose to avoid resetting the timer in such situation. + * After enough retransmissions, the timeout delay becomes + * longer than the rtt, and the stun reply can be handled. + */ + nice_debug("Agent %p : reusing timer of pair %p: %d/%d %d/%dms", + agent, pair, + timer->retransmissions, timer->max_retransmissions, + timer->delay - stun_timer_remainder (timer), timer->delay); + else + stun_timer_start (timer, + priv_compute_conncheck_timer (agent, stream), + agent->stun_max_retransmissions); + pair->recheck_on_timeout = FALSE; } /* TCP-ACTIVE candidate must create a new socket before sending |