conncheck: update stun timer timeout for RFC8445

The new version of the RFC suppressed the difference between reliable
and not reliable maximum value for RTO. We choose to keep the value of
100ms that we used previously, which is lower that the recommended
value, but could be overriden most of the time, when a significant
number of pairs are handled.

We also compute exactly the number of in-progress and waiting
pairs for all streams of the agent, without relying on the value
per-stream, multiplied by the number of active streams.

1 files changed, 24 insertions, 18 deletions

diff --git a/agent/conncheck.c b/agent/conncheck.c
index 234a879..df7c67a 100644
--- a/agent/conncheck.c
+++ b/agent/conncheck.c
@@ -2914,34 +2914,40 @@ size_t priv_get_password (NiceAgent *agent, NiceStream *stream,
   return 0;
 }
 
-/* Implement the computation specific in RFC 5245 section 16 */
+/* Implement the computation specific in RFC 8445 section 14 */
 
 static unsigned int priv_compute_conncheck_timer (NiceAgent *agent, NiceStream *stream)
 {
-  GSList *i;
+  GSList *i, *j;
   guint waiting_and_in_progress = 0;
-  guint n = 0;
   unsigned int rto = 0;
 
-  for (i = stream->conncheck_list; i ; i = i->next) {
-    CandidateCheckPair *p = i->data;
-    if (p->state == NICE_CHECK_IN_PROGRESS ||
-        p->state == NICE_CHECK_WAITING)
-      waiting_and_in_progress++;
+  /* we can compute precisely the number of pairs in-progress or
+   * waiting for all streams, instead of limiting the value to one
+   * stream, and multiplying it by the number of active streams.
+   * Since RFC8445, this number of waiting and in-progress pairs
+   * if maxed by the number of different foundations in the conncheck
+   * list.
+   */
+  for (i = agent->streams; i ; i = i->next) {
+    NiceStream *s = i->data;
+    for (j = s->conncheck_list; j ; j = j->next) {
+      CandidateCheckPair *p = j->data;
+      if (p->state == NICE_CHECK_IN_PROGRESS ||
+          p->state == NICE_CHECK_WAITING)
+        waiting_and_in_progress++;
+    }
   }
 
-  n = priv_number_of_active_check_lists (agent);
-  rto = agent->timer_ta  * n * waiting_and_in_progress;
+  rto = agent->timer_ta  * waiting_and_in_progress;
 
-  /* We assume non-reliable streams are RTP, so we use 100 as the max */
+  /* RFC8445 indicates that the min rto value should be 500ms, but
+   * we prefer a lower value of 100ms, which should be overriden
+   * most of the time, when a significant number of pairs are handled.
+   */
   nice_debug ("Agent %p : timer set to %dms, "
-    "waiting+in_progress=%d, nb_active=%d",
-    agent, agent->reliable ? MAX (rto, 500) : MAX (rto, 100),
-    waiting_and_in_progress, n);
-  if (agent->reliable)
-    return MAX (rto, 500);
-  else
-    return MAX (rto, 100);
+    "waiting+in_progress=%d", agent, MAX (rto, 100), waiting_and_in_progress);
+  return MAX (rto, 100);
 }
 
 /*