/// <summary>
/// Sets the nominated checklist entry. This action completes the checklist processing and
/// indicates the connection checks were successful.
/// </summary>
/// <param name="entry">The checklist entry that was nominated.</param>
private void SetNominatedEntry(ChecklistEntry entry)
{
entry.Nominated = true;
_checklistState = ChecklistState.Completed;
NominatedCandidate = entry.RemoteCandidate;
ConnectionState = RTCIceConnectionState.connected;
OnIceConnectionStateChange?.Invoke(RTCIceConnectionState.connected);
}
/// <summary>
/// Processes the checklist and sends any required STUN requests to perform connectivity checks.
/// </summary>
/// <remarks>
/// The scheduling mechanism for ICE is specified in https://tools.ietf.org/html/rfc8445#section-6.1.4.
/// </remarks>
private void ProcessChecklist(Object stateInfo)
{
try
{
if (ConnectionState == RTCIceConnectionState.checking && _checklist != null && _checklist.Count > 0)
{
if (RemoteIceUser == null || RemoteIcePassword == null)
{
logger.LogWarning("ICE session checklist processing cannot occur as either the remote ICE user or password are not set.");
ConnectionState = RTCIceConnectionState.failed;
}
else
{
lock (_checklist)
{
// The checklist gets sorted into priority order whenever a remote candidate and its corresponding candidate pairs
// are added. At this point it can be relied upon that the checklist is correctly sorted by candidate pair priority.
// Do a check for any timed out entries.
var failedEntries = _checklist.Where(x => x.State == ChecklistEntryState.InProgress &&
DateTime.Now.Subtract(x.LastCheckSentAt).TotalMilliseconds > RTO &&
x.ChecksSent >= N).ToList();
foreach (var failedEntry in failedEntries)
{
logger.LogDebug($"Checks for checklist entry have timed out, state being set to failed: {failedEntry.LocalCandidate} -> {failedEntry.RemoteCandidate}.");
failedEntry.State = ChecklistEntryState.Failed;
}
// Move on to checking for checklist entries that need an initial check sent.
var nextEntry = _checklist.Where(x => x.State == ChecklistEntryState.Waiting).FirstOrDefault();
if (nextEntry != null)
{
SendConnectivityCheck(nextEntry, false);
return;
}
// No waiting entries so check for ones requiring a retransmit.
var retransmitEntry = _checklist.Where(x => x.State == ChecklistEntryState.InProgress &&
DateTime.Now.Subtract(x.LastCheckSentAt).TotalMilliseconds > RTO).FirstOrDefault();
if (retransmitEntry != null)
{
SendConnectivityCheck(retransmitEntry, false);
return;
}
// If this point is reached and all entries are in a failed state then the overall result
// of the ICE check is a failure.
if (_checklist.All(x => x.State == ChecklistEntryState.Failed))
{
_stunChecksTimer.Dispose();
_checklistState = ChecklistState.Failed;
ConnectionState = RTCIceConnectionState.failed;
OnIceConnectionStateChange?.Invoke(ConnectionState);
}
}
}
}
}
catch (Exception excp)
{
logger.LogError("Exception ProcessChecklist. " + excp);
}
}
