Not disposing registration timer in SIPRegistrationUserAgent on unequivocal failure

[mikhail-barg]

Hi, we just stumbled on a problem with SIPRegistrationUserAgent when exitOnUnequivocalFailure is set to true, which is default.

So when a failure happens, the m_exit variable is set to m_exitOnUnequivocalFailure (which is true):

sipsorcery/src/app/SIPUserAgents/SIPRegistrationUserAgent.cs

Lines 513 to 518 in f35cc1e

	else if (sipResponse.Status == SIPResponseStatusCodesEnum.Forbidden || sipResponse.Status == SIPResponseStatusCodesEnum.NotFound)
	{
	// SIP account does not appear to exist.
	m_exit = m_exitOnUnequivocalFailure;
	logger.LogWarning($"Registration unequivocal failure with {sipResponse.Status} for {m_sipAccountAOR}{(m_exit ? ", no further registration attempts will be made" : "")}.");

(and two other similar places).

But then during the Stop() call, m_exit is being checked, and no call to m_registrationTimer.Dispose() happens:

sipsorcery/src/app/SIPUserAgents/SIPRegistrationUserAgent.cs

Lines 333 to 355 in f35cc1e

	public void Stop(bool sendZeroExpiryRegister = true)
	{
	try
	{
	if (!m_exit)
	{
	logger.LogDebug($"Stopping SIP registration user agent for {m_sipAccountAOR}.");
	m_exit = true;
	m_waitForRegistrationMRE.Set();
	if (m_isRegistered && sendZeroExpiryRegister)
	{
	m_attempts = 0;
	m_expiry = 0;
	ThreadPool.QueueUserWorkItem(delegate { SendInitialRegister(); });
	}
	m_registrationTimer.Dispose();
	m_registrationTimer = null;
	}
	}
	catch (Exception excp)

And this is the only place where the timer is being disposed.

This causes an infinite re-registration loop for the account which is already not being used, and other nasty consequences.

[sipsorcery]

Thanks for logging the bug. I've created a PR to fix in #1205.

[mikhail-barg]

Thanks for your support!