public SIPTransaction GetTransaction(SIPResponse sipResponse)
{
if (sipResponse.Header.Vias.TopViaHeader.Branch == null || sipResponse.Header.Vias.TopViaHeader.Branch.Trim().Length == 0)
{
return(null);
}
else
{
string transactionId = SIPTransaction.GetRequestTransactionId(sipResponse.Header.Vias.TopViaHeader.Branch, sipResponse.Header.CSeqMethod);
lock (m_transactions)
{
if (m_transactions.ContainsKey(transactionId))
{
return(m_transactions[transactionId]);
}
else
{
return(null);
}
}
}
}
/// <summary>
/// Transaction matching see RFC3261 17.1.3 & 17.2.3 for matching client and server transactions respectively.
/// IMPORTANT NOTE this transaction matching applies to all requests and responses EXCEPT ACK requests to 2xx responses see 13.2.2.4.
/// For ACK's to 2xx responses the ACK represents a separate transaction. However for a UAS sending an INVITE response the ACK still has to be
/// matched to an existing server transaction in order to transition it to a Confirmed state.
///
/// ACK's:
/// - The ACK for a 2xx response will have the same CallId, From Tag and To Tag.
/// - An ACK for a non-2xx response will have the same branch ID as the INVITE whose response it acknowledges.
/// </summary>
/// <param name="sipRequest"></param>
/// <returns></returns>
public SIPTransaction GetTransaction(SIPRequest sipRequest)
{
// The branch is mandatory but it doesn't stop some UA's not setting it.
if (sipRequest.Header.Vias.TopViaHeader.Branch == null || sipRequest.Header.Vias.TopViaHeader.Branch.Trim().Length == 0)
{
return(null);
}
SIPMethodsEnum transactionMethod = (sipRequest.Method != SIPMethodsEnum.ACK) ? sipRequest.Method : SIPMethodsEnum.INVITE;
string transactionId = SIPTransaction.GetRequestTransactionId(sipRequest.Header.Vias.TopViaHeader.Branch, transactionMethod);
string contactAddress = (sipRequest.Header.Contact != null && sipRequest.Header.Contact.Count > 0) ? sipRequest.Header.Contact[0].ToString() : "no contact";
lock (m_transactions)
{
//if (transactionMethod == SIPMethodsEnum.ACK)
//{
//logger.Info("Matching ACK with contact=" + contactAddress + ", cseq=" + sipRequest.Header.CSeq + ".");
//}
if (transactionId != null && m_transactions.ContainsKey(transactionId))
{
//if (transactionMethod == SIPMethodsEnum.ACK)
//{
//logger.Info("ACK for contact=" + contactAddress + ", cseq=" + sipRequest.Header.CSeq + " was matched by branchid.");
//}
return(m_transactions[transactionId]);
}
else
{
// No normal match found so look fo a 2xx INVITE response waiting for an ACK.
if (sipRequest.Method == SIPMethodsEnum.ACK)
{
//logger.Debug("Looking for ACK transaction, branchid=" + sipRequest.Header.Via.TopViaHeader.Branch + ".");
foreach (SIPTransaction transaction in m_transactions.Values)
{
// According to the standard an ACK should only not get matched by the branchid on the original INVITE for a non-2xx response. However
// my Cisco phone created a new branchid on ACKs to 487 responses and since the Cisco also used the same Call-ID and From tag on the initial
// unauthenticated request and the subsequent authenticated request the condition below was found to be the best way to match the ACK.
/*if (transaction.TransactionType == SIPTransactionTypesEnum.Invite && transaction.TransactionFinalResponse != null && transaction.TransactionState == SIPTransactionStatesEnum.Completed)
* {
* if (transaction.TransactionFinalResponse.Header.CallId == sipRequest.Header.CallId &&
* transaction.TransactionFinalResponse.Header.To.ToTag == sipRequest.Header.To.ToTag &&
* transaction.TransactionFinalResponse.Header.From.FromTag == sipRequest.Header.From.FromTag)
* {
* return transaction;
* }
* }*/
// As an experiment going to try matching on the Call-ID. This field seems to be unique and therefore the chance
// of collisions seemingly very slim. As a safeguard if there happen to be two transactions with the same Call-ID in the list the match will not be made.
// One case where the Call-Id match breaks down is for in-Dialogue requests in that case there will be multiple transactions with the same Call-ID and tags.
//if (transaction.TransactionType == SIPTransactionTypesEnum.Invite && transaction.TransactionFinalResponse != null && transaction.TransactionState == SIPTransactionStatesEnum.Completed)
if (transaction.TransactionType == SIPTransactionTypesEnum.Invite && transaction.TransactionFinalResponse != null)
{
if (transaction.TransactionRequest.Header.CallId == sipRequest.Header.CallId &&
transaction.TransactionFinalResponse.Header.To.ToTag == sipRequest.Header.To.ToTag &&
transaction.TransactionFinalResponse.Header.From.FromTag == sipRequest.Header.From.FromTag &&
transaction.TransactionFinalResponse.Header.CSeq == sipRequest.Header.CSeq)
{
//logger.Info("ACK for contact=" + contactAddress + ", cseq=" + sipRequest.Header.CSeq + " was matched by callid, tags and cseq.");
return(transaction);
}
else if (transaction.TransactionRequest.Header.CallId == sipRequest.Header.CallId &&
transaction.TransactionFinalResponse.Header.CSeq == sipRequest.Header.CSeq &&
IsCallIdUniqueForPending(sipRequest.Header.CallId))
{
string requestEndPoint = (sipRequest.RemoteSIPEndPoint != null) ? sipRequest.RemoteSIPEndPoint.ToString() : " ? ";
//logger.Info("ACK for contact=" + contactAddress + ", cseq=" + sipRequest.Header.CSeq + " was matched using Call-ID mechanism (to tags: " + transaction.TransactionFinalResponse.Header.To.ToTag + "=" + sipRequest.Header.To.ToTag + ", from tags:" + transaction.TransactionFinalResponse.Header.From.FromTag + "=" + sipRequest.Header.From.FromTag + ").");
return(transaction);
}
}
}
//logger.Info("ACK for contact=" + contactAddress + ", cseq=" + sipRequest.Header.CSeq + " was not matched.");
}
return(null);
}
}
}