/// <summary>
/// New transaction ACK requests are for 2xx responses, i.e. INVITE accepted and dialogue being created.
/// </summary>
/// <remarks>
/// From RFC 3261 Chapter 13.2.2.4 - ACK for 2xx final responses
///
/// IMPORTANT:
/// an ACK for a 2xx final response is a new transaction and has a new branch ID.
///
/// The UAC core MUST generate an ACK request for each 2xx received from
/// the transaction layer. The header fields of the ACK are constructed
/// in the same way as for any request sent within a dialog (see Section
/// 12) with the exception of the CSeq and the header fields related to
/// authentication. The sequence number of the CSeq header field MUST be
/// the same as the INVITE being acknowledged, but the CSeq method MUST
/// be ACK. The ACK MUST contain the same credentials as the INVITE. If
/// the 2xx contains an offer (based on the rules above), the ACK MUST
/// carry an answer in its body. If the offer in the 2xx response is not
/// acceptable, the UAC core MUST generate a valid answer in the ACK and
/// then send a BYE immediately.
/// </remarks>
private SIPRequest GetNewTransactionAcknowledgeRequest(SIPMethodsEnum method, SIPResponse sipResponse,
SIPURI ackURI)
{
SIPRequest ackRequest = new SIPRequest(method, ackURI.ToString());
ackRequest.SetSendFromHints(sipResponse.LocalSIPEndPoint);
SIPHeader header = new SIPHeader(TransactionRequest.Header.From, sipResponse.Header.To,
sipResponse.Header.CSeq, sipResponse.Header.CallId);
header.CSeqMethod = method;
header.AuthenticationHeader = TransactionRequest.Header.AuthenticationHeader;
header.ProxySendFrom = base.TransactionRequest.Header.ProxySendFrom;
// If the UAS supplies a desired Record-Route list use that first. Otherwise fall back to any Route list used in the original transaction.
if (sipResponse.Header.RecordRoutes != null)
{
header.Routes = sipResponse.Header.RecordRoutes.Reversed();
}
else if (base.TransactionRequest.Header.Routes != null)
{
header.Routes = base.TransactionRequest.Header.Routes;
}
ackRequest.Header = header;
ackRequest.Header.Vias.PushViaHeader(SIPViaHeader.GetDefaultSIPViaHeader());
return(ackRequest);
}
/// <summary>
/// In transaction ACK requests are for non-2xx responses, i.e. INVITE rejected and no dialogue being created.
/// </summary>
/// <remarks>
/// From RFC 3261 Chapter 17.1.1.3 - ACK for non-2xx final responses
///
/// IMPORTANT:
/// an ACK for a non-2xx response will also have the same branch ID as the INVITE whose response it acknowledges.
///
/// The ACK request constructed by the client transaction MUST contain
/// values for the Call-ID, From, and Request-URI that are equal to the
/// values of those header fields in the request passed to the transport
/// by the client transaction (call this the "original request"). The To
/// header field in the ACK MUST equal the To header field in the
/// response being acknowledged, and therefore will usually differ from
/// the To header field in the original request by the addition of the
/// tag parameter. The ACK MUST contain a single Via header field, and
/// this MUST be equal to the top Via header field of the original
/// request. The CSeq header field in the ACK MUST contain the same
/// value for the sequence number as was present in the original request,
/// but the method parameter MUST be equal to "ACK".
///
/// If the INVITE request whose response is being acknowledged had Route
/// header fields, those header fields MUST appear in the ACK. This is
/// to ensure that the ACK can be routed properly through any downstream
/// stateless proxies.
/// </remarks>
private SIPRequest GetInTransactionACKRequest(SIPResponse sipResponse, SIPURI ackURI)
{
SIPRequest ackRequest = new SIPRequest(SIPMethodsEnum.ACK, ackURI.ToString());
ackRequest.SetSendFromHints(sipResponse.LocalSIPEndPoint);
SIPHeader header = new SIPHeader(TransactionRequest.Header.From, sipResponse.Header.To, sipResponse.Header.CSeq, sipResponse.Header.CallId);
header.CSeqMethod = SIPMethodsEnum.ACK;
header.AuthenticationHeader = TransactionRequest.Header.AuthenticationHeader;
header.Routes = base.TransactionRequest.Header.Routes;
header.ProxySendFrom = base.TransactionRequest.Header.ProxySendFrom;
ackRequest.Header = header;
ackRequest.Header.Vias.PushViaHeader(SIPViaHeader.GetDefaultSIPViaHeader());
return(ackRequest);
}
