/// <summary>
/// Starts the client transaction.
/// </summary>
public void Start()
{
SipCSeqValue vCSeq;
// Add a CSeq header to the request if necessary and intialize the
// transaction's local sequence number.
vCSeq = request.GetHeader <SipCSeqValue>(SipHeader.CSeq);
if (vCSeq == null)
{
request.AddHeader(SipHeader.CSeq, new SipCSeqValue(SipHelper.GenCSeq(), request.MethodText));
}
// Add Max-Forwards if necessary.
if (request.GetHeaderText(SipHeader.MaxForwards) == null)
{
request.AddHeader(SipHeader.MaxForwards, SipHelper.MaxForwards);
}
// Start the transaction
using (TimedLock.Lock(agent))
{
SetState(request.Method == SipMethod.Invite ? SipTransactionState.InviteCalling : SipTransactionState.Trying);
transport.Send(remoteEP, request);
}
}
/// <summary>
/// Creates the proper ACK request based on the original INVITE request sent
/// to the server and the 2xx response received.
/// </summary>
/// <param name="inviteRequest">The INVITE <see cref="SipRequest" /> sent to the server.</param>
/// <param name="response">The 2xx <see cref="SipResponse" /> received from the server.</param>
/// <returns>The created ACK <see cref="SipRequest" />.</returns>
private SipRequest CreateAckRequest(SipRequest inviteRequest, SipResponse response)
{
SipRequest ackRequest;
SipHeader callID;
SipHeader to;
SipHeader from;
SipHeader via;
SipHeader contact;
SipHeader route;
SipCSeqValue vCSeq;
if (inviteRequest.Method != SipMethod.Invite)
{
throw new ArgumentException("INVITE request expected.", "inviteRequest");
}
if (response.IsProvisional)
{
throw new ArgumentException("Non-provisional response expected.", "response");
}
ackRequest = new SipRequest(SipMethod.Ack, inviteRequest.Uri, null);
callID = inviteRequest[SipHeader.CallID];
to = response[SipHeader.To];
from = inviteRequest[SipHeader.From];
via = inviteRequest[SipHeader.Via];
contact = inviteRequest[SipHeader.Contact];
route = inviteRequest[SipHeader.Route];
if (callID == null)
{
throw new SipException("INVITE request is missing header: [Call-ID]");
}
if (to == null)
{
throw new SipException("INVITE response is missing header: [To]");
}
if (from == null)
{
throw new SipException("INVITE request is missing header: [From]");
}
if (contact == null)
{
throw new SipException("INVITE request is missing header: [Contact]");
}
if (via == null)
{
throw new SipException("INVITE request is missing header: [Via]");
}
vCSeq = inviteRequest.GetHeader <SipCSeqValue>(SipHeader.CSeq);
if (vCSeq == null)
{
throw new SipException("INVITE request is missing header: [CSeq]");
}
ackRequest.AddHeader(SipHeader.Via, via.Text);
ackRequest.AddHeader(SipHeader.To, to.Text);
ackRequest.AddHeader(SipHeader.From, from.Text);
ackRequest.AddHeader(SipHeader.Contact, contact.Text);
ackRequest.AddHeader(SipHeader.CallID, callID.Text);
ackRequest.AddHeader(SipHeader.CSeq, new SipCSeqValue(vCSeq.Number, "ACK"));
ackRequest.AddHeader(SipHeader.MaxForwards, SipHelper.MaxForwards);
ackRequest.AddHeader(SipHeader.UserAgent, agent.Core.Settings.UserAgent);
if (route != null)
{
ackRequest.Headers.Add(SipHeader.Route, route.Clone());
}
return(ackRequest);
}
/// <summary>
/// Initiates an asynchronous SIP request transaction.
/// </summary>
/// <param name="request">The <see cref="SipRequest" /> to be submitted.</param>
/// <param name="dialog">The <see cref="SipDialog" /> for requests that initiate a dialog (or <c>null</c>).</param>
/// <param name="callback">The delegate to be called when the operation completes (or <c>null</c>).</param>
/// <param name="state">Application defined state (or <c>null</c>).</param>
/// <returns>The <see cref="IAsyncResult" /> to be used to track the operation's progress.</returns>
/// <remarks>
/// <para>
/// All requests to <see cref="BeginRequest(SipRequest,SipDialog,AsyncCallback,object)" /> must be matched with a
/// call to <see cref="EndRequest" />.
/// </para>
/// <note>
/// This method adds reasonable <b>Call-ID</b> and <b>CSeq</b> headers to the request if these
/// headers are not already present.
/// </note>
/// </remarks>
public IAsyncResult BeginRequest(SipRequest request, SipDialog dialog, AsyncCallback callback, object state)
{
ClientAsyncResult arClient = new ClientAsyncResult(request, dialog, callback, state);
SipValue viaValue;
SipCSeqValue vCSeq;
string transactionID;
SipClientTransaction transaction;
ISipTransport transport;
NetworkBinding remoteEP;
if (dialog != null && request.Method != SipMethod.Invite)
{
throw new InvalidOperationException("Dialogs may be created only for INVITE requests.");
}
arClient.Dialog = dialog;
transport = router.SelectTransport(this, request, out remoteEP);
if (transport == null)
{
throw new SipException("No approriate transport is available.");
}
// Initialize the request's Via header and transaction ID as necessary.
transactionID = SipHelper.GenerateBranchID();
viaValue = new SipValue(string.Format("SIP/2.0/{0} {1}", transport.Name, transport.Settings.ExternalBinding.Address));
viaValue["branch"] = transactionID;
viaValue["rport"] = string.Empty;
request.PrependHeader(SipHeader.Via, viaValue);
// Initialize common headers as necessary
if (!request.ContainsHeader(SipHeader.CallID))
{
request.AddHeader(SipHeader.CallID, SipHelper.GenerateCallID());
}
vCSeq = request.GetHeader <SipCSeqValue>(SipHeader.CSeq);
if (vCSeq == null)
{
vCSeq = new SipCSeqValue(SipHelper.GenCSeq(), request.MethodText);
request.AddHeader(SipHeader.CSeq, vCSeq);
}
// Initialize the transaction
transaction = new SipClientTransaction(this, request, transactionID, transport, remoteEP);
transaction.AgentState = arClient;
// Handle initial dialog INVITE specific initialization
if (dialog != null && request.Method == SipMethod.Invite && dialog.State == SipDialogState.Waiting)
{
// Client-side dialogs need to know the transaction so
// they'll be able to send the confirming ACK.
dialog.InitiatingTransaction = transaction;
// Dialogs need to know about the sequence number used in INVITE requests so
// that the ACK can be generated with the same sequence number.
dialog.AckCSeq = vCSeq.Number;
// The dialog has been intialized enough to be added to the core's
// early dialog table.
core.AddEarlyDialog(dialog);
}
// Start the transaction
using (TimedLock.Lock(this))
{
transactions.Add(transactionID, transaction);
}
transaction.Start();
arClient.Started();
return(arClient);
}
