/// <summary>
/// Adds a header to the message, <b>prepending</b> the value before
/// any existing values if the header already exists.
/// </summary>
/// <param name="name">The header name.</param>
/// <param name="value">The new value.</param>
public void PrependHeader(string name, SipValue value)
{
if (value == null)
{
throw new ArgumentNullException("value");
}
headers.Prepend(name, value.ToString());
}
/// <summary>
/// Attempts to return the client side transaction ID from the message. This is
/// the <b>branch</b> parameter from the top-most <b>Via</b> header.
/// </summary>
/// <param name="transactionID">Returns as the transaction ID on success.</param>
/// <returns><b><c>true</c> if the transaction ID was returned.</b></returns>
public bool TryGetTransactionID(out string transactionID)
{
SipHeader via;
SipValue viaValue;
transactionID = null;
via = base.Headers[SipHeader.Via];
if (via == null)
{
return(false);
}
viaValue = new SipValue(via.Text);
return(viaValue.Parameters.TryGetValue("branch", out transactionID));
}
/// <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);
}
