/// <summary>
/// Begins an asychronous traceroute to the specified destination.
/// </summary>
/// <param name="destination">The destination IP address.</param>
/// <param name="callback">The callback method.</param>
/// <param name="state">The user state.</param>
/// <returns>The result of the asynchronous operation.</returns>
public IAsyncResult Begin(IPAddress destination, AsyncCallback callback, object state)
{
lock (this.settings)
{
// Create a new traceroute state.
TracerouteState asyncState = new TracerouteState(destination, this.settings.DataLength, callback, state);
// Send a traceroute.
this.Send(asyncState);
// Return the asynchronous state.
return asyncState;
}
}
// Private methods.
/// <summary>
/// Send a traceroute message using the specified traceroute state.
/// </summary>
/// <param name="asyncState">The traceroute state.</param>
private void Send(TracerouteState asyncState)
{
// Begin sending a traceroute message using the state.
IAsyncResult result = asyncState.Begin((IAsyncResult asyncResult) =>
{
// Finish sending a traceroute message using the state.
asyncState.End(asyncResult);
// A flag indicated whether the traceroute has completed.
bool completed = false;
lock (this.settings.Sync)
{
// Check whether the traceroute reached the destination.
completed = completed || (asyncState.LastReply != null ? asyncState.Destination.Equals(asyncState.LastReply.Address) &&
(this.settings.StopHopOnSuccess ? asyncState.TtlSuccess : asyncState.CurrentAttempt >= this.settings.MaximumAttempts) : false);
// Check whether the maximum number of hops was reached.
completed = completed || (asyncState.CurrentTtl > this.settings.MaximumHops);
// Check whether the maximum number of failed hops was reached.
completed = completed || (this.settings.StopTracerouteOnFail && (asyncState.LastFailedTtlCount + 1 >= this.settings.MaximumFailedHops) && (asyncState.CurrentAttempt >= this.settings.MaximumAttempts));
// Check whether the operation was canceled.
completed = completed || asyncState.CancellationToken.IsCancellationRequested;
}
// If the traceroute is completed, complete the asynchronous operation.
if (completed) asyncState.Complete();
// Call the callback method.
if (null != asyncState.Callback) asyncState.Callback(asyncState);
// If the operation is not completed.
if (!completed)
{
lock (this.settings.Sync)
{
// If the hop was successful, and the traceroute stops on success; or if the maximum number of attempts was reached.
if ((this.settings.StopHopOnSuccess && asyncState.TtlSuccess) || (asyncState.CurrentAttempt >= this.settings.MaximumAttempts))
{
// Increment the TTL.
asyncState.Next();
}
}
// Send a new message.
this.Send(asyncState);
}
else
{
// Dispose the asynchronous state.
asyncState.Dispose();
}
});
}