/// <summary>
/// Initiates the DNS Server's protocols and starts listening for requests.
/// </summary>
public void Start()
{
EndPoint EndPoint = new IPEndPoint(IPAddress.Any, 51);
Server.SetSocketOption(SocketOptionLevel.IP, SocketOptionName.PacketInformation, true);
Server.Bind(EndPoint);
Processor.LoadDomainNameTable(); //do database stuff.
Server.BeginReceiveFrom(Data, 0, PACKET_LENGTH, SocketFlags.None, ref Sender, new AsyncCallback(Request), null);
VerboseLog?.Invoke("Server has started listening for DNS requests.");
}
/// <summary>
/// Callback function for sending async DNS responses.
/// </summary>
/// <param name="result"></param>
private void ResponseCompleted(IAsyncResult result)
{
try
{
EndPoint ep = (EndPoint)result.AsyncState;
int bytesSend = Server.EndSendTo(result);
if (bytesSend > 0)
{
VerboseLog?.Invoke($"Sent a response to {((IPEndPoint)ep).Address}:{((IPEndPoint)ep).Port}.");
}
}
catch (Exception ex)
{
ErrorLog?.Invoke($"Error ending async response: '{ex.Message}'.");
}
}
/// <summary>
/// Callback function for the Data recieve function.
/// </summary>
/// <param name="result"></param>
private void Request(IAsyncResult result)
{
try
{
Server.EndReceiveFrom(result, ref Sender);
bool success = DNSRequestHandler(Sender, Data);
VerboseLog?.Invoke($"Received data from {((IPEndPoint)Sender).Address}:{((IPEndPoint)Sender).Port}. Response success: {success}.");
Server.BeginReceiveFrom(Data, 0, PACKET_LENGTH, SocketFlags.None, ref Sender, new AsyncCallback(Request), null);
}
catch (SocketException sEx)
{
ErrorLog?.Invoke($"SocketException: '{sEx.Message}' for {((IPEndPoint)Sender).Address}.");
}
catch (DNSException dEx)
{
ErrorLog?.Invoke($"DNS Exception: '{dEx.Message}' for {((IPEndPoint)Sender).Address}.");
}
catch (Exception ex)
{
ErrorLog?.Invoke($"Unexpected Exception: '{ex.Message}'.");
}
}
private void Verbose(string text, params object[] args)
{
VerboseLog?.Invoke(string.Format(text + "\r\n", args));
}
