private void PrepareAndBindUdpSocket(DnsClientEndpointInfo endpointInfo, System.Net.Sockets.Socket udpClient)
{
if (endpointInfo.IsMulticast)
{
udpClient.Bind(new IPEndPoint(endpointInfo.LocalAddress, 0));
}
else
{
udpClient.Connect(endpointInfo.ServerAddress, _port);
}
}
private void UdpBeginSend <TMessage>(DnsClientAsyncState <TMessage> state)
where TMessage : DnsMessageBase, new()
{
if (state.EndpointInfoIndex == state.EndpointInfos.Count)
{
state.UdpClient = null;
state.UdpEndpoint = null;
state.SetCompleted();
return;
}
try
{
DnsClientEndpointInfo endpointInfo = state.EndpointInfos[state.EndpointInfoIndex];
state.UdpEndpoint = new IPEndPoint(endpointInfo.ServerAddress, _port);
state.UdpClient = new System.Net.Sockets.Socket(state.UdpEndpoint.AddressFamily, SocketType.Dgram, ProtocolType.Udp);
PrepareAndBindUdpSocket(endpointInfo, state.UdpClient);
state.TimedOut = false;
state.TimeRemaining = QueryTimeout;
IAsyncResult asyncResult = state.UdpClient.BeginSendTo(state.QueryData, 0, state.QueryLength, SocketFlags.None, state.UdpEndpoint, UdpSendCompleted <TMessage>, state);
state.Timer = new Timer(UdpTimedOut <TMessage>, asyncResult, state.TimeRemaining, Timeout.Infinite);
}
catch (Exception e)
{
Trace.TraceError("Error on dns query: " + e);
try
{
state.UdpClient.Close();
state.Timer.Dispose();
}
catch {}
state.EndpointInfoIndex++;
UdpBeginSend(state);
}
}
private byte[] QueryByUdp(DnsClientEndpointInfo endpointInfo, byte[] messageData, int messageLength, out IPAddress responderAddress)
{
using (System.Net.Sockets.Socket udpClient = new System.Net.Sockets.Socket(endpointInfo.LocalAddress.AddressFamily, SocketType.Dgram, ProtocolType.Udp))
{
try
{
udpClient.ReceiveTimeout = QueryTimeout;
PrepareAndBindUdpSocket(endpointInfo, udpClient);
EndPoint serverEndpoint = new IPEndPoint(endpointInfo.ServerAddress, _port);
udpClient.SendTo(messageData, messageLength, SocketFlags.None, serverEndpoint);
if (endpointInfo.IsMulticast)
{
serverEndpoint = new IPEndPoint(udpClient.AddressFamily == AddressFamily.InterNetwork ? IPAddress.Any : IPAddress.IPv6Any, _port);
}
byte[] buffer = new byte[65535];
int length = udpClient.ReceiveFrom(buffer, 0, buffer.Length, SocketFlags.None, ref serverEndpoint);
responderAddress = ((IPEndPoint)serverEndpoint).Address;
byte[] res = new byte[length];
Buffer.BlockCopy(buffer, 0, res, 0, length);
return(res);
}
catch (Exception e)
{
Trace.TraceError("Error on dns query: " + e);
responderAddress = default(IPAddress);
return(null);
}
}
}