[Windows Phone 7 Software Development] roady001:
I'm developing a WP7 app, working alongside a Windows (server) application. They are talking with each other using sockets.

As soon as the WP7 app opens, I wish to perform a network scan to find the server application.

I already found out how to get the IP address of the WP7. So let's say I know the server should be somewhere at 192.168.0.*. How do I go about scanning this network?

I tried many things, the last of which is the code below. The problem here is that somehow the TIMEOUT_MILLISECONDS parameter seems to be like playing roulette (tried everything in the range of 100-2000 with different success). In addition, if I sweep the whole subnet like in the code below the phone cannot seem to handle the work. I only get it to work if I set the timeout to 2000 (which is way to long) and by scanning up to 5 IP's in the for-loop, instead of the whole subnet.

Is there anyone that knows a better and much more efficient(!) way to do this?

string thisIP = "192.168.0.101"; // I normally get this from some other function
string[] arrIP = thisIP.ToString().Split('.');
string IPBase = arrIP[0] + "." + arrIP[1] + "." + arrIP[2] + ".";

//MessageBox.Show(address.ToString());
for (int i = 2; i < 254; i++) {
string IP = IPBase + i;
CheckConnection CheckConn = new CheckConnection();
string resultConnect = CheckConn.Connect(IP, int.Parse(Resource1.port));
if (resultConnect == "Success") {
CheckConn.Send("isAlive");
string result = CheckConn.Receive();
if (result.Contains("yes")) {
// We have found the server
break;
}
}
CheckConn.Close();
}

public class CheckConnection
{
// Cached Socket object that will be used by each call for the lifetime of this class

Socket _socket = null;
static ManualResetEvent _clientDone = new ManualResetEvent(false);
const int TIMEOUT_MILLISECONDS = 100;
const int MAX_BUFFER_SIZE = 2048;

public string Connect(string hostName, int portNumber) {
string result = string.Empty;
DnsEndPoint hostEntry = new DnsEndPoint(hostName, portNumber);
_socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = hostEntry;
socketEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(delegate(object s, SocketAsyncEventArgs e) {
result = e.SocketError.ToString();
_clientDone.Set();
});
_clientDone.Reset();
_socket.ConnectAsync(socketEventArg);
_clientDone.WaitOne(TIMEOUT_MILLISECONDS);
return result;
}

public string Send(string data) {
string response = "Operation Timeout";
if (_socket != null) {
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = _socket.RemoteEndPoint;
socketEventArg.UserToken = null;
socketEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(delegate(object s, SocketAsyncEventArgs e) {
response = e.SocketError.ToString();
_clientDone.Set();
});

byte[] payload = Encoding.UTF8.GetBytes(data);
socketEventArg.SetBuffer(payload, 0, payload.Length);
_clientDone.Reset();
_socket.SendAsync(socketEventArg);
// Block the UI thread for a maximum of TIMEOUT_MILLISECONDS seconds.
// If no response comes back within this time then proceed
_clientDone.WaitOne(TIMEOUT_MILLISECONDS);
}
else {
response = "Socket is not initialized";
}
return response;

}

public string Receive() {
string response = "Operation Timeout";
if (_socket != null) {
SocketAsyncEventArgs socketEventArg = new SocketAsyncEventArgs();
socketEventArg.RemoteEndPoint = _socket.RemoteEndPoint;
socketEventArg.SetBuffer(new Byte[MAX_BUFFER_SIZE], 0, MAX_BUFFER_SIZE);
socketEventArg.Completed += new EventHandler<SocketAsyncEventArgs>(delegate(object s, SocketAsyncEventArgs e) {
if (e.SocketError == SocketError.Success) {
response = Encoding.UTF8.GetString(e.Buffer, e.Offset, e.BytesTransferred);
response = response.Trim('\0');
}
else {
response = e.SocketError.ToString();
}
_clientDone.Set();

});

_clientDone.Reset();
_socket.ReceiveAsync(socketEventArg);
_clientDone.WaitOne(TIMEOUT_MILLISECONDS);
}
else {
response = "Socket is not initialized";
}
return response;
}

public void Close() {
if (_socket != null) {
_socket.Close();
}
}
}