UDP Server, Output doubles after each Loop - sockets

Question

i have a UDP Server/Client Program wich works well.
I send the received Message from one Client back to all connected Clients, but the Output doubles after each Loop.
I think i have to reset the ListArray with the Clients, but then only the first Message will be Send.
Does somebody has any idea? Thanks!
UDP SERVER
//Listening on Port 12222
int servPort = 12222;
UdpClient client = null;
//Create a new ListArray for the connected Clients
ArrayList IPArray = new ArrayList();
try
{
//Create an instance of UdpClient
client = new UdpClient(servPort);
}
catch (SocketException se)
{
Console.WriteLine(se.ErrorCode + ": " + se.Message);
Environment.Exit(se.ErrorCode);
}
//Create an new IPEndPoint
IPEndPoint remoteIPEndPoint = new IPEndPoint(IPAddress.Any, 0);
//Endless loop
for (; ; )
{
try
{
//Receive a byte array with contents
byte[] byteBuffer = client.Receive(ref remoteIPEndPoint);
//Message from Client
string returnData = Encoding.ASCII.GetString(byteBuffer);
//Add connected Client IPs to ListArray
IPArray.Add(remoteIPEndPoint);
//Send the received Message back to all Clients in the ArrayList
for (int i = 0; i < IPArray.Count; i++)
{
Console.WriteLine("Handling client at " + IPArray[i] + " - " + returnData + " arraylist.Length " + IPArray.Count + "\n");
Byte[] sendBytes = Encoding.ASCII.GetBytes("Clients Send " + returnData + "\n");
client.Send(sendBytes, sendBytes.Length, (IPEndPoint)IPArray[i]);
}
Console.WriteLine("echoed {0} bytes.", byteBuffer.Length);
}
catch (SocketException se)
{
Console.WriteLine(se.ErrorCode + ": " + se.Message);
}
}
}
UDP CLIENT
//Server name or IP address
static String server = "127.0.0.1";
//Port
static int servPort = 12222;
//Convert String to an array of bytes
static string message = "ICH";
static void Main(string[] args)
{
SendReceive();
}
static byte[] sendPacket = Encoding.ASCII.GetBytes(message);
//Create an instance of UdpClient
static UdpClient client = new UdpClient();
static void SendReceive()
{
try
{
//Send the string to the specified Server and Port
client.Send(sendPacket, sendPacket.Length, server, servPort);
Console.WriteLine("Sent {0} bytes to the server...", sendPacket.Length);
IPEndPoint remoteIPEndPoint = new IPEndPoint(IPAddress.Any, 0);
//Attempt Message reply receive
byte[] rcvPacket = client.Receive(ref remoteIPEndPoint);
Console.WriteLine("Received {0} bytes from {1}: {2}",
rcvPacket.Length, remoteIPEndPoint,
Encoding.ASCII.GetString(rcvPacket, 0, rcvPacket.Length));
}
catch (SocketException se)
{
Console.WriteLine(se.ErrorCode + ": " + se.Message);
}
//Console.ReadKey();
//client.Close();
Thread.Sleep(500);
//Endless Loop
SendReceive();
}
UDP SERVER :

Answer 1

The Array with the iP Adresses grows with every Message from the
Client, but i want only the last Message that the Clients has send.
If that is the requirement, then there is no need of the loop. Also, without the help of arraylist, you can display the details of individual clients using the remoteIPEndPoint itself. That is the neater way to do what you want.
Remove the following lines from the UDP Server :
...
//Send the received Message back to all Clients in the ArrayList
for (int i = 0; i < IPArray.Count; i++)
{
Console.WriteLine("Handling client at " + IPArray[i] + " - " + returnData + " arraylist.Length " + IPArray.Count + "\n");
Byte[] sendBytes = Encoding.ASCII.GetBytes("Clients Send " + returnData + "\n");
client.Send(sendBytes, sendBytes.Length, (IPEndPoint)IPArray[i]);
}
...
You need to display the IP-Address and the port number of the client which sent the message. Instead, add the following lines :
//1. Now, you can show the count, but, you can get the indiviudal client detail
//using the remoteIPEndPoint, there is no need of iterating through the array.
Console.WriteLine("This message was sent from " + remoteIPEndPoint.Address.ToString() +
" on their port number " +
remoteIPEndPoint.Port.ToString() + " - " + returnData + "\n");
//2. Then send the data back to the individual client without using ArrayList,
// by passing the client's IPEndPoint in the Send() method.
Byte[] sendBytes = Encoding.ASCII.GetBytes("Clients Send " + returnData + "\n");
client.Send(sendBytes, sendBytes.Length, remoteIPEndPoint);
What it does is that it shows the IP-Address and the port number of the client which sent the message to the server.\
Also, the current way is not a better way for network/socket programming. You should always use separate threads(limit them in a pool using ConnectionQueue) for receving each client's message. Use a ConnectionQueue to maintain an order of threads (which can be reused for each new client-request).