Question

I’m using this client/server code which i found on the net for communication:

client:

    public void Send(string name, string path)
    {
        try
        {
            IPAddress[] ipAddress = Dns.GetHostAddresses("address");
            IPEndPoint ipEnd = new IPEndPoint(ipAddress[0], 5656);
            Socket clientSock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);

            string fileName = "somefile";
            string filePath = path;
            byte[] fileNameByte = Encoding.ASCII.GetBytes(fileName);

            byte[] fileData = File.ReadAllBytes(System.IO.Path.Combine(filePath, fileName)); 
            byte[] clientData = new byte[4 + fileNameByte.Length + fileData.Length];
            byte[] fileNameLen = BitConverter.GetBytes(fileNameByte.Length);

            fileNameLen.CopyTo(clientData, 0);
            fileNameByte.CopyTo(clientData, 4);
            fileData.CopyTo(clientData, 4 + fileNameByte.Length);

            clientSock.Connect(ipEnd);
            clientSock.Send(clientData);
            MessageBox.Show("file has been send: " + fileName);

            clientSock.Close();
        }
        catch (Exception ex)
        {
            Console.WriteLine("File Sending fail." + ex.Message);
        }
    }

server:

public void Receive()
    {
        try
        {
            lblInfo.Content = "That program can transfer small file. I've test up to 850kb file";
            IPEndPoint ipEnd = new IPEndPoint(IPAddress.Any, 5656);
            Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
            sock.Bind(ipEnd);
            sock.Listen(100);
            Socket clientSock = sock.Accept();
            // 1024 * 25.000 = 25mb max that can be received at once with this program.
            byte[] clientData = new byte[1024 * 25000];
            string receivedPath = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\";

            int receivedBytesLen = clientSock.Receive(clientData);

            int fileNameLen = BitConverter.ToInt32(clientData, 0);
            string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

            lblInfo.Content = "Client: connected & File started received.";

            BinaryWriter bWrite = new BinaryWriter(File.Open(receivedPath + fileName, FileMode.Append)); ;
            bWrite.Write(clientData, 4 + fileNameLen, receivedBytesLen - 4 - fileNameLen);

            lblInfo.Content = "File: received & saved at path: " + receivedPath;

            bWrite.Close();
            clientSock.Close();
        }
        catch (Exception ex)
        {
            lblInfo.Content = "File Receiving fail." + ex.Message;
        }
    }

this code works fine for 1 client that transferes a file to the server. i was wondering how i can change this code to make it communicate with multiple clients that can send files to the server?

also, the server code ‘hangs’ at Socket clientSock = sock.Accept(); and waits untill it receives something. It would be nice if there is a ‘listener’ that listens for new incomming files and then loop through the code, instead of endless waiting at that line.

Im new to client/server programming and all ears to other suggestions.

Answer 1

Here you have explanations for creating your loops for new connections :

http://msdn.microsoft.com/en-us/library/dz10xcwh.aspx

IPEndPoint ipEnd = new IPEndPoint(IPAddress.Any, 5656);
Socket listener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.IP);
listener.Bind(ipEnd);
listener.Listen(100);

Console.WriteLine("Waiting for a connection...");
Socket handler = listener.Accept();

while (true)
{
    // 1024 * 25.000 = 25mb max that can be received at once with this program.
    byte[] clientData = new byte[1024 * 25000];
    string receivedPath = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\";

    int bytesRec = handler.Receive(clientData);
    int fileNameLen = BitConverter.ToInt32(clientData, 0);
    string fileName = Encoding.ASCII.GetString(clientData, 4, fileNameLen);

    BinaryWriter bWrite = new BinaryWriter(File.Open(receivedPath + fileName, FileMode.Append)); ;
    bWrite.Write(clientData, 4 + fileNameLen, bytesRec - 4 - fileNameLen);
    bWrite.Close();
}

//dont forget to close handler at server shutdown
//handler.Shutdown(SocketShutdown.Both);
//handler.Close();