How to Reduce Socket Connect Timeout When Connecting to a Disconnected IP Address?

Reducing Socket Connection Timeouts

The Issue: Connecting to an unreachable IP address via a socket often leads to excessively long timeouts (e.g., 15 seconds). This article shows how to shorten this delay.

Original Code:

try
{
    m_clientSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
    IPAddress ip = IPAddress.Parse(serverIp);
    int iPortNo = System.Convert.ToInt16(serverPort);
    IPEndPoint ipEnd = new IPEndPoint(ip, iPortNo);
    m_clientSocket.Connect(ipEnd);
    if (m_clientSocket.Connected)
    {
        lb_connectStatus.Text = "Connection Established";
        WaitForServerData();
    }
}
catch (SocketException se)
{
    lb_connectStatus.Text = "Connection Failed";
    MessageBox.Show(se.Message);
}

Improved Solution: The BeginConnect and EndConnect methods offer more control over timeout behavior. BeginConnect allows specifying a timeout duration.

Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);

// Set connection timeout (5 seconds)
IAsyncResult result = socket.BeginConnect(sIP, iPort, null, null);

bool success = result.AsyncWaitHandle.WaitOne(5000, true); // 5000 milliseconds = 5 seconds

if (socket.Connected)
{
    socket.EndConnect(result);
    // ... proceed with connection ...
}
else
{
    // Crucial: Close the socket to release resources
    socket.Close();
    throw new ApplicationException("Failed to connect to server.");
}

This revised code attempts a connection with a 5-second timeout. If the connection fails within that timeframe, an exception is thrown, and the socket is explicitly closed. This prevents resource leaks and improves responsiveness.

The above is the detailed content of How to Reduce Socket Connect Timeout When Connecting to a Disconnected IP Address?. For more information, please follow other related articles on the PHP Chinese website!