How Can a Server Reliably Detect Client Socket Disconnections?

Ensuring Reliable Detection of Client Socket Disconnections in Server Applications

Networked applications depend on the accurate detection of client disconnections to maintain stability. However, reliably determining when a client has disconnected from a server socket presents a significant challenge.

The Challenge:

How can a server definitively detect when a client disconnects from its socket?

Ineffective Approaches:

Common attempts using methods such as handler.Available, handler.Send, and handler.Receive to identify disconnections have proven unreliable from the server's perspective.

A Robust Solution:

The absence of built-in socket disconnection events necessitates a periodic polling approach. The following SocketExtensions method provides a dependable solution for verifying socket connectivity:

<code class="language-csharp">public static bool IsConnected(this Socket socket)
{
  try
  {
    return !(socket.Poll(1, SelectMode.SelectRead) && socket.Available == 0);
  }
  catch (SocketException) { return false; }
}</code>

This method leverages the Poll method to check for incoming data within a brief timeframe (1 millisecond). A lack of data within this interval indicates a potential disconnection.

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