How to create a conditional breakpoint on a socket port?

Question

I'm working on a C# application, working with TCP sockets. In order to do this, there are following lines of source code:

using System.Net.Sockets;
...
var sock = (Socket)ar.AsyncState;
...
if (sock.Connected)
...

I would like to have a conditional breakpoint on that last line, for the case where TCP port equals 123.
In order to achieve that, I have entered sock in the watch window, and went further in order to find the port. Once found, I do "Add watch", and the following appears in the watch window:

((System.Net.IPEndPoint)sock.RemoteEndPoint).Port

So, I've decided to use this as an entry for the conditional breakpoint:

Conditional Expression
Is true 
((System.Net.IPEndPoint)sock.RemoteEndPoint).Port == 123

However, this yields the following error message:

Breakpoint error: The condition for a breakpoint failed to execute. The condition was '((System.Net.IPEndPoint)sock.RemoteEndPoint).Port == 123'. The error returned was 'Evaluation of method System.Net.Sockets.Socket.get_RemoteEndPoint() calls into native method Interop+Sys.SetAddressFamily(byte*, int, int). Evaluation of native methods in this context is not supported.'. Click OK to stop at this breakpoint.

How can I create a conditional breakpoint for this value?

It looks like you can't, unfortunately, for the reason given. Conditional breakpoints are slow anyway, which isn't ideal for things like socket code (the debugger has to break, evaluate the condition, and decide whether to resume). If you can modify the code, just put an `if` in there, either with a breakpoint or a `Debugger.Break()` in the body — canton7, Nov 30 '22 at 10:49
@canton7: Adding such an `if`-condition was my workaround until somebody gave me an answer here, but apparently that won't be possible. If you're sure that it's not possible, you can write this as an answer, I'll accept it. — Dominique, Nov 30 '22 at 10:58
Try not to add expression to watch, just add it to your code, kinda `if (condition) Debugger.Break()`. — Ryan, Nov 30 '22 at 15:11

score 1 · Accepted Answer · answered Dec 01 '22 at 03:22

Have you tried int tmpPort=((System.Net.IPEndPoint)sock.RemoteEndPoint).Port;

Then add:

Conditional Expression
Is true
tmpPort == 123

However, as canton7 said, we are more inclined to use an if, and then add a breakpoint in it, or use Debugger.Break() to achieve the effect.

How to create a conditional breakpoint on a socket port?

1 Answers1