What happens to a socket on suspend/resume in windows

Question

I have a c# .net4 application that listens on a socket using BeginReceiveFrom and EndRecieveFrom. All works as expected until I put the machine to sleep and then resume.

At that point EndReceieveFrom executes and throws an exception (Cannot access a disposed object). It appears that the socket is disposed when the machine is suspended but I'm not sure how to handle this.

Do I presume that all sockets have been disposed and recreate them all from scratch? I'm having problems tracking down the exact issue as remote debugging also breaks on suspend/resume.

Answer 1

What happens during suspend/resume very much depends on your hardware and networking setup. If your network card is not disabled during suspend, and the suspend is brief, open connections will survive suspend/resume without any problem (open TCP connections can time out on the other end of course).

However, if your network adapter is disabled during the sleep, or it is a USB adapter that gets disabled because it is connected to a disabled hub, or your computer gets a new IP address from DHCP, or your wireless adapter gets reconnected to a different access point, etc., then all current connections are going to be dropped, listening sockets wil no longer be valid, etc.

This is not specific to sleep/resume. Network interfaces can come up and go down at any time, and your code must handle it. You can easily simulate this with a USB network adapter, e.g. yank it out of your computer and your code must handle it.