Let the OS pick a random port for us

[faern]

Hello! 👋 I ran into this repo while looking around for hole punching stuff. I found a possible improvement. I don't know if this has been considered and rejected for some reason already or not. But I thought I would submit it and see if you like it.

By binding to port zero the OS will pick a random free port
to bind to for us. This has multiple advantages over picking a random
port ourselves:

1. We don't need to include a random number generator in our program.
2. We don't risk picking an already used port and fail the bind
   operation. The OS will make sure we get one that is free.

[dsluijk]

Hi Linus,

Thank you for your contribution. I will merge the changes.

Please note that this project is not actively maintained, and was build as a Proof of Work for a different application.

Thanks!

[faern]

Thanks! I'm aware it's more of an example. But examples teach people things. And I wanted future developers who land on this code to see that this is possible to do, and better than selecting a port in userland :)