Can you bind() and connect() both ends of a UDP connection

Question

I\'m writing a point-to-point message queue system, and it has to be able to operate over UDP. I could arbitrarily pick one side or the other to be the \"server\" but it do

Answer 1

I'd look at it more from the idea of what UDP is providing. UDP is an 8 byte header which adds 2 byte send and receive ports (4 bytes total). These ports interact with Berkeley Sockets to provide your traditional socket interface. I.e. you can't bind to an address without a port or vice-versa.

Typically when you send a UDP packet the receive side port (source) is ephemeral and the send side port (destination) is your destination port on the remote computer. You can defeat this default behavior by binding first and then connecting. Now your source port and destination port would be the same so long as the same ports are free on both computers.

In general this behavior (let's call it port hijacking) is frowned upon. This is because you have just limited your send side to only being able to send from one process, as opposed to working within the ephemeral model which dynamically allocates send side source ports.

Incidentally, the other four bytes of an eight byte UDP payload, length and CRC are pretty much totally useless as they are already provided in the IP packet and a UDP header is fixed length. Like come on people, computers are pretty good at doing a little subtraction.