How to ignore your own broadcast udp packets
berkeley-sockets, broadcast, c, networking, udp
Solution
Well at start-up you could broadcast a different message with random (but tracked) value, then wait for that message, to discover your own address, from then on, you can send normal messages, ignoring your sourced messages.
Problem
For the following I'm assuming one network card. I have a component of my program which is designed to let others in the subnet know of its existence. For this, I've implemented a solution where whenever the program starts up (and periodically afterwards) it sends a broadcast to `INADDR_BROADCAST` - whoever listens on the required port will remember where it came from for later use. The problem with this is that I don't want to remember my own broadcasts. I thought that in theory this would be easy to do - simply find out the local ip and compare to what you get in `recvfrom`. However, I've found it difficult to get the local IP: `getaddrinfo` with NULL returns `127.0.0.1`, `getaddrinfo` with the hostname returns the public ip. Can anyone point me in the direction of finding the actual subnet ip ? I think I must be missing something very obvious here but well... I'm still missing it :) Note: I've read other SO questions on broadcasts, in particular this one: UDP-Broadcast on all interfaces but I haven't gotten round to the multiple interface issue yet.