Multiple interfaces: associate IPs with interface

[grandcat]

If there are multiple interfaces, all IPs are merged together and send as a list of addresses to all clients.
As some addresses from one interface may not be reachable via an other interface, outgoing packets have to be personalized by egress interface.

[tmm1]

I've run into this as well and its pretty annoying.

Do you know if there's any API in golang to tell which interface the packet came from?

[tmm1]

Never mind, I found the answer here: http://stackoverflow.com/questions/35442824/how-to-read-both-input-interface-and-remote-socket-address-for-an-udp-datagram-r

I'll see if I can start a PR.