Getting destination address for UDP packets

[Petru Paler]

Hi,

I'm working on a program which binds on all the available interfaces (0.0.0.0)
and listens for/replies with UDP packets.

The problem is that I need to send back responses from the same IP address that
the query arrived to, and this is not usually happening.

Example: supposing I have 1.1.1.2 and 1.1.1.3 aliased on the same interface, and
a query arrives on 1.1.1.3, it's mandatory that the reply packet goes out from
1.1.1.3.

The question is: how do I get (from user space, if possible) the destination
IP address of an UDP packet?

Thanks

Petru