I have created and bound to 2 sockets with the same port (500) and
same address (INADDR_ANY) (I set the REUSEPORT option on both sockets
before calling bind()).  The only difference between these 2 sockets
is an attribute that we've created in order to do specialized
processing on outgoing datagrams.  My problem is is that I'm receiving
datagrams on the wrong socket.  I use select to know when I should go
try to read from a socket.  Where is the decision made as to what
socket the datagram will be received on if the attributes of the
socket are the same?  I'm looking for the real low-level routine in
hopes that I can modify it to take into account our customized
attributes.