[Openswan dev] Error building klips-ipv6 (missing include?)

[D. Hugh Redelmeier]

| From: Paul Wouters <paul at xelerance.com>

| I have been working a bit on the listen code, and I was considering an
| option to just listen to ANY. I am not sure what the history was of not
| listening on all IP's whenever they become available to the system.
| 
| Perhaps Hugh or Hugh can sched some light on that?

Off the top of my head, I can vaguely recollect two issues:

- we want control of which interfaces are used.  The only way was to
  control the IP addresses

- we want to know the inbound IP address on each packet.  recvfrom
  doesn't give you that, so we nail down which IP by only accepting
  a specified IP address on each socket.  So we have to know the IP
  address.

Note: there seems to be something newish called recvfromto that is now
half supported in the code, controlled by HAVE_UDPFROMTO.  But that
code currently ignores to "to" that recvfromto returns.