Without this fix, on an IPv6-only host UnrealIRCd would give you:
[warn] /home/ircd/unrealircd/conf/modules.default.conf:309: Failed to download 'https://www.unrealircd.org/files/geo/classic/GeoIP.dat': Could not connect: Network is unreachable
[warn] Continuing anyway...
This fixes https://bugs.unrealircd.org/view.php?id=6249, which was
also similarly reported by progval in https://bugs.unrealircd.org/view.php?id=6073
This implements only a simple try-IPv4-then-IPv6 approach in case of
clear connect errors. There is no happy eyeball like approach (where it
gives IPv6 a 250ms head start and then tries IPv4 in parallel), if there
is really a 15sec timeout then it doesn't retry IPv6 either (in case you
have IPv4, there is a route, but packets end up blackholed), nor does it
try all IP addresses that the resolver returns (then again, that's not
strictly related to happy eyeballs or IPv4/IPv6).
That would require some major overhaul that is not planned in U6. If you
want better/great protocol support you can always enable cURL in ./Config.
Bram Matthys
a6ae945499