With an IPv6 virtual address map, we can basically hand out a new
IPv6 address for _every_ address we connect to.  That'll be cool, and
will let us maybe get around prop205 issues.

This uses some fancy logic to try to make the code paths in the ipv4
and the ipv6 case as close as possible, and moves to randomly
generated addresses so we don't need to maintain those stupid counters
that will collide if Tor restarts but apps don't.

Also has some XXXX items to fix to make this useful. More design
needed.

This function gives us a single place to set reasonable default flags
for port_cfg_t entries, to avoid bugs like the one where we weren't
setting ipv4_traffic_ok to 1 on SocksPorts initialized in an older
way.

(This is part 3 of making DNS cache use enabled/disabled on a
per-client port basis.  This implements the UseCacheIPv[46]DNS options)

(This is part 2 of making DNS cache use enabled/disabled on a
per-client port basis.  This implements the CacheIPv[46]DNS options,
but not the UseCachedIPv[46] ones.)

(This is part 1 of making DNS cache use enabled/disabled on a
per-client port basis.  These options are shuffled around correctly,
but don't do anything yet.)

We want to be saying fast_mem{cmp,eq,neq} when we're doing a
comparison that's allowed to exit early, or tor_mem{cmp,eq,neq} when
we need a data-invariant timing.  Direct use of memcmp tends to imply
that we haven't thought about the issue.

Conflicts:
	src/config/geoip

Conflicts:
	src/or/dns.c

Fixes bug 7663; bug introduced in 42e3c04a.  Not in any
released version of Tor.

This clears up the remaining issue stopping me from closing bug 6297.

Mike Perry authored 12 years ago and Nick Mathewson committed 12 years ago

Also, add a hack Roger suggested where we're more patient if no circuits are
opened yet.