Some *_free functions threw asserts when passed NULL. Now all of them
accept NULL as input and perform no action when called that way.

This gains us consistence for our free functions, and allows some
code simplifications where an explicit null check is no longer necessary.

When we tried to use the deprecated non-threadsafe evdns
interfaces in Libevent 2 without using the also-deprecated
event_init() interface, Libevent 2 would sensibly crash, since it
has no guess where to find the Libevent library.

Here we use the evdns_base_*() functions instead if they're
present, and fake them if they aren't.

The rest of the code was only including event.h so that it could see
EV_READ and EV_WRITE, which we were using as part of the
connection_watch_events interface for no very good reason.

This patch adds a new compat_libevent.[ch] set of files, and moves our
Libevent compatibility and utilitity functions there.  We build them
into a separate .a so that nothing else in src/commmon depends on
Libevent (partially fixing bug 507).

Also, do not use our own built-in evdns copy when we have Libevent
2.0, whose evdns is finally good enough (thus fixing Bug 920).

Apparently all the stuff that does a linear scan over all the DNS
cache entries can get really expensive when your DNS cache is very
large.  It's hard to say how much this will help performance, since
gprof doesn't count time spent in OpenSSL or zlib, but I'd guess 10%.

Also, this patch removes calls to assert_connection_ok() from inside
the read and write callbacks, which are similarly unneeded, and a
little costlier than I'm happy with.

This is probably worth backporting to 0.2.0.

Jacob Appelbaum authored May 22, 2009 and Nick Mathewson committed May 22, 2009

Specifically if you send SIGUSR1, it will add two lines to the log file:
May 22 07:41:59.576 [notice] Our DNS cache has 3364 entries.
May 22 07:41:59.576 [notice] Our DNS cache size is approximately 1022656
bytes.

[tweaked a bit by nickm]

svn:r18341

svn:r18307

Bugfix on 0.2.1.7-alpha.  Backport candidate. Fixes bug 905.

svn:r18063

Fixes the bug part of bug 789.

svn:r17983

The subversion $Id$ fields made every commit force a rebuild of
whatever file got committed.  They were not actually useful for
telling the version of Tor files in the wild.

svn:r17867

Add some early checks to keep ipv6 addresses from failing by accident.  Now, they fail on purpose, at least till 0.2.2.something.

svn:r17791

Use the literal parse of an address in dns_resolve_impl if parsing the address as an ipv4 or ipv6 address _succeeded_.  Not if it failed.  Bug introduced in r17707 (post 0.2.1.8-alpha), and found by xiando.

svn:r17758

svn:r17734

Add DOCDOC comments for all undocumented functions.  Add missing *s to other comments so that they will get recognized as doxygen.

svn:r17729

Move in-addr.arpa parsing and generation into address.c, and simplify the code that does it elsewhere.  Incidentally, this lets exit servers answer requests for ip6.arpa addresses.

svn:r17707

svn:r17686

(The unfixed ones are being downgraded to regular XXXs mainly on the rationale that they don't seem to be exploding Tor, and they were apparently not showstoppers for 0.2.0.x-final.)

svn:r17682

svn:r17662

svn:r17566

Implement the 0x20-hack to make DNS poisoning harder against us, especially when resolving large names.  Add a cfg option to disable it, since apparently 3/10 of a percent of servers get it wrong.

svn:r17171

Fix the rest of bug 619: reject *:* servers should not do DNS lookups, even if broken clients send them RELAY_BEGIN cells. Patch from rovv.

svn:r17138

svn:r17131

 ipv6: make server-side dns cache remember for each address an ipv6 addr and an ipv4 addr.  This fix is just the struct side.


svn:r16622

 Initial conversion of uint32_t addr to tor_addr_t addr in connection_t and related types.  Most of the Tor wire formats using these new types are in, but the code to generate and use it is not.  This is a big patch.  Let me know what it breaks for you.


svn:r16435

svn:r14474

 apply patch from lodger: reject requests for reverse-dns lookup of names in private address space.  make non-exits reject all dns requests.  Fixes bug 619.


svn:r14410

 Fix the other lingering part of bug 617: make ClientDNSRejectInternalAddresses actually work.


svn:r14107

 Fix a really stupid parthensis error noticed by mwenge.


svn:r13681

 More 64-to-32 fixes. Partial backport candidate. still not done.


svn:r13680

 Defer a couple of XXX020rc items, based on recommendation from arma.


svn:r13654

svn:r13644

 Answer one xxx020 item; move 7 other ones to a new "XXX020rc" category: they should get fixed before we cut a release candidate. arma: please review these to see whether you have fixes/answers for any. Please check out the other 14 XXX020s to see if any look critical for the release candidate.


svn:r13640

elsewhere. bug reported by veracode.


svn:r13597