("ours" merge to avoid taking version bump)

This helps protect against bugs where any part of a buf_t's memory
is passed to a function that expects a NUL-terminated input.

It also closes TROVE-2016-10-001 (aka bug 20384).

This commit adds or improves the module-level documenation for:

  buffers.c circuitstats.c command.c connection_edge.c control.c
  cpuworker.c crypto_curve25519.c crypto_curve25519.h
  crypto_ed25519.c crypto_format.c dircollate.c dirserv.c dns.c
  dns_structs.h fp_pair.c geoip.c hibernate.c keypin.c ntmain.c
  onion.c onion_fast.c onion_ntor.c onion_tap.c periodic.c
  protover.c protover.h reasons.c rephist.c replaycache.c
  routerlist.c routerparse.c routerset.c statefile.c status.c
  tor_main.c workqueue.c

In particular, I've tried to explain (for each documented module)
what each module does, what's in it, what the big idea is, why it
belongs in Tor, and who calls it.  In a few cases, I've added TODO
notes about refactoring opportunities.

I've also renamed an argument, and fixed a few DOCDOC comments.

Coverity couldn't tell that 'addrport' was always non-NULL at this
point in the function, so I'm adding an explicit check. This closes
CID 1374060.

(This is safe, since only windows actually -uses- erstaz_socketpair.)

(I've done this instead of changing the semantics of
router_compare_to_my_exit_policy, because dns.c uses
router_compare_to_my_exit_policy too, in a slightly weird way.)

- function doesn't need to be inline.

- rename function

- Make documentation more pedantically correct

- Remove needless "? 1 : 0."

Patch from ericho.

Fixes 18529. Simple refactoring.

The test code, if it failed, or if it was run in verbose mode, would
use the wrong variable for its loop.  Patch from rubiate uploaded to
19999.

Switch from "AF_UNIX is always equal" to "always unequal" to avoid wacky bugs. See discussion on 20261

Some compilers apparently noticed that p2len was allowed to be equal
to msg, and so maybe we would be doing memset(prompt2, ' ', 0), and
decided that we probably meant to do memset(prompt2, 0, 0x20);
instead.

Stupid compilers, doing optimization before this kind of warning!

My fix is to just fill the entire prompt2 buffer with spaces,
because it's harmless.

Bugfix on e59f0d4c, not in any released Tor.

paolo.ingls@gmail.com authored 8 years ago and Nick Mathewson committed 8 years ago

(Specifically, carriage return after a quoted value in a config
line. Fixes bug 19167; bugfix on 0.2.0.16-alpha when we introduced
support for quoted values. Unit tests, changes file, and this
parenthetical by nickm.)

This is a kludge to deal with the fact that `tor_addr_t` doesn't contain
`sun_path`.  This currently ONLY happens when circuit isolation is being
checked, for an isolation mode that is force disabled anyway, so the
kludge is "ugly but adequate", but realistically, making `tor_addr_t`
and the AF_UNIX SocksPort code do the right thing is probably the better
option.

Closes ticket 20303.

The LIBRESSL_VERSION_NUMBER check is needed because if our openssl
is really libressl, it will have an openssl version number we can't
really believe.