* FIXES #24659: https://bugs.torproject.org/24659

The --disable-module-* configure option removes code from the final binary but
we still build the unit tests with the disable module(s) so we can actually
test that code path all the time and not forget about it.

Signed-off-by: David Goulet <dgoulet@torproject.org>

Make our build system support a disable dirauth module option. It can only be
disabled explicitly with:

  $ ./configure --disable-module-dirauth

If *not* specified that is enabled, an automake conditional variable is set to
true and a defined value for the C code:

  AM_CONDITIONAL: BUILD_MODULE_DIRAUTH
  AC_DEFINE: HAVE_MODULE_DIRAUTH=1

This introduces the dirauth/ module directory in src/or/ for which .c files
are only compiled if the BUILD_MODULE_DIRAUTH is set.

All the header files are compiled in regardless of the support so we can use
the alternative entry point functions of the dirauth subsystem.

Signed-off-by: David Goulet <dgoulet@torproject.org>

When openssl is built with no-deprecated, the TLSv1_1_method()
function isn't visible in the headers.  That's sad, because that
method is what we were looking at.

Instead, we now look at SSL_CIPHER_get_id(), which is present in
OpenSSL 1.0.1 and later, which is _not_ deprecated, and which is
also present in LibreSSL.

Fixes ticket 25353.  Not a bugfix exactly -- we never really worked
with this configuration.

By default, we want to look at the crates directory of the
submodule, not the toplevel of the submodule.  Fixes bug 25679;
bugfix on 0.3.3.1-alpha.

Georg Koppen authored 7 years ago and Nick Mathewson committed 7 years ago

When merging the patches for #25310 the libc version requirement in
`GettingStartedRust.md` and `configure.ac` did not get updated to the
now needed 0.2.39.

Without this fix, we were just getting SRCDIR=`pwd`, which naturally
was breaking out-of-tree builds.

Bugfix on becae4c9; bug not in any
released Tor.

Fixes bug 25474; bugfix on 0.3.2.5-alpha.

Fixes a bug in our zstd-static code.  Bug not in any released
version of Tor.

Add an autoconf test to make sure we won't regret it.

Closes ticket 24484.

We'd been using crypto_digest_dup() and crypto_digest_assign() here,
but they aren't necessary.  Instead we can just use the stack to
store the previous state of the SHA_CTX and avoid a malloc/free pair.

Closes ticket 24914.

For 23847, we want Tor to be able to shut down and then restart in
the same process.  Here's a patch to make the Tor binary do that.
To test it, you need to build with --enable-restart-debugging, and
then you need to set the environment variable TOR_DEBUG_RESTART.
With this option, Tor will then run for 5 seconds, then restart
itself in-process without exiting.  This only happens once.

You can change the 5-second interval using
TOR_DEBUG_RESTART_AFTER_SECONDS.

Implements ticket 24583.

This fixes issue #24652, and is a workaround for Rust issue
https://github.com/rust-lang/rust/issues/46797 .