Some days before this commit, the network experienced a DDoS on the directory
authorities that prevented them to generate a consensus for more than 5 hours
straight.

That in turn entirely disabled onion service v3, client and service side, due
to the subsystem requiring a live consensus to function properly.

We know require a reasonably live consensus which means that the HSv3
subsystem will to its job for using the best consensus tor can find. If the
entire network is using an old consensus, than this should be alright.

If the service happens to use a live consensus while a client is not, it
should still work because the client will use the current SRV it sees which
might be the previous SRV for the service for which it still publish
descriptors for.

If the service is using an old one and somehow can't get a new one while
clients are on a new one, then reachability issues might arise. However, this
is a situation we already have at the moment since the service will simply not
work if it doesn't have a live consensus while a client has one.

Fixes #40237

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

We're getting "fallback annotation annotation in unreachable code"
warnings when we build with ALL_BUGS_ARE_FATAL. This patch fixes
that.

Fixes bug 40241.  Bugfix on 0.3.5.4-alpha.

"ours" to avoid version bump.

"-s ours" to avoid version bump.

We can use our existing mocking functionality to do this: We have
been in this position before.

Fixes part of #40179; bugfix on 0.4.3.1-alpha.

Previously, hashlib.shake_256 was a class (if present); now it can
also be a function.  This change invalidated our old
compatibility/workaround code, and made one of our tests fail.

Fixes bug 40179; bugfix on 0.3.1.6-rc when the workaround code was
added.

In brief: we go through a lot of gymnastics to handle huge protover
numbers, but after years of development we're not even close to 10
for any of our current versions.  We also have a convenient
workaround available in case we ever run out of protocols: if (for
example) we someday need Link=64, we can just add Link2=0 or
something.

This patch is a minimal patch to change tor's behavior; it doesn't
take advantage of the new restrictions.

Implements #40133 and proposal 318.

David Goulet authored 4 years ago and Nick Mathewson committed 4 years ago

If at least one service is configured as a version 2, a log warning is emitted
once and only once.

Closes #40003

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