Fixes bug 40078.
As reported by hdevalence our batch verification logic can cause an assert
crash.
The assert happens because when the batch verification of ed25519-donna fails,
the code in `ed25519_checksig_batch()` falls back to doing a single
verification for each signature.
The crash occurs because batch verification failed, but then all signatures
individually verified just fine.
That's because batch verification and single verification use a different
equation which means that there are sigs that can pass single verification
but fail batch verification.
Fixing this would require modding ed25519-donna which is not in scope for
this ticket, and will be soon deprecated in favor of arti and
ed25519-dalek, so my branch instead removes batch verification.
Now the circuits look like this:
client rend: C -> G -> L2 -> Rend
client intro: C -> G -> L2 -> M -> Intro
client hsdir: C -> G -> L2 -> M -> HSDir
service rend: C -> G -> L2 -> M -> Rend
service intro: C -> G -> L2 -> M -> Intro
service hsdir: C -> G -> L2 -> M -> HSDir
Bridge operators should generally publish their descriptors except for
rare cases, and instead use the BridgeDistribution none setting to
prevent their bridge from being distributed by BridgeDB.
Continue having a tor_gmtime_impl() unit test so that we can detect
any problems in our replacement function; add a new test function to
make sure that gmtime<->timegm are a round-trip on now-ish times.
This is a fix for bug #40383, wherein we ran into trouble because
tor_timegm() does not believe that time_t should include a count of
leap seconds, but FreeBSD's gmtime believes that it should. This
disagreement meant that for a certain amount of time each day,
instead of calculating the most recent midnight, our voting-schedule
functions would calculate the second-most-recent midnight, and lead
to an assertion failure.
I am calling this a bugfix on 0.2.0.3-alpha when we first started
calculating our voting schedule in this way.
