Without this change, if we have a working bridge, and we add a new bridge,
we will schedule the fetch attempt for that new bridge descriptor for
three hours(!) in the future.
This change is especially needed because of bug #40396, where if you have
one working bridge and one bridge whose descriptor you haven't fetched
yet, your Tor will stall until you have successfully fetched that new
descriptor -- in this case for hours.
In the old design, we would put off all further bridge descriptor fetches
once we had any working bridge descriptor. In this new design, we make the
decision per bridge based on whether we successfully got *its* descriptor.
To make this work, we need to also call learned_bridge_descriptor() every
time we get a bridge descriptor, not just when it's a novel descriptor.
Fixes bug 40396.
Also happens to fix bug 40495 (redundant descriptor fetches for every
bridge) since now we delay fetches once we succeed.
A side effect of this change is that if we have any configured bridges
that *aren't* working, we will keep trying to fetch their descriptors
on the modern directory retry schedule -- every couple of seconds for
the first half minute, then backing off after that -- which is a lot
faster than before.
When this method is in place, then any relay which is assigned
MiddleOnly has Exit, V2Dir, Guard, and HSDir cleared
(and has BadExit set if appropriate).
This proposal implements part of Prop335; it's based on a patch
from Neel Chauhan.
When configured to do so, authorities will assign a MiddleOnly flag
to certain relays. Any relay which an authority gives this flag
will not get Exit, V2Dir, Guard, or HSDir, and might get BadExit if
the authority votes for that one.
We keep it around until libevent is fixed, it should be used again. In
the meantime, avoid the compiler to complain of this unused variable.
https://gitlab.torproject.org/dgoulet/tor/-/jobs/43358#L1522
Signed-off-by: David Goulet <dgoulet@torproject.org>
When we looked, this was the third most frequent message at
PROTOCOL_WARN, and doesn't actually tell us what to do about it.
Now:
* we just log it at info
* we log it only once per circuit
* we report, in the heartbeat, how many times it happens, how many
cells it happens with per circuit, and how long these circuits
have been alive (on average).
Fixes the final part of #40400.
