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Fallbacks: use a 24 hour future consensus tolerance

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Tor clients on 0.3.5.6-rc? and later will use a consensus that will become
valid up to 24 hours in the future.

Clients on 0.3.5.5-alpha? and earlier won't accept future consensuses.

Update the fallback expiry tolerance to match tor's checks.

Part of 28768, follow-up on 28591.
This commit is contained in:
teor 2018-12-07 09:41:28 +10:00
parent 766fd6cf76
commit c3fe405e21
2 changed files with 20 additions and 5 deletions
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4
changes/ticket28768
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@ -1,4 +1,4 @@
o Minor features (fallback directory mirrors):
- Accept fallbacks that deliver reasonably live consensuses.
(Consensuses that expired less than 24 hours ago.)
Closes ticket 28768.
(Consensuses that will become valid less than 24 hours in the future,
or that expired less than 24 hours ago.) Closes ticket 28768.

21
scripts/maint/updateFallbackDirs.py
View File

@ -98,14 +98,19 @@ MUST_BE_RUNNING_NOW = (PERFORM_IPV4_DIRPORT_CHECKS
# Clients have been using microdesc consensuses by default for a while now
DOWNLOAD_MICRODESC_CONSENSUS = True
# If a relay delivers an invalid consensus, if it expired less than this many
# seconds ago, accept the relay as a fallback. For the consensus expiry check
# to be accurate, the machine running this script needs an accurate clock.
# If a relay delivers an invalid consensus, if it will become valid less than
# this many seconds in the future, or expired less than this many seconds ago,
# accept the relay as a fallback. For the consensus expiry check to be
# accurate, the machine running this script needs an accurate clock.
#
# Relays on 0.3.0 and later return a 404 when they are about to serve a
# consensus that expired more than 24 hours ago. 0.2.9 and earlier relays
# will serve consensuses that are very old.
#
# Relays on 0.3.5.6-rc? and later return a 404 when they are about to serve a
# consensus that will become valid more than 24 hours in the future. Older
# relays don't serve future consensuses.
#
# A 404 makes relays fail the download check. We use a tolerance of 24 hours,
# so that 0.2.9 relays also fail the download check if they serve a consensus
# that is not reasonably live.
@ -1127,6 +1132,7 @@ class Candidate(object):
).run()[0]
end = datetime.datetime.utcnow()
time_since_expiry = (end - consensus.valid_until).total_seconds()
time_until_valid = (consensus.valid_after - end).total_seconds()
except Exception, stem_error:
end = datetime.datetime.utcnow()
log_excluded('Unable to retrieve a consensus from %s: %s', nickname,
@ -1151,6 +1157,15 @@ class Candidate(object):
status += ', invalid'
level = logging.WARNING
download_failed = True
elif (time_until_valid > 0):
status = 'future consensus, valid in %ds'%(int(time_until_valid))
if time_until_valid <= CONSENSUS_EXPIRY_TOLERANCE:
status += ', tolerating up to %ds'%(CONSENSUS_EXPIRY_TOLERANCE)
level = logging.INFO
else:
status += ', invalid'
level = logging.WARNING
download_failed = True
else:
status = 'ok'
level = logging.DEBUG