Check dizum's prior address

Dizum moved...

  https://trac.torproject.org/projects/tor/ticket/31406

Alex has requested monitoring of its old address, which will hopefully forward
until clients that reference it get deprecated.

consensus_health_checker.py

@@ -344,6 +344,7 @@ def run_checks(consensuses, votes):
     shared_random_present,
     shared_random_commit_partitioning,
     shared_random_reveal_partitioning,
+    old_dizum_address_reachable,
   )
 
   all_issues = []
@@ -914,6 +915,23 @@ def shared_random_reveal_partitioning(latest_consensus, consensuses, votes):
       elif matches[0] != reveal:
         issues.append(Issue(Runlevel.WARNING, 'SHARED_RANDOM_REVEAL_MISMATCH', authority = authority, their_v3ident = v3ident, our_value = matches[0], their_value = reveal, to = [authority]))
 
+
+def old_dizum_address_reachable(latest_consensus, consensuses, votes):
+  """
+  Check that dizum's old address is still reachable...
+
+    https://trac.torproject.org/projects/tor/ticket/31406
+  """
+
+  try:
+    desc = stem.descriptor.remote.their_server_descriptor(endpoints = [('194.109.206.212', 80)]).run()[0]
+
+    if desc.nickname != 'dizum':
+      raise IOError("Unexpected nickname at dizum's old address (%s)" % desc.nickname)
+  except Exception as exc:
+    return Issue(Runlevel.WARNING, 'OLD_DIZUM_UNAVAILABLE', address = '194.109.206.212', error = exc, to = ['dizum'])
+
+
 def get_consensuses():
   """
   Provides a mapping of directory authority nicknames to their present consensus.

data/consensus_health.cfg

@@ -22,6 +22,7 @@ msg TOR_OUT_OF_DATE =>  The following authorities are an out of date version of
 msg BADEXIT_OUT_OF_SYNC => Authorities disagree about the BadExit flag for {fingerprint} ({counts})
 msg BANDWIDTH_AUTHORITIES_OUT_OF_SYNC => Bandwidth authorities have a substantially different number of measured entries: {authorities}
 msg AUTHORITY_UNAVAILABLE => Unable to retrieve the {fetch_type} from {authority} ({url}): {error}
+msg OLD_DIZUM_UNAVAILABLE => Unable to reach dizum's prior address ({address}): {error}
 msg UNABLE_TO_REACH_ORPORT => Unable to reach the ORPort of {authority} ({address}, port {port}): {error}
 msg CURRENT_SHARED_RANDOM_MISSING => Consensus is missing a current shared random value (shared-rand-current-value)
 msg PREVIOUS_SHARED_RANDOM_MISSING => Consensus is missing a previous shared random value (shared-rand-previous-value)