[tor-commits] [chutney/master] Wait before verifying Tor 0.3.5 networks

[nickm at torproject.org]

commit 67f27aea9f1321bd43a61e745a8e047c84e85b9c
Author: teor <teor at riseup.net>
Date:   Mon May 18 19:18:58 2020 +1000

    Wait before verifying Tor 0.3.5 networks
    
    There's some kind of timing bug in Tor 0.3.5, where it fails
    verification immediately after bootstrapping. Add a wait time to work
    around this bug.
    
    Replaces the previous 0.3.5 minimum bootstrap time, which fails for the
    ipv6-exit-min network.
    
    Now we're checking microdescriptors, the 0.3.5 timing bug can't be due
    to descriptor propagation. So there must be some other subtle timing
    bug.
    
    Fortunately, this bug is fixed in 0.4.0 and later.
---
 lib/chutney/TorNet.py | 47 ++++++++++++++++++++++++++++++-----------------
 1 file changed, 30 insertions(+), 17 deletions(-)

diff --git a/lib/chutney/TorNet.py b/lib/chutney/TorNet.py
index c0e3b6a..df3c33d 100644
--- a/lib/chutney/TorNet.py
+++ b/lib/chutney/TorNet.py
@@ -990,38 +990,43 @@ class LocalNodeController(NodeController):
         except KeyError:
             return 0
 
-    # Older tor versions are slow to download microdescs
-    # This version prefix compares less than all 0.4-series, and any
-    # future version series (for example, 0.5, 1.0, and 22.0)
-    MIN_TOR_VERSION_FOR_MICRODESC_FIX = 'Tor 0.4'
-
-    # TODO: delete all this unused code, once we're sure it's not needed
-    MIN_TIME_FOR_COMPLETE_CONSENSUS = V3_AUTH_VOTING_INTERVAL*1.5
-    MIN_START_TIME_LEGACY = 0
-    MIN_START_TIME_RECENT = 0
+    # By default, there is no minimum start time.
+    MIN_START_TIME_DEFAULT = 0
 
     def getMinStartTime(self):
         """Returns the minimum start time before verifying, regardless of
            whether the network has bootstrapped, or the dir info has been
            distributed.
 
-           Based on $CHUTNEY_EXTRA_START_TIME and the tor version.
+           The default can be overridden by the $CHUTNEY_MIN_START_TIME env
+           var.
         """
         # User overrode the dynamic time
         env_min_time = getenv_int('CHUTNEY_MIN_START_TIME', None)
         if env_min_time is not None:
             return env_min_time
+        return LocalNodeController.MIN_START_TIME_DEFAULT
 
+    # Older tor versions need extra time to bootstrap.
+    # (And we're not sure exactly why -  maybe we fixed some bugs in 0.4.0?)
+    #
+    # This version prefix compares less than all 0.4-series, and any
+    # future version series (for example, 0.5, 1.0, and 22.0)
+    MIN_TOR_VERSION_FOR_TIMING_FIX = 'Tor 0.4'
+
+    def isLegacyTorVersion(self):
+        """Is the current Tor version 0.3.5 or earlier?"""
         tor = self._env['tor']
         tor_version = get_tor_version(tor)
-        min_version = LocalNodeController.MIN_TOR_VERSION_FOR_MICRODESC_FIX
+        min_version = LocalNodeController.MIN_TOR_VERSION_FOR_TIMING_FIX
 
         # We could compare the version components, but this works for now
-        # If it's not our Tor, expect it to behave better
+        # (And if it's a custom Tor implementation, it shouldn't have this
+        # particular timing bug.)
         if tor_version.startswith('Tor ') and tor_version < min_version:
-            return LocalNodeController.MIN_START_TIME_LEGACY
+            return True
         else:
-            return LocalNodeController.MIN_START_TIME_RECENT
+            return False
 
     # The extra time after other descriptors have finished, and before
     # verifying.
@@ -1033,16 +1038,22 @@ class LocalNodeController(NodeController):
     # See #33581.
     BRIDGE_WAIT_FOR_UNCHECKED_DIR_INFO = 10
 
+    # Let everything propagate for another consensus period before verifying.
+    LEGACY_WAIT_FOR_UNCHECKED_DIR_INFO = V3_AUTH_VOTING_INTERVAL
+
     def getUncheckedDirInfoWaitTime(self):
         """Returns the amount of time to wait before verifying, after the
            network has bootstrapped, and the dir info has been distributed.
 
-           Based on whether this node is an onion service.
+           Based on whether this node has unchecked directory info, or other
+           known timing issues.
         """
         if self.getOnionService():
             return LocalNodeController.HS_WAIT_FOR_UNCHECKED_DIR_INFO
         elif self.getBridge():
             return LocalNodeController.BRIDGE_WAIT_FOR_UNCHECKED_DIR_INFO
+        elif self.isLegacyTorVersion():
+            return LocalNodeController.LEGACY_WAIT_FOR_UNCHECKED_DIR_INFO
         else:
             return LocalNodeController.DEFAULT_WAIT_FOR_UNCHECKED_DIR_INFO
 
@@ -2371,8 +2382,10 @@ class Network(object):
                                             elapsed=elapsed,
                                             msg="Bootstrap finished")
 
-                # Wait for unchecked dir info (see #33595)
-                print("Waiting {} seconds for other dir info to sync...\n"
+                # Wait for unchecked bridge or onion service dir info.
+                # (See #33581 and #33609.)
+                # Also used to work around a timing bug in Tor 0.3.5.
+                print("Waiting {} seconds for the network to be ready...\n"
                       .format(int(wait_time)))
                 time.sleep(wait_time)
                 now = time.time()