Refactor how config routes are deleted from outgoing RIB to handle offline routers

CHANGELOG.rst

@@ -4,6 +4,8 @@ Version explained:
  - bug   : increase on bug or incremental changes
 
 Version 4.2.22
+ * Fix: route reload for offline neighbors #1126
+   patch: Malcolm Dodds
 
 Version 4.2.21
  * Fix: regressing on announcing routes from the API #1108

lib/exabgp/bgp/neighbor.py

@@ -87,8 +87,6 @@ def __init__(self):
 
         # The routes we have parsed from the configuration
         self.changes = []
-        # On signal update, the previous routes so we can compare what changed
-        self.backup_changes = []
 
         self.operational = None
         self.eor = deque()
@@ -197,6 +195,9 @@ def remove_addpath(self, family):
         if family in self.addpaths():
             self._addpath.remove(family)
 
+    def process_previous_changes(self, previous_changes):
+        self.rib.outgoing.replace(previous_changes, self.changes)
+
     def missing(self):
         if self.local_address is None and not self.auto_discovery:
             return 'local-address'

lib/exabgp/configuration/configuration.py

@@ -329,10 +329,10 @@ def _commit_reload(self):
         self.processes = self.process.processes
         self._neighbors = {}
 
-        # Add the changes prior to the reload to the neighbor to correct handling of deleted routes
+        # Withdraw any old changes
         for neighbor in self.neighbors:
             if neighbor in self._previous_neighbors:
-                self.neighbors[neighbor].backup_changes = self._previous_neighbors[neighbor].changes
+                self.neighbors[neighbor].process_previous_changes(self._previous_neighbors[neighbor].changes)
 
         self._previous_neighbors = {}
         self._cleanup()

lib/exabgp/reactor/peer.py

@@ -482,13 +482,6 @@ def _main(self):
                 if self._reconfigure:
                     self._reconfigure = False
 
-                    # we are here following a configuration change
-                    if self._neighbor:
-                        # see what changed in the configuration
-                        self.neighbor.rib.outgoing.replace(self._neighbor.backup_changes, self._neighbor.changes)
-                        # do not keep the previous routes in memory as they are not useful anymore
-                        self._neighbor.backup_changes = []
-
                 # Take the routes already sent to that peer and resend them
                 if self._resend_routes != SEND.DONE:
                     enhanced = True if refresh_enhanced and self._resend_routes == SEND.REFRESH else False

lib/exabgp/rib/outgoing.py

@@ -100,9 +100,12 @@ def queued_changes(self):
             yield change
 
     def replace(self, previous, changes):
+        nlri = [c.nlri for c in changes]
+
         for change in previous:
-            change.nlri.action = OUT.WITHDRAW
-            self.add_to_rib(change, True)
+            if change.nlri not in nlri:
+                change.nlri.action = OUT.WITHDRAW
+                self.add_to_rib(change, True)
 
         for change in changes:
             self.add_to_rib(change, True)