[monitoring] Implement cost multiplier

Signed-off-by: Yohann D'ANELLO <ynerant@crans.org>

re6st/monitoring.py

@@ -2,8 +2,9 @@ import logging
 import random
 import socket
 import subprocess
+import time
 
-from re6st import utils
+from re6st import utils, ctl
 
 RE6ST_PORT = 326  # Found in tunnel.PORT, but we want to avoid import loops
 MONITORING_PORT = 327  # Port used for monitoring
@@ -42,9 +43,9 @@ class MonitoringManager:
         Refresh routes that are used for link monitoring.
         """
         # Cleanup old routes
-        for link in list(self.links.values()):
-            if link.prefix not in self.tunnel_manager.ctl.neighbours:
-                link.delete()
+        # for link in list(self.links.values()):
+        #     if link.prefix not in self.tunnel_manager.ctl.neighbours:
+        #         link.delete()
 
         # Babel is not initialized yet.
         if not hasattr(self.tunnel_manager.ctl, 'neighbours'):
@@ -69,16 +70,24 @@ class MonitoringLink:
     manager = None
     prefix = None
     address = None
+    neighbour = None
+    last_sent_pings = None
+    last_received_pings = None
+    old_multiplier = None
 
     def __init__(self, monitoring_manager, prefix):
         self.manager = monitoring_manager
         self.prefix = prefix
+        self.last_sent_pings = []
+        self.last_received_pings = []
 
     @property
     def tested_address(self):
         return utils.ipFromBin(self.manager.tunnel_manager._network + self.prefix)
 
     def update_link(self, neighbour):
+        self.neighbour = neighbour
+
         nexthop = neighbour.address
         nexthop = utils.ipFromBin("".join(bin(ord(c))[2:].zfill(8) for c in nexthop))
 
@@ -111,8 +120,10 @@ class MonitoringLink:
     def monitor(self):
         msock = None
         try:
-            print("Send ping from " + self.address + " for " + self.tested_address
-                  + " to " + self.manager.main_address + "...")
+            # print("Send ping from " + self.address + " for " + self.tested_address
+            #       + " to " + self.manager.main_address + "...")
+            self.last_sent_pings.append(time.time())  # Store time even if there is an error.
+
             msock = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
             msock.bind((self.address, MONITORING_PORT))
             msg = b'\x08'
@@ -122,7 +133,8 @@ class MonitoringLink:
             msock.sendto(data, (self.manager.main_address, RE6ST_PORT))
         except Exception, e:
             logging.error("Error while monitoring " + self.tested_address + ": " + str(e))
-            self.manager.tunnel_manager.newVersion()  # Maybe babel dump is not up to date
+            # Maybe babel dump is not up to date
+            self.manager.tunnel_manager.selectTimeout(time.time() + 1, self.manager.tunnel_manager.newVersion)
         finally:
             if msock:
                 try:
@@ -130,18 +142,54 @@ class MonitoringLink:
                 finally:
                     pass
 
+        now = time.time()
+        self.last_sent_pings = [t for t in self.last_sent_pings if now - t < 31]
+        self.last_received_pings = [t for t in self.last_received_pings if now - t < 31]
+
+        if len(self.last_sent_pings) - len(self.last_received_pings) > 4:
+            # 4 pings over 6 failed, consider the link as bad
+            print(self.tested_address + " is a bad neighbour")
+            if self.old_multiplier is None:
+                self.old_multiplier = self.neighbour.cost_multiplier
+            self.manager.tunnel_manager.ctl.send(
+                ctl.SetCostMultiplier(self.neighbour.address, self.neighbour.ifindex, 4096)
+            )
+            self.manager.tunnel_manager.selectTimeout(now + 1, self.manager.tunnel_manager.newVersion)
+
     def ping(self):
+        """
+        We received a ping. We store it, and we reset the cost multiplier
+        since the link seems to be working.
+        """
         self.manager.main_peer._i -= 1  # Don't increment seqno with this packet
-        print("Monitoring!")
-        print(self.address)
+        # print("Monitoring!")
+        # print(self.address)
+
+        self.last_received_pings.append(time.time())
+
+        self.last_sent_pings = [t for t in self.last_sent_pings if time.time() - t < 16]  # The link may work
+
+        # Reset cost multiplier to its old state
+        if self.old_multiplier is not None:
+            print(self.tested_address + " became a good neighbour")
+            self.manager.tunnel_manager.ctl.send(
+                ctl.SetCostMultiplier(self.neighbour.address, self.neighbour.ifindex, self.old_multiplier)
+            )
+            self.old_multiplier = None
+            self.manager.tunnel_manager.selectTimeout(time.time() + 1, self.manager.tunnel_manager.newVersion)
 
     def delete(self):
+        self.last_sent_pings = []
+        self.last_received_pings = []
+        if self.old_multiplier is not None:
+            self.manager.tunnel_manager.ctl.send(
+                ctl.SetCostMultiplier(self.neighbour.address, self.neighbour.ifindex, self.old_multiplier)
+            )
+        self.old_multiplier = None
+
         subprocess.check_call(('ip', '-6', 'address', 'del', self.address, 'dev', self.manager.main_interface))
         subprocess.check_call(('ip', '-6', 'route', 'del', self.manager.main_address,
                                'from', self.address, 'table', '34071'))
 
         if self.prefix in self.manager.links:
             del self.manager.links[self.prefix]
-
-    def __del__(self):
-        self.delete()