Fix: check mrule existence before deletion

Avoid message: "RTNETLINK answers: No such file or directory"

pimdm/Kernel.py

@@ -3,9 +3,11 @@ import socket
 import struct
 import ipaddress
 import traceback
-from socket import if_nametoindex
+from socket import if_nametoindex, AF_INET, AF_INET6
 from threading import RLock, Thread
 from abc import abstractmethod, ABCMeta
+from functools import partial
+from pyroute2 import IPRoute
 
 from pimdm import UnicastRouting, Main
 from pimdm.rwlock.RWLock import RWLockWrite
@@ -23,6 +25,10 @@ class Kernel(metaclass=ABCMeta):
     # Max Number of Virtual Interfaces
     MAXVIFS = 32
 
+    # Rtnetlink flags
+    RTNL_FAMILY_IPMR  = 128
+    RTNL_FAMILY_IP6MR = RTNL_FAMILY_IPMR + 1
+
     def __init__(self, kernel_socket):
         # Kernel is running
         self.running = True
@@ -50,6 +56,12 @@ class Kernel(metaclass=ABCMeta):
         self.interface_logger = Main.logger.getChild('KernelInterface')
         self.tree_logger = Main.logger.getChild('KernelTree')
 
+        # netlink interfacing
+        self.ipr = IPRoute()
+
+        # unformatted mrule command
+        self.to_format_mrule = "ip {ip_version} mrule {cmd} {selector} {interface_name} lookup {table_id}".format
+
         # receive signals from kernel with a background thread
         handler_thread = Thread(target=self.handler)
         handler_thread.daemon = True
@@ -258,6 +270,32 @@ class Kernel(metaclass=ABCMeta):
                 for entry in groups_dict.values():
                     entry.new_or_reset_neighbor(vif_index, neighbor_ip)
 
+    def ex_partial_mrule(self, partial_mrule: partial, ip_family: int):
+        os.system(partial_mrule(ip_version='-6' if ip_family ==  AF_INET6 else ''))
+
+    def add_mrule(self, interface_name: str, table_id: int, ip_family=AF_INET):
+        partial_mrule = partial(self.to_format_mrule, cmd='add', interface_name=interface_name, table_id=table_id)
+        self.ex_partial_mrule(partial(partial_mrule, selector='iif'), ip_family)
+        self.ex_partial_mrule(partial(partial_mrule, selector='oif'), ip_family)
+
+    def delete_mrule(self, interface_name: str, table_id: int, ip_family=AF_INET):
+        partial_mrule = partial(self.to_format_mrule, cmd='del', interface_name=interface_name, table_id=table_id)
+        for rule in self.ipr.get_rules(
+            family=self.RTNL_FAMILY_IP6MR if ip_family == AF_INET6 else self.RTNL_FAMILY_IPMR,
+            table=table_id
+        ):
+            for k,v in rule['attrs']:
+                if k == 'FRA_IIFNAME':
+                    if v == interface_name:
+                        self.ex_partial_mrule(partial(partial_mrule, selector='iif'), ip_family)
+                    else:
+                        break
+                elif k == 'FRA_OIFNAME':
+                    if v == interface_name:
+                        self.ex_partial_mrule(partial(partial_mrule, selector='oif'), ip_family)
+                    else:
+                        break
+
 
 class Kernel4(Kernel):
     # MRT
@@ -329,11 +367,9 @@ class Kernel4(Kernel):
 
         struct_mrt_add_vif = struct.pack("HBBI 4s 4s", index, flags, 1, 0, ip_interface,
                                          socket.inet_aton("0.0.0.0"))
-        os.system("ip mrule del iif {}".format(interface_name))
-        os.system("ip mrule del oif {}".format(interface_name))
+        self.delete_mrule(interface_name, 0)
         if pim_globals.MULTICAST_TABLE_ID != 0:
-            os.system("ip mrule add iif {} lookup {}".format(interface_name, pim_globals.MULTICAST_TABLE_ID))
-            os.system("ip mrule add oif {} lookup {}".format(interface_name, pim_globals.MULTICAST_TABLE_ID))
+            self.add_mrule(interface_name, pim_globals.MULTICAST_TABLE_ID)
         with self.rwlock.genWlock():
             self.socket.setsockopt(socket.IPPROTO_IP, self.MRT_ADD_VIF, struct_mrt_add_vif)
             self.vif_index_to_name_dic[index] = interface_name
@@ -350,8 +386,7 @@ class Kernel4(Kernel):
             index = self.vif_name_to_index_dic.pop(interface_name)
             struct_vifctl = struct.pack("HBBI 4s 4s", index, 0, 0, 0, socket.inet_aton("0.0.0.0"), socket.inet_aton("0.0.0.0"))
 
-            os.system("ip mrule del iif {}".format(interface_name))
-            os.system("ip mrule del oif {}".format(interface_name))
+            self.delete_mrule(interface_name, 0)
             self.socket.setsockopt(socket.IPPROTO_IP, self.MRT_DEL_VIF, struct_vifctl)
 
             self.stop_forwarding(index)
@@ -563,11 +598,9 @@ class Kernel6(Kernel):
         physical_if_index = if_nametoindex(interface_name)
         struct_mrt_add_vif = struct.pack("HBBHI", index, flags, 1, physical_if_index, 0)
 
-        os.system("ip -6 mrule del iif {}".format(interface_name))
-        os.system("ip -6 mrule del oif {}".format(interface_name))
+        self.delete_mrule(interface_name, 0, AF_INET6)
         if pim_globals.MULTICAST_TABLE_ID != 0:
-            os.system("ip -6 mrule add iif {} lookup {}".format(interface_name, pim_globals.MULTICAST_TABLE_ID))
-            os.system("ip -6 mrule add oif {} lookup {}".format(interface_name, pim_globals.MULTICAST_TABLE_ID))
+            self.add_mrule(interface_name, pim_globals.MULTICAST_TABLE_ID, AF_INET6)
 
         with self.rwlock.genWlock():
             self.socket.setsockopt(socket.IPPROTO_IPV6, self.MRT6_ADD_MIF, struct_mrt_add_vif)
@@ -588,8 +621,7 @@ class Kernel6(Kernel):
             struct_vifctl = struct.pack("HBBHI", mif_index, 0, 0, physical_if_index, 0)
             self.socket.setsockopt(socket.IPPROTO_IPV6, self.MRT6_DEL_MIF, struct_vifctl)
 
-            os.system("ip -6 mrule del iif {}".format(interface_name))
-            os.system("ip -6 mrule del oif {}".format(interface_name))
+            self.delete_mrule(interface_name, 0)
 
             self.stop_forwarding(mif_index)