Implement ipRouteTable.ipRouteNextHop in MIB-2 (only default routes) (s…

…onic-net#26)

* Implement ipRouteTable.ipRouteNextHop in MIB-2 (only default routes)

* Fix bug: crash if no default route

src/sonic_ax_impl/mibs/ietf/rfc1213.py

@@ -1,3 +1,4 @@
+import ipaddress
 import python_arptable
 from enum import unique, Enum
 from bisect import bisect_right
@@ -84,8 +85,57 @@ def get_next(self, sub_id):
             return None
         return self.arp_dest_list[right]
 
+class NextHopUpdater(MIBUpdater):
+    def __init__(self):
+        super().__init__()
+        self.db_conn = mibs.init_db()
+        self.update_data()
+
+    def update_data(self):
+        """
+        Update redis (caches config)
+        Pulls the table references for each interface.
+        """
+        self.nexthop_map = {}
+        self.route_list = []
+
+        self.db_conn.connect(mibs.APPL_DB)
+        route_entries = self.db_conn.keys(mibs.APPL_DB, "ROUTE_TABLE:*")
+        if not route_entries:
+            return
+
+        for route_entry in route_entries:
+            routestr = route_entry.decode()
+            ipnstr = routestr[len("ROUTE_TABLE:"):]
+            if ipnstr == "0.0.0.0/0":
+                ipn = ipaddress.ip_network(ipnstr)
+                ent = self.db_conn.get_all(mibs.APPL_DB, routestr, blocking=True)
+                nexthops = ent[b"nexthop"].decode()
+                for nh in nexthops.split(','):
+                    # TODO: if ipn contains IP range, create more sub_id here
+                    sub_id = ip2tuple_v4(ipn.network_address)
+                    self.route_list.append(sub_id)
+                    self.nexthop_map[sub_id] = ipaddress.ip_address(nh).packed
+                    break # Just need the first nexthop
+
+        self.route_list.sort()
+
+    def nexthop(self, sub_id):
+        return self.nexthop_map.get(sub_id, None)
+
+    def get_next(self, sub_id):
+        right = bisect_right(self.route_list, sub_id)
+        if right >= len(self.route_list):
+            return None
+
+        return self.route_list[right]
+
 class IpMib(metaclass=MIBMeta, prefix='.1.3.6.1.2.1.4'):
     arp_updater = ArpUpdater()
+    nexthop_updater = NextHopUpdater()
+
+    ipRouteNextHop = \
+        SubtreeMIBEntry('21.1.7', nexthop_updater, ValueType.IP_ADDRESS, nexthop_updater.nexthop)
 
     ipNetToMediaPhysAddress = \
         SubtreeMIBEntry('22.1.2', arp_updater, ValueType.OCTET_STRING, arp_updater.arp_dest)

tests/test_nexthop.py

@@ -0,0 +1,113 @@
+import os
+import sys
+import ipaddress
+
+modules_path = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, os.path.join(modules_path, 'src'))
+
+from unittest import TestCase
+
+import tests.mock_tables.dbconnector
+
+from ax_interface.mib import MIBTable
+from ax_interface.pdu import PDUHeader
+from ax_interface.pdu_implementations import GetPDU, GetNextPDU
+from ax_interface import ValueType
+from ax_interface.encodings import ObjectIdentifier
+from ax_interface.constants import PduTypes
+from sonic_ax_impl.mibs.ietf import rfc4363
+from sonic_ax_impl.main import SonicMIB
+
+class TestForwardMIB(TestCase):
+    @classmethod
+    def setUpClass(cls):
+        cls.lut = MIBTable(SonicMIB)
+
+    def test_network_order(self):
+        ip = ipaddress.ip_address("0.1.2.3")
+        ipb = ip.packed
+        ips = ".".join(str(int(x)) for x in list(ipb))
+        self.assertEqual(ips, "0.1.2.3")
+
+    def test_getpdu(self):
+        oid = ObjectIdentifier(14, 0, 1, 0, (1, 3, 6, 1, 2, 1, 4, 21, 1, 7, 0, 0, 0, 0))
+        get_pdu = GetPDU(
+            header=PDUHeader(1, PduTypes.GET, 16, 0, 42, 0, 0, 0),
+            oids=[oid]
+        )
+
+        encoded = get_pdu.encode()
+        response = get_pdu.make_response(self.lut)
+        print(response)
+
+        value0 = response.values[0]
+        self.assertEqual(value0.type_, ValueType.IP_ADDRESS)
+        self.assertEqual(str(value0.name), str(oid))
+        self.assertEqual(str(value0.data), ipaddress.ip_address("10.0.0.1").packed.decode())
+
+    def test_getnextpdu(self):
+        get_pdu = GetNextPDU(
+            header=PDUHeader(1, PduTypes.GET, 16, 0, 42, 0, 0, 0),
+            oids=(
+                ObjectIdentifier(10, 0, 0, 0, (1, 3, 6, 1, 2, 1, 4, 21, 1, 7)),
+            )
+        )
+
+        encoded = get_pdu.encode()
+        response = get_pdu.make_response(self.lut)
+        print(response)
+
+        n = len(response.values)
+        value0 = response.values[0]
+        self.assertEqual(value0.type_, ValueType.IP_ADDRESS)
+        self.assertEqual(str(value0.data), ipaddress.ip_address("10.0.0.1").packed.decode())
+
+    def test_getnextpdu_exactmatch(self):
+        oid = ObjectIdentifier(14, 0, 1, 0, (1, 3, 6, 1, 2, 1, 4, 21, 1, 7, 0, 0, 0, 0))
+        get_pdu = GetNextPDU(
+            header=PDUHeader(1, PduTypes.GET, 16, 0, 42, 0, 0, 0),
+            oids=[oid]
+        )
+
+        encoded = get_pdu.encode()
+        response = get_pdu.make_response(self.lut)
+        print(response)
+
+        n = len(response.values)
+        value0 = response.values[0]
+        self.assertEqual(value0.type_, ValueType.IP_ADDRESS)
+        print("test_getnextpdu_exactmatch: ", str(oid))
+        self.assertEqual(str(value0.name), str(oid))
+        self.assertEqual(str(value0.data), ipaddress.ip_address("10.0.0.1").packed.decode())
+
+    def test_getpdu_noinstance(self):
+        get_pdu = GetPDU(
+            header=PDUHeader(1, PduTypes.GET, 16, 0, 42, 0, 0, 0),
+            oids=(
+                ObjectIdentifier(14, 0, 1, 0, (1, 3, 6, 1, 2, 1, 4, 21, 1, 7, 0, 0, 0, 1)),
+            )
+        )
+
+        encoded = get_pdu.encode()
+        response = get_pdu.make_response(self.lut)
+        print(response)
+
+        n = len(response.values)
+        value0 = response.values[0]
+        self.assertEqual(value0.type_, ValueType.NO_SUCH_INSTANCE)
+
+    def test_getnextpdu_empty(self):
+        get_pdu = GetNextPDU(
+            header=PDUHeader(1, PduTypes.GET, 16, 0, 42, 0, 0, 0),
+            oids=(
+                ObjectIdentifier(14, 0, 1, 0, (1, 3, 6, 1, 2, 1, 4, 21, 1, 7, 0, 0, 0, 3)),
+            )
+        )
+
+        encoded = get_pdu.encode()
+        response = get_pdu.make_response(self.lut)
+        print(response)
+
+        n = len(response.values)
+        value0 = response.values[0]
+        self.assertEqual(value0.type_, ValueType.END_OF_MIB_VIEW)