tests: Check if loopback routes are considered valid for nexthop trac…

…king

Signed-off-by: Donatas Abraitis <donatas@opensourcerouting.org>

tests/topotests/bgp_self_prefix/r1/frr.conf

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+!
+int lo
+ ip address 10.0.0.1/32
+!
+int r1-eth0
+ ip address 192.168.1.1/24
+!
+router bgp 65000
+ no bgp ebgp-requires-policy
+ no bgp network import-check
+ neighbor 10.0.0.2 remote-as internal
+ neighbor 10.0.0.2 update-source lo
+ neighbor 10.0.0.2 next-hop-self
+ neighbor 10.0.0.3 remote-as external
+ neighbor 10.0.0.3 update-source lo
+ neighbor 10.0.0.3 next-hop-self
+!
+ip route 10.0.0.2/32 192.168.1.2
+ip route 10.0.0.3/32 192.168.1.3

tests/topotests/bgp_self_prefix/r2/frr.conf

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+!
+int lo
+ ip address 10.0.0.2/32
+!
+int r2-eth0
+ ip address 192.168.1.2/24
+!
+router bgp 65000
+ no bgp ebgp-requires-policy
+ no bgp network import-check
+ neighbor 10.0.0.1 remote-as internal
+ neighbor 10.0.0.1 timers 1 3
+ neighbor 10.0.0.1 timers connect 1
+ neighbor 10.0.0.1 update-source lo
+ neighbor 10.0.0.1 next-hop-self
+ address-family ipv4 unicast
+  network 10.0.0.2/32
+ exit-address-family
+!
+ip route 10.0.0.1/32 192.168.1.1

tests/topotests/bgp_self_prefix/r3/frr.conf

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+!
+int lo
+ ip address 10.0.0.3/32
+!
+int r3-eth0
+ ip address 192.168.1.3/24
+!
+router bgp 65003
+ no bgp ebgp-requires-policy
+ no bgp network import-check
+ neighbor 10.0.0.1 remote-as external
+ neighbor 10.0.0.1 timers 1 3
+ neighbor 10.0.0.1 timers connect 1
+ neighbor 10.0.0.1 update-source lo
+ neighbor 10.0.0.1 next-hop-self
+ address-family ipv4 unicast
+  network 10.0.0.3/32
+ exit-address-family
+!
+ip route 10.0.0.1/32 192.168.1.1

tests/topotests/bgp_self_prefix/test_bgp_self_prefix.py

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+#!/usr/bin/env python
+# SPDX-License-Identifier: ISC
+
+# Copyright (c) 2024 by
+# Donatas Abraitis <donatas@opensourcerouting.org>
+#
+
+import os
+import sys
+import json
+import pytest
+import functools
+
+CWD = os.path.dirname(os.path.realpath(__file__))
+sys.path.append(os.path.join(CWD, "../"))
+
+# pylint: disable=C0413
+from lib import topotest
+from lib.topogen import Topogen, get_topogen
+
+pytestmark = [pytest.mark.bgpd]
+
+
+def setup_module(mod):
+    topodef = {"s1": ("r1", "r2", "r3")}
+    tgen = Topogen(topodef, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    for _, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_frr_config(os.path.join(CWD, "{}/frr.conf".format(rname)))
+
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+def test_bgp_self_prefix():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    r3 = tgen.gears["r3"]
+
+    def _bgp_converge():
+        output = json.loads(r1.vtysh_cmd("show bgp ipv4 unicast json"))
+        expected = {
+            "routes": {
+                "10.0.0.2/32": [
+                    {
+                        "valid": True,
+                        "path": "",
+                        "nexthops": [
+                            {"ip": "10.0.0.2", "hostname": "r2", "afi": "ipv4"}
+                        ],
+                    }
+                ],
+                "10.0.0.3/32": [
+                    {
+                        "valid": True,
+                        "path": "65003",
+                        "nexthops": [
+                            {"ip": "10.0.0.3", "hostname": "r3", "afi": "ipv4"}
+                        ],
+                    }
+                ],
+            }
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_converge,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, "Can't converge"
+
+    def _bgp_check_received_routes():
+        output = json.loads(r3.vtysh_cmd("show bgp ipv4 unicast json"))
+        expected = {
+            "routes": {
+                "10.0.0.2/32": [
+                    {
+                        "valid": True,
+                        "bestpath": True,
+                        "nexthops": [
+                            {"ip": "10.0.0.1", "hostname": "r1", "afi": "ipv4"}
+                        ],
+                    }
+                ],
+            }
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(
+        _bgp_check_received_routes,
+    )
+    _, result = topotest.run_and_expect(test_func, None, count=30, wait=1)
+    assert result is None, "Can't see 10.0.0.2/32"
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))