bgpd: BGP session not established for ipv6 link local address with vrf config

Description:
BGP session not established for ipv6 link local address with vrf config

Problem Description/Summary :
BGP session not established for ipv6 link local address with vrf configyy
1.Configure ipv6 link-local address fe80::1234/64 on dut1 and fe80::4567/64 on dut2
2.Configure BGP neighbors for ipv6 link-local on both dut1 and dut2
3.Verify BGP session is UP over link-local ipv6 address
4.Observed that bgp session not established for ipv6 link local address

Expected Behavior :
BGP session should be established for ipv6 link local address with vrf config

Signed-off-by: sudhanshukumar22 <sudhanshu.kumar@broadcom.com>

Author: sudhanshukumar22

bgpd/bgp_network.c

@@ -660,6 +660,10 @@ static int bgp_update_address(struct interface *ifp, const union sockunion *dst,
 		return 1;
 
 	prefix2sockunion(sel, addr);
+
+	if (IN6_IS_ADDR_LINKLOCAL(&addr->sin6.sin6_addr))
+		addr->sin6.sin6_scope_id = ifp->ifindex;
+
 	return 0;
 }
 

bgpd/bgp_zebra.c

@@ -748,6 +748,9 @@ bool bgp_zebra_nexthop_set(union sockunion *local, union sockunion *remote,
 								? peer->conf_if
 								: peer->ifname,
 							peer->bgp->vrf_id);
+			else if (peer->update_if)
+				ifp = if_lookup_by_name(peer->update_if,
+							peer->bgp->vrf_id);
 		} else if (peer->update_if)
 			ifp = if_lookup_by_name(peer->update_if,
 						peer->bgp->vrf_id);

tests/topotests/bgp_vrf_ipv6_link_local/__init__.py

@@ -0,0 +1,4 @@
+router bgp 65001 vrf blue
+  neighbor fe80:1::2 remote-as 65002
+  neighbor fe80:1::2 timers 3 10
+  neighbor fe80:1::2 interface r1-eth1

tests/topotests/bgp_vrf_ipv6_link_local/r1/bgpd.conf

@@ -0,0 +1,7 @@
+!
+interface r1-eth1 vrf blue
+ ipv6 address fe80:1::1/64
+!
+ip forwarding
+ipv6 forwarding
+!

tests/topotests/bgp_vrf_ipv6_link_local/r1/zebra.conf

@@ -0,0 +1,4 @@
+router bgp 65002 vrf blue
+  neighbor fe80:1::1 remote-as 65001
+  neighbor fe80:1::1 timers 3 10
+  neighbor fe80:1::1 interface r2-eth1

tests/topotests/bgp_vrf_ipv6_link_local/r2/bgpd.conf

@@ -0,0 +1,7 @@
+!
+interface r2-eth1 vrf blue
+ ipv6 address fe80:1::2/64
+!
+ip forwarding
+ipv6 forwarding
+!

tests/topotests/bgp_vrf_ipv6_link_local/r2/zebra.conf

@@ -0,0 +1,126 @@
+#!/usr/bin/env python
+#
+# Copyright 2021 Broadcom.  The term Broadcom refers to Broadcom Inc. and/or
+# its subsidiaries.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+#
+
+"""
+Test link-local address as a BGP peer over VRF.
+"""
+
+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, TopoRouter, get_topogen
+from lib.topolog import logger
+from lib.topotest import iproute2_is_vrf_capable
+from mininet.topo import Topo
+
+
+class TemplateTopo(Topo):
+    def build(self, *_args, **_opts):
+        tgen = get_topogen(self)
+
+        for routern in range(1, 3):
+            tgen.add_router("r{}".format(routern))
+        switch = tgen.add_switch("s1")
+        switch.add_link(tgen.gears["r1"])
+        switch.add_link(tgen.gears["r2"])
+
+        # r1-r2 2
+        switch = tgen.add_switch("s2")
+        switch.add_link(tgen.gears["r1"])
+        switch.add_link(tgen.gears["r2"])
+
+
+def setup_module(mod):
+    # iproute2 needs to support VRFs for this suite to run.
+    if not iproute2_is_vrf_capable():
+        pytest.skip("Installed iproute2 version does not support VRFs")
+
+    tgen = Topogen(TemplateTopo, mod.__name__)
+    tgen.start_topology()
+
+    r1 = tgen.gears["r1"]
+    r2 = tgen.gears["r2"]
+
+    # blue vrf
+    r1.run("ip link add blue type vrf table 1001")
+    r1.run("ip link set up dev blue")
+    r2.run("ip link add blue type vrf table 1001")
+    r2.run("ip link set up dev blue")
+
+    r1.run("ip link add lo1 type dummy")
+    r1.run("ip link set lo1 master blue")
+    r1.run("ip link set up dev lo1")
+    r2.run("ip link add lo1 type dummy")
+    r2.run("ip link set up dev lo1")
+    r2.run("ip link set lo1 master blue")
+
+    r1.run("ip link set r1-eth1 master blue")
+    r2.run("ip link set r2-eth1 master blue")
+
+    r1.run("ip link set up dev  r1-eth1")
+    r2.run("ip link set up dev  r2-eth1")
+    router_list = tgen.routers()
+
+    for i, (rname, router) in enumerate(router_list.items(), 1):
+        router.load_config(
+            TopoRouter.RD_ZEBRA, os.path.join(CWD, "{}/zebra.conf".format(rname))
+        )
+        router.load_config(
+            TopoRouter.RD_BGP, os.path.join(CWD, "{}/bgpd.conf".format(rname))
+        )
+    tgen.start_router()
+
+
+def teardown_module(mod):
+    tgen = get_topogen()
+    tgen.stop_topology()
+
+
+def test_bgp_vrf_link_local():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    def _bgp_ll_neighbor_configured():
+        output = json.loads(
+            tgen.gears["r1"].vtysh_cmd("show ip bgp vrf blue neighbor json")
+        )
+        expected = {
+            "fe80:1::2": {"bgpState": "Established"},
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(_bgp_ll_neighbor_configured)
+    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+
+    assert result is None, 'Failed bgp convergence in "{}"'.format(tgen.gears["r1"])
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))
+