Merge pull request #5855 from ton31337/fix/allow_using_add_sub_for_local-preference

bgpd: Allow using add/subtract for local-preference in route-maps

bgpd/bgp_routemap.c

@@ -4400,10 +4400,10 @@ DEFUN (no_set_distance,
 
 DEFUN (set_local_pref,
        set_local_pref_cmd,
-       "set local-preference (0-4294967295)",
+       "set local-preference WORD",
        SET_STR
        "BGP local preference path attribute\n"
-       "Preference value\n")
+       "Preference value (0-4294967295)\n")
 {
 	int idx_number = 2;
 	return generic_set_add(vty, VTY_GET_CONTEXT(route_map_index),
@@ -4413,11 +4413,11 @@ DEFUN (set_local_pref,
 
 DEFUN (no_set_local_pref,
        no_set_local_pref_cmd,
-       "no set local-preference [(0-4294967295)]",
+       "no set local-preference [WORD]",
        NO_STR
        SET_STR
        "BGP local preference path attribute\n"
-       "Preference value\n")
+       "Preference value (0-4294967295)\n")
 {
 	int idx_localpref = 3;
 	if (argc <= idx_localpref)

doc/user/routemap.rst

@@ -273,6 +273,16 @@ Route Map Set Command
 
    Set the BGP local preference to `local_pref`.
 
+.. index:: set local-preference +LOCAL_PREF
+.. clicmd:: set local-preference +LOCAL_PREF
+
+   Add the BGP local preference to an existing `local_pref`.
+
+.. index:: set local-preference -LOCAL_PREF
+.. clicmd:: set local-preference -LOCAL_PREF
+
+   Subtract the BGP local preference from an existing `local_pref`.
+
 .. index:: [no] set distance DISTANCE
 .. clicmd:: [no] set distance DISTANCE
 

tests/topotests/bgp_set_local-preference_add_subtract/r1/bgpd.conf

@@ -0,0 +1,5 @@
+router bgp 65000
+  neighbor 192.168.255.2 remote-as 65000
+  neighbor 192.168.255.3 remote-as 65000
+  exit-address-family
+!

tests/topotests/bgp_set_local-preference_add_subtract/r1/zebra.conf

@@ -0,0 +1,6 @@
+!
+interface r1-eth0
+  ip address 192.168.255.1/24
+!
+ip forwarding
+!

tests/topotests/bgp_set_local-preference_add_subtract/r2/bgpd.conf

@@ -0,0 +1,9 @@
+router bgp 65000
+  neighbor 192.168.255.1 remote-as 65000
+  address-family ipv4
+    redistribute connected
+    neighbor 192.168.255.1 route-map r1-out out
+  exit-address-family
+!
+route-map r1-out permit 10
+  set local-preference +50

tests/topotests/bgp_set_local-preference_add_subtract/r2/zebra.conf

@@ -0,0 +1,9 @@
+!
+interface lo
+  ip address 172.16.255.254/32
+!
+interface r2-eth0
+  ip address 192.168.255.2/24
+!
+ip forwarding
+!

tests/topotests/bgp_set_local-preference_add_subtract/r3/bgpd.conf

@@ -0,0 +1,9 @@
+router bgp 65000
+  neighbor 192.168.255.1 remote-as 65000
+  address-family ipv4
+    redistribute connected
+    neighbor 192.168.255.1 route-map r1-out out
+  exit-address-family
+!
+route-map r1-out permit 10
+  set local-preference -50

tests/topotests/bgp_set_local-preference_add_subtract/r3/zebra.conf

@@ -0,0 +1,9 @@
+!
+interface lo
+  ip address 172.16.255.254/32
+!
+interface r3-eth0
+  ip address 192.168.255.3/24
+!
+ip forwarding
+!

tests/topotests/bgp_set_local-preference_add_subtract/test_bgp_set_local-preference_add_subtract.py

@@ -0,0 +1,147 @@
+#!/usr/bin/env python
+
+#
+# bgp_set_local-preference_add_subtract.py
+# Part of NetDEF Topology Tests
+#
+# Copyright (c) 2020 by
+# Donatas Abraitis <donatas.abraitis@gmail.com>
+#
+# Permission to use, copy, modify, and/or distribute this software
+# for any purpose with or without fee is hereby granted, provided
+# that the above copyright notice and this permission notice appear
+# in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NETDEF DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NETDEF BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY
+# DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
+# WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
+# ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
+# OF THIS SOFTWARE.
+#
+
+"""
+bgp_set_local-preference_add_subtract.py:
+Test if we can add/subtract the value to/from an existing
+LOCAL_PREF in route-maps.
+"""
+
+import os
+import sys
+import json
+import time
+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 mininet.topo import Topo
+
+class TemplateTopo(Topo):
+    def build(self, *_args, **_opts):
+        tgen = get_topogen(self)
+
+        for routern in range(1, 4):
+            tgen.add_router('r{}'.format(routern))
+
+        switch = tgen.add_switch('s1')
+        switch.add_link(tgen.gears['r1'])
+        switch.add_link(tgen.gears['r2'])
+        switch.add_link(tgen.gears['r3'])
+
+def setup_module(mod):
+    tgen = Topogen(TemplateTopo, mod.__name__)
+    tgen.start_topology()
+
+    router_list = tgen.routers()
+
+    for i, (rname, router) in enumerate(router_list.iteritems(), 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_set_local_preference():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    router = tgen.gears['r1']
+
+    def _bgp_converge(router):
+        output = json.loads(router.vtysh_cmd("show ip bgp neighbor json"))
+        expected = {
+            '192.168.255.2': {
+                'bgpState': 'Established',
+                'addressFamilyInfo': {
+                    'ipv4Unicast': {
+                        'acceptedPrefixCounter': 2
+                    }
+                }
+            },
+            '192.168.255.3': {
+                'bgpState': 'Established',
+                'addressFamilyInfo': {
+                    'ipv4Unicast': {
+                        'acceptedPrefixCounter': 2
+                    }
+                }
+            }
+        }
+        return topotest.json_cmp(output, expected)
+
+    def _bgp_check_local_preference(router):
+        output = json.loads(router.vtysh_cmd("show ip bgp 172.16.255.254/32 json"))
+        expected = {
+            'paths': [
+                {
+                    'localpref': 50,
+                    'nexthops': [
+                        {
+                            'ip': '192.168.255.3'
+                        }
+                    ]
+                },
+                {
+                    'localpref': 150,
+                    'nexthops': [
+                        {
+                            'ip': '192.168.255.2'
+                        }
+                    ]
+                }
+            ]
+        }
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(_bgp_converge, router)
+    success, result = topotest.run_and_expect(test_func, None, count=15, wait=0.5)
+
+    assert result is None, 'Failed to see BGP convergence in "{}"'.format(router)
+
+    test_func = functools.partial(_bgp_check_local_preference, router)
+    success, result = topotest.run_and_expect(test_func, None, count=15, wait=0.5)
+
+    assert result is None, 'Failed to see applied BGP local-preference in "{}"'.format(router)
+
+if __name__ == '__main__':
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))