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Merge pull request #7922 from ton31337/fix/bgpd_blackhole_community_ibgp

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bgpd: Advertise BLACKHOLE community tagged prefixes to iBGP peers
This commit is contained in:
Donald Sharp 2021-01-25 07:22:39 -05:00 committed by GitHub
commit 4912deafad
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GPG Key ID: 4AEE18F83AFDEB23
6 changed files with 65 additions and 14 deletions
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19
bgpd/bgp_route.c
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@ -1836,7 +1836,8 @@ bool subgroup_announce_check(struct bgp_dest *dest, struct bgp_path_info *pi,
/* If community is not disabled check the no-export and local. */
if (!transparent && bgp_community_filter(peer, piattr)) {
if (bgp_debug_update(NULL, p, subgrp->update_group, 0))
zlog_debug("%s: community filter check fail", __func__);
zlog_debug("%s: community filter check fail for %pFX",
__func__, p);
return false;
}
@ -3505,18 +3506,20 @@ bool bgp_update_martian_nexthop(struct bgp *bgp, afi_t afi, safi_t safi,
return ret;
}
static void bgp_attr_add_no_advertise_community(struct attr *attr)
static void bgp_attr_add_no_export_community(struct attr *attr)
{
struct community *old;
struct community *new;
struct community *merge;
struct community *noadv;
struct community *no_export;
old = attr->community;
noadv = community_str2com("no-advertise");
no_export = community_str2com("no-export");
assert(no_export);
if (old) {
merge = community_merge(community_dup(old), noadv);
merge = community_merge(community_dup(old), no_export);
if (!old->refcnt)
community_free(&old);
@ -3524,10 +3527,10 @@ static void bgp_attr_add_no_advertise_community(struct attr *attr)
new = community_uniq_sort(merge);
community_free(&merge);
} else {
new = community_dup(noadv);
new = community_dup(no_export);
}
community_free(&noadv);
community_free(&no_export);
attr->community = new;
attr->flag |= ATTR_FLAG_BIT(BGP_ATTR_COMMUNITIES);
@ -3737,7 +3740,7 @@ int bgp_update(struct peer *peer, const struct prefix *p, uint32_t addpath_id,
if (new_attr.community
&& community_include(new_attr.community,
COMMUNITY_BLACKHOLE))
bgp_attr_add_no_advertise_community(&new_attr);
bgp_attr_add_no_export_community(&new_attr);
/* If we receive the graceful-shutdown community from an eBGP
* peer we must lower local-preference */

1
tests/topotests/bgp_blackhole_community/r2/bgpd.conf
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@ -3,4 +3,5 @@ router bgp 65002
no bgp ebgp-requires-policy
neighbor r2-eth0 interface remote-as external
neighbor r2-eth1 interface remote-as external
neighbor r2-eth2 interface remote-as internal
!

3
tests/topotests/bgp_blackhole_community/r2/zebra.conf
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@ -5,5 +5,8 @@ interface r2-eth0
interface r2-eth1
ip address 192.168.1.1/24
!
interface r2-eth2
ip address 192.168.2.1/24
!
ip forwarding
!

5
tests/topotests/bgp_blackhole_community/r4/bgpd.conf Normal file
View File

@ -0,0 +1,5 @@
!
router bgp 65002
no bgp ebgp-requires-policy
neighbor r4-eth0 interface remote-as internal
!

6
tests/topotests/bgp_blackhole_community/r4/zebra.conf Normal file
View File

@ -0,0 +1,6 @@
!
interface r4-eth0
ip address 192.168.2.2/24
!
ip forwarding
!

45
tests/topotests/bgp_blackhole_community/test_bgp_blackhole_community.py
View File

@ -21,7 +21,7 @@
"""
Test if 172.16.255.254/32 tagged with BLACKHOLE community is not
re-advertised downstream.
re-advertised downstream outside local AS.
"""
import os
@ -38,13 +38,14 @@ from lib import topotest
from lib.topogen import Topogen, TopoRouter, get_topogen
from lib.topolog import logger
from mininet.topo import Topo
from lib.common_config import step
class TemplateTopo(Topo):
def build(self, *_args, **_opts):
tgen = get_topogen(self)
for routern in range(1, 4):
for routern in range(1, 5):
tgen.add_router("r{}".format(routern))
switch = tgen.add_switch("s1")
@ -55,6 +56,10 @@ class TemplateTopo(Topo):
switch.add_link(tgen.gears["r2"])
switch.add_link(tgen.gears["r3"])
switch = tgen.add_switch("s3")
switch.add_link(tgen.gears["r2"])
switch.add_link(tgen.gears["r4"])
def setup_module(mod):
tgen = Topogen(TemplateTopo, mod.__name__)
@ -88,10 +93,10 @@ def test_bgp_blackhole_community():
output = json.loads(
tgen.gears["r2"].vtysh_cmd("show ip bgp 172.16.255.254/32 json")
)
expected = {"paths": [{"community": {"list": ["blackhole", "noAdvertise"]}}]}
expected = {"paths": [{"community": {"list": ["blackhole", "noExport"]}}]}
return topotest.json_cmp(output, expected)
def _bgp_no_advertise():
def _bgp_no_advertise_ebgp():
output = json.loads(
tgen.gears["r2"].vtysh_cmd(
"show ip bgp neighbor r2-eth1 advertised-routes json"
@ -105,15 +110,43 @@ def test_bgp_blackhole_community():
return topotest.json_cmp(output, expected)
def _bgp_no_advertise_ibgp():
output = json.loads(
tgen.gears["r2"].vtysh_cmd(
"show ip bgp neighbor r2-eth2 advertised-routes json"
)
)
expected = {
"advertisedRoutes": {"172.16.255.254/32": {}},
"totalPrefixCounter": 2,
}
return topotest.json_cmp(output, expected)
test_func = functools.partial(_bgp_converge)
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["r2"])
test_func = functools.partial(_bgp_no_advertise)
step("Check if 172.16.255.254/32 is not advertised to eBGP peers")
test_func = functools.partial(_bgp_no_advertise_ebgp)
success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
assert result is None, 'Advertised blackhole tagged prefix in "{}"'.format(
assert (
result is None
), 'Advertised blackhole tagged prefix to eBGP peers in "{}"'.format(
tgen.gears["r2"]
)
step("Check if 172.16.255.254/32 is advertised to iBGP peers")
test_func = functools.partial(_bgp_no_advertise_ibgp)
success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
assert (
result is None
), 'Withdrawn blackhole tagged prefix to iBGP peers in "{}"'.format(
tgen.gears["r2"]
)