Merge pull request #9545 from ton31337/feature/disable-addpath-rx

bgpd: Add disable-addpath-rx knob

bgpd/bgp_open.c

@@ -1534,6 +1534,11 @@ void bgp_open_capability(struct stream *s, struct peer *peer)
 
 	FOREACH_AFI_SAFI (afi, safi) {
 		if (peer->afc[afi][safi]) {
+			bool adv_addpath_rx =
+				!CHECK_FLAG(peer->af_flags[afi][safi],
+					    PEER_FLAG_DISABLE_ADDPATH_RX);
+			uint8_t flags = 0;
+
 			/* Convert AFI, SAFI to values for packet. */
 			bgp_map_afi_safi_int2iana(afi, safi, &pkt_afi,
 						  &pkt_safi);
@@ -1541,19 +1546,25 @@ void bgp_open_capability(struct stream *s, struct peer *peer)
 			stream_putw(s, pkt_afi);
 			stream_putc(s, pkt_safi);
 
-			if (adv_addpath_tx) {
-				stream_putc(s, BGP_ADDPATH_RX | BGP_ADDPATH_TX);
+			if (adv_addpath_rx) {
+				SET_FLAG(flags, BGP_ADDPATH_RX);
 				SET_FLAG(peer->af_cap[afi][safi],
 					 PEER_CAP_ADDPATH_AF_RX_ADV);
+			} else {
+				UNSET_FLAG(peer->af_cap[afi][safi],
+					   PEER_CAP_ADDPATH_AF_RX_ADV);
+			}
+
+			if (adv_addpath_tx) {
+				SET_FLAG(flags, BGP_ADDPATH_TX);
 				SET_FLAG(peer->af_cap[afi][safi],
 					 PEER_CAP_ADDPATH_AF_TX_ADV);
 			} else {
-				stream_putc(s, BGP_ADDPATH_RX);
-				SET_FLAG(peer->af_cap[afi][safi],
-					 PEER_CAP_ADDPATH_AF_RX_ADV);
 				UNSET_FLAG(peer->af_cap[afi][safi],
 					   PEER_CAP_ADDPATH_AF_TX_ADV);
 			}
+
+			stream_putc(s, flags);
 		}
 	}
 

bgpd/bgp_vty.c

@@ -7968,6 +7968,48 @@ DEFUN (no_neighbor_ttl_security,
 	return bgp_vty_return(vty, peer_ttl_security_hops_unset(peer));
 }
 
+/* disable-addpath-rx */
+DEFUN(neighbor_disable_addpath_rx,
+      neighbor_disable_addpath_rx_cmd,
+      "neighbor <A.B.C.D|X:X::X:X|WORD> disable-addpath-rx",
+      NEIGHBOR_STR
+      NEIGHBOR_ADDR_STR2
+      "Do not accept additional paths\n")
+{
+	char *peer_str = argv[1]->arg;
+	struct peer *peer;
+	afi_t afi = bgp_node_afi(vty);
+	safi_t safi = bgp_node_safi(vty);
+
+	peer = peer_and_group_lookup_vty(vty, peer_str);
+	if (!peer)
+		return CMD_WARNING_CONFIG_FAILED;
+
+	return peer_af_flag_set_vty(vty, peer_str, afi, safi,
+				    PEER_FLAG_DISABLE_ADDPATH_RX);
+}
+
+DEFUN(no_neighbor_disable_addpath_rx,
+      no_neighbor_disable_addpath_rx_cmd,
+      "no neighbor <A.B.C.D|X:X::X:X|WORD> disable-addpath-rx",
+      NO_STR
+      NEIGHBOR_STR
+      NEIGHBOR_ADDR_STR2
+      "Do not accept additional paths\n")
+{
+	char *peer_str = argv[2]->arg;
+	struct peer *peer;
+	afi_t afi = bgp_node_afi(vty);
+	safi_t safi = bgp_node_safi(vty);
+
+	peer = peer_and_group_lookup_vty(vty, peer_str);
+	if (!peer)
+		return CMD_WARNING_CONFIG_FAILED;
+
+	return peer_af_flag_unset_vty(vty, peer_str, afi, safi,
+				      PEER_FLAG_DISABLE_ADDPATH_RX);
+}
+
 DEFUN (neighbor_addpath_tx_all_paths,
        neighbor_addpath_tx_all_paths_cmd,
        "neighbor <A.B.C.D|X:X::X:X|WORD> addpath-tx-all-paths",
@@ -16606,6 +16648,9 @@ static void bgp_config_write_peer_af(struct vty *vty, struct bgp *bgp,
 		}
 	}
 
+	if (CHECK_FLAG(peer->af_flags[afi][safi], PEER_FLAG_DISABLE_ADDPATH_RX))
+		vty_out(vty, "  neighbor %s disable-addpath-rx\n", addr);
+
 	/* ORF capability.  */
 	if (peergroup_af_flag_check(peer, afi, safi, PEER_FLAG_ORF_PREFIX_SM)
 	    || peergroup_af_flag_check(peer, afi, safi,
@@ -18228,6 +18273,24 @@ void bgp_vty_init(void)
 	install_element(BGP_FLOWSPECV6_NODE,
 			&no_neighbor_route_server_client_cmd);
 
+	/* "neighbor disable-addpath-rx" commands. */
+	install_element(BGP_IPV4_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV4_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV4M_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV4M_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV4L_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV4L_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6M_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6M_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6L_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_IPV6L_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_VPNV4_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_VPNV4_NODE, &no_neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_VPNV6_NODE, &neighbor_disable_addpath_rx_cmd);
+	install_element(BGP_VPNV6_NODE, &no_neighbor_disable_addpath_rx_cmd);
+
 	/* "neighbor addpath-tx-all-paths" commands.*/
 	install_element(BGP_NODE, &neighbor_addpath_tx_all_paths_hidden_cmd);
 	install_element(BGP_NODE, &no_neighbor_addpath_tx_all_paths_hidden_cmd);

bgpd/bgpd.c

@@ -4208,6 +4208,7 @@ static const struct peer_flag_action peer_af_flag_action_list[] = {
 	{PEER_FLAG_AS_OVERRIDE, 1, peer_change_reset_out},
 	{PEER_FLAG_REMOVE_PRIVATE_AS_ALL_REPLACE, 1, peer_change_reset_out},
 	{PEER_FLAG_WEIGHT, 0, peer_change_reset_in},
+	{PEER_FLAG_DISABLE_ADDPATH_RX, 0, peer_change_reset},
 	{0, 0, 0}};
 
 /* Proper action set. */

bgpd/bgpd.h

@@ -1356,6 +1356,7 @@ struct peer {
 #define PEER_FLAG_SEND_LARGE_COMMUNITY      (1U << 26) /* Send large Communities */
 #define PEER_FLAG_MAX_PREFIX_OUT            (1U << 27) /* outgoing maximum prefix */
 #define PEER_FLAG_MAX_PREFIX_FORCE          (1U << 28) /* maximum-prefix <num> force */
+#define PEER_FLAG_DISABLE_ADDPATH_RX        (1U << 29) /* disable-addpath-rx */
 
 	enum bgp_addpath_strat addpath_type[AFI_MAX][SAFI_MAX];
 

doc/user/bgp.rst

@@ -1582,6 +1582,10 @@ Configuring Peers
    Configure BGP to send best known paths to neighbor in order to preserve multi
    path capabilities inside a network.
 
+.. clicmd:: neighbor <A.B.C.D|X:X::X:X|WORD> disable-addpath-rx
+
+   Do not accept additional paths from this neighbor.
+
 .. clicmd:: neighbor PEER ttl-security hops NUMBER
 
    This command enforces Generalized TTL Security Mechanism (GTSM), as
@@ -4375,8 +4379,8 @@ Show command json output:
 BGP fast-convergence support
 ============================
 Whenever BGP peer address becomes unreachable we must bring down the BGP
-session immediately. Currently only single-hop EBGP sessions are brought 
-down immediately.IBGP and multi-hop EBGP sessions wait for hold-timer 
+session immediately. Currently only single-hop EBGP sessions are brought
+down immediately.IBGP and multi-hop EBGP sessions wait for hold-timer
 expiry to bring down the sessions.
 
 This new configuration option helps user to teardown BGP sessions immediately

tests/topotests/bgp_disable_addpath_rx/r1/bgpd.conf

@@ -0,0 +1,8 @@
+!
+router bgp 65001
+ no bgp ebgp-requires-policy
+ neighbor 192.168.1.2 remote-as external
+ address-family ipv4 unicast
+  neighbor 192.168.1.2 disable-addpath-rx
+ exit-address-family
+!

tests/topotests/bgp_disable_addpath_rx/r1/zebra.conf

@@ -0,0 +1,4 @@
+!
+int r1-eth0
+ ip address 192.168.1.1/24
+!

tests/topotests/bgp_disable_addpath_rx/r2/bgpd.conf

@@ -0,0 +1,9 @@
+router bgp 65002
+ no bgp ebgp-requires-policy
+ neighbor 192.168.1.1 remote-as external
+ neighbor 192.168.2.3 remote-as external
+ neighbor 192.168.2.4 remote-as external
+ address-family ipv4 unicast
+  neighbor 192.168.1.1 addpath-tx-all-paths
+ exit-address-family
+!

tests/topotests/bgp_disable_addpath_rx/r2/zebra.conf

@@ -0,0 +1,7 @@
+!
+int r2-eth0
+ ip address 192.168.1.2/24
+!
+int r2-eth1
+ ip address 192.168.2.2/24
+!

tests/topotests/bgp_disable_addpath_rx/r3/bgpd.conf

@@ -0,0 +1,7 @@
+router bgp 65003
+ no bgp ebgp-requires-policy
+ neighbor 192.168.2.2 remote-as external
+ address-family ipv4 unicast
+  redistribute connected
+ exit-address-family
+!

tests/topotests/bgp_disable_addpath_rx/r3/zebra.conf

@@ -0,0 +1,7 @@
+!
+int lo
+ ip address 172.16.16.254/32
+!
+int r3-eth0
+ ip address 192.168.2.3/24
+!

tests/topotests/bgp_disable_addpath_rx/r4/bgpd.conf

@@ -0,0 +1,7 @@
+router bgp 65004
+ no bgp ebgp-requires-policy
+ neighbor 192.168.2.2 remote-as external
+ address-family ipv4 unicast
+  redistribute connected
+ exit-address-family
+!

tests/topotests/bgp_disable_addpath_rx/r4/zebra.conf

@@ -0,0 +1,7 @@
+!
+int lo
+ ip address 172.16.16.254/32
+!
+int r4-eth0
+ ip address 192.168.2.4/24
+!

tests/topotests/bgp_disable_addpath_rx/test_disable_addpath_rx.py

@@ -0,0 +1,148 @@
+#!/usr/bin/env python
+
+# Copyright (c) 2021 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.
+#
+
+"""
+Test if AddPath RX direction is not negotiated via AddPath capability.
+"""
+
+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
+from lib.common_config import step
+
+pytestmark = [pytest.mark.bgpd]
+
+
+class TemplateTopo(Topo):
+    def build(self, *_args, **_opts):
+        tgen = get_topogen(self)
+
+        for routern in range(1, 5):
+            tgen.add_router("r{}".format(routern))
+
+        switch = tgen.add_switch("s1")
+        switch.add_link(tgen.gears["r1"])
+        switch.add_link(tgen.gears["r2"])
+
+        switch = tgen.add_switch("s2")
+        switch.add_link(tgen.gears["r2"])
+        switch.add_link(tgen.gears["r3"])
+        switch.add_link(tgen.gears["r4"])
+
+
+def setup_module(mod):
+    tgen = Topogen(TemplateTopo, mod.__name__)
+    tgen.start_topology()
+
+    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_disable_addpath_rx():
+    tgen = get_topogen()
+
+    if tgen.routers_have_failure():
+        pytest.skip(tgen.errors)
+
+    r1 = tgen.gears["r1"]
+    r2 = tgen.gears["r2"]
+
+    step(
+        "Check if r2 advertised only 2 paths to r1 (despite addpath-tx-all-paths enabled on r2)."
+    )
+
+    def check_bgp_advertised_routes(router):
+        output = json.loads(
+            router.vtysh_cmd(
+                "show bgp ipv4 unicast neighbor 192.168.1.1 advertised-routes json"
+            )
+        )
+        expected = {
+            "advertisedRoutes": {
+                "172.16.16.254/32": {
+                    "addrPrefix": "172.16.16.254",
+                    "prefixLen": 32,
+                },
+                "192.168.2.0/24": {
+                    "addrPrefix": "192.168.2.0",
+                    "prefixLen": 24,
+                },
+            },
+            "totalPrefixCounter": 2,
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(check_bgp_advertised_routes, r2)
+    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "AddPath TX not working."
+
+    step("Check if AddPath RX is disabled on r1 and we receive only 2 paths.")
+
+    def check_bgp_disabled_addpath_rx(router):
+        output = json.loads(router.vtysh_cmd("show bgp neighbor 192.168.1.2 json"))
+        expected = {
+            "192.168.1.2": {
+                "bgpState": "Established",
+                "neighborCapabilities": {
+                    "addPath": {
+                        "ipv4Unicast": {"txReceived": True, "rxReceived": True}
+                    },
+                },
+                "addressFamilyInfo": {"ipv4Unicast": {"acceptedPrefixCounter": 2}},
+            }
+        }
+
+        return topotest.json_cmp(output, expected)
+
+    test_func = functools.partial(check_bgp_disabled_addpath_rx, r1)
+    success, result = topotest.run_and_expect(test_func, None, count=60, wait=0.5)
+    assert result is None, "AddPath RX advertised, but should not."
+
+
+if __name__ == "__main__":
+    args = ["-s"] + sys.argv[1:]
+    sys.exit(pytest.main(args))