From 6b093863ecca602d40ef5a22f07b3cfc432671f5 Mon Sep 17 00:00:00 2001
From: Donald Sharp <sharpd@cumulusnetworks.com>
Date: Fri, 18 May 2018 15:41:46 -0400
Subject: [PATCH] zebra: Allow runtime determination of v6 RR semantics

The linux kernel is getting the same Route Replace semantics
for v6 that v4 uses.  Allow the end-user to know if their
kernel has this ability and if so to specify it so zebra
can take advantage of this.

Why not do auto-detection?  Because you would have to write
code in zebra to add a route then add the same route again
with different nexthops to see if which semantics it is using.
It sure is easier to just add a cli that allows the user to
do it.

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
---
 zebra/main.c       | 51 +++++++++++++++++++++++++++-------------------
 zebra/rib.h        |  1 +
 zebra/rt_netlink.c |  2 +-
 3 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/zebra/main.c b/zebra/main.c
index 9a495c894..da9fe9512 100644
--- a/zebra/main.c
+++ b/zebra/main.c
@@ -75,24 +75,29 @@ int allow_delete = 0;
 /* Don't delete kernel route. */
 int keep_kernel_mode = 0;
 
+bool v6_rr_semantics = false;
+
 #ifdef HAVE_NETLINK
 /* Receive buffer size for netlink socket */
 uint32_t nl_rcvbufsize = 4194304;
 #endif /* HAVE_NETLINK */
 
+#define OPTION_V6_RR_SEMANTICS 2000
 /* Command line options. */
-struct option longopts[] = {{"batch", no_argument, NULL, 'b'},
-			    {"allow_delete", no_argument, NULL, 'a'},
-			    {"keep_kernel", no_argument, NULL, 'k'},
-			    {"socket", required_argument, NULL, 'z'},
-			    {"ecmp", required_argument, NULL, 'e'},
-			    {"label_socket", no_argument, NULL, 'l'},
-			    {"retain", no_argument, NULL, 'r'},
+struct option longopts[] = {
+	{"batch", no_argument, NULL, 'b'},
+	{"allow_delete", no_argument, NULL, 'a'},
+	{"keep_kernel", no_argument, NULL, 'k'},
+	{"socket", required_argument, NULL, 'z'},
+	{"ecmp", required_argument, NULL, 'e'},
+	{"label_socket", no_argument, NULL, 'l'},
+	{"retain", no_argument, NULL, 'r'},
 #ifdef HAVE_NETLINK
-			    {"vrfwnetns", no_argument, NULL, 'n'},
-			    {"nl-bufsize", required_argument, NULL, 's'},
+	{"vrfwnetns", no_argument, NULL, 'n'},
+	{"nl-bufsize", required_argument, NULL, 's'},
+	{"v6-rr-semantics", no_argument, NULL, OPTION_V6_RR_SEMANTICS},
 #endif /* HAVE_NETLINK */
-			    {0}};
+	{0}};
 
 zebra_capabilities_t _caps_p[] = {
 	ZCAP_NET_ADMIN, ZCAP_SYS_ADMIN, ZCAP_NET_RAW,
@@ -224,21 +229,22 @@ int main(int argc, char **argv)
 #endif
 		,
 		longopts,
-		"  -b, --batch        Runs in batch mode\n"
-		"  -a, --allow_delete Allow other processes to delete zebra routes\n"
-		"  -z, --socket       Set path of zebra socket\n"
-		"  -e, --ecmp         Specify ECMP to use.\n"
-		"  -l, --label_socket Socket to external label manager\n"
-		"  -k, --keep_kernel  Don't delete old routes which installed by zebra.\n"
-		"  -r, --retain       When program terminates, retain added route by zebra.\n"
+		"  -b, --batch           Runs in batch mode\n"
+		"  -a, --allow_delete    Allow other processes to delete zebra routes\n"
+		"  -z, --socket          Set path of zebra socket\n"
+		"  -e, --ecmp            Specify ECMP to use.\n"
+		"  -l, --label_socket    Socket to external label manager\n"
+		"  -k, --keep_kernel     Don't delete old routes which installed by zebra.\n"
+		"  -r, --retain          When program terminates, retain added route by zebra.\n"
 #ifdef HAVE_NETLINK
-		"  -n, --vrfwnetns    Set VRF with NetNS\n"
-		"  -s, --nl-bufsize   Set netlink receive buffer size\n"
+		"  -n, --vrfwnetns       Set VRF with NetNS\n"
+		"  -s, --nl-bufsize      Set netlink receive buffer size\n"
+		"      --v6-rr-semantics Use v6 RR semantics\n"
 #endif /* HAVE_NETLINK */
 #if defined(HANDLE_ZAPI_FUZZING)
-		"  -c <file>          Bypass normal startup use this file for tetsting of zapi"
+		"  -c <file>             Bypass normal startup use this file for tetsting of zapi"
 #endif
-		);
+	);
 
 	while (1) {
 		int opt = frr_getopt(argc, argv, NULL);
@@ -292,6 +298,9 @@ int main(int argc, char **argv)
 			logicalrouter_configure_backend(
 				LOGICALROUTER_BACKEND_OFF);
 			break;
+		case OPTION_V6_RR_SEMANTICS:
+			v6_rr_semantics = true;
+			break;
 #endif /* HAVE_NETLINK */
 #if defined(HANDLE_ZAPI_FUZZING)
 		case 'c':
diff --git a/zebra/rib.h b/zebra/rib.h
index 7b9e6d56a..209f085ed 100644
--- a/zebra/rib.h
+++ b/zebra/rib.h
@@ -456,4 +456,5 @@ extern void static_config_install_delayed_routes(struct zebra_vrf *zvrf);
 
 extern pid_t pid;
 
+extern bool v6_rr_semantics;
 #endif /*_ZEBRA_RIB_H */
diff --git a/zebra/rt_netlink.c b/zebra/rt_netlink.c
index 2fd7bee05..8ab70c8d4 100644
--- a/zebra/rt_netlink.c
+++ b/zebra/rt_netlink.c
@@ -1696,7 +1696,7 @@ void kernel_route_rib(struct route_node *rn, struct prefix *p,
 	assert(old || new);
 
 	if (new) {
-		if (p->family == AF_INET)
+		if (p->family == AF_INET || v6_rr_semantics)
 			ret = netlink_route_multipath(RTM_NEWROUTE, p, src_p,
 						      new, (old) ? 1 : 0);
 		else {
-- 
2.39.2