Allow LR to send RAs with only link local Ipv6.

This fixes a bug in OVN that causes ovn-controller to fail when Logical
Router Port configures send_periodic=true, but the Logical Router itself
doesn't have any globally routable IPv6 networks.

This is supported by RFC 4861 [0], in sections 6.2.2 and 4.2

This is part of a larger effort to get BGP unnumbered working within OVN.

[0]: https://datatracker.ietf.org/doc/html/rfc4861

Signed-off-by: MJ Ponsonby <mj.ponsonby@canonical.com>
Signed-off-by: 0-day Robot <robot@bytheb.org>

controller/pinctrl.c

@@ -4171,7 +4171,8 @@ ipv6_ra_update_config(const struct sbrec_port_binding *pb)
     }
 
     const char *prefixes = smap_get(&pb->options, "ipv6_ra_prefixes");
-    if (prefixes && !extract_ip_addresses(prefixes, &config->prefixes)) {
+    if (prefixes && *prefixes != '\0' &&
+        !extract_ip_addresses(prefixes, &config->prefixes)) {
         VLOG_WARN("Invalid IPv6 prefixes: %s", prefixes);
         goto fail;
     }

tests/ovn.at

@@ -16543,7 +16543,7 @@ ovs-vsctl add-br br-phys
 ovn_attach n1 br-phys 192.168.0.3
 
 check ovn-nbctl lr-add ro
-check ovn-nbctl lrp-add ro ro-sw 00:00:00:00:00:01 aef0:0:0:0:0:0:0:1/64
+check ovn-nbctl lrp-add ro ro-sw 00:00:00:00:00:01
 
 check ovn-nbctl ls-add sw
 check ovn-nbctl lsp-add sw sw-ro
@@ -16649,6 +16649,11 @@ ra_test() {
     rm -f expected
 }
 
+echo "Baseline test with ipv6"
+ra_test 0 00 0 0 0 c0
+
+ovn-nbctl --wait=hv set Logical_Router_port ro-sw networks='aef0\:\:1/64'
+
 echo "Baseline test with no MTU"
 ra_test 0 00 0 0 0 c0 40 aef00000000000000000000000000000
 
@@ -16794,7 +16799,7 @@ check ovs-vsctl set open . external-ids:ovn-bridge-mappings=phys:br-phys
 ovn_attach n1 br-phys 192.168.0.3
 
 check ovn-nbctl lr-add ro
-check ovn-nbctl lrp-add ro ro-sw 00:00:00:00:00:01 aef0:0:0:0:0:0:0:1/64
+check ovn-nbctl lrp-add ro ro-sw 00:00:00:00:00:01
 
 check ovn-nbctl ls-add sw
 check ovn-nbctl lsp-add sw ln
@@ -16909,7 +16914,12 @@ ra_test() {
     rm -f expected
 }
 
-# check that RAs are sent to vifs
+# check that RAs are sent to vifs without ipv6 prefix
+ra_test 0 00 0 0 0 c0
+
+ovn-nbctl --wait=hv set Logical_Router_port ro-sw networks='aef0\:\:1/64'
+
+# check that RAs are sent to vifs with ipv6 prefix
 ra_test 0 00 0 0 0 c0 40 aef00000000000000000000000000000
 
 # check that RAs don't leak into provider networks