platform: sort known IPv6 addresses by scope before a syncbg/rh1578668

https://bugzilla.redhat.com/show_bug.cgi?id=1578668

1 files changed, 27 insertions, 0 deletions

diff --git a/src/platform/nm-platform.c b/src/platform/nm-platform.c
index 727e064bd5..e3d194c022 100644
--- a/src/platform/nm-platform.c
+++ b/src/platform/nm-platform.c
@@ -3595,6 +3595,25 @@ delete_and_next2:
 	return TRUE;
 }
 
+static guint
+ip6_address_scope_priority (struct in6_addr *addr)
+{
+	if (IN6_IS_ADDR_LINKLOCAL (addr))
+		return 1;
+	if (IN6_IS_ADDR_SITELOCAL (addr))
+		return 2;
+	return 3;
+}
+
+static gint
+ip6_address_scope_cmp (gconstpointer a, gconstpointer b)
+{
+	NMPlatformIP6Address *x = NMP_OBJECT_CAST_IP6_ADDRESS (*(void **) a);
+	NMPlatformIP6Address *y = NMP_OBJECT_CAST_IP6_ADDRESS (*(void **) b);
+
+	return ip6_address_scope_priority (&x->address) - ip6_address_scope_priority (&y->address);
+}
+
 /**
  * nm_platform_ip6_address_sync:
  * @self: platform instance
@@ -3628,6 +3647,14 @@ nm_platform_ip6_address_sync (NMPlatform *self,
 	NMPLookup lookup;
 	guint32 ifa_flags;
 
+	/* The order we want to enforce is only among addresses with the same
+	 * scope, as the kernel keeps addresses sorted by scope. Therefore,
+	 * apply the same sorting to known addresses, so that we don't try to
+	 * unnecessary change the order of addresses with different scopes.
+	 */
+	if (known_addresses)
+		g_ptr_array_sort (known_addresses, ip6_address_scope_cmp);
+
 	if (!_addr_array_clean_expired (AF_INET6, ifindex, known_addresses, now, &known_addresses_idx))
 		known_addresses = NULL;