core: fix MTU handling while merging/subtracting IP configs (bgo #721420)

https://bugzilla.gnome.org/show_bug.cgi?id=721420
https://bugzilla.redhat.com/show_bug.cgi?id=1047083

2 files changed, 60 insertions, 2 deletions

diff --git a/src/nm-ip4-config.c b/src/nm-ip4-config.c
index 034d2e9127..505bc851ff 100644
--- a/src/nm-ip4-config.c
+++ b/src/nm-ip4-config.c
@@ -15,7 +15,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright (C) 2005 - 2013 Red Hat, Inc.
+ * Copyright (C) 2005 - 2014 Red Hat, Inc.
  * Copyright (C) 2006 - 2008 Novell, Inc.
  */
 
@@ -502,9 +502,14 @@ nm_ip4_config_merge (NMIP4Config *dst, const NMIP4Config *src)
 	for (i = 0; i < nm_ip4_config_get_num_searches (src); i++)
 		nm_ip4_config_add_search (dst, nm_ip4_config_get_search (src, i));
 
+	/* MSS */
 	if (!nm_ip4_config_get_mss (dst))
 		nm_ip4_config_set_mss (dst, nm_ip4_config_get_mss (src));
 
+	/* MTU */
+	if (!nm_ip4_config_get_mtu (dst))
+		nm_ip4_config_set_mtu (dst, nm_ip4_config_get_mtu (src));
+
 	/* NIS */
 	for (i = 0; i < nm_ip4_config_get_num_nis_servers (src); i++)
 		nm_ip4_config_add_nis_server (dst, nm_ip4_config_get_nis_server (src, i));
@@ -611,9 +616,14 @@ nm_ip4_config_subtract (NMIP4Config *dst, const NMIP4Config *src)
 		}
 	}
 
+	/* MSS */
 	if (nm_ip4_config_get_mss (src) == nm_ip4_config_get_mss (dst))
 		nm_ip4_config_set_mss (dst, 0);
 
+	/* MTU */
+	if (nm_ip4_config_get_mtu (src) == nm_ip4_config_get_mtu (dst))
+		nm_ip4_config_set_mtu (dst, 0);
+
 	/* NIS */
 	for (i = 0; i < nm_ip4_config_get_num_nis_servers (src); i++) {
 		guint32 src_nis = nm_ip4_config_get_nis_server (src, i);
diff --git a/src/tests/test-ip4-config.c b/src/tests/test-ip4-config.c
index e2d56948b3..f08ed24265 100644
--- a/src/tests/test-ip4-config.c
+++ b/src/tests/test-ip4-config.c
@@ -14,7 +14,7 @@
  * with this program; if not, write to the Free Software Foundation, Inc.,
  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  *
- * Copyright (C) 2013 Red Hat, Inc.
+ * Copyright (C) 2013 - 2014 Red Hat, Inc.
  *
  */
 
@@ -116,6 +116,8 @@ test_subtract (void)
 	const char *expected_search = "somewhere.com";
 	guint32 expected_nis = addr_to_num ("1.2.3.13");
 	guint32 expected_wins = addr_to_num ("2.3.4.5");
+	guint32 expected_mss = 1400;
+	guint32 expected_mtu = 1492;
 
 	src = build_test_config ();
 
@@ -135,6 +137,9 @@ test_subtract (void)
 	nm_ip4_config_add_nis_server (dst, expected_nis);
 	nm_ip4_config_add_wins (dst, expected_wins);
 
+	nm_ip4_config_set_mss (dst, expected_mss);
+	nm_ip4_config_set_mtu (dst, expected_mtu);
+
 	nm_ip4_config_subtract (dst, src);
 
 	/* ensure what's left is what we expect */
@@ -169,6 +174,9 @@ test_subtract (void)
 	g_assert_cmpuint (nm_ip4_config_get_num_wins (dst), ==, 1);
 	g_assert_cmpuint (nm_ip4_config_get_wins (dst, 0), ==, expected_wins);
 
+	g_assert_cmpuint (nm_ip4_config_get_mss (dst), ==, expected_mss);
+	g_assert_cmpuint (nm_ip4_config_get_mtu (dst), ==, expected_mtu);
+
 	g_object_unref (src);
 	g_object_unref (dst);
 }
@@ -286,6 +294,45 @@ test_add_route_with_source (void)
 	g_object_unref (a);
 }
 
+static void
+test_merge_subtract_mss_mtu (void)
+{
+	NMIP4Config *cfg1, *cfg2, *cfg3;
+	guint32 expected_mss2 = 1400;
+	guint32 expected_mtu2 = 1492;
+	guint32 expected_mss3 = 555;
+	guint32 expected_mtu3 = 666;
+
+	cfg1 = build_test_config ();
+	cfg2 = build_test_config ();
+	cfg3 = build_test_config ();
+
+	/* add MSS, MTU to configs to test them */
+	nm_ip4_config_set_mss (cfg2, expected_mss2);
+	nm_ip4_config_set_mtu (cfg2, expected_mtu2);
+	nm_ip4_config_set_mss (cfg3, expected_mss3);
+	nm_ip4_config_set_mtu (cfg3, expected_mtu3);
+
+	nm_ip4_config_merge (cfg1, cfg2);
+	/* ensure MSS and MTU are in cfg1 */
+	g_assert_cmpuint (nm_ip4_config_get_mss (cfg1), ==, expected_mss2);
+	g_assert_cmpuint (nm_ip4_config_get_mtu (cfg1), ==, expected_mtu2);
+
+	nm_ip4_config_merge (cfg1, cfg3);
+	/* ensure again the same MSS and MTU are in cfg1 */
+	g_assert_cmpuint (nm_ip4_config_get_mss (cfg1), ==, expected_mss2);
+	g_assert_cmpuint (nm_ip4_config_get_mtu (cfg1), ==, expected_mtu2);
+
+	nm_ip4_config_subtract (cfg1, cfg2);
+	/* ensure MSS and MTU are zero in cfg1 */
+	g_assert_cmpuint (nm_ip4_config_get_mss (cfg1), ==, 0);
+	g_assert_cmpuint (nm_ip4_config_get_mtu (cfg1), ==, 0);
+
+	g_object_unref (cfg1);
+	g_object_unref (cfg2);
+	g_object_unref (cfg3);
+}
+
 /*******************************************/
 
 int
@@ -299,6 +346,7 @@ main (int argc, char **argv)
 	g_test_add_func ("/ip4-config/compare-with-source", test_compare_with_source);
 	g_test_add_func ("/ip4-config/add-address-with-source", test_add_address_with_source);
 	g_test_add_func ("/ip4-config/add-route-with-source", test_add_route_with_source);
+	g_test_add_func ("/ip4-config/merge-subtract-mss-mtu", test_merge_subtract_mss_mtu);
 
 	return g_test_run ();
 }