utils: fix check_possible_match() function

We can only allow possible match if all the differences are exceptions.
Before, we accepted the connection if an exception was found, but it is wrong
because there may be another difference (that is fatal).

src/NetworkManagerUtils.c

@@ -649,22 +649,47 @@ nm_utils_read_resolv_conf_nameservers (const char *rc_contents)
 	return nameservers;
 }
 
+static GHashTable *
+check_property_in_hash (GHashTable *hash,
+                        const char *s_name,
+                        const char *p_name)
+{
+	GHashTable *props;
+
+	props = g_hash_table_lookup (hash, s_name);
+	if (   !props
+	    || !g_hash_table_lookup (props, p_name)) {
+		return NULL;
+	}
+	return props;
+}
+
+static void
+remove_from_hash (GHashTable *s_hash,
+                  GHashTable *p_hash,
+                  const char *s_name,
+                  const char *p_name)
+{
+	g_hash_table_remove (p_hash, p_name);
+	if (g_hash_table_size (p_hash) == 0)
+		g_hash_table_remove (s_hash, s_name);
+}
+
 static gboolean
-check_ip6_method_link_local_auto (NMConnection *orig,
+check_ip6_method (NMConnection *orig,
-                                  NMConnection *candidate,
+                  NMConnection *candidate,
-                                  GHashTable *settings)
+                  GHashTable *settings)
 {
 	GHashTable *props;
 	const char *orig_ip6_method, *candidate_ip6_method;
 	NMSettingIP6Config *candidate_ip6;
+	gboolean allow = FALSE;
 
-	props = g_hash_table_lookup (settings, NM_SETTING_IP6_CONFIG_SETTING_NAME);
+	props = check_property_in_hash (settings,
-	if (   !props
+	                                NM_SETTING_IP6_CONFIG_SETTING_NAME,
-	    || (g_hash_table_size (props) != 1)
+	                                NM_SETTING_IP6_CONFIG_METHOD);
-	    || !g_hash_table_lookup (props, NM_SETTING_IP6_CONFIG_METHOD)) {
+	if (!props)
-		/* For now 'method' is the only difference we handle here */
+		return TRUE;
-		return FALSE;
-	}
 
 	/* If the original connection is 'link-local' and the candidate is both 'auto'
 	 * and may-fail=TRUE, then the candidate is OK to use.  may-fail is included
@@ -679,60 +704,41 @@ check_ip6_method_link_local_auto (NMConnection *orig,
 	if (   strcmp (orig_ip6_method, NM_SETTING_IP6_CONFIG_METHOD_LINK_LOCAL) == 0
 	    && strcmp (candidate_ip6_method, NM_SETTING_IP6_CONFIG_METHOD_AUTO) == 0
 	    && (!candidate_ip6 || nm_setting_ip6_config_get_may_fail (candidate_ip6))) {
-		return TRUE;
+		allow = TRUE;
-	}
-
-	return FALSE;
-}
-
-static gboolean
-check_ip6_method_link_local_ignore (NMConnection *orig,
-                                    NMConnection *candidate,
-                                    GHashTable *settings)
-{
-	GHashTable *props;
-	const char *orig_ip6_method, *candidate_ip6_method;
-
-	props = g_hash_table_lookup (settings, NM_SETTING_IP6_CONFIG_SETTING_NAME);
-	if (   !props
-	    || (g_hash_table_size (props) != 1)
-	    || !g_hash_table_lookup (props, NM_SETTING_IP6_CONFIG_METHOD)) {
-		/* We only handle ipv6 'method' here */
-		return FALSE;
 	}
 
 	/* If the original connection method is 'link-local' and the candidate method
 	 * is 'ignore' we can take the connection, because NM didn't simply take care
 	 * of IPv6.
 	 */
-	orig_ip6_method = nm_utils_get_ip_config_method (orig, NM_TYPE_SETTING_IP6_CONFIG);
-	candidate_ip6_method = nm_utils_get_ip_config_method (candidate, NM_TYPE_SETTING_IP6_CONFIG);
-
 	if (   strcmp (orig_ip6_method, NM_SETTING_IP6_CONFIG_METHOD_LINK_LOCAL) == 0
 	    && strcmp (candidate_ip6_method, NM_SETTING_IP6_CONFIG_METHOD_IGNORE) == 0) {
-		return TRUE;
+		allow = TRUE;
 	}
 
-	return FALSE;
+	if (allow) {
+		remove_from_hash (settings, props,
+		                  NM_SETTING_IP6_CONFIG_SETTING_NAME,
+		                  NM_SETTING_IP6_CONFIG_METHOD);
+	}
+	return allow;
 }
 
 static gboolean
-check_ip4_method_disabled_auto (NMConnection *orig,
+check_ip4_method (NMConnection *orig,
-                                NMConnection *candidate,
+                  NMConnection *candidate,
-                                GHashTable *settings,
+                  GHashTable *settings,
-                                gboolean device_has_carrier)
+                  gboolean device_has_carrier)
 {
 	GHashTable *props;
 	const char *orig_ip4_method, *candidate_ip4_method;
 	NMSettingIP4Config *candidate_ip4;
 
-	props = g_hash_table_lookup (settings, NM_SETTING_IP4_CONFIG_SETTING_NAME);
+	props = check_property_in_hash (settings,
-	if (   !props
+	                                NM_SETTING_IP4_CONFIG_SETTING_NAME,
-	    || (g_hash_table_size (props) != 1)
+	                                NM_SETTING_IP4_CONFIG_METHOD);
-	    || !g_hash_table_lookup (props, NM_SETTING_IP4_CONFIG_METHOD)) {
+	if (!props)
-		/* For now 'method' is the only difference we handle here */
+		return TRUE;
-		return FALSE;
-	}
 
 	/* If the original connection is 'disabled' (device had no IP addresses)
 	 * but it has no carrier, that most likely means that IP addressing could
@@ -747,9 +753,11 @@ check_ip4_method_disabled_auto (NMConnection *orig,
 	    && strcmp (candidate_ip4_method, NM_SETTING_IP4_CONFIG_METHOD_AUTO) == 0
 	    && (!candidate_ip4 || nm_setting_ip4_config_get_may_fail (candidate_ip4))
 	    && (device_has_carrier == FALSE)) {
+		remove_from_hash (settings, props,
+		                  NM_SETTING_IP4_CONFIG_SETTING_NAME,
+		                  NM_SETTING_IP4_CONFIG_METHOD);
 		return TRUE;
 	}
-
 	return FALSE;
 }
 
@@ -762,13 +770,11 @@ check_connection_interface_name (NMConnection *orig,
 	const char *orig_ifname, *cand_ifname;
 	NMSettingConnection *s_con_orig, *s_con_cand;
 
-	props = g_hash_table_lookup (settings, NM_SETTING_CONNECTION_SETTING_NAME);
+	props = check_property_in_hash (settings,
-	if (   !props
+	                                NM_SETTING_CONNECTION_SETTING_NAME,
-	    || (g_hash_table_size (props) != 1)
+	                                NM_SETTING_CONNECTION_INTERFACE_NAME);
-	    || !g_hash_table_lookup (props, NM_SETTING_CONNECTION_INTERFACE_NAME)) {
+	if (!props)
-		/* We only handle 'interface-name' here. */
+		return TRUE;
-		return FALSE;
-	}
 
 	/* If one of the interface name is NULL, we accept that connection */
 	s_con_orig = nm_connection_get_setting_connection (orig);
@@ -776,9 +782,12 @@ check_connection_interface_name (NMConnection *orig,
 	orig_ifname = nm_setting_connection_get_interface_name (s_con_orig);
 	cand_ifname = nm_setting_connection_get_interface_name (s_con_cand);
 
-	if (!orig_ifname || !cand_ifname)
+	if (!orig_ifname || !cand_ifname) {
+		remove_from_hash (settings, props,
+		                  NM_SETTING_CONNECTION_SETTING_NAME,
+		                  NM_SETTING_CONNECTION_INTERFACE_NAME);
 		return TRUE;
-
+	}
 	return FALSE;
 }
 
@@ -790,19 +799,19 @@ check_possible_match (NMConnection *orig,
 {
 	g_return_val_if_fail (settings != NULL, NULL);
 
-	if (check_ip6_method_link_local_auto (orig, candidate, settings))
+	if (!check_ip6_method (orig, candidate, settings))
-		return candidate;
+		return NULL;
 
-	if (check_ip6_method_link_local_ignore (orig, candidate, settings))
+	if (!check_ip4_method (orig, candidate, settings, device_has_carrier))
-		return candidate;
+		return NULL;
 
-	if (check_ip4_method_disabled_auto (orig, candidate, settings, device_has_carrier))
+	if (!check_connection_interface_name (orig, candidate, settings))
-		return candidate;
+		return NULL;
 
-	if (check_connection_interface_name (orig, candidate, settings))
+	if (g_hash_table_size (settings) == 0)
 		return candidate;
-
+	else
-	return NULL;
+		return NULL;
 }
 
 /**