core: fuzzier matching of generated connections to persistent ones

When generating a connection, if the device has no non-link-local IPv6 address, then it's unclear whether (a) the connection was link-local originally, or (b) the connection was 'auto' but IPv6 failed or timed out. In this case, if there is a persistent connection that is 'auto' but the generated connection is 'link-local', the persistent connection should be used. Add a more-testable framework for doing the connection matching to handle this.
2013-11-15 13:09:12 -06:00
parent 75d694db9b
commit befa9083e8
5 changed files with 124 additions and 24 deletions
--- a/src/NetworkManagerUtils.c
+++ b/src/NetworkManagerUtils.c
@@ -659,3 +659,93 @@ nm_utils_read_resolv_conf_nameservers (const char *rc_contents)
 	return nameservers;
 }

+static NMConnection *
+check_possible_match (NMConnection *orig,
+                      NMConnection *candidate,
+                      GHashTable *settings)
+{
+	GHashTable *props;
+	const char *orig_ip6_method, *candidate_ip6_method;
+	NMSettingIP6Config *candidate_ip6;
+
+	g_return_val_if_fail (settings != NULL, NULL);
+
+	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)) {
+		/* For now 'method' is the only difference we handle here */
+		return NULL;
+	}
+
+	/* 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
+	 * in the decision because if the candidate is 'auto' but may-fail=FALSE, then
+	 * the connection could not possibly have been previously activated on the
+	 * device if the device has no non-link-local IPv6 address.
+	 */
+	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);
+	candidate_ip6 = nm_connection_get_setting_ip6_config (candidate);
+
+	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 candidate;
+	}
+
+	return NULL;
+}
+
+/**
+ * nm_utils_match_connection:
+ * @connections: a (optionally pre-sorted) list of connections from which to
+ * find a matching connection to @original based on "inferrable" properties
+ * @original: the #NMConnection to find a match for from @connections
+ * @match_filter_func: a function to check whether each connection from @connections
+ * should be considered for matching.  This function should return %TRUE if the
+ * connection should be considered, %FALSE if the connection should be ignored
+ * @match_compat_data: data pointer passed to @match_filter_func
+ *
+ * Checks each connection from @connections until a matching connection is found
+ * considering only setting properties marked with %NM_SETTING_PARAM_INFERRABLE
+ * and checking a few other characteristics like IPv6 method.  If the caller
+ * desires some priority order of the connections, @connections should be
+ * sorted before calling this function.
+ *
+ * Returns: the best #NMConnection matching @original, or %NULL if no connection
+ * matches well enough.
+ */
+NMConnection *
+nm_utils_match_connection (GSList *connections,
+                           NMConnection *original,
+                           NMUtilsMatchFilterFunc match_filter_func,
+                           gpointer match_filter_data)
+{
+	NMConnection *best_match = NULL;
+	GSList *iter;
+
+	for (iter = connections; iter; iter = iter->next) {
+		NMConnection *candidate = NM_CONNECTION (iter->data);
+		GHashTable *diffs = NULL;
+
+		if (match_filter_func) {
+			if (!match_filter_func (candidate, match_filter_data))
+				continue;
+		}
+
+		if (!nm_connection_diff (original, candidate, NM_SETTING_COMPARE_FLAG_INFERRABLE, &diffs)) {
+			if (!best_match)
+				best_match = check_possible_match (original, candidate, diffs);
+			g_hash_table_unref (diffs);
+			continue;
+		}
+
+		/* Exact match */
+		return candidate;
+	}
+
+	/* Best match (if any) */
+	return best_match;
+}
+