D-Bus name lifetime tracking support

1 files changed, 251 insertions, 0 deletions

diff --git a/hcid/dbus-common.c b/hcid/dbus-common.c
index f3bf47c4..35807330 100644
--- a/hcid/dbus-common.c
+++ b/hcid/dbus-common.c
@@ -26,4 +26,255 @@
 #endif
 
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <errno.h>
+#include <syslog.h>
+
+#include <dbus/dbus.h>
+
+#include "list.h"
+#include "dbus.h"
+
+static int name_listener_initialized = 0;
+
+struct name_callback {
+	name_cb_t func;
+	void *user_data;
+};
+
+struct name_data {
+	char *name;
+	struct slist *callbacks;
+};
+
+static struct slist *name_listeners = NULL;
+
+static struct name_data *name_data_find(const char *name)
+{
+	struct slist *current;
+
+	for (current = name_listeners; current != NULL; current = current->next) {
+		struct name_data *data = current->data;
+		if (strcmp(name, data->name) == 0)
+			return data;
+	}
+
+	return NULL;
+}
+
+static struct name_callback *name_callback_find(struct slist *callbacks,
+						name_cb_t func, void *user_data)
+{
+	struct slist *current;
+
+	for (current = callbacks; current != NULL; current = current->next) {
+		struct name_callback *cb = current->data;
+		if (cb->func == func && cb->user_data == user_data)
+			return cb;
+	}
+
+	return NULL;
+}
+
+static int name_data_add(const char *name, name_cb_t func, void *user_data)
+{
+	int first = 0;
+	struct name_data *data;
+	struct name_callback *cb;
+
+	cb = malloc(sizeof(struct name_callback));
+	if (!cb)
+		goto out;
+
+	cb->func = func;
+	cb->user_data = user_data;
+
+	data = name_data_find(name);
+	if (!data) {
+		data = malloc(sizeof(struct name_data));
+		if (!data) {
+			free(cb);
+			goto out;
+		}
+
+		data->name = strdup(name);
+		if (!data->name) {
+			free(cb);
+			goto out;
+		}
+
+		data->callbacks = NULL;
+		name_listeners = slist_append(name_listeners, data);
+		first = 1;
+	}
+
+	data->callbacks = slist_append(data->callbacks, cb);
+
+out:
+	return first;
+}
+
+static void name_data_free(struct name_data *data)
+{
+	free(data->name);
+	free(data);
+}
+
+static void name_data_remove(const char *name, name_cb_t func, void *user_data)
+{
+	struct name_data *data;
+	struct name_callback *cb = NULL;
+
+	data = name_data_find(name);
+	if (!data)
+		return;
+
+	cb = name_callback_find(data->callbacks, func, user_data);
+	if (!cb)
+		return;
+
+	data->callbacks = slist_remove(data->callbacks, cb);
+	free(cb);
+
+	if (!data->callbacks) {
+		name_listeners = slist_remove(name_listeners, data);
+		name_data_free(data);
+	}
+}
+
+static DBusHandlerResult name_exit_filter(DBusConnection *connection,
+						DBusMessage *message,
+						void *user_data)
+{
+	struct slist *l;
+	struct name_data *data;
+	char *name, *old, *new;
+
+	if (!dbus_message_is_signal(message,
+				DBUS_INTERFACE_DBUS,
+				"NameOwnerChanged"))
+		goto out;
+
+	if (!dbus_message_get_args(message, NULL,
+				DBUS_TYPE_STRING, &name,
+				DBUS_TYPE_STRING, &old,
+				DBUS_TYPE_STRING, &new,
+				DBUS_TYPE_INVALID)) {
+		syslog(LOG_ERR, "Invalid arguments for NameOwnerChanged signal");
+		goto out;
+	}
+
+	/* We are not interested of service creations */
+	if (*new != '\0')
+		goto out;
+
+	data = name_data_find(name);
+	if (!data) {
+		syslog(LOG_ERR, "Got NameOwnerChanged signal for %s which has no listeners",
+				name);
+		goto out;
+	}
+
+	for (l = data->callbacks; l != NULL; l = l->next) {
+		struct name_callback *cb = l->data;
+		cb->func(name, cb->user_data);
+	}
+
+	name_listeners = slist_remove(name_listeners, data);
+	name_data_free(data);
+
+out:
+	return DBUS_HANDLER_RESULT_NOT_YET_HANDLED;
+}
+
+
+int name_listener_add(DBusConnection *connection, const char *name,
+			name_cb_t func, void *user_data)
+{
+	DBusError err;
+	char match_string[128];
+	int first;
+
+	syslog(LOG_DEBUG, "name_listener_add(%s)", name);
+
+	if (!name_listener_initialized) {
+		if (!dbus_connection_add_filter(connection, name_exit_filter, NULL, NULL)) {
+			syslog(LOG_ERR, "dbus_connection_add_filter() failed");
+			return -1;
+		}
+		name_listener_initialized = 1;
+	}
+
+	first = name_data_add(name, func, user_data);
+	/* The filter is already added if this is not the first callback
+	 * registration for the name */
+	if (!first)
+		return 0;
+
+	snprintf(match_string, sizeof(match_string),
+			"interface=%s,member=NameOwnerChanged,arg0=%s",
+			DBUS_INTERFACE_DBUS, name);
+
+	dbus_error_init(&err);
+	dbus_bus_add_match(connection, match_string, &err);
+
+	if (dbus_error_is_set(&err)) {
+		syslog(LOG_ERR, "Adding owner match rule for %s failed: %s",
+				name, err.message);
+		dbus_error_free(&err);
+		name_data_remove(name, func, user_data);
+		return -1;
+	}
+
+	return 0;
+}
+
+int name_listener_remove(DBusConnection *connection, const char *name,
+				name_cb_t func, void *user_data)
+{
+	struct name_data *data;
+	struct name_callback *cb;
+	DBusError err;
+	char match_string[128];
+
+	syslog(LOG_DEBUG, "name_listener_remove(%s)", name);
+
+	data = name_data_find(name);
+	if (!data) {
+		syslog(LOG_ERR, "remove_name_listener: no listener for %s",
+				name);
+		return -1;
+	}
+
+	cb = name_callback_find(data->callbacks, func, user_data);
+	if (!cb) {
+		syslog(LOG_ERR, "No matching callback found for %s", name);
+		return -1;
+	}
+
+	data->callbacks = slist_remove(data->callbacks, cb);
+
+	/* Don't remove the filter if other callbacks exist */
+	if (data->callbacks)
+		return 0;
+
+	snprintf(match_string, sizeof(match_string),
+			"interface=%s,member=NameOwnerChanged,arg0=%s",
+			DBUS_INTERFACE_DBUS, name);
+
+	dbus_error_init(&err);
+	dbus_bus_remove_match(connection, match_string, &err);
+
+	if (dbus_error_is_set(&err)) {
+		syslog(LOG_ERR, "Removing owner match rule for %s failed: %s",
+				name, err.message);
+		dbus_error_free(&err);
+		return -1;
+	}
+
+	name_data_remove(name, func, user_data);
+
+	return 0;
+}
+