+static int process_builtin(sd_bus *bus, sd_bus_message *m) {
+ _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
+ int r;
+
+ assert(bus);
+ assert(m);
+
+ if (m->header->type != SD_BUS_MESSAGE_TYPE_METHOD_CALL)
+ return 0;
+
+ if (!streq_ptr(m->interface, "org.freedesktop.DBus.Peer"))
+ return 0;
+
+ if (m->header->flags & SD_BUS_MESSAGE_NO_REPLY_EXPECTED)
+ return 1;
+
+ if (streq_ptr(m->member, "Ping"))
+ r = sd_bus_message_new_method_return(bus, m, &reply);
+ else if (streq_ptr(m->member, "GetMachineId")) {
+ sd_id128_t id;
+ char sid[33];
+
+ r = sd_id128_get_machine(&id);
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_new_method_return(bus, m, &reply);
+ if (r < 0)
+ return r;
+
+ r = sd_bus_message_append(reply, "s", sd_id128_to_string(id, sid));
+ } else {
+ _cleanup_bus_error_free_ sd_bus_error error = SD_BUS_ERROR_INIT;
+
+ sd_bus_error_set(&error,
+ "org.freedesktop.DBus.Error.UnknownMethod",
+ "Unknown method '%s' on interface '%s'.", m->member, m->interface);
+
+ r = sd_bus_message_new_method_error(bus, m, &error, &reply);
+ }
+
+ if (r < 0)
+ return r;
+
+ r = sd_bus_send(bus, reply, NULL);
+ if (r < 0)
+ return r;
+
+ return 1;
+}
+