+/*
+ * Send custom notification packet as keep-alive during memory read/write.
+ *
+ * From gdb 7.0 (released 2009-10-06) an unknown notification received during
+ * memory read/write would be silently dropped.
+ * Before gdb 7.0 any character, with exclusion of "+-$", would be considered
+ * as junk and ignored.
+ * In both cases the reception will reset the timeout counter in gdb, thus
+ * working as a keep-alive.
+ * Check putpkt_binary() and getpkt_sane() in gdb commit
+ * 74531fed1f2d662debc2c209b8b3faddceb55960
+ *
+ * Enable remote debug in gdb with 'set debug remote 1' to either dump the junk
+ * characters in gdb pre-7.0 and the notification from gdb 7.0.
+ */
+static void gdb_async_notif(struct connection *connection)
+{
+ static unsigned char count;
+ unsigned char checksum = 0;
+ char buf[22];
+
+ int len = sprintf(buf, "%%oocd_keepalive:%2.2x", count++);
+ for (int i = 1; i < len; i++)
+ checksum += buf[i];
+ len += sprintf(buf + len, "#%2.2x", checksum);
+
+#ifdef _DEBUG_GDB_IO_
+ LOG_DEBUG("sending packet '%s'", buf);
+#endif
+
+ gdb_write(connection, buf, len);
+}
+
+static void gdb_keep_client_alive(struct connection *connection)
+{
+ struct gdb_connection *gdb_con = connection->priv;
+
+ switch (gdb_con->output_flag) {
+ case GDB_OUTPUT_NO:
+ /* no need for keep-alive */
+ break;
+ case GDB_OUTPUT_NOTIF:
+ /* send asynchronous notification */
+ gdb_async_notif(connection);
+ break;
+ case GDB_OUTPUT_ALL:
+ /* send an empty O packet */
+ gdb_output_con(connection, "");
+ break;
+ default:
+ break;
+ }
+}
+
+static const struct service_driver gdb_service_driver = {
+ .name = "gdb",
+ .new_connection_during_keep_alive_handler = NULL,
+ .new_connection_handler = gdb_new_connection,
+ .input_handler = gdb_input,
+ .connection_closed_handler = gdb_connection_closed,
+ .keep_client_alive_handler = gdb_keep_client_alive,
+};
+