[age restriction] progress 8/n

More work towards support for extensions and age restriction

- updated gana
- added handler for DB-Event
- added TEH_extensions_init() and _done()
- added global for age restriction
- added stub for post handler
- added SQL-table for extension metadata
- added enum type for extensions and other data structures

Also:
- fixed some warnings -Wmaybe-unitialized

1 files changed, 51 insertions, 0 deletions

diff --git a/src/exchange/taler-exchange-httpd_extensions.h b/src/exchange/taler-exchange-httpd_extensions.h
new file mode 100644
index 000000000..3c86e2662
--- /dev/null
+++ b/src/exchange/taler-exchange-httpd_extensions.h
@@ -0,0 +1,51 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2021 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Affero General Public License as published by the Free Software
+  Foundation; either version 3, or (at your option) any later version.
+
+  TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+  A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more details.
+
+  You should have received a copy of the GNU Affero General Public License along with
+  TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file taler-exchange-httpd_extensions.h
+ * @brief Manage extensions
+ * @author Özgür Kesim
+ */
+#ifndef TALER_EXCHANGE_HTTPD_EXTENSIONS_H
+#define TALER_EXCHANGE_HTTPD_EXTENSIONS_H
+
+#include <gnunet/gnunet_util_lib.h>
+#include <microhttpd.h>
+#include "taler-exchange-httpd.h"
+
+
+/**
+ * Initialize extensions
+ *
+ * @return #GNUNET_OK on success
+ */
+enum GNUNET_GenericReturnValue
+TEH_extensions_init (void);
+
+/**
+ * Terminate the extension subsystem
+ */
+void
+TEH_extensions_done (void);
+
+/**
+ * Something changed in the database. Rebuild the extension state metadata.
+ * This function should be called if the exchange learns about a new signature
+ * from our master key.
+ */
+void
+TEH_extensions_update_state (void);
+
+#endif