WiP: added auction_brandt as extension

- added an extension to handle auctions via libbrandt
  - /extensions/auction_brandt GET and POST handler defined
  - initial parsing of transcript.json implemented, yet WiP

- multiple cleanups and changes to extension handling

3 files changed, 63 insertions, 10 deletions

diff --git a/src/exchange/taler-exchange-httpd.c b/src/exchange/taler-exchange-httpd.c
index d7651d79..68fc9fb7 100644
--- a/src/exchange/taler-exchange-httpd.c
+++ b/src/exchange/taler-exchange-httpd.c
@@ -1040,6 +1040,42 @@ handle_post_auditors (struct TEH_RequestContext *rc,
                                root);
 }
 
+/**
+ * Handle GET "/extensions/..." requests.
+ *
+ * @param rc request context
+ * @param args array of additional options
+ * @return MHD result code
+ */
+static MHD_RESULT
+handle_get_extensions (struct TEH_RequestContext *rc,
+                       const char *const args[])
+{
+  const struct TALER_Extension *ext = NULL;
+
+  if (NULL == args[0])
+  {
+    GNUNET_break_op (0);
+    return r404 (rc->connection,
+                 "/extensions/$EXTENSION");
+  }
+
+  ext = TALER_extensions_get_by_name (args[0]);
+  if (NULL == ext)
+  {
+    GNUNET_break_op (0);
+    return r404 (rc->connection,
+                 "/extensions/$EXTENSION unknown");
+  }
+
+  if (NULL == ext->http_get_handler)
+    return MHD_HTTP_NOT_IMPLEMENTED;
+
+  return ext->http_get_handler (
+    rc->connection,
+    &args[1]);
+}
+
 
 /**
  * Handle POST "/extensions/..." requests.
@@ -1301,6 +1337,13 @@ handle_mhd_request (void *cls,
     /* extensions endpoints */
     {
       .url = "extensions",
+      .method = MHD_HTTP_METHOD_GET,
+      .handler.get = &handle_get_extensions,
+      .nargs = 4, /* Arbitrary upper bound */
+      .nargs_is_upper_bound = true,
+    },
+    {
+      .url = "extensions",
       .method = MHD_HTTP_METHOD_POST,
       .handler.post = &handle_post_extensions,
       .nargs = 4, /* Arbitrary upper bound */
diff --git a/src/exchange/taler-exchange-httpd_extensions.c b/src/exchange/taler-exchange-httpd_extensions.c
index 2a99d7a2..2aee1b5c 100644
--- a/src/exchange/taler-exchange-httpd_extensions.c
+++ b/src/exchange/taler-exchange-httpd_extensions.c
@@ -78,6 +78,7 @@ extension_update_event_cb (void *cls,
   }
 
   // Get the config from the database as string
+  if (extension->has_config)
   {
     char *config_str = NULL;
     enum GNUNET_DB_QueryStatus qs;
@@ -117,26 +118,26 @@ extension_update_event_cb (void *cls,
                   err.text,
                   err.source);
       GNUNET_break (0);
-      free(config_str);
+      free (config_str);
       return;
     }
 
     // Call the parser for the extension
     ret = extension->load_json_config (
       (struct TALER_Extension *) extension,
-      json_object_get(config, "config"));
+      json_object_get (config, "config"));
 
     if (GNUNET_OK != ret)
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Couldn't parse configuration for extension %s from the database: %s\n",
                   extension->name,
-		  config_str);
+                  config_str);
       GNUNET_break (0);
     }
 
-    free(config_str);
-    json_decref(config);
+    free (config_str);
+    json_decref (config);
   }
 
   /* Special case age restriction: Update global flag and mask  */
@@ -190,12 +191,16 @@ TEH_extensions_init ()
        it = it->next)
   {
     const struct TALER_Extension *ext = it->extension;
+    uint32_t typ = htonl (ext->type);
     char *conf = json_dumps (ext->config_to_json (ext), JSON_COMPACT);
 
     TEH_plugin->set_extension_config (TEH_plugin->cls,
                                       ext->name,
                                       conf);
-    extension_update_event_cb (NULL, &ext->type, sizeof(ext->type));
+
+    extension_update_event_cb (NULL,
+                               &typ,
+                               sizeof(typ));
     free (conf);
   }
 
diff --git a/src/exchange/taler-exchange-httpd_keys.c b/src/exchange/taler-exchange-httpd_keys.c
index 4fb8a717..4761f314 100644
--- a/src/exchange/taler-exchange-httpd_keys.c
+++ b/src/exchange/taler-exchange-httpd_keys.c
@@ -1916,18 +1916,23 @@ create_krd (struct TEH_KeyStateHandle *ksh,
 
       /* flag our findings so far */
       has_extensions = true;
-      GNUNET_assert (NULL != extension->config_json);
 
       ext = GNUNET_JSON_PACK (
         GNUNET_JSON_pack_bool ("critical",
                                extension->critical),
         GNUNET_JSON_pack_string ("version",
-                                 extension->version),
-        GNUNET_JSON_pack_object_incref ("config",
-                                        extension->config_json)
+                                 extension->version)
         );
       GNUNET_assert (NULL != ext);
 
+      if (extension->has_config)
+      {
+        GNUNET_assert (extension->config_json);
+        json_object_set_new (ext,
+                             "config",
+                             extension->config_json);
+      }
+
       r = json_object_set_new (
         extensions,
         extension->name,