[age restriction] progress 12/n

- taler-offline-tool now handles extensions
  - command "extensions" added with subcommands "show" and "sign"
  - parses extensions from taler config
  - shows and signs of extensions and their configurations
  - creates signed set of configurations for upload
  - added test for retrieval of extension config

- simplified signature verification for extensions
  - remove per-extension signatures, also from DB schema
  - adjust prepared statements accordingly
  - adjust DB event handler for extensions
  - allow NULL for config for extension in DB schema
  - handler for /management/extensions adjusted to new datastructures

- changed test for TALER_denom_blind/TALER_denom_sign_blinded with and
  without TALER_AgeHash

- minor updates and various fixes

4 files changed, 20 insertions, 27 deletions

diff --git a/src/include/taler_crypto_lib.h b/src/include/taler_crypto_lib.h
index f1fa0285d..6a805b645 100644
--- a/src/include/taler_crypto_lib.h
+++ b/src/include/taler_crypto_lib.h
@@ -2536,7 +2536,7 @@ TALER_merchant_wire_signature_make (
  */
 void
 TALER_exchange_offline_extension_config_hash_sign (
-  const struct TALER_ExtensionConfigHash h_config,
+  const struct TALER_ExtensionConfigHash *h_config,
   const struct TALER_MasterPrivateKeyP *master_priv,
   struct TALER_MasterSignatureP *master_sig);
 
@@ -2552,7 +2552,7 @@ TALER_exchange_offline_extension_config_hash_sign (
  */
 enum GNUNET_GenericReturnValue
 TALER_exchange_offline_extension_config_hash_verify (
-  const struct TALER_ExtensionConfigHash h_config,
+  const struct TALER_ExtensionConfigHash *h_config,
   const struct TALER_MasterPublicKeyP *master_pub,
   const struct TALER_MasterSignatureP *master_sig
   );
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index 7fb5b4ec0..5bc87cf47 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -2682,12 +2682,14 @@ TALER_EXCHANGE_post_management_keys_cancel (
 
 /**
  * Information needed for a POST /management/extensions operation.
+ *
+ * It represents the interface ExchangeKeysResponse as defined in
+ * https://docs.taler.net/design-documents/006-extensions.html#exchange
  */
 struct TALER_EXCHANGE_ManagementPostExtensionsData
 {
-  struct TALER_Extension *extensions;
-  struct TALER_MasterSignatureP *extensions_sigs;
-  uint32_t num_extensions;
+  json_t *extensions;
+  struct TALER_MasterSignatureP extensions_sig;
 };
 
 /**
@@ -2708,11 +2710,12 @@ struct TALER_EXCHANGE_ManagementPostExtensionsHandle;
 
 
 /**
- * FIXME-oec: Provide correct explanation of this function.
+ * Uploads the configurations of enabled extensions to the exchange, signed
+ * with the master key.
  *
  * @param ctx the context
  * @param url HTTP base URL for the exchange
- * @param pkd signature data to POST
+ * @param ped signature data to POST
  * @param cb function to call with the exchange's result
  * @param cb_cls closure for @a cb
  * @return the request handle; NULL upon error
@@ -2721,7 +2724,7 @@ struct TALER_EXCHANGE_ManagementPostExtensionsHandle *
 TALER_EXCHANGE_management_post_extensions (
   struct GNUNET_CURL_Context *ctx,
   const char *url,
-  const struct TALER_EXCHANGE_ManagementPostExtensionsData *pkd,
+  struct TALER_EXCHANGE_ManagementPostExtensionsData *ped,
   TALER_EXCHANGE_ManagementPostExtensionsCallback cb,
   void *cb_cls);
 
diff --git a/src/include/taler_exchangedb_plugin.h b/src/include/taler_exchangedb_plugin.h
index 5eb168e14..cd68e1edb 100644
--- a/src/include/taler_exchangedb_plugin.h
+++ b/src/include/taler_exchangedb_plugin.h
@@ -4026,15 +4026,13 @@ struct TALER_EXCHANGEDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param extension_name the name of the extension
-   * @param config JSON object of the configuration as string
-   * @param config_sig signature of the configuration by the offline master key
+   * @param config JSON object of the configuration as string, maybe NULL (== disabled extension)
    * @return transaction status code
    */
   enum GNUNET_DB_QueryStatus
   (*set_extension_config)(void *cls,
                           const char *extension_name,
-                          const char *config,
-                          const struct TALER_MasterSignatureP *config_sig);
+                          const char *config);
 
   /**
    * Function called to retrieve the configuration of an extension
@@ -4042,8 +4040,7 @@ struct TALER_EXCHANGEDB_Plugin
    *
    * @param cls the @e cls of this struct with the plugin-specific state
    * @param extension_name the name of the extension
-   * @param[out] config JSON object of the configuration as string
-   * @param[out] config_sig signature of the configuration by the master key
+   * @param[out] config JSON object of the configuration as string, maybe NULL (== disabled extension)
    * @return transaction status code
    */
   enum GNUNET_DB_QueryStatus
diff --git a/src/include/taler_extensions.h b/src/include/taler_extensions.h
index 243811eb5..31e5c6738 100644
--- a/src/include/taler_extensions.h
+++ b/src/include/taler_extensions.h
@@ -28,29 +28,22 @@
 
 #define TALER_EXTENSION_SECTION_PREFIX "exchange-extension-"
 
-enum TALER_Extension_ReturnValue
-{
-  TALER_Extension_OK = 0,
-  TALER_Extension_ERROR_PARSING = 1,
-  TALER_Extension_ERROR_INVALID = 2,
-  TALER_Extension_ERROR_SYS = 3
-};
-
 enum TALER_Extension_Type
 {
   TALER_Extension_AgeRestriction = 0,
   TALER_Extension_Peer2Peer = 1,
-  TALER_Extension_Max = 2 // Must be last
+  TALER_Extension_MaxPredefined = 2 // Must be last
 };
 
 /*
- * TODO oec: documentation
+ * Represents the implementation of an extension.
  */
 struct TALER_Extension
 {
   enum TALER_Extension_Type type;
   char *name;
   bool critical;
+  bool enabled;
   void *config;
 
   enum GNUNET_GenericReturnValue (*test_config)(const json_t *config);
@@ -68,7 +61,7 @@ struct TALER_Extension
  * Finds and returns a supported extension by a given name.
  *
  * @param name name of the extension to lookup
- * @param extensions list of TALER_Extensions as haystack, terminated by an entry of type TALER_Extension_Max
+ * @param extensions list of TALER_Extensions as haystack, terminated by a NULL-entry
  * @param[out] ext set to the extension, if found, NULL otherwise
  * @return GNUNET_OK if extension was found, GNUNET_NO otherwise
  */
@@ -109,7 +102,7 @@ TALER_extension_get_by_name (const char *name,
  * @param[out] mask Mask representation for age restriction.
  * @return Error, if age groups were invalid, OK otherwise.
  */
-enum TALER_Extension_ReturnValue
+enum GNUNET_GenericReturnValue
 TALER_parse_age_group_string (const char *groups,
                               struct TALER_AgeMask *mask);
 
@@ -133,7 +126,7 @@ TALER_age_mask_to_string (const struct TALER_AgeMask *mask);
  * @return Error if extension for age restriction was set but age groups were
  *         invalid, OK otherwise.
  */
-enum TALER_Extension_ReturnValue
+enum GNUNET_GenericReturnValue
 TALER_get_age_mask (const struct GNUNET_CONFIGURATION_Handle *cfg,
                     struct TALER_AgeMask *mask);