Refactor extensions

- Extensions are now compiled as shared libraries and loaded at runtime
  according to the TALER configuration.

- So far, only age restriction is loaded as extension.

- Groundwork for extension auction_brandt started.

6 files changed, 148 insertions, 67 deletions

diff --git a/src/exchange/taler-exchange-httpd.c b/src/exchange/taler-exchange-httpd.c
index 496d3d29..d7651d79 100644
--- a/src/exchange/taler-exchange-httpd.c
+++ b/src/exchange/taler-exchange-httpd.c
@@ -98,6 +98,13 @@ static int allow_address_reuse;
 const struct GNUNET_CONFIGURATION_Handle *TEH_cfg;
 
 /**
+ * Configuration of age restriction
+ *
+ * Set after loading the library, enabled in database event handler.
+ */
+struct TALER_AgeRestrictionConfig TEH_age_restriction_config = {0};
+
+/**
  * Handle to the HTTP server.
  */
 static struct MHD_Daemon *mhd;
@@ -139,11 +146,6 @@ char *TEH_currency;
 char *TEH_base_url;
 
 /**
- * Age restriction flags and mask
- */
-bool TEH_age_restriction_enabled = true;
-
-/**
  * Default timeout in seconds for HTTP requests.
  */
 static unsigned int connection_timeout = 30;
@@ -170,6 +172,7 @@ bool TEH_suicide;
  * TALER_SIGNATURE_MASTER_EXTENSION.
  */
 struct TALER_MasterSignatureP TEH_extensions_sig;
+bool TEH_extensions_signed = false;
 
 /**
  * Value to return from main()
@@ -1039,6 +1042,46 @@ handle_post_auditors (struct TEH_RequestContext *rc,
 
 
 /**
+ * Handle POST "/extensions/..." requests.
+ *
+ * @param rc request context
+ * @param root uploaded JSON data
+ * @param args array of additional options
+ * @return MHD result code
+ */
+static MHD_RESULT
+handle_post_extensions (struct TEH_RequestContext *rc,
+                        const json_t *root,
+                        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_post_handler)
+    return MHD_HTTP_NOT_IMPLEMENTED;
+
+  return ext->http_post_handler (
+    rc->connection,
+    root,
+    &args[1]);
+}
+
+
+/**
  * Handle incoming HTTP request.
  *
  * @param cls closure for MHD daemon (unused)
@@ -1255,6 +1298,14 @@ handle_mhd_request (void *cls,
       .nargs = 4,
       .nargs_is_upper_bound = true
     },
+    /* extensions endpoints */
+    {
+      .url = "extensions",
+      .method = MHD_HTTP_METHOD_POST,
+      .handler.post = &handle_post_extensions,
+      .nargs = 4, /* Arbitrary upper bound */
+      .nargs_is_upper_bound = true,
+    },
     /* mark end of list */
     {
       .url = NULL
diff --git a/src/exchange/taler-exchange-httpd.h b/src/exchange/taler-exchange-httpd.h
index 0fda5ed8..77aab249 100644
--- a/src/exchange/taler-exchange-httpd.h
+++ b/src/exchange/taler-exchange-httpd.h
@@ -197,11 +197,6 @@ extern struct TALER_EXCHANGEDB_Plugin *TEH_plugin;
  */
 extern char *TEH_currency;
 
-/*
- * Age restriction extension state
- */
-extern bool TEH_age_restriction_enabled;
-
 /**
  * Our (externally visible) base URL.
  */
@@ -221,6 +216,7 @@ extern struct GNUNET_CURL_Context *TEH_curl_ctx;
  * Signature of the offline master key of all enabled extensions' configuration
  */
 extern struct TALER_MasterSignatureP TEH_extensions_sig;
+extern bool TEH_extensions_signed;
 
 /**
  * @brief Struct describing an URL and the handler for it.
@@ -366,4 +362,7 @@ struct TEH_RequestHandler
 };
 
 
+/* Age restriction configuration */
+extern struct TALER_AgeRestrictionConfig TEH_age_restriction_config;
+
 #endif
diff --git a/src/exchange/taler-exchange-httpd_extensions.c b/src/exchange/taler-exchange-httpd_extensions.c
index d6c26f6f..2a99d7a2 100644
--- a/src/exchange/taler-exchange-httpd_extensions.c
+++ b/src/exchange/taler-exchange-httpd_extensions.c
@@ -100,6 +100,9 @@ extension_update_event_cb (void *cls,
     // No config found -> disable extension
     if (NULL == config_str)
     {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "No configuration found for extension %s, disabling it\n",
+                  extension->name);
       extension->disable ((struct TALER_Extension *) extension);
       return;
     }
@@ -114,28 +117,40 @@ extension_update_event_cb (void *cls,
                   err.text,
                   err.source);
       GNUNET_break (0);
+      free(config_str);
       return;
     }
 
     // Call the parser for the extension
     ret = extension->load_json_config (
       (struct TALER_Extension *) extension,
-      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",
-                  extension->name);
+                  "Couldn't parse configuration for extension %s from the database: %s\n",
+                  extension->name,
+		  config_str);
       GNUNET_break (0);
     }
+
+    free(config_str);
+    json_decref(config);
   }
 
   /* Special case age restriction: Update global flag and mask  */
   if (TALER_Extension_AgeRestriction == type)
   {
-    TEH_age_restriction_enabled =
-      TALER_extensions_age_restriction_is_enabled ();
+    const struct TALER_AgeRestrictionConfig *conf =
+      TALER_extensions_get_age_restriction_config ();
+    if (NULL != conf)
+      TEH_age_restriction_config = *conf;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "[age restriction] DB event has changed the config to %s with mask: %s\n",
+                conf->enabled ? "enabled": "disabled",
+                TALER_age_mask_to_string (&conf->mask));
+
   }
 }
 
@@ -143,14 +158,21 @@ extension_update_event_cb (void *cls,
 enum GNUNET_GenericReturnValue
 TEH_extensions_init ()
 {
-  GNUNET_assert (GNUNET_OK ==
-                 TALER_extension_age_restriction_register ());
-
   /* Set the event handler for updates */
   struct GNUNET_DB_EventHeaderP ev = {
     .size = htons (sizeof (ev)),
     .type = htons (TALER_DBEVENT_EXCHANGE_EXTENSIONS_UPDATED),
   };
+
+  /* Load the shared libraries first */
+  if (GNUNET_OK !=
+      TALER_extensions_load (TEH_cfg))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "failed to load extensions");
+    return GNUNET_SYSERR;
+  }
+
   extensions_eh = TEH_plugin->event_listen (TEH_plugin->cls,
                                             GNUNET_TIME_UNIT_FOREVER_REL,
                                             &ev,
@@ -162,17 +184,20 @@ TEH_extensions_init ()
     return GNUNET_SYSERR;
   }
 
-  /* FIXME #7270: shall we load the extensions from the config right away?
-   * We do have to for now, as otherwise denominations with age restriction
-   * will not have the age mask set right upon initial generation.
-   */
-  TALER_extensions_load_taler_config (TEH_cfg);
-
   /* Trigger the initial load of configuration from the db */
-  for (const struct TALER_Extension *it = TALER_extensions_get_head ();
-       NULL != it->next;
+  for (const struct TALER_Extensions *it = TALER_extensions_get_head ();
+       NULL != it && NULL != it->extension;
        it = it->next)
-    extension_update_event_cb (NULL, &it->type, sizeof(it->type));
+  {
+    const struct TALER_Extension *ext = it->extension;
+    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));
+    free (conf);
+  }
 
   return GNUNET_OK;
 }
diff --git a/src/exchange/taler-exchange-httpd_keys.c b/src/exchange/taler-exchange-httpd_keys.c
index a6ad9976..4fb8a717 100644
--- a/src/exchange/taler-exchange-httpd_keys.c
+++ b/src/exchange/taler-exchange-httpd_keys.c
@@ -815,10 +815,7 @@ static struct TALER_AgeMask
 load_age_mask (const char*section_name)
 {
   static const struct TALER_AgeMask null_mask = {0};
-  struct TALER_AgeMask age_mask = TALER_extensions_age_restriction_ageMask ();
-
-  if (age_mask.bits == 0)
-    return null_mask;
+  enum GNUNET_GenericReturnValue ret;
 
   if (GNUNET_OK != (GNUNET_CONFIGURATION_have_value (
                       TEH_cfg,
@@ -826,22 +823,29 @@ load_age_mask (const char*section_name)
                       "AGE_RESTRICTED")))
     return null_mask;
 
+  if (GNUNET_SYSERR ==
+      (ret = GNUNET_CONFIGURATION_get_value_yesno (TEH_cfg,
+                                                   section_name,
+                                                   "AGE_RESTRICTED")))
   {
-    enum GNUNET_GenericReturnValue ret;
+    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
+                               section_name,
+                               "AGE_RESTRICTED",
+                               "Value must be YES or NO\n");
+    return null_mask;
+  }
 
-    if (GNUNET_SYSERR ==
-        (ret = GNUNET_CONFIGURATION_get_value_yesno (TEH_cfg,
-                                                     section_name,
-                                                     "AGE_RESTRICTED")))
-    {
-      GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
-                                 section_name,
-                                 "AGE_RESTRICTED",
-                                 "Value must be YES or NO\n");
-      return null_mask;
-    }
+  if (GNUNET_OK == ret)
+  {
+    if (! TEH_age_restriction_config.enabled)
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "age restriction set in section %s, yet, age restriction is not enabled\n",
+                  section_name);
+    return TEH_age_restriction_config.mask;
   }
-  return age_mask;
+
+
+  return null_mask;
 }
 
 
@@ -1898,34 +1902,29 @@ create_krd (struct TEH_KeyStateHandle *ksh,
     bool has_extensions = false;
 
     /* Fill in the configurations of the enabled extensions */
-    for (const struct TALER_Extension *extension = TALER_extensions_get_head ();
-         NULL != extension;
-         extension = extension->next)
+    for (const struct TALER_Extensions *iter = TALER_extensions_get_head ();
+         NULL != iter && NULL != iter->extension;
+         iter = iter->next)
     {
+      const struct TALER_Extension *extension = iter->extension;
       json_t *ext;
-      json_t *config_json;
       int r;
 
-      /* skip if not configured == disabled */
-      if (NULL == extension->config ||
-          NULL == extension->config_json)
+      /* skip if not enabled */
+      if (! extension->enabled)
         continue;
 
       /* flag our findings so far */
       has_extensions = true;
-
       GNUNET_assert (NULL != extension->config_json);
 
-      config_json = json_copy (extension->config_json);
-      GNUNET_assert (NULL != config_json);
-
       ext = GNUNET_JSON_PACK (
         GNUNET_JSON_pack_bool ("critical",
                                extension->critical),
         GNUNET_JSON_pack_string ("version",
                                  extension->version),
-        GNUNET_JSON_pack_object_steal ("config",
-                                       config_json)
+        GNUNET_JSON_pack_object_incref ("config",
+                                        extension->config_json)
         );
       GNUNET_assert (NULL != ext);
 
@@ -1948,12 +1947,16 @@ create_krd (struct TEH_KeyStateHandle *ksh,
         extensions);
       GNUNET_assert (0 == r);
 
-      sig = GNUNET_JSON_PACK (
-        GNUNET_JSON_pack_data_auto ("extensions_sig",
-                                    &TEH_extensions_sig));
+      /* Add the signature of the extensions, if it is not zero */
+      if (TEH_extensions_signed)
+      {
+        sig = GNUNET_JSON_PACK (
+          GNUNET_JSON_pack_data_auto ("extensions_sig",
+                                      &TEH_extensions_sig));
 
-      r = json_object_update (keys, sig);
-      GNUNET_assert (0 == r);
+        r = json_object_update (keys, sig);
+        GNUNET_assert (0 == r);
+      }
     }
     else
     {
@@ -2560,6 +2563,7 @@ build_key_state (struct HelperState *hs,
                        true);
     return NULL;
   }
+
   /* NOTE: ONLY fetches non-revoked AND master-signed signkeys! */
   qs = TEH_plugin->iterate_active_signkeys (TEH_plugin->cls,
                                             &signkey_info_cb,
diff --git a/src/exchange/taler-exchange-httpd_management_extensions.c b/src/exchange/taler-exchange-httpd_management_extensions.c
index a663b1b0..c70ad25e 100644
--- a/src/exchange/taler-exchange-httpd_management_extensions.c
+++ b/src/exchange/taler-exchange-httpd_management_extensions.c
@@ -108,6 +108,8 @@ set_extensions (void *cls,
       taler_ext->name,
       config);
 
+    free (config);
+
     if (qs < 0)
     {
       if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
@@ -137,6 +139,7 @@ set_extensions (void *cls,
 
   /* All extensions configured, update the signature */
   TEH_extensions_sig = sec->extensions_sig;
+  TEH_extensions_signed = true;
 
   return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT; /* only 'success', so >=0, matters here */
 }
diff --git a/src/exchange/taler-exchange-httpd_refreshes_reveal.c b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
index a25d6ff4..09ab572b 100644
--- a/src/exchange/taler-exchange-httpd_refreshes_reveal.c
+++ b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
@@ -603,7 +603,7 @@ resolve_refreshes_reveal_denominations (
                         &rrc->coin_envelope_hash);
   }
 
-  if (TEH_age_restriction_enabled &&
+  if (TEH_age_restriction_config.enabled &&
       ((NULL == old_age_commitment_json) !=
        TALER_AgeCommitmentHash_isNullOrZero (
          &rctx->melt.session.coin.h_age_commitment)))
@@ -614,7 +614,7 @@ resolve_refreshes_reveal_denominations (
 
   /* Reconstruct the old age commitment and verify its hash matches the one
    * from the melt request */
-  if (TEH_age_restriction_enabled &&
+  if (TEH_age_restriction_config.enabled &&
       (NULL != old_age_commitment_json))
   {
     enum GNUNET_GenericReturnValue res;
@@ -623,8 +623,7 @@ resolve_refreshes_reveal_denominations (
     bool failed = true;
 
     /* Has been checked in handle_refreshes_reveal_json() */
-    GNUNET_assert (ng ==
-                   TALER_extensions_age_restriction_num_groups ());
+    GNUNET_assert (ng == TEH_age_restriction_config.num_groups);
 
     rctx->old_age_commitment = GNUNET_new (struct TALER_AgeCommitment);
     oac = rctx->old_age_commitment;
@@ -931,7 +930,7 @@ handle_refreshes_reveal_json (struct MHD_Connection *connection,
   /* Sanity check of age commitment: If it was provided, it _must_ be an array
    * of the size the # of age groups */
   if (NULL != old_age_commitment_json
-      && TALER_extensions_age_restriction_num_groups () !=
+      && TEH_age_restriction_config.num_groups !=
       json_array_size (old_age_commitment_json))
   {
     GNUNET_break_op (0);