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.

1 files changed, 72 insertions, 53 deletions

diff --git a/src/extensions/extensions.c b/src/extensions/extensions.c
index 0df0bae3..95fb8cf0 100644
--- a/src/extensions/extensions.c
+++ b/src/extensions/extensions.c
@@ -24,21 +24,22 @@
 #include "taler_extensions.h"
 #include "stdint.h"
 
-
 /* head of the list of all registered extensions */
-static struct TALER_Extension *TE_extensions = NULL;
-
+static struct TALER_Extensions TE_extensions = {
+  .next = NULL,
+  .extension = NULL,
+};
 
-const struct TALER_Extension *
+const struct TALER_Extensions *
 TALER_extensions_get_head ()
 {
-  return TE_extensions;
+  return &TE_extensions;
 }
 
 
-enum GNUNET_GenericReturnValue
-TALER_extensions_add (
-  struct TALER_Extension *extension)
+static enum GNUNET_GenericReturnValue
+add_extension (
+  const struct TALER_Extension *extension)
 {
   /* Sanity checks */
   if ((NULL == extension) ||
@@ -47,28 +48,30 @@ TALER_extensions_add (
       (NULL == extension->disable) ||
       (NULL == extension->test_json_config) ||
       (NULL == extension->load_json_config) ||
-      (NULL == extension->config_to_json) ||
-      (NULL == extension->load_taler_config))
+      (NULL == extension->config_to_json))
   {
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "invalid extension\n");
     return GNUNET_SYSERR;
   }
 
-  if (NULL == TE_extensions) /* first extension ?*/
-    TE_extensions = (struct TALER_Extension *) extension;
+  if (NULL == TE_extensions.extension) /* first extension ?*/
+    TE_extensions.extension = extension;
   else
   {
-    struct TALER_Extension *iter;
-    struct TALER_Extension *last;
+    struct TALER_Extensions *iter;
+    struct TALER_Extensions *last;
 
     /* Check for collisions */
-    for (iter = TE_extensions; NULL != iter; iter = iter->next)
+    for (iter = &TE_extensions;
+         NULL != iter && NULL != iter->extension;
+         iter = iter->next)
     {
+      const struct TALER_Extension *ext = iter->extension;
       last = iter;
-      if (extension->type == iter->type ||
+      if (extension->type == ext->type ||
           0 == strcasecmp (extension->name,
-                           iter->name))
+                           ext->name))
       {
         GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                     "extension collision for `%s'\n",
@@ -78,7 +81,11 @@ TALER_extensions_add (
     }
 
     /* No collisions found, so add this extension to the list */
-    last->next = extension;
+    {
+      struct TALER_Extensions *extn = GNUNET_new (struct TALER_Extensions);
+      extn->extension = extension;
+      last->next = extn;
+    }
   }
 
   return GNUNET_OK;
@@ -89,12 +96,12 @@ const struct TALER_Extension *
 TALER_extensions_get_by_type (
   enum TALER_Extension_Type type)
 {
-  for (const struct TALER_Extension *it = TE_extensions;
-       NULL != it;
+  for (const struct TALER_Extensions *it = &TE_extensions;
+       NULL != it && NULL != it->extension;
        it = it->next)
   {
-    if (it->type == type)
-      return it;
+    if (it->extension->type == type)
+      return it->extension;
   }
 
   /* No extension found. */
@@ -109,8 +116,7 @@ TALER_extensions_is_enabled_type (
   const struct TALER_Extension *ext =
     TALER_extensions_get_by_type (type);
 
-  return (NULL != ext &&
-          TALER_extensions_is_enabled (ext));
+  return (NULL != ext && ext->enabled);
 }
 
 
@@ -118,14 +124,15 @@ const struct TALER_Extension *
 TALER_extensions_get_by_name (
   const char *name)
 {
-  for (const struct TALER_Extension *it = TE_extensions;
+  for (const struct TALER_Extensions *it = &TE_extensions;
        NULL != it;
        it = it->next)
   {
-    if (0 == strcasecmp (name, it->name))
-      return it;
+    if (0 == strcasecmp (name, it->extension->name))
+      return it->extension;
   }
-  /* No extension found. */
+  /* No extension found, try to load it. */
+
   return NULL;
 }
 
@@ -178,7 +185,8 @@ configure_extension (
 {
   struct LoadConfClosure *col = cls;
   const char *name;
-  const struct TALER_Extension *extension;
+  char *lib_name;
+  struct TALER_Extension *extension;
 
   if (GNUNET_OK != col->error)
     return;
@@ -190,33 +198,49 @@ configure_extension (
 
   name = section + sizeof(TALER_EXTENSION_SECTION_PREFIX) - 1;
 
-  if (NULL ==
-      (extension = TALER_extensions_get_by_name (name)))
+
+  /* Load the extension library */
+  GNUNET_asprintf (&lib_name,
+                   "libtaler_extension_%s",
+                   name);
+  extension = GNUNET_PLUGIN_load (
+    lib_name,
+    (void *) col->cfg);
+  if (NULL == extension)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                "Unsupported extension `%s` (section [%s]).\n", name,
+                "Couldn't load extension library to `%s` (section [%s]).\n",
+                name,
                 section);
     col->error = GNUNET_SYSERR;
     return;
   }
 
-  if (GNUNET_OK !=
-      extension->load_taler_config (
-        (struct TALER_Extension *) extension,
-        col->cfg))
+
+  if (GNUNET_OK != add_extension (extension))
   {
+    /* TODO: Ignoring return values here */
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                "Couldn't parse configuration for extension `%s` (section [%s]).\n",
+                "Couldn't add extension `%s` (section [%s]).\n",
                 name,
                 section);
     col->error = GNUNET_SYSERR;
+    GNUNET_PLUGIN_unload (
+      lib_name,
+      (void *) col->cfg);
     return;
   }
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "extension library '%s' loaded\n",
+              lib_name);
 }
 
 
+static bool extensions_loaded = false;
+
 enum GNUNET_GenericReturnValue
-TALER_extensions_load_taler_config (
+TALER_extensions_load (
   const struct GNUNET_CONFIGURATION_Handle *cfg)
 {
   struct LoadConfClosure col = {
@@ -224,9 +248,16 @@ TALER_extensions_load_taler_config (
     .error = GNUNET_OK,
   };
 
+  if (extensions_loaded)
+    return GNUNET_OK;
+
   GNUNET_CONFIGURATION_iterate_sections (cfg,
                                          &configure_extension,
                                          &col);
+
+  if (GNUNET_OK == col.error)
+    extensions_loaded = true;
+
   return col.error;
 }
 
@@ -309,28 +340,16 @@ TALER_extensions_load_json_config (
   }
 
   /* make sure to disable all extensions that weren't mentioned in the json */
-  for (const struct TALER_Extension *it = TALER_extensions_get_head ();
+  for (const struct TALER_Extensions *it = TALER_extensions_get_head ();
        NULL != it;
        it = it->next)
   {
-    if (NULL == json_object_get (extensions, it->name))
-      it->disable ((struct TALER_Extension *) it);
+    if (NULL == json_object_get (extensions, it->extension->name))
+      it->extension->disable ((struct TALER_Extension *) it);
   }
 
   return GNUNET_OK;
 }
 
 
-bool
-TALER_extensions_age_restriction_is_enabled ()
-{
-  const struct TALER_Extension *age =
-    TALER_extensions_get_by_type (TALER_Extension_AgeRestriction);
-
-  return (NULL != age &&
-          NULL != age->config_json &&
-          TALER_extensions_age_restriction_is_configured ());
-}
-
-
 /* end of extensions.c */