policy extensions and age restriction refactoring

- refactoring of extension-plugin-mechanism
- refactoring of age restriction extension
- added policy extensions plugin plumbing
- added DB schema and api
  - policy_details
  - policy_fulfillments

11 files changed, 508 insertions, 163 deletions

diff --git a/src/exchange/taler-exchange-httpd.c b/src/exchange/taler-exchange-httpd.c
index 34f93879a..691e1ef7d 100644
--- a/src/exchange/taler-exchange-httpd.c
+++ b/src/exchange/taler-exchange-httpd.c
@@ -102,6 +102,14 @@ 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.
+ */
+bool TEH_age_restriction_enabled = false;
+struct TALER_AgeRestrictionConfig TEH_age_restriction_config = {0};
+
+/**
  * Handle to the HTTP server.
  */
 static struct MHD_Daemon *mhd;
@@ -143,11 +151,6 @@ 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;
@@ -174,6 +177,7 @@ bool TEH_suicide;
  * TALER_SIGNATURE_MASTER_EXTENSION.
  */
 struct TALER_MasterSignatureP TEH_extensions_sig;
+bool TEH_extensions_signed = false;
 
 /**
  * Value to return from main()
diff --git a/src/exchange/taler-exchange-httpd.h b/src/exchange/taler-exchange-httpd.h
index 0fda5ed8d..4d3fb4901 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 +362,8 @@ struct TEH_RequestHandler
 };
 
 
+/* Age restriction configuration */
+extern bool TEH_age_restriction_enabled;
+extern struct TALER_AgeRestrictionConfig TEH_age_restriction_config;
+
 #endif
diff --git a/src/exchange/taler-exchange-httpd_batch-deposit.c b/src/exchange/taler-exchange-httpd_batch-deposit.c
index c2a9cbd54..4d4197ab6 100644
--- a/src/exchange/taler-exchange-httpd_batch-deposit.c
+++ b/src/exchange/taler-exchange-httpd_batch-deposit.c
@@ -87,15 +87,27 @@ struct BatchDepositContext
   const char *payto_uri;
 
   /**
-   * Additional details for extensions relevant for this
+   * Additional details for policy extension relevant for this
    * deposit operation, possibly NULL!
    */
-  json_t *extension_details;
+  json_t *policy_json;
 
   /**
-   * Hash over @e extension_details.
+   * Will be true if policy_json were provided
    */
-  struct TALER_ExtensionContractHashP h_extensions;
+  bool has_policy;
+
+  /**
+   * If @e policy_json was present, the corresponding policy extension
+   * calculates these details.  These will be persisted in the policy_details
+   * table.
+   */
+  struct TALER_PolicyDetails policy_details;
+
+  /**
+   * Hash over @e policy_details.
+   */
+  struct TALER_ExtensionPolicyHashP h_policy;
 
   /**
    * Time when this request was generated.  Used, for example, to
@@ -173,7 +185,7 @@ again:
            &TEH_keys_exchange_sign_,
            &bdc->h_contract_terms,
            &bdc->h_wire,
-           &bdc->h_extensions,
+           bdc->has_policy ? &bdc->h_policy: NULL,
            bdc->exchange_timestamp,
            bdc->wire_deadline,
            bdc->refund_deadline,
@@ -242,7 +254,7 @@ batch_deposit_transaction (void *cls,
                            MHD_RESULT *mhd_ret)
 {
   struct BatchDepositContext *dc = cls;
-  enum GNUNET_DB_QueryStatus qs;
+  enum GNUNET_DB_QueryStatus qs = GNUNET_SYSERR;
   bool balance_ok;
   bool in_conflict;
 
@@ -469,18 +481,19 @@ parse_coin (struct MHD_Connection *connection,
 
   TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
   if (GNUNET_OK !=
-      TALER_wallet_deposit_verify (&deposit->amount_with_fee,
-                                   &deposit->deposit_fee,
-                                   &dc->h_wire,
-                                   &dc->h_contract_terms,
-                                   &deposit->coin.h_age_commitment,
-                                   &dc->h_extensions,
-                                   &deposit->coin.denom_pub_hash,
-                                   dc->timestamp,
-                                   &dc->merchant_pub,
-                                   dc->refund_deadline,
-                                   &deposit->coin.coin_pub,
-                                   &deposit->csig))
+      TALER_wallet_deposit_verify (
+        &deposit->amount_with_fee,
+        &deposit->deposit_fee,
+        &dc->h_wire,
+        &dc->h_contract_terms,
+        &deposit->coin.h_age_commitment,
+        dc->has_policy ? &dc->h_policy : NULL,
+        &deposit->coin.denom_pub_hash,
+        dc->timestamp,
+        &dc->merchant_pub,
+        dc->refund_deadline,
+        &deposit->coin.coin_pub,
+        &deposit->csig))
   {
     TALER_LOG_WARNING ("Invalid signature on /batch-deposit request\n");
     GNUNET_JSON_parse_free (spec);
@@ -496,11 +509,6 @@ parse_coin (struct MHD_Connection *connection,
   deposit->h_contract_terms = dc->h_contract_terms;
   deposit->wire_salt = dc->wire_salt;
   deposit->receiver_wire_account = (char *) dc->payto_uri;
-  /* FIXME-OEC: #7270 should NOT insert the extension details N times,
-     but rather insert them ONCE and then per-coin only use
-     the resulting extension UUID/serial; so the data structure
-     here should be changed once we look at extensions in earnest.  */
-  deposit->extension_details = dc->extension_details;
   deposit->timestamp = dc->timestamp;
   deposit->refund_deadline = dc->refund_deadline;
   deposit->wire_deadline = dc->wire_deadline;
@@ -517,7 +525,7 @@ TEH_handler_batch_deposit (struct TEH_RequestContext *rc,
   struct BatchDepositContext dc;
   json_t *coins;
   bool no_refund_deadline = true;
-  bool no_extensions = true;
+  bool no_policy_json = true;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_string ("merchant_payto_uri",
                              &dc.payto_uri),
@@ -530,9 +538,9 @@ TEH_handler_batch_deposit (struct TEH_RequestContext *rc,
     GNUNET_JSON_spec_json ("coins",
                            &coins),
     GNUNET_JSON_spec_mark_optional (
-      GNUNET_JSON_spec_json ("extension_details",
-                             &dc.extension_details),
-      &no_extensions),
+      GNUNET_JSON_spec_json ("policy",
+                             &dc.policy_json),
+      &no_policy_json),
     GNUNET_JSON_spec_timestamp ("timestamp",
                                 &dc.timestamp),
     GNUNET_JSON_spec_mark_optional (
@@ -563,6 +571,8 @@ TEH_handler_batch_deposit (struct TEH_RequestContext *rc,
     return MHD_YES;   /* failure */
   }
 
+  dc.has_policy = ! no_policy_json;
+
   /* validate merchant's wire details (as far as we can) */
   {
     char *emsg;
@@ -607,11 +617,26 @@ TEH_handler_batch_deposit (struct TEH_RequestContext *rc,
   TALER_merchant_wire_signature_hash (dc.payto_uri,
                                       &dc.wire_salt,
                                       &dc.h_wire);
-  /* FIXME-OEC: #7270 hash actual extension JSON object here */
-  // if (! no_extensions)
-  memset (&dc.h_extensions,
-          0,
-          sizeof (dc.h_extensions));
+
+  /* handle policy, if present */
+  if (dc.has_policy)
+  {
+    const char *error_hint = NULL;
+
+    if (GNUNET_OK !=
+        TALER_extensions_create_policy_details (
+          dc.policy_json,
+          &dc.policy_details,
+          &error_hint))
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_POLICY_NOT_ACCEPTED,
+                                         error_hint);
+
+    TALER_deposit_policy_hash (dc.policy_json,
+                               &dc.h_policy);
+  }
+
   dc.num_coins = json_array_size (coins);
   if (0 == dc.num_coins)
   {
@@ -635,12 +660,32 @@ TEH_handler_batch_deposit (struct TEH_RequestContext *rc,
                                   struct TALER_EXCHANGEDB_Deposit);
   for (unsigned int i = 0; i<dc.num_coins; i++)
   {
-    if (GNUNET_OK !=
-        (res = parse_coin (connection,
-                           json_array_get (coins,
-                                           i),
-                           &dc,
-                           &dc.deposits[i])))
+    do {
+      res = parse_coin (connection,
+                        json_array_get (coins, i),
+                        &dc,
+                        &dc.deposits[i]);
+      if (GNUNET_OK != res)
+        break;
+
+      /* If applicable, accumulate all contributions into the policy_details */
+      if (dc.has_policy)
+      {
+        /* FIXME: how do deposit-fee and policy-fee interact? */
+        struct TALER_Amount amount_without_fee;
+
+        res = TALER_amount_subtract (&amount_without_fee,
+                                     &dc.deposits[i].amount_with_fee,
+                                     &dc.deposits[i].deposit_fee
+                                     );
+        res = TALER_amount_add (
+          &dc.policy_details.accumulated_total,
+          &dc.policy_details.accumulated_total,
+          &amount_without_fee);
+      }
+    } while(0);
+
+    if (GNUNET_OK != res)
     {
       for (unsigned int j = 0; j<i; j++)
         TALER_denom_sig_free (&dc.deposits[j].coin.denom_sig);
diff --git a/src/exchange/taler-exchange-httpd_deposit.c b/src/exchange/taler-exchange-httpd_deposit.c
index 0484ab071..455888a89 100644
--- a/src/exchange/taler-exchange-httpd_deposit.c
+++ b/src/exchange/taler-exchange-httpd_deposit.c
@@ -21,6 +21,7 @@
  * @author Florian Dold
  * @author Benedikt Mueller
  * @author Christian Grothoff
+ * @author Özgür Kesim
  */
 #include "platform.h"
 #include <gnunet/gnunet_util_lib.h>
@@ -47,7 +48,7 @@
  * @param connection connection to the client
  * @param coin_pub public key of the coin
  * @param h_wire hash of wire details
- * @param h_extensions hash of applicable extensions
+ * @param h_policy hash of applicable policy extension
  * @param h_contract_terms hash of contract details
  * @param exchange_timestamp exchange's timestamp
  * @param refund_deadline until when this deposit be refunded
@@ -61,7 +62,7 @@ reply_deposit_success (
   struct MHD_Connection *connection,
   const struct TALER_CoinSpendPublicKeyP *coin_pub,
   const struct TALER_MerchantWireHashP *h_wire,
-  const struct TALER_ExtensionContractHashP *h_extensions,
+  const struct TALER_ExtensionPolicyHashP *h_policy,
   const struct TALER_PrivateContractHashP *h_contract_terms,
   struct GNUNET_TIME_Timestamp exchange_timestamp,
   struct GNUNET_TIME_Timestamp refund_deadline,
@@ -78,7 +79,7 @@ reply_deposit_success (
          &TEH_keys_exchange_sign_,
          h_contract_terms,
          h_wire,
-         h_extensions,
+         h_policy,
          exchange_timestamp,
          wire_deadline,
          refund_deadline,
@@ -131,6 +132,29 @@ struct DepositContext
    */
   uint64_t known_coin_id;
 
+  /*
+   * True if @e policy_json was provided
+   */
+  bool has_policy;
+
+  /**
+   * If @e has_policy is true, the corresponding policy extension calculates
+   * these details.  These will be persisted in the policy_details table.
+   */
+  struct TALER_PolicyDetails policy_details;
+
+  /**
+   * Hash over the policy data for this deposit (remains unknown to the
+   * Exchange).  Needed for the verification of the deposit's signature
+   */
+  struct TALER_ExtensionPolicyHashP h_policy;
+
+  /**
+   * When has_policy is true, and deposit->policy_details are
+   * persisted, this contains the id of the record in the policy_details table.
+   */
+  uint64_t policy_details_serial_id;
+
 };
 
 
@@ -163,14 +187,35 @@ deposit_transaction (void *cls,
                             mhd_ret);
   if (qs < 0)
     return qs;
-  qs = TEH_plugin->do_deposit (TEH_plugin->cls,
-                               dc->deposit,
-                               dc->known_coin_id,
-                               &dc->h_payto,
-                               false, /* FIXME-OEC: extension blocked #7270 */
-                               &dc->exchange_timestamp,
-                               &balance_ok,
-                               &in_conflict);
+
+
+  /* If the deposit has a policy associated to it, persist it.  This will
+   * insert or update the record. */
+  if (dc->has_policy)
+  {
+    qs = TEH_plugin->persist_policy_details (
+      TEH_plugin->cls,
+      &dc->policy_details,
+      &dc->policy_details_serial_id,
+      &dc->policy_details.accumulated_total,
+      &dc->policy_details.fulfillment_state);
+
+    if (qs < 0)
+      return qs;
+  }
+
+
+  qs = TEH_plugin->do_deposit (
+    TEH_plugin->cls,
+    dc->deposit,
+    dc->known_coin_id,
+    &dc->h_payto,
+    (dc->has_policy)
+             ? &dc->policy_details_serial_id
+             : NULL,
+    &dc->exchange_timestamp,
+    &balance_ok,
+    &in_conflict);
   if (qs < 0)
   {
     if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
@@ -216,6 +261,8 @@ TEH_handler_deposit (struct MHD_Connection *connection,
   struct DepositContext dc;
   struct TALER_EXCHANGEDB_Deposit deposit;
   const char *payto_uri;
+  struct TALER_ExtensionPolicyHashP *ph_policy = NULL;
+  bool no_policy_json;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_string ("merchant_payto_uri",
                              &payto_uri),
@@ -240,12 +287,18 @@ TEH_handler_deposit (struct MHD_Connection *connection,
                                  &deposit.csig),
     GNUNET_JSON_spec_timestamp ("timestamp",
                                 &deposit.timestamp),
+    /* TODO: refund_deadline and merchant_pub will move into the
+     * extension policy_merchant_refunds */
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("refund_deadline",
                                   &deposit.refund_deadline),
       NULL),
     GNUNET_JSON_spec_timestamp ("wire_transfer_deadline",
                                 &deposit.wire_deadline),
+    GNUNET_JSON_spec_mark_optional (
+      GNUNET_JSON_spec_json ("policy",
+                             &dc.policy_details.policy_json),
+      &no_policy_json),
     GNUNET_JSON_spec_end ()
   };
   struct TALER_MerchantWireHashP h_wire;
@@ -271,6 +324,9 @@ TEH_handler_deposit (struct MHD_Connection *connection,
       return MHD_YES; /* failure */
     }
   }
+
+  dc.has_policy = ! no_policy_json;
+
   /* validate merchant's wire details (as far as we can) */
   {
     char *emsg;
@@ -419,6 +475,26 @@ TEH_handler_deposit (struct MHD_Connection *connection,
                                        NULL);
   }
 
+  /* Check policy input and create policy details */
+  if (dc.has_policy)
+  {
+    const char *error_hint = NULL;
+
+    if (GNUNET_OK !=
+        TALER_extensions_create_policy_details (
+          dc.policy_details.policy_json,
+          &dc.policy_details,
+          &error_hint))
+      return TALER_MHD_reply_with_error (connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_DEPOSITS_POLICY_NOT_ACCEPTED,
+                                         error_hint);
+
+    TALER_deposit_policy_hash (dc.policy_details.policy_json,
+                               &dc.h_policy);
+    ph_policy = &dc.h_policy;
+  }
+
   TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
   if (GNUNET_OK !=
       TALER_wallet_deposit_verify (&deposit.amount_with_fee,
@@ -426,7 +502,7 @@ TEH_handler_deposit (struct MHD_Connection *connection,
                                    &h_wire,
                                    &deposit.h_contract_terms,
                                    &deposit.coin.h_age_commitment,
-                                   NULL /* FIXME: h_extensions! */,
+                                   ph_policy,
                                    &deposit.coin.denom_pub_hash,
                                    deposit.timestamp,
                                    &deposit.merchant_pub,
@@ -481,7 +557,7 @@ TEH_handler_deposit (struct MHD_Connection *connection,
     res = reply_deposit_success (connection,
                                  &deposit.coin.coin_pub,
                                  &h_wire,
-                                 NULL /* FIXME: h_extensions! */,
+                                 ph_policy,
                                  &deposit.h_contract_terms,
                                  dc.exchange_timestamp,
                                  deposit.refund_deadline,
diff --git a/src/exchange/taler-exchange-httpd_extensions.c b/src/exchange/taler-exchange-httpd_extensions.c
index d6c26f6f4..30d1c5ac9 100644
--- a/src/exchange/taler-exchange-httpd_extensions.c
+++ b/src/exchange/taler-exchange-httpd_extensions.c
@@ -14,7 +14,7 @@
 */
 /**
  * @file taler-exchange-httpd_extensions.c
- * @brief Handle extensions (age-restriction, peer2peer)
+ * @brief Handle extensions (age-restriction, policy extensions)
  * @author Özgür Kesim
  */
 #include "platform.h"
@@ -77,65 +77,84 @@ extension_update_event_cb (void *cls,
     return;
   }
 
-  // Get the config from the database as string
+  // Get the manifest from the database as string
   {
-    char *config_str = NULL;
+    char *manifest_str = NULL;
     enum GNUNET_DB_QueryStatus qs;
     json_error_t err;
-    json_t *config;
+    json_t *manifest_js;
     enum GNUNET_GenericReturnValue ret;
 
-    qs = TEH_plugin->get_extension_config (TEH_plugin->cls,
-                                           extension->name,
-                                           &config_str);
+    qs = TEH_plugin->get_extension_manifest (TEH_plugin->cls,
+                                             extension->name,
+                                             &manifest_str);
 
     if (qs < 0)
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                  "Couldn't get extension config\n");
+                  "Couldn't get extension manifest\n");
       GNUNET_break (0);
       return;
     }
 
     // No config found -> disable extension
-    if (NULL == config_str)
+    if (NULL == manifest_str)
     {
+      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                  "No manifest found for extension %s, disabling it\n",
+                  extension->name);
       extension->disable ((struct TALER_Extension *) extension);
       return;
     }
 
     // Parse the string as JSON
-    config = json_loads (config_str, JSON_DECODE_ANY, &err);
-    if (NULL == config)
+    manifest_js = json_loads (manifest_str, JSON_DECODE_ANY, &err);
+    if (NULL == manifest_js)
     {
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                  "Failed to parse config for extension `%s' as JSON: %s (%s)\n",
+                  "Failed to parse manifest for extension `%s' as JSON: %s (%s)\n",
                   extension->name,
                   err.text,
                   err.source);
       GNUNET_break (0);
+      free (manifest_js);
       return;
     }
 
     // Call the parser for the extension
-    ret = extension->load_json_config (
+    ret = extension->load_config (
       (struct TALER_Extension *) extension,
-      config);
+      json_object_get (manifest_js, "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 manifest in the database: %s\n",
+                  extension->name,
+                  manifest_str);
       GNUNET_break (0);
     }
+
+    free (manifest_str);
+    json_decref (manifest_js);
   }
 
   /* 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 ();
+    TEH_age_restriction_enabled = false;
+    if (NULL != conf)
+    {
+      TEH_age_restriction_enabled = true;
+      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",
+                TEH_age_restriction_enabled ? "enabled": "DISABLED",
+                TALER_age_mask_to_string (&conf->mask));
+
   }
 }
 
@@ -143,14 +162,30 @@ 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_init (TEH_cfg))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "failed to load extensions");
+    return GNUNET_SYSERR;
+  }
+
+  /* Check for age restriction */
+  {
+    const struct TALER_AgeRestrictionConfig *arc;
+
+    if (NULL !=
+        (arc = TALER_extensions_get_age_restriction_config ()))
+      TEH_age_restriction_config = *arc;
+  }
+
   extensions_eh = TEH_plugin->event_listen (TEH_plugin->cls,
                                             GNUNET_TIME_UNIT_FOREVER_REL,
                                             &ev,
@@ -162,17 +197,24 @@ 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;
+    uint32_t typ = htonl (ext->type);
+    char *manifest = json_dumps (ext->manifest (ext), JSON_COMPACT);
+
+    TEH_plugin->set_extension_manifest (TEH_plugin->cls,
+                                        ext->name,
+                                        manifest);
+
+    extension_update_event_cb (NULL,
+                               &typ,
+                               sizeof(typ));
+    free (manifest);
+  }
 
   return GNUNET_OK;
 }
@@ -190,4 +232,168 @@ TEH_extensions_done ()
 }
 
 
+/*
+ * @brief Execute database transactions for /extensions/policy_* POST requests.
+ *
+ * @param cls a `struct TALER_PolicyFulfillmentOutcome`
+ * @param connection MHD request context
+ * @param[out] mhd_ret set to MHD status on error
+ * @return transaction status
+ */
+static enum GNUNET_DB_QueryStatus
+policy_fulfillment_transaction (
+  void *cls,
+  struct MHD_Connection *connection,
+  MHD_RESULT *mhd_ret)
+{
+  struct TALER_PolicyFulfillmentTransactionData *fulfillment = cls;
+
+  return TEH_plugin->add_policy_fulfillment_proof (TEH_plugin->cls,
+                                                   fulfillment);
+}
+
+
+MHD_RESULT
+TEH_extensions_post_handler (
+  struct TEH_RequestContext *rc,
+  const json_t *root,
+  const char *const args[])
+{
+  const struct TALER_Extension *ext = NULL;
+  json_t *output;
+  struct TALER_PolicyDetails *policy_details = NULL;
+  size_t policy_details_count = 0;
+
+
+  if (NULL == args[0])
+  {
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (rc->connection,
+                                       MHD_HTTP_NOT_FOUND,
+                                       TALER_EC_EXCHANGE_GENERIC_OPERATION_UNKNOWN,
+                                       "/extensions/$EXTENSION");
+  }
+
+  ext = TALER_extensions_get_by_name (args[0]);
+  if (NULL == ext)
+  {
+    GNUNET_break_op (0);
+    return TALER_MHD_reply_with_error (rc->connection,
+                                       MHD_HTTP_NOT_FOUND,
+                                       TALER_EC_EXCHANGE_GENERIC_OPERATION_UNKNOWN,
+                                       "/extensions/$EXTENSION unknown");
+  }
+
+  if (NULL == ext->policy_post_handler)
+    return TALER_MHD_reply_with_error (rc->connection,
+                                       MHD_HTTP_NOT_IMPLEMENTED,
+                                       TALER_EC_EXCHANGE_GENERIC_OPERATION_UNKNOWN,
+                                       "POST /extensions/$EXTENSION not supported");
+
+  /*  Extract hash_codes and retrieve related policy_details from the DB */
+  {
+    enum GNUNET_GenericReturnValue ret;
+    enum GNUNET_DB_QueryStatus qs;
+    const char *error_msg;
+    struct GNUNET_HashCode *hcs;
+    size_t len;
+    json_t*val;
+    size_t idx;
+    json_t *jhash_codes = json_object_get (root,
+                                           "policy_hash_codes");
+    if (! json_is_array (jhash_codes))
+      return TALER_MHD_reply_with_error (rc->connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_GENERIC_OPERATION_UNKNOWN,
+                                         "policy_hash_codes are missing");
+
+    len = json_array_size (jhash_codes);
+    hcs = GNUNET_new_array (len,
+                            struct GNUNET_HashCode);
+    policy_details = GNUNET_new_array (len,
+                                       struct TALER_PolicyDetails);
+
+    json_array_foreach (jhash_codes, idx, val)
+    {
+      struct GNUNET_JSON_Specification spec[] = {
+        GNUNET_JSON_spec_fixed_auto (NULL, &hcs[idx]),
+        GNUNET_JSON_spec_end ()
+      };
+
+      ret = GNUNET_JSON_parse (val,
+                               spec,
+                               &error_msg,
+                               NULL);
+      if (GNUNET_OK != ret)
+        break;
+
+      qs = TEH_plugin->get_policy_details (TEH_plugin->cls,
+                                           &hcs[idx],
+                                           &policy_details[idx]);
+      if (qs < 0)
+      {
+        error_msg = "a policy_hash_code couldn't be found";
+        break;
+      }
+    }
+
+    GNUNET_free (hcs);
+    if (GNUNET_OK != ret)
+    {
+      GNUNET_free (policy_details);
+      return TALER_MHD_reply_with_error (rc->connection,
+                                         MHD_HTTP_BAD_REQUEST,
+                                         TALER_EC_EXCHANGE_GENERIC_OPERATION_UNKNOWN,
+                                         error_msg);
+    }
+  }
+
+
+  {
+    enum GNUNET_GenericReturnValue ret;
+
+    ret = ext->policy_post_handler (root,
+                                    &args[1],
+                                    policy_details,
+                                    policy_details_count,
+                                    &output);
+
+    if (GNUNET_OK != ret)
+    {
+      TALER_MHD_reply_json_steal (
+        rc->connection,
+        output,
+        MHD_HTTP_BAD_REQUEST);
+    }
+
+    /* execute fulfillment transaction */
+    {
+      MHD_RESULT mhd_ret;
+      struct TALER_PolicyFulfillmentTransactionData fulfillment = {
+        .proof = root,
+        .timestamp = GNUNET_TIME_timestamp_get (),
+        .details = policy_details,
+        .details_count = policy_details_count
+      };
+
+      if (GNUNET_OK !=
+          TEH_DB_run_transaction (rc->connection,
+                                  "execute policy fulfillment",
+                                  TEH_MT_REQUEST_POLICY_FULFILLMENT,
+                                  &mhd_ret,
+                                  &policy_fulfillment_transaction,
+                                  &fulfillment))
+      {
+        json_decref (output);
+        return mhd_ret;
+      }
+    }
+  }
+
+  return TALER_MHD_reply_json_steal (rc->connection,
+                                     output,
+                                     MHD_HTTP_OK);
+}
+
+
 /* end of taler-exchange-httpd_extensions.c */
diff --git a/src/exchange/taler-exchange-httpd_extensions.h b/src/exchange/taler-exchange-httpd_extensions.h
index 4659b653e..e435f8f03 100644
--- a/src/exchange/taler-exchange-httpd_extensions.h
+++ b/src/exchange/taler-exchange-httpd_extensions.h
@@ -40,4 +40,19 @@ TEH_extensions_init (void);
 void
 TEH_extensions_done (void);
 
+
+/**
+ * Handle POST "/extensions/..." requests.
+ *
+ * @param rc request context
+ * @param root uploaded JSON data
+ * @param args array of additional options
+ * @return MHD result code
+ */
+MHD_RESULT
+TEH_extensions_post_handler (
+  struct TEH_RequestContext *rc,
+  const json_t *root,
+  const char *const args[]);
+
 #endif
diff --git a/src/exchange/taler-exchange-httpd_keys.c b/src/exchange/taler-exchange-httpd_keys.c
index 9b7f28bd0..30c336539 100644
--- a/src/exchange/taler-exchange-httpd_keys.c
+++ b/src/exchange/taler-exchange-httpd_keys.c
@@ -17,6 +17,7 @@
  * @file taler-exchange-httpd_keys.c
  * @brief management of our various keys
  * @author Christian Grothoff
+ * @author Özgür Kesim
  */
 #include "platform.h"
 #include "taler_json_lib.h"
@@ -815,10 +816,7 @@ 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 +824,29 @@ 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_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;
 }
 
 
@@ -1898,41 +1903,29 @@ 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)
     {
-      json_t *ext;
-      json_t *config_json;
+      const struct TALER_Extension *extension = iter->extension;
+      json_t *manifest;
       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_assert (NULL != ext);
+      manifest = extension->manifest (extension);
+      GNUNET_assert (manifest);
 
       r = json_object_set_new (
         extensions,
         extension->name,
-        ext);
+        manifest);
       GNUNET_assert (0 == r);
     }
 
@@ -1948,12 +1941,16 @@ 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
     {
diff --git a/src/exchange/taler-exchange-httpd_management_extensions.c b/src/exchange/taler-exchange-httpd_management_extensions.c
index a663b1b06..989b88fb6 100644
--- a/src/exchange/taler-exchange-httpd_management_extensions.c
+++ b/src/exchange/taler-exchange-httpd_management_extensions.c
@@ -38,7 +38,7 @@
 struct Extension
 {
   enum TALER_Extension_Type type;
-  json_t *config;
+  json_t *manifest;
 };
 
 /**
@@ -52,7 +52,7 @@ struct SetExtensionsContext
 };
 
 /**
- * Function implementing database transaction to set the configuration of
+ * Function implementing database transaction to set the manifests of
  * extensions.  It runs the transaction logic.
  *  - IF it returns a non-error code, the transaction logic MUST NOT queue a
  *    MHD response.
@@ -74,13 +74,13 @@ set_extensions (void *cls,
 {
   struct SetExtensionsContext *sec = cls;
 
-  /* save the configurations of all extensions */
+  /* save the manifests of all extensions */
   for (uint32_t i = 0; i<sec->num_extensions; i++)
   {
     struct Extension *ext = &sec->extensions[i];
     const struct TALER_Extension *taler_ext;
     enum GNUNET_DB_QueryStatus qs;
-    char *config;
+    char *manifest;
 
     taler_ext = TALER_extensions_get_by_type (ext->type);
     if (NULL == taler_ext)
@@ -90,10 +90,8 @@ set_extensions (void *cls,
       return GNUNET_DB_STATUS_HARD_ERROR;
     }
 
-    GNUNET_assert (NULL != ext->config);
-
-    config = json_dumps (ext->config, JSON_COMPACT | JSON_SORT_KEYS);
-    if (NULL == config)
+    manifest = json_dumps (ext->manifest, JSON_COMPACT | JSON_SORT_KEYS);
+    if (NULL == manifest)
     {
       GNUNET_break (0);
       *mhd_ret = TALER_MHD_reply_with_error (connection,
@@ -103,10 +101,12 @@ set_extensions (void *cls,
       return GNUNET_DB_STATUS_HARD_ERROR;
     }
 
-    qs = TEH_plugin->set_extension_config (
+    qs = TEH_plugin->set_extension_manifest (
       TEH_plugin->cls,
       taler_ext->name,
-      config);
+      manifest);
+
+    free (manifest);
 
     if (qs < 0)
     {
@@ -137,6 +137,7 @@ 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 */
 }
@@ -150,7 +151,7 @@ verify_extensions_from_json (
   const char*name;
   const struct TALER_Extension *extension;
   size_t i = 0;
-  json_t *blob;
+  json_t *manifest;
 
   GNUNET_assert (NULL != extensions);
   GNUNET_assert (json_is_object (extensions));
@@ -159,7 +160,7 @@ verify_extensions_from_json (
   sec->extensions = GNUNET_new_array (sec->num_extensions,
                                       struct Extension);
 
-  json_object_foreach (extensions, name, blob)
+  json_object_foreach (extensions, name, manifest)
   {
     int critical = 0;
     json_t *config;
@@ -175,18 +176,18 @@ verify_extensions_from_json (
     }
 
     if (GNUNET_OK !=
-        TALER_extensions_is_json_config (
-          blob, &critical, &version, &config))
+        TALER_extensions_parse_manifest (
+          manifest, &critical, &version, &config))
       return GNUNET_SYSERR;
 
     if (critical != extension->critical
         || 0 != strcmp (version, extension->version) // FIXME-oec: libtool compare
         || NULL == config
-        || GNUNET_OK != extension->test_json_config (config))
+        || GNUNET_OK != extension->load_config (NULL, config))
       return GNUNET_SYSERR;
 
     sec->extensions[i].type = extension->type;
-    sec->extensions[i].config = config;
+    sec->extensions[i].manifest = json_copy (manifest);
   }
 
   return GNUNET_OK;
@@ -223,7 +224,8 @@ TEH_handler_management_post_extensions (
   }
 
   /* Ensure we have an object */
-  if (! json_is_object (extensions))
+  if ((! json_is_object (extensions)) &&
+      (! json_is_null (extensions)))
   {
     GNUNET_JSON_parse_free (top_spec);
     return TALER_MHD_reply_with_error (
@@ -235,13 +237,13 @@ TEH_handler_management_post_extensions (
 
   /* Verify the signature */
   {
-    struct TALER_ExtensionConfigHashP h_config;
+    struct TALER_ExtensionManifestsHashP h_manifests;
 
     if (GNUNET_OK !=
-        TALER_JSON_extensions_config_hash (extensions, &h_config) ||
+        TALER_JSON_extensions_manifests_hash (extensions, &h_manifests) ||
         GNUNET_OK !=
-        TALER_exchange_offline_extension_config_hash_verify (
-          &h_config,
+        TALER_exchange_offline_extension_manifests_hash_verify (
+          &h_manifests,
           &TEH_master_public_key,
           &sec.extensions_sig))
     {
@@ -298,9 +300,9 @@ TEH_handler_management_post_extensions (
 CLEANUP:
   for (unsigned int i = 0; i < sec.num_extensions; i++)
   {
-    if (NULL != sec.extensions[i].config)
+    if (NULL != sec.extensions[i].manifest)
     {
-      json_decref (sec.extensions[i].config);
+      json_decref (sec.extensions[i].manifest);
     }
   }
   GNUNET_free (sec.extensions);
diff --git a/src/exchange/taler-exchange-httpd_metrics.h b/src/exchange/taler-exchange-httpd_metrics.h
index c1b7326ff..cae371f7c 100644
--- a/src/exchange/taler-exchange-httpd_metrics.h
+++ b/src/exchange/taler-exchange-httpd_metrics.h
@@ -44,7 +44,8 @@ enum TEH_MetricTypeRequest
   TEH_MT_REQUEST_IDEMPOTENT_MELT = 10,
   TEH_MT_REQUEST_IDEMPOTENT_BATCH_WITHDRAW = 11,
   TEH_MT_REQUEST_BATCH_DEPOSIT = 12,
-  TEH_MT_REQUEST_COUNT = 13 /* MUST BE LAST! */
+  TEH_MT_REQUEST_POLICY_FULFILLMENT = 13,
+  TEH_MT_REQUEST_COUNT = 14 /* MUST BE LAST! */
 };
 
 /**
diff --git a/src/exchange/taler-exchange-httpd_refreshes_reveal.c b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
index a25d6ff43..85090cedc 100644
--- a/src/exchange/taler-exchange-httpd_refreshes_reveal.c
+++ b/src/exchange/taler-exchange-httpd_refreshes_reveal.c
@@ -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);
diff --git a/src/exchange/taler-exchange-httpd_responses.c b/src/exchange/taler-exchange-httpd_responses.c
index a81d1b6e5..ca110ad45 100644
--- a/src/exchange/taler-exchange-httpd_responses.c
+++ b/src/exchange/taler-exchange-httpd_responses.c
@@ -76,7 +76,7 @@ TEH_RESPONSE_compile_transaction_history (
               &h_wire,
               &deposit->h_contract_terms,
               &deposit->h_age_commitment,
-              NULL /* h_extensions! */,
+              &deposit->h_policy,
               &deposit->h_denom_pub,
               deposit->timestamp,
               &deposit->merchant_pub,