merchant

taler-merchant-httpd_private-post-orders.c (139427B)

---

 /*
   This file is part of TALER
   (C) 2014-2025 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify
   it under the terms of the GNU Affero General Public License as
   published by the Free Software Foundation; either version 3,
   or (at your option) any later version.
 
   TALER is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public
   License along with TALER; see the file COPYING.  If not,
   see <http://www.gnu.org/licenses/>
 */
 
 /**
  * @file taler-merchant-httpd_private-post-orders.c
  * @brief the POST /orders handler
  * @author Christian Grothoff
  * @author Marcello Stanisci
  * @author Christian Blättler
  */
 #include "platform.h"
 #include <gnunet/gnunet_common.h>
 #include <gnunet/gnunet_db_lib.h>
 #include <gnunet/gnunet_json_lib.h>
 #include <gnunet/gnunet_time_lib.h>
 #include <jansson.h>
 #include <microhttpd.h>
 #include <string.h>
 #include <taler/taler_error_codes.h>
 #include <taler/taler_signatures.h>
 #include <taler/taler_json_lib.h>
 #include <taler/taler_dbevents.h>
 #include <taler/taler_util.h>
 #include <taler_merchant_util.h>
 #include <time.h>
 #include "taler-merchant-httpd.h"
 #include "taler-merchant-httpd_private-post-orders.h"
 #include "taler-merchant-httpd_exchanges.h"
 #include "taler-merchant-httpd_contract.h"
 #include "taler-merchant-httpd_helper.h"
 #include "taler-merchant-httpd_private-get-orders.h"
 
 #include "taler_merchantdb_plugin.h"
 
 
 /**
  * How often do we retry the simple INSERT database transaction?
  */
 #define MAX_RETRIES 3
 
 /**
  * Maximum number of inventory products per order.
  */
 #define MAX_PRODUCTS 1024
 
 /**
  * What is the label under which we find/place the merchant's
  * jurisdiction in the locations list by default?
  */
 #define STANDARD_LABEL_MERCHANT_JURISDICTION "_mj"
 
 /**
  * What is the label under which we find/place the merchant's
  * address in the locations list by default?
  */
 #define STANDARD_LABEL_MERCHANT_ADDRESS "_ma"
 
 /**
  * How long do we wait at most for /keys from the exchange(s)?
  * Ensures that we do not block forever just because some exchange
  * fails to respond *or* because our taler-merchant-keyscheck
  * refuses a forced download.
  */
 #define MAX_KEYS_WAIT \
         GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 2500)
 
 /**
  * Generate the base URL for the given merchant instance.
  *
  * @param connection the MHD connection
  * @param instance_id the merchant instance ID
  * @returns the merchant instance's base URL
  */
 static char *
 make_merchant_base_url (struct MHD_Connection *connection,
                         const char *instance_id)
 {
   struct GNUNET_Buffer buf;
 
   if (GNUNET_OK !=
       TMH_base_url_by_connection (connection,
                                   instance_id,
                                   &buf))
     return NULL;
   GNUNET_buffer_write_path (&buf,
                             "");
   return GNUNET_buffer_reap_str (&buf);
 }
 
 
 /**
  * Information about a product we are supposed to add to the order
  * based on what we know it from our inventory.
  */
 struct InventoryProduct
 {
   /**
    * Identifier of the product in the inventory.
    */
   const char *product_id;
 
   /**
    * Number of units of the product to add to the order (integer part).
    */
   uint64_t quantity;
 
   /**
    * Fractional part of the quantity in units of 1/1000000 of the base value.
    */
   uint32_t quantity_frac;
 
   /**
    * True if the integer quantity field was missing in the request.
    */
   bool quantity_missing;
 
   /**
    * String representation of the quantity, if supplied.
    */
   const char *unit_quantity;
 
   /**
    * True if the string quantity field was missing in the request.
    */
   bool unit_quantity_missing;
 };
 
 
 /**
  * Handle for a rekey operation where we (re)request
  * the /keys from the exchange.
  */
 struct RekeyExchange
 {
   /**
    * Kept in a DLL.
    */
   struct RekeyExchange *prev;
 
   /**
    * Kept in a DLL.
    */
   struct RekeyExchange *next;
 
   /**
    * order this is for.
    */
   struct OrderContext *oc;
 
   /**
    * Base URL of the exchange.
    */
   char *url;
 
   /**
    * Request for keys.
    */
   struct TMH_EXCHANGES_KeysOperation *fo;
 
 };
 
 
 /**
  * Data structure where we evaluate the viability of a given
  * wire method for this order.
  */
 struct WireMethodCandidate
 {
   /**
    * Kept in a DLL.
    */
   struct WireMethodCandidate *next;
 
   /**
    * Kept in a DLL.
    */
   struct WireMethodCandidate *prev;
 
   /**
    * The wire method we are evaluating.
    */
   const struct TMH_WireMethod *wm;
 
   /**
    * List of exchanges to use when we use this wire method.
    */
   json_t *exchanges;
 
   /**
    * Array of maximum amounts that could be paid over all available exchanges
    * for this @a wm. Used to determine if this order creation requests exceeds
    * legal limits.
    */
   struct TALER_Amount *total_exchange_limits;
 
   /**
    * Length of the @e total_exchange_limits array.
    */
   unsigned int num_total_exchange_limits;
 
 };
 
 
 /**
  * Information we keep per order we are processing.
  */
 struct OrderContext
 {
   /**
    * Information set in the ORDER_PHASE_PARSE_REQUEST phase.
    */
   struct
   {
     /**
      * Order field of the request
      */
     json_t *order;
 
     /**
      * Set to how long refunds will be allowed.
      */
     struct GNUNET_TIME_Relative refund_delay;
 
     /**
      * RFC8905 payment target type to find a matching merchant account
      */
     const char *payment_target;
 
     /**
      * Shared key to use with @e pos_algorithm.
      */
     char *pos_key;
 
     /**
      * Selected algorithm (by template) when we are to
      * generate an OTP code for payment confirmation.
      */
     enum TALER_MerchantConfirmationAlgorithm pos_algorithm;
 
     /**
      * Hash of the POST request data, used to detect
      * idempotent requests.
      */
     struct TALER_MerchantPostDataHashP h_post_data;
 
     /**
      * Length of the @e inventory_products array.
      */
     unsigned int inventory_products_length;
 
     /**
      * Specifies that some products are to be included in the
      * order from the inventory. For these inventory management
      * is performed (so the products must be in stock).
      */
     struct InventoryProduct *inventory_products;
 
     /**
      * Length of the @e uuids array.
      */
     unsigned int uuids_length;
 
     /**
      * array of UUIDs used to reserve products from @a inventory_products.
      */
     struct GNUNET_Uuid *uuids;
 
     /**
      * Claim token for the request.
      */
     struct TALER_ClaimTokenP claim_token;
 
     /**
      * Session ID (optional) to use for the order.
      */
     const char *session_id;
 
   } parse_request;
 
   /**
    * Information set in the ORDER_PHASE_PARSE_ORDER phase.
    */
   struct
   {
 
     /**
      * Our order ID.
      */
     char *order_id;
 
     /**
      * Summary of the contract.
      */
     const char *summary;
 
     /**
      * Internationalized summary.
      */
     const json_t *summary_i18n;
 
     /**
      * URL that will show that the contract was successful
      * after it has been paid for.
      */
     const char *fulfillment_url;
 
     /**
     * Message shown to the customer after paying for the contract.
     * Either fulfillment_url or fulfillment_message must be specified.
     */
     const char *fulfillment_message;
 
     /**
      * Map from IETF BCP 47 language tags to localized fulfillment messages.
      */
     const json_t *fulfillment_message_i18n;
 
     /**
     * Array of products that are part of the purchase.
     */
     const json_t *products;
 
     /**
      * URL where the same contract could be ordered again (if available).
      */
     const char *public_reorder_url;
 
     /**
      * Merchant base URL.
      */
     char *merchant_base_url;
 
     /**
      * Timestamp of the order.
      */
     struct GNUNET_TIME_Timestamp timestamp;
 
     /**
      * Deadline for refunds.
      */
     struct GNUNET_TIME_Timestamp refund_deadline;
 
     /**
      * Payment deadline.
      */
     struct GNUNET_TIME_Timestamp pay_deadline;
 
     /**
      * Wire transfer deadline.
      */
     struct GNUNET_TIME_Timestamp wire_deadline;
 
     /**
      * Wire transfer round-up interval to apply.
      */
     enum GNUNET_TIME_RounderInterval wire_deadline_rounder;
 
     /**
      * Delivery date.
      */
     struct GNUNET_TIME_Timestamp delivery_date;
 
     /**
      * Delivery location.
      */
     const json_t *delivery_location;
 
     /**
      * Specifies for how long the wallet should try to get an
      * automatic refund for the purchase.
      */
     struct GNUNET_TIME_Relative auto_refund;
 
     /**
      * Nonce generated by the wallet and echoed by the merchant
      * in this field when the proposal is generated.
      */
     const char *nonce;
 
     /**
      * Extra data that is only interpreted by the merchant frontend.
      */
     const json_t *extra;
 
     /**
      * Minimum age required by the order.
      */
     uint32_t minimum_age;
 
     /**
      * Version of the contract terms.
      */
     enum TALER_MERCHANT_ContractVersion version;
 
     /**
      * Details present depending on @e version.
      */
     union
     {
       /**
        * Details only present for v0.
        */
       struct
       {
         /**
          * Gross amount value of the contract. Used to
          * compute @e max_stefan_fee.
          */
         struct TALER_Amount brutto;
 
         /**
          * Maximum fee as given by the client request.
          */
         struct TALER_Amount max_fee;
       } v0;
 
       /**
        * Details only present for v1.
        */
       struct
       {
         /**
          * Array of contract choices. Is null for v0 contracts.
          */
         const json_t *choices;
       } v1;
     } details;
 
   } parse_order;
 
   /**
    * Information set in the ORDER_PHASE_PARSE_CHOICES phase.
    */
   struct
   {
     /**
      * Array of possible specific contracts the wallet/customer may choose
      * from by selecting the respective index when signing the deposit
      * confirmation.
      */
     struct TALER_MERCHANT_ContractChoice *choices;
 
     /**
      * Length of the @e choices array.
      */
     unsigned int choices_len;
 
     /**
      * Array of token families referenced in the contract.
      */
     struct TALER_MERCHANT_ContractTokenFamily *token_families;
 
     /**
      * Length of the @e token_families array.
      */
     unsigned int token_families_len;
   } parse_choices;
 
   /**
    * Information set in the ORDER_PHASE_MERGE_INVENTORY phase.
    */
   struct
   {
     /**
      * Merged array of products in the @e order.
      */
     json_t *products;
   } merge_inventory;
 
   /**
    * Information set in the ORDER_PHASE_ADD_PAYMENT_DETAILS phase.
    */
   struct
   {
 
     /**
      * DLL of wire methods under evaluation.
      */
     struct WireMethodCandidate *wmc_head;
 
     /**
      * DLL of wire methods under evaluation.
      */
     struct WireMethodCandidate *wmc_tail;
 
     /**
      * Array of maximum amounts that appear in the contract choices
      * per currency.
      * Determines the maximum amounts that a client could pay for this
      * order and which we must thus make sure is acceptable for the
      * selected wire method/account if possible.
      */
     struct TALER_Amount *max_choice_limits;
 
     /**
      * Length of the @e max_choice_limits array.
      */
     unsigned int num_max_choice_limits;
 
     /**
      * Set to true if we may need an exchange. True if any amount is non-zero.
      */
     bool need_exchange;
 
   } add_payment_details;
 
   /**
    * Information set in the ORDER_PHASE_SELECT_WIRE_METHOD phase.
    */
   struct
   {
 
     /**
      * Array of exchanges we find acceptable for this order and wire method.
      */
     json_t *exchanges;
 
     /**
      * Wire method (and our bank account) we have selected
      * to be included for this order.
      */
     const struct TMH_WireMethod *wm;
 
   } select_wire_method;
 
   /**
    * Information set in the ORDER_PHASE_SET_EXCHANGES phase.
    */
   struct
   {
 
     /**
      * Forced requests to /keys to update our exchange
      * information.
      */
     struct RekeyExchange *pending_reload_head;
 
     /**
      * Forced requests to /keys to update our exchange
      * information.
      */
     struct RekeyExchange *pending_reload_tail;
 
     /**
      * How long do we wait at most until giving up on getting keys?
      */
     struct GNUNET_TIME_Absolute keys_timeout;
 
     /**
      * Task to wake us up on @e keys_timeout.
      */
     struct GNUNET_SCHEDULER_Task *wakeup_task;
 
     /**
      * Did we previously force reloading of /keys from
      * all exchanges? Set to 'true' to prevent us from
      * doing it again (and again...).
      */
     bool forced_reload;
 
     /**
      * Did we find a working exchange?
      */
     bool exchange_ok;
 
     /**
      * Did we find an exchange that justifies
      * reloading keys?
      */
     bool promising_exchange;
 
     /**
      * Set to true once we have attempted to load exchanges
      * for the first time.
      */
     bool exchanges_tried;
 
     /**
      * Details depending on the contract version.
      */
     union
     {
 
       /**
        * Details for contract v0.
        */
       struct
       {
         /**
          * Maximum fee for @e order based on STEFAN curves.
          * Used to set @e max_fee if not provided as part of
          * @e order.
          */
         struct TALER_Amount max_stefan_fee;
 
       } v0;
 
       /**
        * Details for contract v1.
        */
       struct
       {
         /**
          * Maximum fee for @e order based on STEFAN curves by
          * contract choice.
          * Used to set @e max_fee if not provided as part of
          * @e order.
          */
         struct TALER_Amount *max_stefan_fees;
 
       } v1;
 
     } details;
 
   } set_exchanges;
 
   /**
    * Information set in the ORDER_PHASE_SET_MAX_FEE phase.
    */
   struct
   {
 
     /**
      * Details depending on the contract version.
      */
     union
     {
 
       /**
        * Details for contract v0.
        */
       struct
       {
         /**
          * Maximum fee
          */
         struct TALER_Amount max_fee;
       } v0;
 
       /**
        * Details for contract v1.
        */
       struct
       {
         /**
          * Maximum fees by contract choice.
          */
         struct TALER_Amount *max_fees;
 
       } v1;
 
     } details;
   } set_max_fee;
 
   /**
    * Information set in the ORDER_PHASE_EXECUTE_ORDER phase.
    */
   struct
   {
     /**
      * Which product (by offset) is out of stock, UINT_MAX if all were in-stock.
      */
     unsigned int out_of_stock_index;
 
     /**
      * Set to a previous claim token *if* @e idempotent
      * is also true.
      */
     struct TALER_ClaimTokenP token;
 
     /**
      * Set to true if the order was idempotent and there
      * was an equivalent one before.
      */
     bool idempotent;
 
     /**
      * Set to true if the order is in conflict with a
      * previous order with the same order ID.
      */
     bool conflict;
   } execute_order;
 
   struct
   {
     /**
      * Contract terms to store in the database.
      */
     json_t *contract;
   } serialize_order;
 
   /**
    * Connection of the request.
    */
   struct MHD_Connection *connection;
 
   /**
    * Kept in a DLL while suspended.
    */
   struct OrderContext *next;
 
   /**
    * Kept in a DLL while suspended.
    */
   struct OrderContext *prev;
 
   /**
    * Handler context for the request.
    */
   struct TMH_HandlerContext *hc;
 
   /**
    * #GNUNET_YES if suspended.
    */
   enum GNUNET_GenericReturnValue suspended;
 
   /**
    * Current phase of setting up the order.
    */
   enum
   {
     ORDER_PHASE_PARSE_REQUEST,
     ORDER_PHASE_PARSE_ORDER,
     ORDER_PHASE_PARSE_CHOICES,
     ORDER_PHASE_MERGE_INVENTORY,
     ORDER_PHASE_ADD_PAYMENT_DETAILS,
     ORDER_PHASE_SET_EXCHANGES,
     ORDER_PHASE_SELECT_WIRE_METHOD,
     ORDER_PHASE_SET_MAX_FEE,
     ORDER_PHASE_SERIALIZE_ORDER,
     ORDER_PHASE_SALT_FORGETTABLE,
     ORDER_PHASE_CHECK_CONTRACT,
     ORDER_PHASE_EXECUTE_ORDER,
 
     /**
      * Processing is done, we should return #MHD_YES.
      */
     ORDER_PHASE_FINISHED_MHD_YES,
 
     /**
      * Processing is done, we should return #MHD_NO.
      */
     ORDER_PHASE_FINISHED_MHD_NO
   } phase;
 
 
 };
 
 
 /**
  * Kept in a DLL while suspended.
  */
 static struct OrderContext *oc_head;
 
 /**
  * Kept in a DLL while suspended.
  */
 static struct OrderContext *oc_tail;
 
 
 void
 TMH_force_orders_resume ()
 {
   struct OrderContext *oc;
 
   while (NULL != (oc = oc_head))
   {
     GNUNET_CONTAINER_DLL_remove (oc_head,
                                  oc_tail,
                                  oc);
     oc->suspended = GNUNET_SYSERR;
     MHD_resume_connection (oc->connection);
   }
 }
 
 
 /**
  * Add the given @a val to the @a array.  Adds the
  * amount to a given entry in @a array if one with the same
  * currency exists, otherwise extends the @a array.
  *
  * @param[in,out] array pointer to array of amounts
  * @param[in,out] array_len length of @a array
  * @param val amount to add
  * @param cap cap for the sums to enforce, can be NULL
  */
 static void
 add_to_currency_vector (struct TALER_Amount **array,
                         unsigned int *array_len,
                         const struct TALER_Amount *val,
                         const struct TALER_Amount *cap)
 {
   for (unsigned int i = 0; i<*array_len; i++)
   {
     struct TALER_Amount *ai = &(*array)[i];
 
     if (GNUNET_OK ==
         TALER_amount_cmp_currency (ai,
                                    val))
     {
       enum TALER_AmountArithmeticResult aar;
 
       aar = TALER_amount_add (ai,
                               ai,
                               val);
       /* If we have a cap, we tolerate the overflow */
       GNUNET_assert ( (aar >= 0) ||
                       ( (TALER_AAR_INVALID_RESULT_OVERFLOW == aar) &&
                         (NULL != cap) ) );
       if (TALER_AAR_INVALID_RESULT_OVERFLOW == aar)
       {
         *ai = *cap;
       }
       else if (NULL != cap)
         GNUNET_assert (GNUNET_OK ==
                        TALER_amount_min (ai,
                                          ai,
                                          cap));
       return;
     }
   }
   GNUNET_array_append (*array,
                        *array_len,
                        *val);
   if (NULL != cap)
   {
     struct TALER_Amount *ai = &(*array)[(*array_len) - 1];
 
     GNUNET_assert (GNUNET_OK ==
                    TALER_amount_min (ai,
                                      ai,
                                      cap));
   }
 }
 
 
 /**
  * Update the phase of @a oc based on @a mret.
  *
  * @param[in,out] oc order to update phase for
  * @param mret #MHD_NO to close with #MHD_NO
  *             #MHD_YES to close with #MHD_YES
  */
 static void
 finalize_order (struct OrderContext *oc,
                 MHD_RESULT mret)
 {
   oc->phase = (MHD_YES == mret)
     ? ORDER_PHASE_FINISHED_MHD_YES
     : ORDER_PHASE_FINISHED_MHD_NO;
 }
 
 
 /**
  * Update the phase of @a oc based on @a ret.
  *
  * @param[in,out] oc order to update phase for
  * @param ret #GNUNET_SYSERR to close with #MHD_NO
  *            #GNUNET_NO to close with #MHD_YES
  *            #GNUNET_OK is not allowed!
  */
 static void
 finalize_order2 (struct OrderContext *oc,
                  enum GNUNET_GenericReturnValue ret)
 {
   GNUNET_assert (GNUNET_OK != ret);
   oc->phase = (GNUNET_NO == ret)
     ? ORDER_PHASE_FINISHED_MHD_YES
     : ORDER_PHASE_FINISHED_MHD_NO;
 }
 
 
 /**
  * Generate an error response for @a oc.
  *
  * @param[in,out] oc order context to respond to
  * @param http_status HTTP status code to set
  * @param ec error code to set
  * @param detail error message detail to set
  */
 static void
 reply_with_error (struct OrderContext *oc,
                   unsigned int http_status,
                   enum TALER_ErrorCode ec,
                   const char *detail)
 {
   MHD_RESULT mret;
 
   mret = TALER_MHD_reply_with_error (oc->connection,
                                      http_status,
                                      ec,
                                      detail);
   finalize_order (oc,
                   mret);
 }
 
 
 /**
  * Clean up memory used by @a wmc.
  *
  * @param[in,out] oc order context the WMC is part of
  * @param[in] wmc wire method candidate to free
  */
 static void
 free_wmc (struct OrderContext *oc,
           struct WireMethodCandidate *wmc)
 {
   GNUNET_CONTAINER_DLL_remove (oc->add_payment_details.wmc_head,
                                oc->add_payment_details.wmc_tail,
                                wmc);
   GNUNET_array_grow (wmc->total_exchange_limits,
                      wmc->num_total_exchange_limits,
                      0);
   json_decref (wmc->exchanges);
   GNUNET_free (wmc);
 }
 
 
 /**
  * Clean up memory used by @a cls.
  *
  * @param[in] cls the `struct OrderContext` to clean up
  */
 static void
 clean_order (void *cls)
 {
   struct OrderContext *oc = cls;
   struct RekeyExchange *rx;
 
   while (NULL != oc->add_payment_details.wmc_head)
     free_wmc (oc,
               oc->add_payment_details.wmc_head);
   while (NULL != (rx = oc->set_exchanges.pending_reload_head))
   {
     GNUNET_CONTAINER_DLL_remove (oc->set_exchanges.pending_reload_head,
                                  oc->set_exchanges.pending_reload_tail,
                                  rx);
     TMH_EXCHANGES_keys4exchange_cancel (rx->fo);
     GNUNET_free (rx->url);
     GNUNET_free (rx);
   }
   GNUNET_array_grow (oc->add_payment_details.max_choice_limits,
                      oc->add_payment_details.num_max_choice_limits,
                      0);
   if (NULL != oc->set_exchanges.wakeup_task)
   {
     GNUNET_SCHEDULER_cancel (oc->set_exchanges.wakeup_task);
     oc->set_exchanges.wakeup_task = NULL;
   }
   if (NULL != oc->select_wire_method.exchanges)
   {
     json_decref (oc->select_wire_method.exchanges);
     oc->select_wire_method.exchanges = NULL;
   }
   switch (oc->parse_order.version)
   {
   case TALER_MERCHANT_CONTRACT_VERSION_0:
     break;
   case TALER_MERCHANT_CONTRACT_VERSION_1:
     GNUNET_free (oc->set_max_fee.details.v1.max_fees);
     GNUNET_free (oc->set_exchanges.details.v1.max_stefan_fees);
     break;
   }
   if (NULL != oc->merge_inventory.products)
   {
     json_decref (oc->merge_inventory.products);
     oc->merge_inventory.products = NULL;
   }
   for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
   {
     TALER_MERCHANT_contract_choice_free (&oc->parse_choices.choices[i]);
   }
   GNUNET_array_grow (oc->parse_choices.choices,
                      oc->parse_choices.choices_len,
                      0);
   for (unsigned int i = 0; i<oc->parse_choices.token_families_len; i++)
   {
     struct TALER_MERCHANT_ContractTokenFamily *mctf
       = &oc->parse_choices.token_families[i];
 
     GNUNET_free (mctf->slug);
     GNUNET_free (mctf->name);
     GNUNET_free (mctf->description);
     json_decref (mctf->description_i18n);
     switch (mctf->kind)
     {
     case TALER_MERCHANT_CONTRACT_TOKEN_KIND_INVALID:
       GNUNET_break (0);
       break;
     case TALER_MERCHANT_CONTRACT_TOKEN_KIND_SUBSCRIPTION:
       for (size_t j = 0; j<mctf->details.subscription.trusted_domains_len; j++)
         GNUNET_free (mctf->details.subscription.trusted_domains[j]);
       GNUNET_free (mctf->details.subscription.trusted_domains);
       break;
     case TALER_MERCHANT_CONTRACT_TOKEN_KIND_DISCOUNT:
       for (size_t j = 0; j<mctf->details.discount.expected_domains_len; j++)
         GNUNET_free (mctf->details.discount.expected_domains[j]);
       GNUNET_free (mctf->details.discount.expected_domains);
       break;
     }
     for (unsigned int j = 0; j<mctf->keys_len; j++)
     {
       GNUNET_CRYPTO_blind_sign_pub_decref (mctf->keys[j].pub.public_key);
     }
     GNUNET_array_grow (mctf->keys,
                        mctf->keys_len,
                        0);
   }
   GNUNET_array_grow (oc->parse_choices.token_families,
                      oc->parse_choices.token_families_len,
                      0);
   GNUNET_array_grow (oc->parse_request.inventory_products,
                      oc->parse_request.inventory_products_length,
                      0);
   GNUNET_array_grow (oc->parse_request.uuids,
                      oc->parse_request.uuids_length,
                      0);
   GNUNET_free (oc->parse_request.pos_key);
   json_decref (oc->parse_request.order);
   json_decref (oc->serialize_order.contract);
   GNUNET_free (oc->parse_order.order_id);
   GNUNET_free (oc->parse_order.merchant_base_url);
   GNUNET_free (oc);
 }
 
 
 /* ***************** ORDER_PHASE_EXECUTE_ORDER **************** */
 
 /**
  * Compute remaining stock (integer and fractional parts) for a product.
  *
  * @param pd product details with current totals/sold/lost
  * @param[out] available_value remaining whole units (normalized, non-negative)
  * @param[out] available_frac remaining fractional units (0..MERCHANT_UNIT_FRAC_BASE-1)
  */
 static void
 compute_available_quantity (const struct TALER_MERCHANTDB_ProductDetails *pd,
                             uint64_t *available_value,
                             uint32_t *available_frac)
 {
   int64_t value;
   int64_t frac;
 
   GNUNET_assert (NULL != available_value);
   GNUNET_assert (NULL != available_frac);
 
   if ( (INT64_MAX == pd->total_stock) &&
        (INT32_MAX == pd->total_stock_frac) )
   {
     *available_value = pd->total_stock;
     *available_frac = pd->total_stock_frac;
     return;
   }
 
   value = (int64_t) pd->total_stock
           - (int64_t) pd->total_sold
           - (int64_t) pd->total_lost;
   frac = (int64_t) pd->total_stock_frac
          - (int64_t) pd->total_sold_frac
          - (int64_t) pd->total_lost_frac;
 
   if (frac < 0)
   {
     int64_t borrow = ((-frac) + MERCHANT_UNIT_FRAC_BASE - 1)
                      / MERCHANT_UNIT_FRAC_BASE;
     value -= borrow;
     frac += borrow * (int64_t) MERCHANT_UNIT_FRAC_BASE;
   }
   else if (frac >= MERCHANT_UNIT_FRAC_BASE)
   {
     int64_t carry = frac / MERCHANT_UNIT_FRAC_BASE;
     value += carry;
     frac -= carry * (int64_t) MERCHANT_UNIT_FRAC_BASE;
   }
 
   if (value < 0)
   {
     value = 0;
     frac = 0;
   }
 
   *available_value = (uint64_t) value;
   *available_frac = (uint32_t) frac;
 }
 
 
 /**
  * Execute the database transaction to setup the order.
  *
  * @param[in,out] oc order context
  * @return transaction status, #GNUNET_DB_STATUS_SUCCESS_NO_RESULTS if @a uuids were insufficient to reserve required inventory
  */
 static enum GNUNET_DB_QueryStatus
 execute_transaction (struct OrderContext *oc)
 {
   enum GNUNET_DB_QueryStatus qs;
   struct GNUNET_TIME_Timestamp timestamp;
   uint64_t order_serial;
 
   if (GNUNET_OK !=
       TMH_db->start (TMH_db->cls,
                      "insert_order"))
   {
     GNUNET_break (0);
     return GNUNET_DB_STATUS_HARD_ERROR;
   }
 
   /* Test if we already have an order with this id */
   {
     json_t *contract_terms;
     struct TALER_MerchantPostDataHashP orig_post;
 
     qs = TMH_db->lookup_order (TMH_db->cls,
                                oc->hc->instance->settings.id,
                                oc->parse_order.order_id,
                                &oc->execute_order.token,
                                &orig_post,
                                &contract_terms);
     /* If yes, check for idempotency */
     if (0 > qs)
     {
       GNUNET_break (0);
       TMH_db->rollback (TMH_db->cls);
       return qs;
     }
     if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
     {
       TMH_db->rollback (TMH_db->cls);
       json_decref (contract_terms);
       /* Comparing the contract terms is sufficient because all the other
          params get added to it at some point. */
       if (0 == GNUNET_memcmp (&orig_post,
                               &oc->parse_request.h_post_data))
       {
         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                     "Order creation idempotent\n");
         oc->execute_order.idempotent = true;
         return qs;
       }
       GNUNET_break_op (0);
       oc->execute_order.conflict = true;
       return qs;
     }
   }
 
   /* Setup order */
   qs = TMH_db->insert_order (TMH_db->cls,
                              oc->hc->instance->settings.id,
                              oc->parse_order.order_id,
                              oc->parse_request.session_id,
                              &oc->parse_request.h_post_data,
                              oc->parse_order.pay_deadline,
                              &oc->parse_request.claim_token,
                              oc->serialize_order.contract,  /* called 'contract terms' at database. */
                              oc->parse_request.pos_key,
                              oc->parse_request.pos_algorithm);
   if (qs <= 0)
   {
     /* qs == 0: probably instance does not exist (anymore) */
     TMH_db->rollback (TMH_db->cls);
     return qs;
   }
   /* Migrate locks from UUIDs to new order: first release old locks */
   for (unsigned int i = 0; i<oc->parse_request.uuids_length; i++)
   {
     qs = TMH_db->unlock_inventory (TMH_db->cls,
                                    &oc->parse_request.uuids[i]);
     if (qs < 0)
     {
       TMH_db->rollback (TMH_db->cls);
       return qs;
     }
     /* qs == 0 is OK here, that just means we did not HAVE any lock under this
        UUID */
   }
   /* Migrate locks from UUIDs to new order: acquire new locks
      (note: this can basically ONLY fail on serializability OR
      because the UUID locks were insufficient for the desired
      quantities). */
   for (unsigned int i = 0; i<oc->parse_request.inventory_products_length; i++)
   {
     qs = TMH_db->insert_order_lock (
       TMH_db->cls,
       oc->hc->instance->settings.id,
       oc->parse_order.order_id,
       oc->parse_request.inventory_products[i].product_id,
       oc->parse_request.inventory_products[i].quantity,
       oc->parse_request.inventory_products[i].quantity_frac);
     if (qs < 0)
     {
       TMH_db->rollback (TMH_db->cls);
       return qs;
     }
     if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
     {
       /* qs == 0: lock acquisition failed due to insufficient stocks */
       TMH_db->rollback (TMH_db->cls);
       oc->execute_order.out_of_stock_index = i; /* indicate which product is causing the issue */
       return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
     }
   }
   oc->execute_order.out_of_stock_index = UINT_MAX;
 
   /* Get the order serial and timestamp for the order we just created to
      update long-poll clients. */
   qs = TMH_db->lookup_order_summary (TMH_db->cls,
                                      oc->hc->instance->settings.id,
                                      oc->parse_order.order_id,
                                      &timestamp,
                                      &order_serial);
   if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT != qs)
   {
     TMH_db->rollback (TMH_db->cls);
     return qs;
   }
 
   {
     json_t *jhook;
 
     jhook = GNUNET_JSON_PACK (
       GNUNET_JSON_pack_string ("order_id",
                                oc->parse_order.order_id),
       GNUNET_JSON_pack_object_incref ("contract",
                                       oc->serialize_order.contract),
       GNUNET_JSON_pack_string ("instance_id",
                                oc->hc->instance->settings.id)
       );
     GNUNET_assert (NULL != jhook);
     qs = TMH_trigger_webhook (oc->hc->instance->settings.id,
                               "order_created",
                               jhook);
     json_decref (jhook);
     if (0 > qs)
     {
       TMH_db->rollback (TMH_db->cls);
       if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
         return qs;
       GNUNET_break (GNUNET_DB_STATUS_HARD_ERROR == qs);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_STORE_FAILED,
                         "failed to trigger webhooks");
       return qs;
     }
   }
 
   TMH_notify_order_change (oc->hc->instance,
                            TMH_OSF_NONE,
                            timestamp,
                            order_serial);
   /* finally, commit transaction (note: if it fails, we ALSO re-acquire
      the UUID locks, which is exactly what we want) */
   qs = TMH_db->commit (TMH_db->cls);
   if (0 > qs)
     return qs;
   return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;   /* 1 == success! */
 }
 
 
 /**
  * Transform an order into a proposal and store it in the
  * database. Write the resulting proposal or an error message
  * of a MHD connection.
  *
  * @param[in,out] oc order context
  */
 static void
 phase_execute_order (struct OrderContext *oc)
 {
   const struct TALER_MERCHANTDB_InstanceSettings *settings =
     &oc->hc->instance->settings;
   enum GNUNET_DB_QueryStatus qs;
 
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Executing database transaction to create order '%s' for instance '%s'\n",
               oc->parse_order.order_id,
               settings->id);
   for (unsigned int i = 0; i<MAX_RETRIES; i++)
   {
     TMH_db->preflight (TMH_db->cls);
     qs = execute_transaction (oc);
     if (GNUNET_DB_STATUS_SOFT_ERROR != qs)
       break;
   }
   if (0 >= qs)
   {
     /* Special report if retries insufficient */
     if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
     {
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_SOFT_FAILURE,
                         NULL);
       return;
     }
     if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
     {
       /* should be: contract (!) with same order ID
          already exists */
       reply_with_error (
         oc,
         MHD_HTTP_CONFLICT,
         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_ALREADY_EXISTS,
         oc->parse_order.order_id);
       return;
     }
     /* Other hard transaction error (disk full, etc.) */
     GNUNET_break (0);
     reply_with_error (
       oc,
       MHD_HTTP_INTERNAL_SERVER_ERROR,
       TALER_EC_GENERIC_DB_COMMIT_FAILED,
       NULL);
     return;
   }
 
   /* DB transaction succeeded, check for idempotent */
   if (oc->execute_order.idempotent)
   {
     MHD_RESULT ret;
 
     ret = TALER_MHD_REPLY_JSON_PACK (
       oc->connection,
       MHD_HTTP_OK,
       GNUNET_JSON_pack_string ("order_id",
                                oc->parse_order.order_id),
       GNUNET_JSON_pack_timestamp ("pay_deadline",
                                   oc->parse_order.pay_deadline),
       GNUNET_JSON_pack_allow_null (
         GNUNET_JSON_pack_data_varsize (
           "token",
           GNUNET_is_zero (&oc->execute_order.token)
           ? NULL
           : &oc->execute_order.token,
           sizeof (oc->execute_order.token))));
     finalize_order (oc,
                     ret);
     return;
   }
   if (oc->execute_order.conflict)
   {
     reply_with_error (
       oc,
       MHD_HTTP_CONFLICT,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_ALREADY_EXISTS,
       oc->parse_order.order_id);
     return;
   }
 
   /* DB transaction succeeded, check for out-of-stock */
   if (oc->execute_order.out_of_stock_index < UINT_MAX)
   {
     /* We had a product that has insufficient quantities,
        generate the details for the response. */
     struct TALER_MERCHANTDB_ProductDetails pd;
     MHD_RESULT ret;
     const struct InventoryProduct *ip;
     size_t num_categories = 0;
     uint64_t *categories = NULL;
     uint64_t available_quantity;
     uint32_t available_quantity_frac;
     char requested_quantity_buf[64];
     char available_quantity_buf[64];
 
     ip = &oc->parse_request.inventory_products[
       oc->execute_order.out_of_stock_index];
     memset (&pd,
             0,
             sizeof (pd));
     qs = TMH_db->lookup_product (
       TMH_db->cls,
       oc->hc->instance->settings.id,
       ip->product_id,
       &pd,
       &num_categories,
       &categories);
     switch (qs)
     {
     case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
       GNUNET_free (categories);
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Order creation failed: product out of stock\n");
 
       compute_available_quantity (&pd,
                                   &available_quantity,
                                   &available_quantity_frac);
       TMH_format_fractional_string (TMH_VK_QUANTITY,
                                     ip->quantity,
                                     ip->quantity_frac,
                                     sizeof (requested_quantity_buf),
                                     requested_quantity_buf);
       TMH_format_fractional_string (TMH_VK_QUANTITY,
                                     available_quantity,
                                     available_quantity_frac,
                                     sizeof (available_quantity_buf),
                                     available_quantity_buf);
       ret = TALER_MHD_REPLY_JSON_PACK (
         oc->connection,
         MHD_HTTP_GONE,
         GNUNET_JSON_pack_string (
           "product_id",
           ip->product_id),
         GNUNET_JSON_pack_uint64 (
           "requested_quantity",
           ip->quantity),
         GNUNET_JSON_pack_string (
           "unit_requested_quantity",
           requested_quantity_buf),
         GNUNET_JSON_pack_uint64 (
           "available_quantity",
           available_quantity),
         GNUNET_JSON_pack_string (
           "unit_available_quantity",
           available_quantity_buf),
         GNUNET_JSON_pack_allow_null (
           GNUNET_JSON_pack_timestamp (
             "restock_expected",
             pd.next_restock)));
       TALER_MERCHANTDB_product_details_free (&pd);
       finalize_order (oc,
                       ret);
       return;
     case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Order creation failed: unknown product out of stock\n");
       finalize_order (oc,
                       TALER_MHD_REPLY_JSON_PACK (
                         oc->connection,
                         MHD_HTTP_GONE,
                         GNUNET_JSON_pack_string (
                           "product_id",
                           ip->product_id),
                         GNUNET_JSON_pack_uint64 (
                           "requested_quantity",
                           ip->quantity),
                         GNUNET_JSON_pack_uint64 (
                           "available_quantity",
                           0)));
       return;
     case GNUNET_DB_STATUS_SOFT_ERROR:
       GNUNET_break (0);
       reply_with_error (
         oc,
         MHD_HTTP_INTERNAL_SERVER_ERROR,
         TALER_EC_GENERIC_DB_SOFT_FAILURE,
         NULL);
       return;
     case GNUNET_DB_STATUS_HARD_ERROR:
       GNUNET_break (0);
       reply_with_error (
         oc,
         MHD_HTTP_INTERNAL_SERVER_ERROR,
         TALER_EC_GENERIC_DB_FETCH_FAILED,
         NULL);
       return;
     }
     GNUNET_break (0);
     oc->phase = ORDER_PHASE_FINISHED_MHD_NO;
     return;
   } /* end 'out of stock' case */
 
   /* Everything in-stock, generate positive response */
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Order creation succeeded\n");
 
   {
     MHD_RESULT ret;
 
     ret = TALER_MHD_REPLY_JSON_PACK (
       oc->connection,
       MHD_HTTP_OK,
       GNUNET_JSON_pack_string ("order_id",
                                oc->parse_order.order_id),
       GNUNET_JSON_pack_allow_null (
         GNUNET_JSON_pack_data_varsize (
           "token",
           GNUNET_is_zero (&oc->parse_request.claim_token)
           ? NULL
           : &oc->parse_request.claim_token,
           sizeof (oc->parse_request.claim_token))));
     finalize_order (oc,
                     ret);
   }
 }
 
 
 /* ***************** ORDER_PHASE_CHECK_CONTRACT **************** */
 
 
 /**
  * Check that the contract is now well-formed. Upon success, continue
  * processing with execute_order().
  *
  * @param[in,out] oc order context
  */
 static void
 phase_check_contract (struct OrderContext *oc)
 {
   struct TALER_PrivateContractHashP h_control;
 
   switch (TALER_JSON_contract_hash (oc->serialize_order.contract,
                                     &h_control))
   {
   case GNUNET_SYSERR:
     GNUNET_break (0);
     reply_with_error (
       oc,
       MHD_HTTP_INTERNAL_SERVER_ERROR,
       TALER_EC_GENERIC_FAILED_COMPUTE_JSON_HASH,
       "could not compute hash of serialized order");
     return;
   case GNUNET_NO:
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_GENERIC_FAILED_COMPUTE_JSON_HASH,
       "order contained unallowed values");
     return;
   case GNUNET_OK:
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Contract hash is %s\n",
                 GNUNET_h2s (&h_control.hash));
     oc->phase++;
     return;
   }
   GNUNET_assert (0);
 }
 
 
 /* ***************** ORDER_PHASE_SALT_FORGETTABLE **************** */
 
 
 /**
  * Modify the final contract terms adding salts for
  * items that are forgettable.
  *
  * @param[in,out] oc order context
  */
 static void
 phase_salt_forgettable (struct OrderContext *oc)
 {
   if (GNUNET_OK !=
       TALER_JSON_contract_seed_forgettable (oc->parse_request.order,
                                             oc->serialize_order.contract))
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_GENERIC_JSON_INVALID,
       "could not compute hash of order due to bogus forgettable fields");
     return;
   }
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_SERIALIZE_ORDER **************** */
 
 /**
  * Get rounded time interval. @a start is calculated by rounding
  * @a ts down to the nearest multiple of @a precision.
  *
  * @param precision rounding precision.
  *        year, month, day, hour, minute are supported.
  * @param ts timestamp to round
  * @param[out] start start of the interval
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 static enum GNUNET_GenericReturnValue
 get_rounded_time_interval_down (struct GNUNET_TIME_Relative precision,
                                 struct GNUNET_TIME_Timestamp ts,
                                 struct GNUNET_TIME_Timestamp *start)
 {
   enum GNUNET_TIME_RounderInterval ri;
 
   ri = GNUNET_TIME_relative_to_round_interval (precision);
   if ( (GNUNET_TIME_RI_NONE == ri) &&
        (! GNUNET_TIME_relative_is_zero (precision)) )
   {
     *start = ts;
     return GNUNET_SYSERR;
   }
   *start = GNUNET_TIME_absolute_to_timestamp (
     GNUNET_TIME_round_down (ts.abs_time,
                             ri));
   return GNUNET_OK;
 }
 
 
 /**
  * Get rounded time interval. @a start is calculated by rounding
  * @a ts up to the nearest multiple of @a precision.
  *
  * @param precision rounding precision.
  *        year, month, day, hour, minute are supported.
  * @param ts timestamp to round
  * @param[out] start start of the interval
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 static enum GNUNET_GenericReturnValue
 get_rounded_time_interval_up (struct GNUNET_TIME_Relative precision,
                               struct GNUNET_TIME_Timestamp ts,
                               struct GNUNET_TIME_Timestamp *start)
 {
   enum GNUNET_TIME_RounderInterval ri;
 
   ri = GNUNET_TIME_relative_to_round_interval (precision);
   if ( (GNUNET_TIME_RI_NONE == ri) &&
        (! GNUNET_TIME_relative_is_zero (precision)) )
   {
     *start = ts;
     return GNUNET_SYSERR;
   }
   *start = GNUNET_TIME_absolute_to_timestamp (
     GNUNET_TIME_round_up (ts.abs_time,
                           ri));
   return GNUNET_OK;
 }
 
 
 /**
  * Find the family entry for the family of the given @a slug
  * in @a oc.
  *
  * @param[in] oc order context to search
  * @param slug slug to search for
  * @return NULL if @a slug was not found
  */
 static struct TALER_MERCHANT_ContractTokenFamily *
 find_family (const struct OrderContext *oc,
              const char *slug)
 {
   for (unsigned int i = 0; i<oc->parse_choices.token_families_len; i++)
   {
     if (0 == strcmp (oc->parse_choices.token_families[i].slug,
                      slug))
     {
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Token family %s already in order\n",
                   slug);
       return &oc->parse_choices.token_families[i];
     }
   }
   return NULL;
 }
 
 
 /**
  * Function called with each applicable family key that should
  * be added to the respective token family of the order.
  *
  * @param cls a `struct OrderContext *` to expand
  * @param tfkd token family key details to add to the contract
  */
 static void
 add_family_key (void *cls,
                 const struct TALER_MERCHANTDB_TokenFamilyKeyDetails *tfkd)
 {
   struct OrderContext *oc = cls;
   const struct TALER_MERCHANTDB_TokenFamilyDetails *tf = &tfkd->token_family;
   struct TALER_MERCHANT_ContractTokenFamily *family;
 
   family = find_family (oc,
                         tf->slug);
   if (NULL == family)
   {
     /* Family not yet in our contract terms, create new entry */
     struct TALER_MERCHANT_ContractTokenFamily new_family = {
       .slug = GNUNET_strdup (tf->slug),
       .name = GNUNET_strdup (tf->name),
       .description = GNUNET_strdup (tf->description),
       .description_i18n = json_incref (tf->description_i18n),
     };
 
     switch (tf->kind)
     {
     case TALER_MERCHANTDB_TFK_Subscription:
       {
         json_t *tdomains = json_object_get (tf->extra_data,
                                             "trusted_domains");
         json_t *dom;
         size_t i;
 
         new_family.kind = TALER_MERCHANT_CONTRACT_TOKEN_KIND_SUBSCRIPTION;
         new_family.critical = true;
         new_family.details.subscription.trusted_domains_len
           = json_array_size (tdomains);
         GNUNET_assert (new_family.details.subscription.trusted_domains_len
                        < UINT_MAX);
         new_family.details.subscription.trusted_domains
           = GNUNET_new_array (
               new_family.details.subscription.trusted_domains_len,
               char *);
         json_array_foreach (tdomains, i, dom)
         {
           const char *val;
 
           val = json_string_value (dom);
           GNUNET_break (NULL != val);
           if (NULL != val)
             new_family.details.subscription.trusted_domains[i]
               = GNUNET_strdup (val);
         }
         break;
       }
     case TALER_MERCHANTDB_TFK_Discount:
       {
         json_t *edomains = json_object_get (tf->extra_data,
                                             "expected_domains");
         json_t *dom;
         size_t i;
 
         new_family.kind = TALER_MERCHANT_CONTRACT_TOKEN_KIND_DISCOUNT;
         new_family.critical = false;
         new_family.details.discount.expected_domains_len
           = json_array_size (edomains);
         GNUNET_assert (new_family.details.discount.expected_domains_len
                        < UINT_MAX);
         new_family.details.discount.expected_domains
           = GNUNET_new_array (
               new_family.details.discount.expected_domains_len,
               char *);
         json_array_foreach (edomains, i, dom)
         {
           const char *val;
 
           val = json_string_value (dom);
           GNUNET_break (NULL != val);
           if (NULL != val)
             new_family.details.discount.expected_domains[i]
               = GNUNET_strdup (val);
         }
         break;
       }
     }
     GNUNET_array_append (oc->parse_choices.token_families,
                          oc->parse_choices.token_families_len,
                          new_family);
     family = &oc->parse_choices.token_families[
       oc->parse_choices.token_families_len - 1];
   }
   if (NULL == tfkd->pub.public_key)
     return;
   for (unsigned int i = 0; i<family->keys_len; i++)
   {
     if (TALER_token_issue_pub_cmp (&family->keys[i].pub,
                                    &tfkd->pub))
     {
       /* A matching key is already in the list. */
       return;
     }
   }
 
   {
     struct TALER_MERCHANT_ContractTokenFamilyKey key;
 
     TALER_token_issue_pub_copy (&key.pub,
                                 &tfkd->pub);
     key.valid_after = tfkd->signature_validity_start;
     key.valid_before = tfkd->signature_validity_end;
     GNUNET_array_append (family->keys,
                          family->keys_len,
                          key);
   }
 }
 
 
 /**
  * Check if the token family with the given @a slug is already present in the
  * list of token families for this order. If not, fetch its details and add it
  * to the list.
  *
  * @param[in,out] oc order context
  * @param slug slug of the token family
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 static enum GNUNET_GenericReturnValue
 add_input_token_family (struct OrderContext *oc,
                         const char *slug)
 {
   struct GNUNET_TIME_Timestamp now = GNUNET_TIME_timestamp_get ();
   struct GNUNET_TIME_Timestamp end = oc->parse_order.pay_deadline;
   enum GNUNET_DB_QueryStatus qs;
   enum TALER_ErrorCode ec = TALER_EC_INVALID; /* make compiler happy */
   unsigned int http_status = 0; /* make compiler happy */
 
   qs = TMH_db->lookup_token_family_keys (TMH_db->cls,
                                          oc->hc->instance->settings.id,
                                          slug,
                                          now,
                                          end,
                                          &add_family_key,
                                          oc);
   switch (qs)
   {
   case GNUNET_DB_STATUS_HARD_ERROR:
     GNUNET_break (0);
     http_status = MHD_HTTP_INTERNAL_SERVER_ERROR;
     ec = TALER_EC_GENERIC_DB_FETCH_FAILED;
     break;
   case GNUNET_DB_STATUS_SOFT_ERROR:
     GNUNET_break (0);
     http_status = MHD_HTTP_INTERNAL_SERVER_ERROR;
     ec = TALER_EC_GENERIC_DB_SOFT_FAILURE;
     break;
   case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Input token family slug %s unknown\n",
                 slug);
     http_status = MHD_HTTP_NOT_FOUND;
     ec = TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_TOKEN_FAMILY_SLUG_UNKNOWN;
     break;
   case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
     return GNUNET_OK;
   }
   reply_with_error (oc,
                     http_status,
                     ec,
                     slug);
   return GNUNET_SYSERR;
 }
 
 
 /**
  * Find the index of a key in the @a family that is valid at
  * the time @a valid_at.
  *
  * @param family to search
  * @param valid_at time when the key must be valid
  * @param[out] key_index index to initialize
  * @return #GNUNET_OK if a matching key was found
  */
 static enum GNUNET_GenericReturnValue
 find_key_index (struct TALER_MERCHANT_ContractTokenFamily *family,
                 struct GNUNET_TIME_Timestamp valid_at,
                 unsigned int *key_index)
 {
   for (unsigned int i = 0; i<family->keys_len; i++)
   {
     if ( (GNUNET_TIME_timestamp_cmp (family->keys[i].valid_after,
                                      <=,
                                      valid_at)) &&
          (GNUNET_TIME_timestamp_cmp (family->keys[i].valid_before,
                                      >=,
                                      valid_at)) )
     {
       /* The token family and a matching key already exist. */
       *key_index = i;
       return GNUNET_OK;
     }
   }
   return GNUNET_NO;
 }
 
 
 /**
  * Create fresh key pair based on @a cipher_spec.
  *
  * @param cipher_spec which kind of key pair should we generate
  * @param[out] priv set to new private key
  * @param[out] pub set to new public key
  * @return #GNUNET_OK on success
  */
 static enum GNUNET_GenericReturnValue
 create_key (const char *cipher_spec,
             struct TALER_TokenIssuePrivateKey *priv,
             struct TALER_TokenIssuePublicKey *pub)
 {
   unsigned int len;
   char dummy;
 
   if (0 == strcmp ("cs",
                    cipher_spec))
   {
     GNUNET_CRYPTO_blind_sign_keys_create (
       &priv->private_key,
       &pub->public_key,
       GNUNET_CRYPTO_BSA_CS);
     return GNUNET_OK;
   }
   if (1 ==
       sscanf (cipher_spec,
               "rsa(%u)%c",
               &len,
               &dummy))
   {
     GNUNET_CRYPTO_blind_sign_keys_create (
       &priv->private_key,
       &pub->public_key,
       GNUNET_CRYPTO_BSA_RSA,
       len);
     return GNUNET_OK;
   }
   return GNUNET_SYSERR;
 }
 
 
 /**
  * Check if the token family with the given @a slug is already present in the
  * list of token families for this order. If not, fetch its details and add it
  * to the list. Also checks if there is a public key with that expires after
  * the payment deadline.  If not, generates a new key pair and stores it in
  * the database.
  *
  * @param[in,out] oc order context
  * @param slug slug of the token family
  * @param valid_at time when the token returned must be valid
  * @param[out] key_index set to the index of the respective public
  *    key in the @a slug's token family keys array.
  * @return #GNUNET_OK on success, #GNUNET_SYSERR on error
  */
 static enum GNUNET_GenericReturnValue
 add_output_token_family (struct OrderContext *oc,
                          const char *slug,
                          struct GNUNET_TIME_Timestamp valid_at,
                          unsigned int *key_index)
 {
   struct TALER_MERCHANTDB_TokenFamilyKeyDetails key_details;
   struct TALER_MERCHANT_ContractTokenFamily *family;
   enum GNUNET_DB_QueryStatus qs;
 
   family = find_family (oc,
                         slug);
   if ( (NULL != family) &&
        (GNUNET_OK ==
         find_key_index (family,
                         valid_at,
                         key_index)) )
     return GNUNET_OK;
   qs = TMH_db->lookup_token_family_key (TMH_db->cls,
                                         oc->hc->instance->settings.id,
                                         slug,
                                         valid_at,
                                         oc->parse_order.pay_deadline,
                                         &key_details);
   switch (qs)
   {
   case GNUNET_DB_STATUS_HARD_ERROR:
     GNUNET_break (0);
     reply_with_error (oc,
                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                       TALER_EC_GENERIC_DB_FETCH_FAILED,
                       "lookup_token_family_key");
     return GNUNET_SYSERR;
   case GNUNET_DB_STATUS_SOFT_ERROR:
     /* Single-statement transaction shouldn't possibly cause serialization errors.
        Thus treating like a hard error. */
     GNUNET_break (0);
     reply_with_error (oc,
                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                       TALER_EC_GENERIC_DB_SOFT_FAILURE,
                       "lookup_token_family_key");
     return GNUNET_SYSERR;
   case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Output token family slug %s unknown\n",
                 slug);
     reply_with_error (oc,
                       MHD_HTTP_NOT_FOUND,
                       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_TOKEN_FAMILY_SLUG_UNKNOWN,
                       slug);
     return GNUNET_SYSERR;
   case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
     break;
   }
 
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Lookup of token family %s at %llu yielded %s\n",
               slug,
               (unsigned long long) valid_at.abs_time.abs_value_us,
               NULL == key_details.pub.public_key ? "no key" : "a key");
 
   if (NULL == family)
   {
     add_family_key (oc,
                     &key_details);
     family = find_family (oc,
                           slug);
     GNUNET_assert (NULL != family);
   }
   /* we don't need the full family details anymore */
   GNUNET_free (key_details.token_family.slug);
   GNUNET_free (key_details.token_family.name);
   GNUNET_free (key_details.token_family.description);
   json_decref (key_details.token_family.description_i18n);
   json_decref (key_details.token_family.extra_data);
 
   if (NULL != key_details.pub.public_key)
   {
     /* lookup_token_family_key must have found a matching key,
        and it must have been added. Find and use the index. */
     GNUNET_CRYPTO_blind_sign_pub_decref (key_details.pub.public_key);
     GNUNET_CRYPTO_blind_sign_priv_decref (key_details.priv.private_key);
     GNUNET_free (key_details.token_family.cipher_spec);
     GNUNET_assert (GNUNET_OK ==
                    find_key_index (family,
                                    valid_at,
                                    key_index));
     return GNUNET_OK;
   }
 
   /* No suitable key exists, create one! */
   {
     struct TALER_MERCHANT_ContractTokenFamilyKey key;
     enum GNUNET_DB_QueryStatus iqs;
     struct TALER_TokenIssuePrivateKey token_priv;
     struct GNUNET_TIME_Timestamp key_expires;
     struct GNUNET_TIME_Timestamp round_start;
 
     if (GNUNET_OK !=
         get_rounded_time_interval_down (
           key_details.token_family.validity_granularity,
           valid_at,
           &round_start))
     {
       GNUNET_break (0);
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Unsupported validity granularity interval %s found in database for token family %s!\n",
                   GNUNET_TIME_relative2s (
                     key_details.token_family.validity_granularity,
                     false),
                   slug);
       GNUNET_free (key_details.token_family.cipher_spec);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
                         "get_rounded_time_interval_down failed");
       return GNUNET_SYSERR;
     }
     if (GNUNET_TIME_relative_cmp (
           key_details.token_family.duration,
           <,
           GNUNET_TIME_relative_add (
             key_details.token_family.validity_granularity,
             key_details.token_family.start_offset)))
     {
       GNUNET_break (0);
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Inconsistent duration %s found in database for token family %s (below validity granularity plus start_offset)!\n",
                   GNUNET_TIME_relative2s (key_details.token_family.duration,
                                           false),
                   slug);
       GNUNET_free (key_details.token_family.cipher_spec);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
                         "duration, validty_granularity and start_offset inconsistent for token family");
       return GNUNET_SYSERR;
     }
     key.valid_after
       = GNUNET_TIME_timestamp_max (
           GNUNET_TIME_absolute_to_timestamp (
             GNUNET_TIME_absolute_subtract (
               round_start.abs_time,
               key_details.token_family.start_offset)),
           key_details.token_family.valid_after);
     key.valid_before
       = GNUNET_TIME_timestamp_min (
           GNUNET_TIME_absolute_to_timestamp (
             GNUNET_TIME_absolute_add (
               key.valid_after.abs_time,
               key_details.token_family.duration)),
           key_details.token_family.valid_before);
     GNUNET_assert (GNUNET_OK ==
                    get_rounded_time_interval_down (
                      key_details.token_family.validity_granularity,
                      key.valid_before,
                      &key_expires));
     if (GNUNET_TIME_timestamp_cmp (
           key_expires,
           ==,
           round_start))
     {
       /* valid_before does not actually end after the
          next rounded validity period would start;
          determine next rounded validity period
          start point and extend valid_before to cover
          the full validity period */
       GNUNET_assert (
         GNUNET_OK ==
         get_rounded_time_interval_up (
           key_details.token_family.validity_granularity,
           key.valid_before,
           &key_expires));
       /* This should basically always end up being key_expires */
       key.valid_before = GNUNET_TIME_timestamp_max (key.valid_before,
                                                     key_expires);
     }
     if (GNUNET_OK !=
         create_key (key_details.token_family.cipher_spec,
                     &token_priv,
                     &key.pub))
     {
       GNUNET_break (0);
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Unsupported cipher family %s found in database for token family %s!\n",
                   key_details.token_family.cipher_spec,
                   slug);
       GNUNET_free (key_details.token_family.cipher_spec);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
                         "invalid cipher stored in local database for token family");
       return GNUNET_SYSERR;
     }
     GNUNET_free (key_details.token_family.cipher_spec);
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Storing new key for slug %s of %s\n",
                 slug,
                 oc->hc->instance->settings.id);
     iqs = TMH_db->insert_token_family_key (TMH_db->cls,
                                            oc->hc->instance->settings.id,
                                            slug,
                                            &key.pub,
                                            &token_priv,
                                            key_expires,
                                            key.valid_after,
                                            key.valid_before);
     GNUNET_CRYPTO_blind_sign_priv_decref (token_priv.private_key);
     switch (iqs)
     {
     case GNUNET_DB_STATUS_HARD_ERROR:
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_STORE_FAILED,
                         NULL);
       return GNUNET_SYSERR;
     case GNUNET_DB_STATUS_SOFT_ERROR:
       /* Single-statement transaction shouldn't possibly cause serialization errors.
          Thus treating like a hard error. */
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_SOFT_FAILURE,
                         NULL);
       return GNUNET_SYSERR;
     case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_STORE_FAILED,
                         NULL);
       return GNUNET_SYSERR;
     case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
       break;
     }
     *key_index = family->keys_len;
     GNUNET_array_append (family->keys,
                          family->keys_len,
                          key);
   }
   return GNUNET_OK;
 }
 
 
 /**
  * Build JSON array that represents all of the token families
  * in the contract.
  *
  * @param[in] oc v1-style order context
  * @return JSON array with token families for the contract
  */
 static json_t *
 output_token_families (struct OrderContext *oc)
 {
   json_t *token_families = json_object ();
 
   GNUNET_assert (NULL != token_families);
   for (unsigned int i = 0; i<oc->parse_choices.token_families_len; i++)
   {
     const struct TALER_MERCHANT_ContractTokenFamily *family
       = &oc->parse_choices.token_families[i];
     json_t *jfamily;
 
     jfamily = TALER_MERCHANT_json_from_token_family (family);
 
     GNUNET_assert (jfamily != NULL);
 
     GNUNET_assert (0 ==
                    json_object_set_new (token_families,
                                         family->slug,
                                         jfamily));
   }
   return token_families;
 }
 
 
 /**
  * Build JSON array that represents all of the contract choices
  * in the contract.
  *
  * @param[in] oc v1-style order context
  * @return JSON array with token families for the contract
  */
 static json_t *
 output_contract_choices (struct OrderContext *oc)
 {
   json_t *choices = json_array ();
 
   GNUNET_assert (NULL != choices);
   for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
   {
     oc->parse_choices.choices[i].max_fee =
       oc->set_max_fee.details.v1.max_fees[i];
     GNUNET_assert (0 == json_array_append_new (
                      choices,
                      TALER_MERCHANT_json_from_contract_choice (
                        &oc->parse_choices.choices[i],
                        false)));
   }
 
   return choices;
 }
 
 
 /**
  * Serialize order into @a oc->serialize_order.contract,
  * ready to be stored in the database. Upon success, continue
  * processing with check_contract().
  *
  * @param[in,out] oc order context
  */
 static void
 phase_serialize_order (struct OrderContext *oc)
 {
   const struct TALER_MERCHANTDB_InstanceSettings *settings =
     &oc->hc->instance->settings;
   json_t *merchant;
 
   merchant = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_string ("name",
                              settings->name),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("website",
                                settings->website)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("email",
                                settings->email)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("logo",
                                settings->logo)));
   GNUNET_assert (NULL != merchant);
   {
     json_t *loca;
 
     /* Handle merchant address */
     loca = settings->address;
     if (NULL != loca)
     {
       loca = json_deep_copy (loca);
       GNUNET_assert (NULL != loca);
       GNUNET_assert (0 ==
                      json_object_set_new (merchant,
                                           "address",
                                           loca));
     }
   }
   {
     json_t *juri;
 
     /* Handle merchant jurisdiction */
     juri = settings->jurisdiction;
     if (NULL != juri)
     {
       juri = json_deep_copy (juri);
       GNUNET_assert (NULL != juri);
       GNUNET_assert (0 ==
                      json_object_set_new (merchant,
                                           "jurisdiction",
                                           juri));
     }
   }
 
   oc->serialize_order.contract = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_int64 ("version",
                             oc->parse_order.version),
     GNUNET_JSON_pack_string ("summary",
                              oc->parse_order.summary),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref (
         "summary_i18n",
         (json_t *) oc->parse_order.summary_i18n)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("public_reorder_url",
                                oc->parse_order.public_reorder_url)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("fulfillment_message",
                                oc->parse_order.fulfillment_message)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref (
         "fulfillment_message_i18n",
         (json_t *) oc->parse_order.fulfillment_message_i18n)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_string ("fulfillment_url",
                                oc->parse_order.fulfillment_url)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_uint64 ("minimum_age",
                                oc->parse_order.minimum_age)),
     GNUNET_JSON_pack_array_incref ("products",
                                    oc->merge_inventory.products),
     GNUNET_JSON_pack_data_auto ("h_wire",
                                 &oc->select_wire_method.wm->h_wire),
     GNUNET_JSON_pack_string ("wire_method",
                              oc->select_wire_method.wm->wire_method),
     GNUNET_JSON_pack_string ("order_id",
                              oc->parse_order.order_id),
     GNUNET_JSON_pack_timestamp ("timestamp",
                                 oc->parse_order.timestamp),
     GNUNET_JSON_pack_timestamp ("pay_deadline",
                                 oc->parse_order.pay_deadline),
     GNUNET_JSON_pack_timestamp ("wire_transfer_deadline",
                                 oc->parse_order.wire_deadline),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_timestamp ("delivery_date",
                                   oc->parse_order.delivery_date)),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref (
         "delivery_location",
         (json_t *) oc->parse_order.delivery_location)),
     GNUNET_JSON_pack_string ("merchant_base_url",
                              oc->parse_order.merchant_base_url),
     GNUNET_JSON_pack_object_steal ("merchant",
                                    merchant),
     GNUNET_JSON_pack_data_auto ("merchant_pub",
                                 &oc->hc->instance->merchant_pub),
     GNUNET_JSON_pack_array_incref ("exchanges",
                                    oc->select_wire_method.exchanges),
     GNUNET_JSON_pack_allow_null (
       GNUNET_JSON_pack_object_incref ("extra",
                                       (json_t *) oc->parse_order.extra))
     );
 
   {
     json_t *xtra;
 
     switch (oc->parse_order.version)
     {
     case TALER_MERCHANT_CONTRACT_VERSION_0:
       xtra = GNUNET_JSON_PACK (
         TALER_JSON_pack_amount ("max_fee",
                                 &oc->set_max_fee.details.v0.max_fee),
         TALER_JSON_pack_amount ("amount",
                                 &oc->parse_order.details.v0.brutto));
       break;
     case TALER_MERCHANT_CONTRACT_VERSION_1:
       {
         json_t *token_families = output_token_families (oc);
         json_t *choices = output_contract_choices (oc);
 
         if ( (NULL == token_families) ||
              (NULL == choices) )
         {
           GNUNET_break (0);
           return;
         }
         xtra = GNUNET_JSON_PACK (
           GNUNET_JSON_pack_array_steal ("choices",
                                         choices),
           GNUNET_JSON_pack_object_steal ("token_families",
                                          token_families));
         break;
       }
     default:
       GNUNET_assert (0);
     }
     GNUNET_assert (0 ==
                    json_object_update (oc->serialize_order.contract,
                                        xtra));
     json_decref (xtra);
   }
 
 
   /* Pack does not work here, because it doesn't set zero-values for timestamps */
   GNUNET_assert (0 ==
                  json_object_set_new (oc->serialize_order.contract,
                                       "refund_deadline",
                                       GNUNET_JSON_from_timestamp (
                                         oc->parse_order.refund_deadline)));
   /* auto_refund should only be set if it is not 0 */
   if (! GNUNET_TIME_relative_is_zero (oc->parse_order.auto_refund))
   {
     /* Pack does not work here, because it sets zero-values for relative times */
     GNUNET_assert (0 ==
                    json_object_set_new (oc->serialize_order.contract,
                                         "auto_refund",
                                         GNUNET_JSON_from_time_rel (
                                           oc->parse_order.auto_refund)));
   }
 
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_SET_MAX_FEE **************** */
 
 
 /**
  * Set @a max_fee in @a oc based on @a max_stefan_fee value if not overridden
  * by @a client_fee.  If neither is set, set the fee to zero using currency
  * from @a brutto.
  *
  * @param[in,out] oc order context
  * @param brutto brutto amount to compute fee for
  * @param client_fee client-given fee override (or invalid)
  * @param max_stefan_fee maximum STEFAN fee of any exchange
  * @param max_fee set to the maximum stefan fee
  */
 static void
 compute_fee (struct OrderContext *oc,
              const struct TALER_Amount *brutto,
              const struct TALER_Amount *client_fee,
              const struct TALER_Amount *max_stefan_fee,
              struct TALER_Amount *max_fee)
 {
   const struct TALER_MERCHANTDB_InstanceSettings *settings
     = &oc->hc->instance->settings;
 
   if (GNUNET_OK ==
       TALER_amount_is_valid (client_fee))
   {
     *max_fee = *client_fee;
     return;
   }
   if ( (settings->use_stefan) &&
        (NULL != max_stefan_fee) &&
        (GNUNET_OK ==
         TALER_amount_is_valid (max_stefan_fee)) )
   {
     *max_fee = *max_stefan_fee;
     return;
   }
   GNUNET_assert (
     GNUNET_OK ==
     TALER_amount_set_zero (brutto->currency,
                            max_fee));
 }
 
 
 /**
  * Initialize "set_max_fee" in @a oc based on STEFAN value or client
  * preference. Upon success, continue processing in next phase.
  *
  * @param[in,out] oc order context
  */
 static void
 phase_set_max_fee (struct OrderContext *oc)
 {
   switch (oc->parse_order.version)
   {
   case TALER_MERCHANT_CONTRACT_VERSION_0:
     compute_fee (oc,
                  &oc->parse_order.details.v0.brutto,
                  &oc->parse_order.details.v0.max_fee,
                  &oc->set_exchanges.details.v0.max_stefan_fee,
                  &oc->set_max_fee.details.v0.max_fee);
     break;
   case TALER_MERCHANT_CONTRACT_VERSION_1:
     oc->set_max_fee.details.v1.max_fees
       = GNUNET_new_array (oc->parse_choices.choices_len,
                           struct TALER_Amount);
     for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
       compute_fee (oc,
                    &oc->parse_choices.choices[i].amount,
                    &oc->parse_choices.choices[i].max_fee,
                    NULL != oc->set_exchanges.details.v1.max_stefan_fees
                    ? &oc->set_exchanges.details.v1.max_stefan_fees[i]
                    : NULL,
                    &oc->set_max_fee.details.v1.max_fees[i]);
     break;
   default:
     GNUNET_break (0);
     break;
   }
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_SELECT_WIRE_METHOD **************** */
 
 /**
  * Check that the @a brutto amount is at or below the
  * limits we have for the respective wire method candidate.
  *
  * @param wmc wire method candidate to check
  * @param brutto amount to check
  * @return true if the amount is OK, false if it is too high
  */
 static bool
 check_limits (struct WireMethodCandidate *wmc,
               const struct TALER_Amount *brutto)
 {
   for (unsigned int i = 0; i<wmc->num_total_exchange_limits; i++)
   {
     const struct TALER_Amount *total_exchange_limit
       = &wmc->total_exchange_limits[i];
 
     if (GNUNET_OK !=
         TALER_amount_cmp_currency (brutto,
                                    total_exchange_limit))
       continue;
     if (1 !=
         TALER_amount_cmp (brutto,
                           total_exchange_limit))
       return true;
   }
   return false;
 }
 
 
 /**
  * Phase to select a wire method that will be acceptable for the order.
  * If none is "perfect" (allows all choices), might jump back to the
  * previous phase to force "/keys" downloads to see if that helps.
  *
  * @param[in,out] oc order context
  */
 static void
 phase_select_wire_method (struct OrderContext *oc)
 {
   const struct TALER_Amount *ea;
   struct WireMethodCandidate *best = NULL;
   unsigned int max_choices = 0;
   unsigned int want_choices = 0;
 
   for (struct WireMethodCandidate *wmc = oc->add_payment_details.wmc_head;
        NULL != wmc;
        wmc = wmc->next)
   {
     unsigned int num_choices = 0;
 
     switch (oc->parse_order.version)
     {
     case TALER_MERCHANT_CONTRACT_VERSION_0:
       want_choices = 1;
       ea = &oc->parse_order.details.v0.brutto;
       if (TALER_amount_is_zero (ea) ||
           check_limits (wmc,
                         ea))
         num_choices++;
       break;
     case TALER_MERCHANT_CONTRACT_VERSION_1:
       want_choices = oc->parse_choices.choices_len;
       for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
       {
         ea = &oc->parse_choices.choices[i].amount;
         if (TALER_amount_is_zero (ea) ||
             check_limits (wmc,
                           ea))
           num_choices++;
       }
       break;
     default:
       GNUNET_assert (0);
     }
     if (num_choices > max_choices)
     {
       best = wmc;
       max_choices = num_choices;
     }
   }
 
   if ( (want_choices > max_choices) &&
        (oc->set_exchanges.promising_exchange) &&
        (! oc->set_exchanges.forced_reload) )
   {
     oc->set_exchanges.exchange_ok = false;
     /* Not all choices in the contract can work with these
        exchanges, try again with forcing /keys download */
     for (struct WireMethodCandidate *wmc = oc->add_payment_details.wmc_head;
          NULL != wmc;
          wmc = wmc->next)
     {
       json_array_clear (wmc->exchanges);
       GNUNET_array_grow (wmc->total_exchange_limits,
                          wmc->num_total_exchange_limits,
                          0);
     }
     oc->phase = ORDER_PHASE_SET_EXCHANGES;
     return;
   }
 
   if ( (NULL == best) &&
        (NULL != oc->parse_request.payment_target) )
   {
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Cannot create order: lacking suitable exchanges for payment target `%s'\n",
                 oc->parse_request.payment_target);
     reply_with_error (
       oc,
       MHD_HTTP_CONFLICT,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_EXCHANGES_FOR_WIRE_METHOD,
       oc->parse_request.payment_target);
     return;
   }
 
   if (NULL == best)
   {
     /* We actually do not have ANY workable exchange(s) */
     reply_with_error (
       oc,
       MHD_HTTP_UNAVAILABLE_FOR_LEGAL_REASONS,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_AMOUNT_EXCEEDS_LEGAL_LIMITS,
       NULL);
     return;
   }
 
   if (want_choices > max_choices)
   {
     /* Some choices are unpayable */
     GNUNET_log (
       GNUNET_ERROR_TYPE_WARNING,
       "Creating order, but some choices do not work with the selected wire method\n");
   }
   if ( (0 == json_array_size (best->exchanges)) &&
        (oc->add_payment_details.need_exchange) )
   {
     /* We did not find any reasonable exchange */
     GNUNET_log (
       GNUNET_ERROR_TYPE_WARNING,
       "Creating order, but only for choices without payment\n");
   }
 
   oc->select_wire_method.wm
     = best->wm;
   oc->select_wire_method.exchanges
     = json_incref (best->exchanges);
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_SET_EXCHANGES **************** */
 
 /**
  * Exchange `/keys` processing is done, resume handling
  * the order.
  *
  * @param[in,out] oc context to resume
  */
 static void
 resume_with_keys (struct OrderContext *oc)
 {
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Resuming order processing after /keys downloads\n");
   GNUNET_assert (GNUNET_YES == oc->suspended);
   GNUNET_CONTAINER_DLL_remove (oc_head,
                                oc_tail,
                                oc);
   oc->suspended = GNUNET_NO;
   MHD_resume_connection (oc->connection);
   TALER_MHD_daemon_trigger (); /* we resumed, kick MHD */
 }
 
 
 /**
  * Given a @a brutto amount for exchange with @a keys, set the
  * @a stefan_fee. Note that @a stefan_fee is updated to the maximum
  * of the input and the computed fee.
  *
  * @param[in,out] keys exchange keys
  * @param brutto some brutto amount the client is to pay
  * @param[in,out] stefan_fee set to STEFAN fee to be paid by the merchant
  */
 static void
 compute_stefan_fee (const struct TALER_EXCHANGE_Keys *keys,
                     const struct TALER_Amount *brutto,
                     struct TALER_Amount *stefan_fee)
 {
   struct TALER_Amount net;
 
   if (GNUNET_SYSERR !=
       TALER_EXCHANGE_keys_stefan_b2n (keys,
                                       brutto,
                                       &net))
   {
     struct TALER_Amount fee;
 
     TALER_EXCHANGE_keys_stefan_round (keys,
                                       &net);
     if (-1 == TALER_amount_cmp (brutto,
                                 &net))
     {
       /* brutto < netto! */
       /* => after rounding, there is no real difference */
       net = *brutto;
     }
     GNUNET_assert (0 <=
                    TALER_amount_subtract (&fee,
                                           brutto,
                                           &net));
     if ( (GNUNET_OK !=
           TALER_amount_is_valid (stefan_fee)) ||
          (-1 == TALER_amount_cmp (stefan_fee,
                                   &fee)) )
     {
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Updated STEFAN-based fee to %s\n",
                   TALER_amount2s (&fee));
       *stefan_fee = fee;
     }
   }
 }
 
 
 /**
  * Update MAX STEFAN fees based on @a keys.
  *
  * @param[in,out] oc order context to update
  * @param keys keys to derive STEFAN fees from
  */
 static void
 update_stefan (struct OrderContext *oc,
                const struct TALER_EXCHANGE_Keys *keys)
 {
   switch (oc->parse_order.version)
   {
   case TALER_MERCHANT_CONTRACT_VERSION_0:
     compute_stefan_fee (keys,
                         &oc->parse_order.details.v0.brutto,
                         &oc->set_exchanges.details.v0.max_stefan_fee);
     break;
   case TALER_MERCHANT_CONTRACT_VERSION_1:
     oc->set_exchanges.details.v1.max_stefan_fees
       = GNUNET_new_array (oc->parse_choices.choices_len,
                           struct TALER_Amount);
     for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
       if (0 == strcasecmp (keys->currency,
                            oc->parse_choices.choices[i].amount.currency))
         compute_stefan_fee (keys,
                             &oc->parse_choices.choices[i].amount,
                             &oc->set_exchanges.details.v1.max_stefan_fees[i]);
     break;
   default:
     GNUNET_assert (0);
   }
 }
 
 
 /**
  * Check our KYC status at all exchanges as our current limit is
  * too low and we failed to create an order.
  *
  * @param oc order context
  * @param wmc wire method candidate to notify for
  * @param exchange_url exchange to notify about
  */
 static void
 notify_kyc_required (const struct OrderContext *oc,
                      const struct WireMethodCandidate *wmc,
                      const char *exchange_url)
 {
   struct GNUNET_DB_EventHeaderP es = {
     .size = htons (sizeof (es)),
     .type = htons (TALER_DBEVENT_MERCHANT_EXCHANGE_KYC_RULE_TRIGGERED)
   };
   char *hws;
   char *extra;
 
   hws = GNUNET_STRINGS_data_to_string_alloc (
     &wmc->wm->h_wire,
     sizeof (wmc->wm->h_wire));
 
   GNUNET_asprintf (&extra,
                    "%s %s",
                    hws,
                    exchange_url);
   TMH_db->event_notify (TMH_db->cls,
                         &es,
                         extra,
                         strlen (extra) + 1);
   GNUNET_free (extra);
   GNUNET_free (hws);
 }
 
 
 /**
  * Checks the limits that apply for this @a exchange and
  * the @a wmc and if the exchange is acceptable at all, adds it
  * to the list of exchanges for the @a wmc.
  *
  * @param oc context of the order
  * @param exchange internal handle for the exchange
  * @param exchange_url base URL of this exchange
  * @param wmc wire method to evaluate this exchange for
  * @return true if the exchange is acceptable for the contract
  */
 static bool
 get_acceptable (struct OrderContext *oc,
                 const struct TMH_Exchange *exchange,
                 const char *exchange_url,
                 struct WireMethodCandidate *wmc)
 {
   const struct TALER_Amount *max_needed = NULL;
   unsigned int priority = 42; /* make compiler happy */
   json_t *j_exchange;
   enum TMH_ExchangeStatus res;
   struct TALER_Amount max_amount;
 
   for (unsigned int i = 0; i<oc->add_payment_details.num_max_choice_limits; i++)
   {
     struct TALER_Amount *val = &oc->add_payment_details.max_choice_limits[i];
 
     if (0 == strcasecmp (val->currency,
                          TMH_EXCHANGES_get_currency (exchange)))
     {
       max_needed = val;
       break;
     }
   }
   if (NULL == max_needed)
   {
     /* exchange currency not relevant for any of our choices, skip it */
     return false;
   }
 
   max_amount = *max_needed;
   res = TMH_exchange_check_debit (
     oc->hc->instance->settings.id,
     exchange,
     wmc->wm,
     &max_amount);
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Exchange %s evaluated at %d with max %s\n",
               exchange_url,
               res,
               TALER_amount2s (&max_amount));
   if (TALER_amount_is_zero (&max_amount))
   {
     if (! TALER_amount_is_zero (max_needed))
     {
       /* Trigger re-checking the current deposit limit when
        * paying non-zero amount with zero deposit limit */
       notify_kyc_required (oc,
                            wmc,
                            exchange_url);
     }
     /* If deposit is impossible, we don't list the
      * exchange in the contract terms. */
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Exchange %s deposit limit is zero, skipping it\n",
                 exchange_url);
     return false;
   }
   switch (res)
   {
   case TMH_ES_OK:
   case TMH_ES_RETRY_OK:
     priority = 1024;   /* high */
     oc->set_exchanges.exchange_ok = true;
     break;
   case TMH_ES_NO_ACC:
     if (oc->set_exchanges.forced_reload)
       priority = 0;   /* fresh negative response */
     else
       priority = 512; /* stale negative response */
     break;
   case TMH_ES_NO_CURR:
     if (oc->set_exchanges.forced_reload)
       priority = 0;   /* fresh negative response */
     else
       priority = 512; /* stale negative response */
     break;
   case TMH_ES_NO_KEYS:
     if (oc->set_exchanges.forced_reload)
       priority = 256;   /* fresh, no accounts yet */
     else
       priority = 768;  /* stale, no accounts yet */
     break;
   case TMH_ES_NO_ACC_RETRY_OK:
     if (oc->set_exchanges.forced_reload)
     {
       priority = 0;   /* fresh negative response */
     }
     else
     {
       oc->set_exchanges.promising_exchange = true;
       priority = 512; /* stale negative response */
     }
     break;
   case TMH_ES_NO_CURR_RETRY_OK:
     if (oc->set_exchanges.forced_reload)
       priority = 0;   /* fresh negative response */
     else
       priority = 512; /* stale negative response */
     break;
   case TMH_ES_NO_KEYS_RETRY_OK:
     if (oc->set_exchanges.forced_reload)
     {
       priority = 256;   /* fresh, no accounts yet */
     }
     else
     {
       oc->set_exchanges.promising_exchange = true;
       priority = 768;  /* stale, no accounts yet */
     }
     break;
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Exchange %s deposit limit is %s, adding it!\n",
               exchange_url,
               TALER_amount2s (&max_amount));
 
   j_exchange = GNUNET_JSON_PACK (
     GNUNET_JSON_pack_string ("url",
                              exchange_url),
     GNUNET_JSON_pack_uint64 ("priority",
                              priority),
     TALER_JSON_pack_amount ("max_contribution",
                             &max_amount),
     GNUNET_JSON_pack_data_auto ("master_pub",
                                 TMH_EXCHANGES_get_master_pub (exchange)));
   GNUNET_assert (NULL != j_exchange);
   /* Add exchange to list of exchanges for this wire method
      candidate */
   GNUNET_assert (0 ==
                  json_array_append_new (wmc->exchanges,
                                         j_exchange));
   add_to_currency_vector (&wmc->total_exchange_limits,
                           &wmc->num_total_exchange_limits,
                           &max_amount,
                           max_needed);
   return true;
 }
 
 
 /**
  * Function called with the result of a #TMH_EXCHANGES_keys4exchange()
  * operation.
  *
  * @param cls closure with our `struct RekeyExchange *`
  * @param keys the keys of the exchange
  * @param exchange representation of the exchange
  */
 static void
 keys_cb (
   void *cls,
   struct TALER_EXCHANGE_Keys *keys,
   struct TMH_Exchange *exchange)
 {
   struct RekeyExchange *rx = cls;
   struct OrderContext *oc = rx->oc;
   const struct TALER_MERCHANTDB_InstanceSettings *settings =
     &oc->hc->instance->settings;
   bool applicable = false;
 
   rx->fo = NULL;
   GNUNET_CONTAINER_DLL_remove (oc->set_exchanges.pending_reload_head,
                                oc->set_exchanges.pending_reload_tail,
                                rx);
   if (NULL == keys)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Failed to download %skeys\n",
                 rx->url);
     oc->set_exchanges.promising_exchange = true;
     goto cleanup;
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Got response for %skeys\n",
               rx->url);
 
   /* Evaluate the use of this exchange for each wire method candidate */
   for (unsigned int j = 0; j<keys->accounts_len; j++)
   {
     struct TALER_FullPayto full_payto = keys->accounts[j].fpayto_uri;
     char *wire_method = TALER_payto_get_method (full_payto.full_payto);
 
     for (struct WireMethodCandidate *wmc = oc->add_payment_details.wmc_head;
          NULL != wmc;
          wmc = wmc->next)
     {
       if (0 == strcmp (wmc->wm->wire_method,
                        wire_method) )
       {
         applicable |= get_acceptable (oc,
                                       exchange,
                                       rx->url,
                                       wmc);
       }
     }
     GNUNET_free (wire_method);
   }
   if (applicable &&
       settings->use_stefan)
     update_stefan (oc,
                    keys);
 cleanup:
   GNUNET_free (rx->url);
   GNUNET_free (rx);
   if (NULL != oc->set_exchanges.pending_reload_head)
     return;
   resume_with_keys (oc);
 }
 
 
 /**
  * Force re-downloading of /keys from @a exchange,
  * we currently have no acceptable exchange, so we
  * should try to get one.
  *
  * @param cls closure with our `struct OrderContext`
  * @param url base URL of the exchange
  * @param exchange internal handle for the exchange
  */
 static void
 get_exchange_keys (void *cls,
                    const char *url,
                    const struct TMH_Exchange *exchange)
 {
   struct OrderContext *oc = cls;
   struct RekeyExchange *rx;
 
   rx = GNUNET_new (struct RekeyExchange);
   rx->oc = oc;
   rx->url = GNUNET_strdup (url);
   GNUNET_CONTAINER_DLL_insert (oc->set_exchanges.pending_reload_head,
                                oc->set_exchanges.pending_reload_tail,
                                rx);
   if (oc->set_exchanges.forced_reload)
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Forcing download of %skeys\n",
                 url);
   rx->fo = TMH_EXCHANGES_keys4exchange (url,
                                         oc->set_exchanges.forced_reload,
                                         &keys_cb,
                                         rx);
 }
 
 
 /**
  * Task run when we are timing out on /keys and will just
  * proceed with what we got.
  *
  * @param cls our `struct OrderContext *` to resume
  */
 static void
 wakeup_timeout (void *cls)
 {
   struct OrderContext *oc = cls;
 
   oc->set_exchanges.wakeup_task = NULL;
   GNUNET_assert (GNUNET_YES == oc->suspended);
   GNUNET_CONTAINER_DLL_remove (oc_head,
                                oc_tail,
                                oc);
   MHD_resume_connection (oc->connection);
   oc->suspended = GNUNET_NO;
   TALER_MHD_daemon_trigger (); /* we resumed, kick MHD */
 }
 
 
 /**
  * Set list of acceptable exchanges in @a oc. Upon success, continues
  * processing with add_payment_details().
  *
  * @param[in,out] oc order context
  * @return true to suspend execution
  */
 static bool
 phase_set_exchanges (struct OrderContext *oc)
 {
   if (NULL != oc->set_exchanges.wakeup_task)
   {
     GNUNET_SCHEDULER_cancel (oc->set_exchanges.wakeup_task);
     oc->set_exchanges.wakeup_task = NULL;
   }
 
   if (! oc->add_payment_details.need_exchange)
   {
     /* Total amount is zero, so we don't actually need exchanges! */
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Order total is zero, no need for exchanges\n");
     oc->select_wire_method.exchanges = json_array ();
     GNUNET_assert (NULL != oc->select_wire_method.exchanges);
     /* Pick first one, doesn't matter as the amount is zero */
     oc->select_wire_method.wm = oc->hc->instance->wm_head;
     oc->phase = ORDER_PHASE_SET_MAX_FEE;
     return false;
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Trying to find exchanges\n");
   if (NULL == oc->set_exchanges.pending_reload_head)
   {
     if (! oc->set_exchanges.exchanges_tried)
     {
       oc->set_exchanges.exchanges_tried = true;
       oc->set_exchanges.keys_timeout
         = GNUNET_TIME_relative_to_absolute (MAX_KEYS_WAIT);
       TMH_exchange_get_trusted (&get_exchange_keys,
                                 oc);
     }
     else if ( (! oc->set_exchanges.forced_reload) &&
               (oc->set_exchanges.promising_exchange) &&
               (! oc->set_exchanges.exchange_ok) )
     {
       for (struct WireMethodCandidate *wmc = oc->add_payment_details.wmc_head;
            NULL != wmc;
            wmc = wmc->next)
         GNUNET_break (0 ==
                       json_array_clear (wmc->exchanges));
       /* Try one more time with forcing /keys download */
       oc->set_exchanges.forced_reload = true;
       TMH_exchange_get_trusted (&get_exchange_keys,
                                 oc);
     }
   }
   if (GNUNET_TIME_absolute_is_past (oc->set_exchanges.keys_timeout))
   {
     struct RekeyExchange *rx;
 
     while (NULL != (rx = oc->set_exchanges.pending_reload_head))
     {
       GNUNET_CONTAINER_DLL_remove (oc->set_exchanges.pending_reload_head,
                                    oc->set_exchanges.pending_reload_tail,
                                    rx);
       TMH_EXCHANGES_keys4exchange_cancel (rx->fo);
       GNUNET_free (rx->url);
       GNUNET_free (rx);
     }
   }
   if (NULL != oc->set_exchanges.pending_reload_head)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Still trying to (re)load %skeys\n",
                 oc->set_exchanges.pending_reload_head->url);
     oc->set_exchanges.wakeup_task
       = GNUNET_SCHEDULER_add_at (oc->set_exchanges.keys_timeout,
                                  &wakeup_timeout,
                                  oc);
     MHD_suspend_connection (oc->connection);
     oc->suspended = GNUNET_YES;
     GNUNET_CONTAINER_DLL_insert (oc_head,
                                  oc_tail,
                                  oc);
     return true; /* reloads pending */
   }
   oc->phase++;
   return false;
 }
 
 
 /* ***************** ORDER_PHASE_ADD_PAYMENT_DETAILS **************** */
 
 /**
  * Process the @a payment_target and add the details of how the
  * order could be paid to @a order. On success, continue
  * processing with add_payment_fees().
  *
  * @param[in,out] oc order context
  */
 static void
 phase_add_payment_details (struct OrderContext *oc)
 {
   /* First, determine the maximum amounts that could be paid per currency */
   switch (oc->parse_order.version)
   {
   case TALER_MERCHANT_CONTRACT_VERSION_0:
     GNUNET_array_append (oc->add_payment_details.max_choice_limits,
                          oc->add_payment_details.num_max_choice_limits,
                          oc->parse_order.details.v0.brutto);
     if (! TALER_amount_is_zero (
           &oc->parse_order.details.v0.brutto))
     {
       oc->add_payment_details.need_exchange = true;
     }
     break;
   case TALER_MERCHANT_CONTRACT_VERSION_1:
     for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
     {
       const struct TALER_Amount *amount
         = &oc->parse_choices.choices[i].amount;
       bool found = false;
 
       if (! TALER_amount_is_zero (amount))
       {
         oc->add_payment_details.need_exchange = true;
       }
       for (unsigned int j = 0; j<oc->add_payment_details.num_max_choice_limits;
            j++)
       {
         struct TALER_Amount *mx = &oc->add_payment_details.max_choice_limits[j];
         if (GNUNET_YES ==
             TALER_amount_cmp_currency (mx,
                                        amount))
         {
           TALER_amount_max (mx,
                             mx,
                             amount);
           found = true;
           break;
         }
       }
       if (! found)
       {
         GNUNET_array_append (oc->add_payment_details.max_choice_limits,
                              oc->add_payment_details.num_max_choice_limits,
                              *amount);
       }
     }
     break;
   default:
     GNUNET_assert (0);
   }
 
   /* Then, create a candidate for each available wire method */
   for (struct TMH_WireMethod *wm = oc->hc->instance->wm_head;
        NULL != wm;
        wm = wm->next)
   {
     struct WireMethodCandidate *wmc;
 
     /* Locate wire method that has a matching payment target */
     if (! wm->active)
       continue; /* ignore inactive methods */
     if ( (NULL != oc->parse_request.payment_target) &&
          (0 != strcasecmp (oc->parse_request.payment_target,
                            wm->wire_method) ) )
       continue; /* honor client preference */
     wmc = GNUNET_new (struct WireMethodCandidate);
     wmc->wm = wm;
     wmc->exchanges = json_array ();
     GNUNET_assert (NULL != wmc->exchanges);
     GNUNET_CONTAINER_DLL_insert (oc->add_payment_details.wmc_head,
                                  oc->add_payment_details.wmc_tail,
                                  wmc);
   }
 
   if (NULL == oc->add_payment_details.wmc_head)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "No wire method available for instance '%s'\n",
                 oc->hc->instance->settings.id);
     reply_with_error (oc,
                       MHD_HTTP_NOT_FOUND,
                       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_INSTANCE_CONFIGURATION_LACKS_WIRE,
                       oc->parse_request.payment_target);
     return;
   }
 
   /* next, we'll evaluate available exchanges */
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_MERGE_INVENTORY **************** */
 
 
 /**
  * Merge the inventory products into products, querying the
  * database about the details of those products. Upon success,
  * continue processing by calling add_payment_details().
  *
  * @param[in,out] oc order context to process
  */
 static void
 phase_merge_inventory (struct OrderContext *oc)
 {
   /**
    * parse_request.inventory_products => instructions to add products to contract terms
    * parse_order.products => contains products that are not from the backend-managed inventory.
    */
   if (NULL != oc->parse_order.products)
     oc->merge_inventory.products
       = json_deep_copy (oc->parse_order.products);
   else
     oc->merge_inventory.products
       = json_array ();
   /* Populate products from inventory product array and database */
   {
     GNUNET_assert (NULL != oc->merge_inventory.products);
     for (unsigned int i = 0; i<oc->parse_request.inventory_products_length; i++)
     {
       struct InventoryProduct *ip
         = &oc->parse_request.inventory_products[i];
       struct TALER_MERCHANTDB_ProductDetails pd;
       enum GNUNET_DB_QueryStatus qs;
       size_t num_categories = 0;
       uint64_t *categories = NULL;
 
       qs = TMH_db->lookup_product (TMH_db->cls,
                                    oc->hc->instance->settings.id,
                                    ip->product_id,
                                    &pd,
                                    &num_categories,
                                    &categories);
       if (qs <= 0)
       {
         enum TALER_ErrorCode ec = TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE;
         unsigned int http_status = 0;
 
         switch (qs)
         {
         case GNUNET_DB_STATUS_HARD_ERROR:
           GNUNET_break (0);
           http_status = MHD_HTTP_INTERNAL_SERVER_ERROR;
           ec = TALER_EC_GENERIC_DB_FETCH_FAILED;
           break;
         case GNUNET_DB_STATUS_SOFT_ERROR:
           GNUNET_break (0);
           http_status = MHD_HTTP_INTERNAL_SERVER_ERROR;
           ec = TALER_EC_GENERIC_DB_SOFT_FAILURE;
           break;
         case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
           GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                       "Product %s from order unknown\n",
                       ip->product_id);
           http_status = MHD_HTTP_NOT_FOUND;
           ec = TALER_EC_MERCHANT_GENERIC_PRODUCT_UNKNOWN;
           break;
         case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
           /* case listed to make compilers happy */
           GNUNET_assert (0);
         }
         reply_with_error (oc,
                           http_status,
                           ec,
                           ip->product_id);
         return;
       }
       GNUNET_free (categories);
       oc->parse_order.minimum_age
         = GNUNET_MAX (oc->parse_order.minimum_age,
                       pd.minimum_age);
       {
         const char *eparam;
 
         if ( (! ip->quantity_missing) &&
              (ip->quantity > (uint64_t) INT64_MAX) )
         {
           GNUNET_break_op (0);
           reply_with_error (oc,
                             MHD_HTTP_BAD_REQUEST,
                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
                             "quantity");
           TALER_MERCHANTDB_product_details_free (&pd);
           return;
         }
         if (GNUNET_OK !=
             TMH_process_quantity_inputs (TMH_VK_QUANTITY,
                                          pd.allow_fractional_quantity,
                                          ip->quantity_missing,
                                          (int64_t) ip->quantity,
                                          ip->unit_quantity_missing,
                                          ip->unit_quantity,
                                          &ip->quantity,
                                          &ip->quantity_frac,
                                          &eparam))
         {
           GNUNET_break_op (0);
           reply_with_error (oc,
                             MHD_HTTP_BAD_REQUEST,
                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
                             eparam);
           TALER_MERCHANTDB_product_details_free (&pd);
           return;
         }
       }
       {
         json_t *p;
         char unit_quantity_buf[64];
 
         TMH_format_fractional_string (TMH_VK_QUANTITY,
                                       ip->quantity,
                                       ip->quantity_frac,
                                       sizeof (unit_quantity_buf),
                                       unit_quantity_buf);
 
         p = GNUNET_JSON_PACK (
           GNUNET_JSON_pack_string ("product_name",
                                    pd.product_name),
           GNUNET_JSON_pack_string ("description",
                                    pd.description),
           GNUNET_JSON_pack_object_incref ("description_i18n",
                                           pd.description_i18n),
           GNUNET_JSON_pack_string ("unit",
                                    pd.unit),
           TALER_JSON_pack_amount ("price",
                                   &pd.price),
           GNUNET_JSON_pack_array_incref ("taxes",
                                          pd.taxes),
           GNUNET_JSON_pack_string ("image",
                                    pd.image),
           GNUNET_JSON_pack_uint64 (
             "quantity",
             ip->quantity),
           GNUNET_JSON_pack_string ("unit_quantity",
                                    unit_quantity_buf));
         GNUNET_assert (NULL != p);
         GNUNET_assert (0 ==
                        json_array_append_new (oc->merge_inventory.products,
                                               p));
       }
       TALER_MERCHANTDB_product_details_free (&pd);
     }
   }
   /* check if final product list is well-formed */
   if (! TMH_products_array_valid (oc->merge_inventory.products))
   {
     GNUNET_break_op (0);
     reply_with_error (oc,
                       MHD_HTTP_BAD_REQUEST,
                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                       "order:products");
     return;
   }
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_PARSE_CHOICES **************** */
 
 #ifdef HAVE_DONAU_DONAU_SERVICE_H
 /**
  * Callback function that is called for each donau instance.
  * It simply adds the provided donau_url to the json.
  *
  * @param cls closure with our `struct TALER_MERCHANT_ContractOutput *`
  * @param donau_url the URL of the donau instance
  */
 static void
 add_donau_url (void *cls,
                const char *donau_url)
 {
   struct TALER_MERCHANT_ContractOutput *output = cls;
 
   GNUNET_array_append (output->details.donation_receipt.donau_urls,
                        output->details.donation_receipt.donau_urls_len,
                        GNUNET_strdup (donau_url));
 }
 
 
 /**
  * Add the donau output to the contract output.
  *
  * @param oc order context
  * @param output contract output to add donau URLs to
  */
 static bool
 add_donau_output (struct OrderContext *oc,
                   struct TALER_MERCHANT_ContractOutput *output)
 {
   enum GNUNET_DB_QueryStatus qs;
 
   qs = TMH_db->select_donau_instances_filtered (
     TMH_db->cls,
     output->details.donation_receipt.amount.currency,
     &add_donau_url,
     output);
   if (qs < 0)
   {
     GNUNET_break (0);
     reply_with_error (oc,
                       MHD_HTTP_INTERNAL_SERVER_ERROR,
                       TALER_EC_GENERIC_DB_FETCH_FAILED,
                       "donau url parsing db call");
     for (unsigned int i = 0;
          i < output->details.donation_receipt.donau_urls_len;
          i++)
       GNUNET_free (output->details.donation_receipt.donau_urls[i]);
     GNUNET_array_grow (output->details.donation_receipt.donau_urls,
                        output->details.donation_receipt.donau_urls_len,
                        0);
     return false;
   }
   return true;
 }
 
 
 #endif
 
 /**
  * Parse contract choices. Upon success, continue
  * processing with merge_inventory().
  *
  * @param[in,out] oc order context
  */
 static void
 phase_parse_choices (struct OrderContext *oc)
 {
   const json_t *jchoices;
 
   switch (oc->parse_order.version)
   {
   case TALER_MERCHANT_CONTRACT_VERSION_0:
     oc->phase++;
     return;
   case TALER_MERCHANT_CONTRACT_VERSION_1:
     /* handle below */
     break;
   default:
     GNUNET_assert (0);
   }
 
   jchoices = oc->parse_order.details.v1.choices;
 
   if (! json_is_array (jchoices))
     GNUNET_assert (0);
   if (0 == json_array_size (jchoices))
   {
     reply_with_error (oc,
                       MHD_HTTP_BAD_REQUEST,
                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                       "choices");
     return;
   }
   GNUNET_array_grow (oc->parse_choices.choices,
                      oc->parse_choices.choices_len,
                      json_array_size (jchoices));
   for (unsigned int i = 0; i<oc->parse_choices.choices_len; i++)
   {
     struct TALER_MERCHANT_ContractChoice *choice
       = &oc->parse_choices.choices[i];
     const char *error_name;
     unsigned int error_line;
     const json_t *jinputs;
     const json_t *joutputs;
     bool no_fee;
     struct GNUNET_JSON_Specification spec[] = {
       TALER_JSON_spec_amount_any ("amount",
                                   &choice->amount),
       GNUNET_JSON_spec_mark_optional (
         TALER_JSON_spec_amount_any ("max_fee",
                                     &choice->max_fee),
         &no_fee),
       GNUNET_JSON_spec_mark_optional (
         GNUNET_JSON_spec_string_copy ("description",
                                       &choice->description),
         NULL),
       GNUNET_JSON_spec_mark_optional (
         GNUNET_JSON_spec_object_copy ("description_i18n",
                                       &choice->description_i18n),
         NULL),
       GNUNET_JSON_spec_mark_optional (
         GNUNET_JSON_spec_array_const ("inputs",
                                       &jinputs),
         NULL),
       GNUNET_JSON_spec_mark_optional (
         GNUNET_JSON_spec_array_const ("outputs",
                                       &joutputs),
         NULL),
       GNUNET_JSON_spec_end ()
     };
     enum GNUNET_GenericReturnValue ret;
 
     ret = GNUNET_JSON_parse (json_array_get (jchoices,
                                              i),
                              spec,
                              &error_name,
                              &error_line);
     if (GNUNET_OK != ret)
     {
       GNUNET_break_op (0);
       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                   "Choice parsing failed: %s:%u\n",
                   error_name,
                   error_line);
       reply_with_error (oc,
                         MHD_HTTP_BAD_REQUEST,
                         TALER_EC_GENERIC_PARAMETER_MALFORMED,
                         "choice");
       return;
     }
     if ( (! no_fee) &&
          (GNUNET_OK !=
           TALER_amount_cmp_currency (&choice->amount,
                                      &choice->max_fee)) )
     {
       GNUNET_break_op (0);
       GNUNET_JSON_parse_free (spec);
       reply_with_error (oc,
                         MHD_HTTP_BAD_REQUEST,
                         TALER_EC_GENERIC_CURRENCY_MISMATCH,
                         "different currencies used for 'max_fee' and 'amount' currency");
       return;
     }
 
     if (! TMH_test_exchange_configured_for_currency (
           choice->amount.currency))
     {
       GNUNET_break_op (0);
       GNUNET_JSON_parse_free (spec);
       reply_with_error (oc,
                         MHD_HTTP_CONFLICT,
                         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_EXCHANGE_FOR_CURRENCY,
                         choice->amount.currency);
       return;
     }
 
     if (NULL != jinputs)
     {
       const json_t *jinput;
       size_t idx;
       json_array_foreach ((json_t *) jinputs, idx, jinput)
       {
         struct TALER_MERCHANT_ContractInput input = {
           .details.token.count = 1
         };
 
         if (GNUNET_OK !=
             TALER_MERCHANT_parse_choice_input ((json_t *) jinput,
                                                &input,
                                                idx,
                                                true))
         {
           GNUNET_break_op (0);
           reply_with_error (oc,
                             MHD_HTTP_BAD_REQUEST,
                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
                             "input");
           return;
         }
 
         switch (input.type)
         {
         case TALER_MERCHANT_CONTRACT_INPUT_TYPE_INVALID:
           GNUNET_assert (0);
           break;
         case TALER_MERCHANT_CONTRACT_INPUT_TYPE_TOKEN:
           /* Ignore inputs tokens with 'count' field set to 0 */
           if (0 == input.details.token.count)
             continue;
 
           if (GNUNET_OK !=
               add_input_token_family (oc,
                                       input.details.token.token_family_slug))
 
           {
             GNUNET_break_op (0);
             reply_with_error (oc,
                               MHD_HTTP_BAD_REQUEST,
                               TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_TOKEN_FAMILY_SLUG_UNKNOWN,
                               input.details.token.token_family_slug);
             return;
           }
 
           GNUNET_array_append (choice->inputs,
                                choice->inputs_len,
                                input);
           continue;
         }
         GNUNET_assert (0);
       }
     }
 
     if (NULL != joutputs)
     {
       const json_t *joutput;
       size_t idx;
       json_array_foreach ((json_t *) joutputs, idx, joutput)
       {
         struct TALER_MERCHANT_ContractOutput output = {
           .details.token.count = 1
         };
 
         if (GNUNET_OK !=
             TALER_MERCHANT_parse_choice_output ((json_t *) joutput,
                                                 &output,
                                                 idx,
                                                 true))
         {
           reply_with_error (oc,
                             MHD_HTTP_BAD_REQUEST,
                             TALER_EC_GENERIC_PARAMETER_MALFORMED,
                             "output");
           return;
         }
 
         switch (output.type)
         {
         case TALER_MERCHANT_CONTRACT_OUTPUT_TYPE_INVALID:
           GNUNET_assert (0);
           break;
         case TALER_MERCHANT_CONTRACT_OUTPUT_TYPE_DONATION_RECEIPT:
 #ifdef HAVE_DONAU_DONAU_SERVICE_H
           output.details.donation_receipt.amount = choice->amount;
           if (! add_donau_output (oc,
                                   &output))
           {
             GNUNET_break (0);
             return;
           }
           GNUNET_array_append (choice->outputs,
                                choice->outputs_len,
                                output);
 #endif
           continue;
         case TALER_MERCHANT_CONTRACT_OUTPUT_TYPE_TOKEN:
           /* Ignore inputs tokens with 'count' field set to 0 */
           if (0 == output.details.token.count)
             continue;
 
           if (0 == output.details.token.valid_at.abs_time.abs_value_us)
             output.details.token.valid_at
               = GNUNET_TIME_timestamp_get ();
           if (GNUNET_OK !=
               add_output_token_family (oc,
                                        output.details.token.token_family_slug,
                                        output.details.token.valid_at,
                                        &output.details.token.key_index))
 
           {
             /* note: reply_with_error() was already called */
             GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                         "Could not handle output token family `%s'\n",
                         output.details.token.token_family_slug);
             return;
           }
 
           GNUNET_array_append (choice->outputs,
                                choice->outputs_len,
                                output);
           continue;
         }
         GNUNET_assert (0);
       }
     }
   }
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_PARSE_ORDER **************** */
 
 
 /**
  * Parse the order field of the request. Upon success, continue
  * processing with parse_choices().
  *
  * @param[in,out] oc order context
  */
 static void
 phase_parse_order (struct OrderContext *oc)
 {
   const struct TALER_MERCHANTDB_InstanceSettings *settings =
     &oc->hc->instance->settings;
   const char *merchant_base_url = NULL;
   uint64_t version = 0;
   const json_t *jmerchant = NULL;
   const char *order_id = NULL;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_uint64 ("version",
                                &version),
       NULL),
     GNUNET_JSON_spec_string ("summary",
                              &oc->parse_order.summary),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_array_const ("products",
                                     &oc->parse_order.products),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_object_const ("summary_i18n",
                                      &oc->parse_order.summary_i18n),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("order_id",
                                &order_id),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("fulfillment_message",
                                &oc->parse_order.fulfillment_message),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_object_const ("fulfillment_message_i18n",
                                      &oc->parse_order.fulfillment_message_i18n),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("fulfillment_url",
                                &oc->parse_order.fulfillment_url),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("public_reorder_url",
                                &oc->parse_order.public_reorder_url),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       TALER_JSON_spec_web_url ("merchant_base_url",
                                &merchant_base_url),
       NULL),
     /* For sanity check, this field must NOT be present */
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_object_const ("merchant",
                                      &jmerchant),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("timestamp",
                                   &oc->parse_order.timestamp),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("refund_deadline",
                                   &oc->parse_order.refund_deadline),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("pay_deadline",
                                   &oc->parse_order.pay_deadline),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("wire_transfer_deadline",
                                   &oc->parse_order.wire_deadline),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_object_const ("delivery_location",
                                      &oc->parse_order.delivery_location),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_timestamp ("delivery_date",
                                   &oc->parse_order.delivery_date),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_uint32 ("minimum_age",
                                &oc->parse_order.minimum_age),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_relative_time ("auto_refund",
                                       &oc->parse_order.auto_refund),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_object_const ("extra",
                                      &oc->parse_order.extra),
       NULL),
     GNUNET_JSON_spec_end ()
   };
   enum GNUNET_GenericReturnValue ret;
   bool computed_refund_deadline;
 
   oc->parse_order.refund_deadline = GNUNET_TIME_UNIT_FOREVER_TS;
   oc->parse_order.wire_deadline = GNUNET_TIME_UNIT_FOREVER_TS;
   ret = TALER_MHD_parse_json_data (oc->connection,
                                    oc->parse_request.order,
                                    spec);
   if (GNUNET_OK != ret)
   {
     GNUNET_break_op (0);
     finalize_order2 (oc,
                      ret);
     return;
   }
   if (NULL != order_id)
   {
     size_t len = strlen (order_id);
 
     for (size_t i = 0; i<len; i++)
     {
       char c = order_id[i];
 
       if (! ( ( (c >= 'A') &&
                 (c <= 'Z') ) ||
               ( (c >= 'a') &&
                 (c <= 'z') ) ||
               ( (c >= '0') &&
                 (c <= '9') ) ||
               (c == '-') ||
               (c == '_') ||
               (c == '.') ||
               (c == ':') ) )
       {
         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                     "Invalid character `%c' in order ID `%s'\n",
                     c,
                     order_id);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_CURRENCY_MISMATCH,
                           "Invalid character in order_id");
         return;
       }
     }
   }
   switch (version)
   {
   case 0:
     {
       bool no_fee;
       const json_t *choices = NULL;
       struct GNUNET_JSON_Specification specv0[] = {
         TALER_JSON_spec_amount_any (
           "amount",
           &oc->parse_order.details.v0.brutto),
         GNUNET_JSON_spec_mark_optional (
           TALER_JSON_spec_amount_any (
             "max_fee",
             &oc->parse_order.details.v0.max_fee),
           &no_fee),
         /* for sanity check, must be *absent*! */
         GNUNET_JSON_spec_mark_optional (
           GNUNET_JSON_spec_array_const ("choices",
                                         &choices),
           NULL),
         GNUNET_JSON_spec_end ()
       };
 
       ret = TALER_MHD_parse_json_data (oc->connection,
                                        oc->parse_request.order,
                                        specv0);
       if (GNUNET_OK != ret)
       {
         GNUNET_break_op (0);
         finalize_order2 (oc,
                          ret);
         return;
       }
       if ( (! no_fee) &&
            (GNUNET_OK !=
             TALER_amount_cmp_currency (&oc->parse_order.details.v0.brutto,
                                        &oc->parse_order.details.v0.max_fee)) )
       {
         GNUNET_break_op (0);
         GNUNET_JSON_parse_free (spec);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_CURRENCY_MISMATCH,
                           "different currencies used for 'max_fee' and 'amount' currency");
         return;
       }
       if (! TMH_test_exchange_configured_for_currency (
             oc->parse_order.details.v0.brutto.currency))
       {
         GNUNET_break_op (0);
         GNUNET_JSON_parse_free (spec);
         reply_with_error (oc,
                           MHD_HTTP_CONFLICT,
                           TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_EXCHANGE_FOR_CURRENCY,
                           oc->parse_order.details.v0.brutto.currency);
         return;
       }
       if (NULL != choices)
       {
         GNUNET_break_op (0);
         GNUNET_JSON_parse_free (spec);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_UNEXPECTED_REQUEST_ERROR,
                           "choices array must be null for v0 contracts");
         return;
       }
       oc->parse_order.version = TALER_MERCHANT_CONTRACT_VERSION_0;
       break;
     }
   case 1:
     {
       struct GNUNET_JSON_Specification specv1[] = {
         GNUNET_JSON_spec_array_const (
           "choices",
           &oc->parse_order.details.v1.choices),
         GNUNET_JSON_spec_end ()
       };
 
       ret = TALER_MHD_parse_json_data (oc->connection,
                                        oc->parse_request.order,
                                        specv1);
       if (GNUNET_OK != ret)
       {
         GNUNET_break_op (0);
         finalize_order2 (oc,
                          ret);
         return;
       }
       oc->parse_order.version = TALER_MERCHANT_CONTRACT_VERSION_1;
       break;
     }
   default:
     GNUNET_break_op (0);
     GNUNET_JSON_parse_free (spec);
     reply_with_error (oc,
                       MHD_HTTP_BAD_REQUEST,
                       TALER_EC_GENERIC_VERSION_MALFORMED,
                       "invalid version specified in order, supported are null, '0' or '1'");
     return;
   }
 
   /* Add order_id if it doesn't exist. */
   if (NULL != order_id)
   {
     oc->parse_order.order_id = GNUNET_strdup (order_id);
   }
   else
   {
     char buf[256];
     time_t timer;
     struct tm *tm_info;
     size_t off;
     uint64_t rand;
     char *last;
 
     time (&timer);
     tm_info = localtime (&timer);
     if (NULL == tm_info)
     {
       GNUNET_JSON_parse_free (spec);
       reply_with_error (
         oc,
         MHD_HTTP_INTERNAL_SERVER_ERROR,
         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_LOCALTIME,
         NULL);
       return;
     }
     off = strftime (buf,
                     sizeof (buf) - 1,
                     "%Y.%j",
                     tm_info);
     /* Check for error state of strftime */
     GNUNET_assert (0 != off);
     buf[off++] = '-';
     rand = GNUNET_CRYPTO_random_u64 (GNUNET_CRYPTO_QUALITY_WEAK,
                                      UINT64_MAX);
     last = GNUNET_STRINGS_data_to_string (&rand,
                                           sizeof (uint64_t),
                                           &buf[off],
                                           sizeof (buf) - off);
     GNUNET_assert (NULL != last);
     *last = '\0';
 
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Assigning order ID `%s' server-side\n",
                 buf);
 
     oc->parse_order.order_id = GNUNET_strdup (buf);
     GNUNET_assert (NULL != oc->parse_order.order_id);
   }
 
   /* Patch fulfillment URL with order_id (implements #6467). */
   if (NULL != oc->parse_order.fulfillment_url)
   {
     const char *pos;
 
     pos = strstr (oc->parse_order.fulfillment_url,
                   "${ORDER_ID}");
     if (NULL != pos)
     {
       /* replace ${ORDER_ID} with the real order_id */
       char *nurl;
 
       /* We only allow one placeholder */
       if (strstr (pos + strlen ("${ORDER_ID}"),
                   "${ORDER_ID}"))
       {
         GNUNET_break_op (0);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_PARAMETER_MALFORMED,
                           "fulfillment_url");
         return;
       }
 
       GNUNET_asprintf (&nurl,
                        "%.*s%s%s",
                        /* first output URL until ${ORDER_ID} */
                        (int) (pos - oc->parse_order.fulfillment_url),
                        oc->parse_order.fulfillment_url,
                        /* replace ${ORDER_ID} with the right order_id */
                        oc->parse_order.order_id,
                        /* append rest of original URL */
                        pos + strlen ("${ORDER_ID}"));
 
       oc->parse_order.fulfillment_url = GNUNET_strdup (nurl);
 
       GNUNET_free (nurl);
     }
   }
 
   if ( (GNUNET_TIME_absolute_is_zero (oc->parse_order.pay_deadline.abs_time)) ||
        (GNUNET_TIME_absolute_is_never (oc->parse_order.pay_deadline.abs_time)) )
   {
     oc->parse_order.pay_deadline = GNUNET_TIME_relative_to_timestamp (
       settings->default_pay_delay);
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Pay deadline was zero (or never), setting to %s\n",
                 GNUNET_TIME_timestamp2s (oc->parse_order.pay_deadline));
   }
   else if (GNUNET_TIME_absolute_is_past (oc->parse_order.pay_deadline.abs_time))
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_PAY_DEADLINE_IN_PAST,
       NULL);
     return;
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Pay deadline is %s\n",
               GNUNET_TIME_timestamp2s (oc->parse_order.pay_deadline));
 
   /* Check soundness of refund deadline, and that a timestamp
    * is actually present.  */
   {
     struct GNUNET_TIME_Timestamp now = GNUNET_TIME_timestamp_get ();
 
     /* Add timestamp if it doesn't exist (or is zero) */
     if (GNUNET_TIME_absolute_is_zero (oc->parse_order.timestamp.abs_time))
     {
       oc->parse_order.timestamp = now;
     }
 
     /* If no refund_deadline given, set one based on refund_delay.  */
     if (GNUNET_TIME_absolute_is_never (
           oc->parse_order.refund_deadline.abs_time))
     {
       if (GNUNET_TIME_relative_is_zero (oc->parse_request.refund_delay))
       {
         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                     "Refund delay is zero, no refunds are possible for this order\n");
         oc->parse_order.refund_deadline = GNUNET_TIME_UNIT_ZERO_TS;
       }
       else
       {
         computed_refund_deadline = true;
         oc->parse_order.refund_deadline
           = GNUNET_TIME_absolute_to_timestamp (
               GNUNET_TIME_absolute_add (oc->parse_order.pay_deadline.abs_time,
                                         oc->parse_request.refund_delay));
       }
     }
 
     if ( (! GNUNET_TIME_absolute_is_zero (
             oc->parse_order.delivery_date.abs_time)) &&
          (GNUNET_TIME_absolute_is_past (
             oc->parse_order.delivery_date.abs_time)) )
     {
       GNUNET_break_op (0);
       reply_with_error (
         oc,
         MHD_HTTP_BAD_REQUEST,
         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_DELIVERY_DATE_IN_PAST,
         NULL);
       return;
     }
   }
 
   if ( (! GNUNET_TIME_absolute_is_zero (
           oc->parse_order.refund_deadline.abs_time)) &&
        (GNUNET_TIME_absolute_is_past (
           oc->parse_order.refund_deadline.abs_time)) )
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_REFUND_DEADLINE_IN_PAST,
       NULL);
     return;
   }
 
   if (GNUNET_TIME_absolute_is_never (oc->parse_order.wire_deadline.abs_time))
   {
     struct GNUNET_TIME_Absolute start;
 
     start = GNUNET_TIME_absolute_max (
       oc->parse_order.refund_deadline.abs_time,
       oc->parse_order.pay_deadline.abs_time);
     oc->parse_order.wire_deadline
       = GNUNET_TIME_absolute_to_timestamp (
           GNUNET_TIME_round_up (
             GNUNET_TIME_absolute_add (
               start,
               settings->default_wire_transfer_delay),
             settings->default_wire_transfer_rounding_interval));
     if (GNUNET_TIME_absolute_is_never (
           oc->parse_order.wire_deadline.abs_time))
     {
       GNUNET_break_op (0);
       reply_with_error (
         oc,
         MHD_HTTP_BAD_REQUEST,
         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_WIRE_DEADLINE_IS_NEVER,
         "order:wire_transfer_deadline");
       return;
     }
   }
   else if (computed_refund_deadline)
   {
     /* if we computed the refund_deadline from default settings
        and did have a configured wire_deadline, make sure that
        the refund_deadline is at or below the wire_deadline. */
     oc->parse_order.refund_deadline
       = GNUNET_TIME_timestamp_min (oc->parse_order.refund_deadline,
                                    oc->parse_order.wire_deadline);
   }
   if (GNUNET_TIME_timestamp_cmp (oc->parse_order.wire_deadline,
                                  <,
                                  oc->parse_order.refund_deadline))
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_REFUND_AFTER_WIRE_DEADLINE,
       "order:wire_transfer_deadline;order:refund_deadline");
     return;
   }
 
   if (NULL != merchant_base_url)
   {
     if (('\0' == *merchant_base_url) ||
         ('/' != merchant_base_url[strlen (merchant_base_url) - 1]))
     {
       GNUNET_break_op (0);
       reply_with_error (
         oc,
         MHD_HTTP_BAD_REQUEST,
         TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_PROPOSAL_PARSE_ERROR,
         "merchant_base_url is not valid");
       return;
     }
     oc->parse_order.merchant_base_url
       = GNUNET_strdup (merchant_base_url);
   }
   else
   {
     char *url;
 
     url = make_merchant_base_url (oc->connection,
                                   settings->id);
     if (NULL == url)
     {
       GNUNET_break_op (0);
       reply_with_error (
         oc,
         MHD_HTTP_BAD_REQUEST,
         TALER_EC_GENERIC_PARAMETER_MISSING,
         "order:merchant_base_url");
       return;
     }
     oc->parse_order.merchant_base_url = url;
   }
 
   if ( (NULL != oc->parse_order.products) &&
        (! TMH_products_array_valid (oc->parse_order.products)) )
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_GENERIC_PARAMETER_MALFORMED,
       "order.products");
     return;
   }
 
   /* Merchant information must not already be present */
   if (NULL != jmerchant)
   {
     GNUNET_break_op (0);
     reply_with_error (
       oc,
       MHD_HTTP_BAD_REQUEST,
       TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_PROPOSAL_PARSE_ERROR,
       "'merchant' field already set, but must be provided by backend");
     return;
   }
 
   if ( (NULL != oc->parse_order.delivery_location) &&
        (! TMH_location_object_valid (oc->parse_order.delivery_location)) )
   {
     GNUNET_break_op (0);
     reply_with_error (oc,
                       MHD_HTTP_BAD_REQUEST,
                       TALER_EC_GENERIC_PARAMETER_MALFORMED,
                       "delivery_location");
     return;
   }
 
   oc->phase++;
 }
 
 
 /* ***************** ORDER_PHASE_PARSE_REQUEST **************** */
 
 /**
  * Parse the client request. Upon success,
  * continue processing by calling parse_order().
  *
  * @param[in,out] oc order context to process
  */
 static void
 phase_parse_request (struct OrderContext *oc)
 {
   const json_t *ip = NULL;
   const json_t *uuid = NULL;
   const char *otp_id = NULL;
   bool create_token = true; /* default */
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_json ("order",
                            &oc->parse_request.order),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_relative_time ("refund_delay",
                                       &oc->parse_request.refund_delay),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("payment_target",
                                &oc->parse_request.payment_target),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_array_const ("inventory_products",
                                     &ip),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("session_id",
                                &oc->parse_request.session_id),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_array_const ("lock_uuids",
                                     &uuid),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_bool ("create_token",
                              &create_token),
       NULL),
     GNUNET_JSON_spec_mark_optional (
       GNUNET_JSON_spec_string ("otp_id",
                                &otp_id),
       NULL),
     GNUNET_JSON_spec_end ()
   };
   enum GNUNET_GenericReturnValue ret;
 
   oc->parse_request.refund_delay
     = oc->hc->instance->settings.default_refund_delay;
   ret = TALER_MHD_parse_json_data (oc->connection,
                                    oc->hc->request_body,
                                    spec);
   if (GNUNET_OK != ret)
   {
     GNUNET_break_op (0);
     finalize_order2 (oc,
                      ret);
     return;
   }
   GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
               "Refund delay is %s\n",
               GNUNET_TIME_relative2s (oc->parse_request.refund_delay,
                                       false));
   TMH_db->expire_locks (TMH_db->cls);
   if (NULL != otp_id)
   {
     struct TALER_MERCHANTDB_OtpDeviceDetails td;
     enum GNUNET_DB_QueryStatus qs;
 
     memset (&td,
             0,
             sizeof (td));
     qs = TMH_db->select_otp (TMH_db->cls,
                              oc->hc->instance->settings.id,
                              otp_id,
                              &td);
     switch (qs)
     {
     case GNUNET_DB_STATUS_HARD_ERROR:
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_FETCH_FAILED,
                         "select_otp");
       return;
     case GNUNET_DB_STATUS_SOFT_ERROR:
       GNUNET_break (0);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_DB_SOFT_FAILURE,
                         "select_otp");
       return;
     case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
       reply_with_error (oc,
                         MHD_HTTP_NOT_FOUND,
                         TALER_EC_MERCHANT_GENERIC_OTP_DEVICE_UNKNOWN,
                         otp_id);
       return;
     case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
       break;
     }
     oc->parse_request.pos_key = td.otp_key;
     oc->parse_request.pos_algorithm = td.otp_algorithm;
     GNUNET_free (td.otp_description);
   }
   if (create_token)
   {
     GNUNET_CRYPTO_random_block (GNUNET_CRYPTO_QUALITY_NONCE,
                                 &oc->parse_request.claim_token,
                                 sizeof (oc->parse_request.claim_token));
   }
   /* Compute h_post_data (for idempotency check) */
   {
     char *req_body_enc;
 
     /* Dump normalized JSON to string. */
     if (NULL == (req_body_enc
                    = json_dumps (oc->hc->request_body,
                                  JSON_ENCODE_ANY
                                  | JSON_COMPACT
                                  | JSON_SORT_KEYS)))
     {
       GNUNET_break (0);
       GNUNET_JSON_parse_free (spec);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_ALLOCATION_FAILURE,
                         "request body normalization for hashing");
       return;
     }
     GNUNET_CRYPTO_hash (req_body_enc,
                         strlen (req_body_enc),
                         &oc->parse_request.h_post_data.hash);
     GNUNET_free (req_body_enc);
   }
 
   /* parse the inventory_products (optionally given) */
   if (NULL != ip)
   {
     unsigned int ipl = (unsigned int) json_array_size (ip);
 
     if ( (json_array_size (ip) != (size_t) ipl) ||
          (ipl > MAX_PRODUCTS) )
     {
       GNUNET_break (0);
       GNUNET_JSON_parse_free (spec);
       reply_with_error (oc,
                         MHD_HTTP_INTERNAL_SERVER_ERROR,
                         TALER_EC_GENERIC_ALLOCATION_FAILURE,
                         "inventory products too long");
       return;
     }
     GNUNET_array_grow (oc->parse_request.inventory_products,
                        oc->parse_request.inventory_products_length,
                        (unsigned int) json_array_size (ip));
     for (unsigned int i = 0; i<oc->parse_request.inventory_products_length; i++)
     {
       struct InventoryProduct *ipr = &oc->parse_request.inventory_products[i];
       const char *error_name;
       unsigned int error_line;
       struct GNUNET_JSON_Specification ispec[] = {
         GNUNET_JSON_spec_string ("product_id",
                                  &ipr->product_id),
         GNUNET_JSON_spec_mark_optional (
           GNUNET_JSON_spec_uint64 ("quantity",
                                    &ipr->quantity),
           &ipr->quantity_missing),
         GNUNET_JSON_spec_mark_optional (
           GNUNET_JSON_spec_string ("unit_quantity",
                                    &ipr->unit_quantity),
           &ipr->unit_quantity_missing),
         GNUNET_JSON_spec_end ()
       };
 
       ret = GNUNET_JSON_parse (json_array_get (ip,
                                                i),
                                ispec,
                                &error_name,
                                &error_line);
       if (GNUNET_OK != ret)
       {
         GNUNET_break_op (0);
         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                     "Product parsing failed at #%u: %s:%u\n",
                     i,
                     error_name,
                     error_line);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_PARAMETER_MALFORMED,
                           "inventory_products");
         return;
       }
       if (ipr->quantity_missing && ipr->unit_quantity_missing)
       {
         ipr->quantity = 1;
         ipr->quantity_missing = false;
       }
     }
   }
 
   /* parse the lock_uuids (optionally given) */
   if (NULL != uuid)
   {
     GNUNET_array_grow (oc->parse_request.uuids,
                        oc->parse_request.uuids_length,
                        json_array_size (uuid));
     for (unsigned int i = 0; i<oc->parse_request.uuids_length; i++)
     {
       json_t *ui = json_array_get (uuid,
                                    i);
 
       if (! json_is_string (ui))
       {
         GNUNET_break_op (0);
         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                     "UUID parsing failed at #%u\n",
                     i);
         reply_with_error (oc,
                           MHD_HTTP_BAD_REQUEST,
                           TALER_EC_GENERIC_PARAMETER_MALFORMED,
                           "lock_uuids");
         return;
       }
       TMH_uuid_from_string (json_string_value (ui),
                             &oc->parse_request.uuids[i]);
     }
   }
   oc->phase++;
 }
 
 
 /* ***************** Main handler **************** */
 
 
 MHD_RESULT
 TMH_private_post_orders (
   const struct TMH_RequestHandler *rh,
   struct MHD_Connection *connection,
   struct TMH_HandlerContext *hc)
 {
   struct OrderContext *oc = hc->ctx;
 
   if (NULL == oc)
   {
     oc = GNUNET_new (struct OrderContext);
     hc->ctx = oc;
     hc->cc = &clean_order;
     oc->connection = connection;
     oc->hc = hc;
   }
   while (1)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Processing order in phase %d\n",
                 oc->phase);
     switch (oc->phase)
     {
     case ORDER_PHASE_PARSE_REQUEST:
       phase_parse_request (oc);
       break;
     case ORDER_PHASE_PARSE_ORDER:
       phase_parse_order (oc);
       break;
     case ORDER_PHASE_PARSE_CHOICES:
       phase_parse_choices (oc);
       break;
     case ORDER_PHASE_MERGE_INVENTORY:
       phase_merge_inventory (oc);
       break;
     case ORDER_PHASE_ADD_PAYMENT_DETAILS:
       phase_add_payment_details (oc);
       break;
     case ORDER_PHASE_SET_EXCHANGES:
       if (phase_set_exchanges (oc))
         return MHD_YES;
       break;
     case ORDER_PHASE_SELECT_WIRE_METHOD:
       phase_select_wire_method (oc);
       break;
     case ORDER_PHASE_SET_MAX_FEE:
       phase_set_max_fee (oc);
       break;
     case ORDER_PHASE_SERIALIZE_ORDER:
       phase_serialize_order (oc);
       break;
     case ORDER_PHASE_CHECK_CONTRACT:
       phase_check_contract (oc);
       break;
     case ORDER_PHASE_SALT_FORGETTABLE:
       phase_salt_forgettable (oc);
       break;
     case ORDER_PHASE_EXECUTE_ORDER:
       phase_execute_order (oc);
       break;
     case ORDER_PHASE_FINISHED_MHD_YES:
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Finished processing order (1)\n");
       return MHD_YES;
     case ORDER_PHASE_FINISHED_MHD_NO:
       GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                   "Finished processing order (0)\n");
       return MHD_NO;
     }
   }
 }
 
 
 /* end of taler-merchant-httpd_private-post-orders.c */