implement GET /orders in libtalermerchant

8 files changed, 652 insertions, 57 deletions

diff --git a/src/backend/Makefile.am b/src/backend/Makefile.am
index 7be26748..74c3b201 100644
--- a/src/backend/Makefile.am
+++ b/src/backend/Makefile.am
@@ -37,6 +37,8 @@ taler_merchant_httpd_SOURCES = \
     taler-merchant-httpd_private-get-products.h \
   taler-merchant-httpd_private-get-products-ID.c \
     taler-merchant-httpd_private-get-products-ID.h \
+  taler-merchant-httpd_private-get-orders.c \
+    taler-merchant-httpd_private-get-orders.h \
   taler-merchant-httpd_private-patch-instances-ID.c \
     taler-merchant-httpd_private-patch-instances-ID.h \
   taler-merchant-httpd_private-patch-products-ID.c \
diff --git a/src/backend/taler-merchant-httpd.c b/src/backend/taler-merchant-httpd.c
index 9005b161..2534e07d 100644
--- a/src/backend/taler-merchant-httpd.c
+++ b/src/backend/taler-merchant-httpd.c
@@ -35,6 +35,7 @@
 #include "taler-merchant-httpd_private-get-instances-ID.h"
 #include "taler-merchant-httpd_private-get-products.h"
 #include "taler-merchant-httpd_private-get-products-ID.h"
+#include "taler-merchant-httpd_private-get-orders.h"
 #include "taler-merchant-httpd_private-patch-instances-ID.h"
 #include "taler-merchant-httpd_private-patch-products-ID.h"
 #include "taler-merchant-httpd_private-post-instances.h"
@@ -406,6 +407,7 @@ do_shutdown (void *cls)
   struct TMH_SuspendedConnection *sc;
 
   (void) cls;
+  TMH_force_get_orders_resume ();
 #if 0
   TMH_force_pc_resume ();
   TMH_force_trh_resume ();
diff --git a/src/backend/taler-merchant-httpd.h b/src/backend/taler-merchant-httpd.h
index 4d4aa7df..a6867e24 100644
--- a/src/backend/taler-merchant-httpd.h
+++ b/src/backend/taler-merchant-httpd.h
@@ -213,14 +213,6 @@ struct TMH_RequestHandler
 
 
 /**
- * Each MHD response handler that sets the "connection_cls" to a
- * non-NULL value must use a struct that has this struct as its first
- * member.  This struct contains a single callback, which will be
- * invoked to clean up the memory when the contection is completed.
- */
-struct TMH_HandlerContext;
-
-/**
  * Signature of a function used to clean up the context
  * we keep in the "connection_cls" of MHD when handling
  * a request.
diff --git a/src/backend/taler-merchant-httpd_private-post-orders.c b/src/backend/taler-merchant-httpd_private-post-orders.c
index af75999a..99e2a584 100644
--- a/src/backend/taler-merchant-httpd_private-post-orders.c
+++ b/src/backend/taler-merchant-httpd_private-post-orders.c
@@ -831,14 +831,8 @@ merge_inventory (struct MHD_Connection *connection,
   }
 
   {
-    bool have_total = false;
-    bool want_total;
-    struct TALER_Amount total;
     json_t *np = json_array ();
 
-    want_total = (NULL == json_object_get (order,
-                                           "total"));
-
     for (unsigned int i = 0; i<inventory_products_length; i++)
     {
       struct TALER_MERCHANTDB_ProductDetails pd;
@@ -898,52 +892,11 @@ merge_inventory (struct MHD_Connection *connection,
         GNUNET_assert (0 ==
                        json_array_append_new (np,
                                               p));
-        if (have_total)
-        {
-          if (0 <
-              TALER_amount_add (&total,
-                                &total,
-                                &pd.price))
-          {
-            GNUNET_break (0);
-            json_decref (np);
-            return TALER_MHD_reply_with_error (connection,
-                                               MHD_HTTP_INTERNAL_SERVER_ERROR,
-                                               TALER_EC_ORDERS_TOTAL_SUM_FAILED,
-                                               "failed to add up product prices");
-          }
-        }
-        else
-        {
-          have_total = true;
-          total = pd.price;
-        }
-
       }
       GNUNET_free (pd.description);
       GNUNET_free (pd.unit);
       json_decref (pd.address);
     }
-    if ( (have_total) &&
-         (want_total) )
-    {
-      GNUNET_assert (0 ==
-                     json_object_set_new (order,
-                                          "total",
-                                          TALER_JSON_from_amount (&total)));
-    }
-    if ( (! have_total) &&
-         (want_total) )
-    {
-      GNUNET_break_op (0);
-      json_decref (np);
-      return TALER_MHD_reply_with_error (
-        connection,
-        MHD_HTTP_BAD_REQUEST,
-        TALER_EC_ORDERS_TOTAL_MISSING,
-        "total missing in order, and we could not calculate it");
-    }
-
     /* merge into existing products list */
     {
       json_t *xp;
diff --git a/src/include/taler_merchant_service.h b/src/include/taler_merchant_service.h
index 8976210e..bc5eae14 100644
--- a/src/include/taler_merchant_service.h
+++ b/src/include/taler_merchant_service.h
@@ -1200,6 +1200,122 @@ TALER_MERCHANT_orders_post_cancel (
 
 
 /**
+ * Handle for a GET /orders operation.
+ */
+struct TALER_MERCHANT_OrdersGetHandle;
+
+/**
+ * Individual order (minimal information returned via GET /orders).
+ */
+struct TALER_MERCHANT_OrderEntry
+{
+  /**
+   * Order identifier.
+   */
+  const char *order_id;
+
+};
+
+
+/**
+ * Function called with the result of the GET /orders operation.
+ *
+ * @param cls closure
+ * @param hr HTTP response details
+ * @param orders_length length of the @a orders array
+ * @param orders array of orders the requested instance has made
+ */
+typedef void
+(*TALER_MERCHANT_OrdersGetCallback)(
+  void *cls,
+  const struct TALER_MERCHANT_HttpResponse *hr,
+  unsigned int orders_length,
+  const struct TALER_MERCHANT_OrderEntry orders[]);
+
+
+/**
+ * Make a GET /orders request.
+ *
+ * @param ctx the context
+ * @param backend_url HTTP base URL for the backend
+ * @param cb function to call with the backend's inventory information
+ * @param cb_cls closure for @a cb
+ * @return the request handle; NULL upon error
+ */
+struct TALER_MERCHANT_OrdersGetHandle *
+TALER_MERCHANT_orders_get (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  TALER_MERCHANT_OrdersGetCallback cb,
+  void *cb_cls);
+
+
+/**
+ * Possible values for a binary filter.
+ */
+enum TALER_MERCHANT_YesNoAll
+{
+  /**
+   * If condition is yes.
+   */
+  TALER_MERCHANT_YNA_YES = 1,
+
+  /**
+  * If condition is no.
+  */
+  TALER_MERCHANT_YNA_NO = 2,
+
+  /**
+   * Condition disabled.
+   */
+  TALER_MERCHANT_YNA_ALL = 3
+};
+
+
+/**
+ * Make a GET /orders request with filters.
+ *
+ * @param ctx the context
+ * @param backend_url HTTP base URL for the backend
+ * @param paid filter on payment status
+ * @param refunded filter on refund status
+ * @param wired filter on wire transfer status
+ * @param date range limit by date
+ * @param start_row range limit by order table row
+ * @param delta range from which @a date and @a start_row apply, positive
+ *              to return delta items after the given limit(s), negative to
+ *              return delta items before the given limit(s)
+ * @param timeout how long to wait (long polling) of zero results match the query
+ * @param cb function to call with the backend's inventory information
+ * @param cb_cls closure for @a cb
+ * @return the request handle; NULL upon error
+ */
+struct TALER_MERCHANT_OrdersGetHandle *
+TALER_MERCHANT_orders_get2 (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  enum TALER_MERCHANT_YesNoAll paid,
+  enum TALER_MERCHANT_YesNoAll refunded,
+  enum TALER_MERCHANT_YesNoAll wired,
+  struct GNUNET_TIME_Absolute date,
+  uint64_t start_row,
+  int64_t delta,
+  struct GNUNET_TIME_Relative timeout,
+  TALER_MERCHANT_OrdersGetCallback cb,
+  void *cb_cls);
+
+
+/**
+ * Cancel GET /orders operation.
+ *
+ * @param pgh operation to cancel
+ */
+void
+TALER_MERCHANT_orders_get_cancel (
+  struct TALER_MERCHANT_OrdersGetHandle *pgh);
+
+
+/**
  * Handle for a DELETE /orders/$ID operation.
  */
 struct TALER_MERCHANT_OrderDeleteHandle;
diff --git a/src/include/taler_merchantdb_plugin.h b/src/include/taler_merchantdb_plugin.h
index c74b67c9..956c526a 100644
--- a/src/include/taler_merchantdb_plugin.h
+++ b/src/include/taler_merchantdb_plugin.h
@@ -218,6 +218,83 @@ struct TALER_MERCHANTDB_ProductDetails
 };
 
 
+/**
+ * Possible values for a binary filter.
+ */
+enum TALER_MERCHANTDB_YesNoAll
+{
+  /**
+   * If condition is yes.
+   */
+  TALER_MERCHANTDB_YNA_YES = 1,
+
+  /**
+  * If condition is no.
+  */
+  TALER_MERCHANTDB_YNA_NO = 2,
+
+  /**
+   * Condition disabled.
+   */
+  TALER_MERCHANTDB_YNA_ALL = 3
+};
+
+
+/**
+ * Filter preferences.
+ */
+struct TALER_MERCHANTDB_OrderFilter
+{
+  /**
+   * Filter by payment status.
+   */
+  enum TALER_MERCHANTDB_YesNoAll paid;
+
+  /**
+   * Filter by refund status.
+   */
+  enum TALER_MERCHANTDB_YesNoAll refunded;
+
+  /**
+   * Filter by wire transfer status.
+   */
+  enum TALER_MERCHANTDB_YesNoAll wired;
+
+  /**
+   * Filter orders by date, exact meaning depends on @e delta.
+   */
+  struct GNUNET_TIME_Absolute date;
+
+  /**
+   * Filter orders by order serial number, exact meaning depends on @e delta.
+   */
+  uint64_t start_row;
+
+  /**
+   * takes value of the form N (-N), so that at most N values strictly older
+   * (younger) than start and date are returned.
+   */
+  int64_t delta;
+
+  /**
+   * Timeout for long-polling.
+   */
+  struct GNUNET_TIME_Relative timeout;
+
+};
+
+
+/**
+ * Typically called by `lookup_orders`.
+ *
+ * @param cls a `json_t *` JSON array to build
+ * @param order_id ID of the order
+ */
+typedef void
+(*TALER_MERCHANTDB_OrdersCallback)(void *cls,
+                                   const char *order_id);
+
+
 /* **************** OLD: ******************** */
 
 /**
@@ -628,13 +705,12 @@ struct TALER_MERCHANTDB_Plugin
                   const char *instance_id,
                   const char *order_id);
 
-
   /**
    * Retrieve order given its @a order_id and the @a instance_id.
    *
    * @param cls closure
    * @param instance_id instance to obtain order of
-   * @param order id order id used to perform the lookup
+   * @param order_id order id used to perform the lookup
    * @param[out] contract_terms where to store the retrieved contract terms,
    *             NULL to only test if the order exists
    * @return transaction status
@@ -645,6 +721,23 @@ struct TALER_MERCHANTDB_Plugin
                   const char *order_id,
                   json_t **contract_terms);
 
+  /**
+   * Retrieve orders given the @a instance_id.
+   *
+   * @param cls closure
+   * @param instance_id instance to obtain order of
+   * @param of filter to apply when looking up orders
+   * @param[out] contract_terms where to store the retrieved contract terms,
+   *             NULL to only test if the order exists
+   * @return transaction status
+   */
+  enum GNUNET_DB_QueryStatus
+  (*lookup_orders)(void *cls,
+                   const char *instance_id,
+                   const struct TALER_MERCHANTDB_OrderFilter *of,
+                   TALER_MERCHANTDB_OrdersCallback cb,
+                   void *cb_cls);
+
 
   /**
    * Insert order into db.
diff --git a/src/lib/Makefile.am b/src/lib/Makefile.am
index 82ea7677..2911c758 100644
--- a/src/lib/Makefile.am
+++ b/src/lib/Makefile.am
@@ -22,6 +22,7 @@ libtalermerchant_la_SOURCES = \
   merchant_api_get_instances.c \
   merchant_api_get_product.c \
   merchant_api_get_products.c \
+  merchant_api_get_orders.c \
   merchant_api_lock_product.c \
   merchant_api_patch_instance.c \
   merchant_api_patch_product.c \
diff --git a/src/lib/merchant_api_get_orders.c b/src/lib/merchant_api_get_orders.c
new file mode 100644
index 00000000..1b65b995
--- /dev/null
+++ b/src/lib/merchant_api_get_orders.c
@@ -0,0 +1,436 @@
+/*
+  This file is part of TALER
+  Copyright (C) 2014-2018, 2020 Taler Systems SA
+
+  TALER is free software; you can redistribute it and/or modify it under the
+  terms of the GNU Lesser General Public License as published by the Free Software
+  Foundation; either version 2.1, 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 Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License along with
+  TALER; see the file COPYING.LGPL.  If not, see
+  <http://www.gnu.org/licenses/>
+*/
+/**
+ * @file lib/merchant_api_get_orders.c
+ * @brief Implementation of the GET /orders request of the merchant's HTTP API
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <curl/curl.h>
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP status codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_merchant_service.h"
+#include <taler/taler_json_lib.h>
+#include <taler/taler_signatures.h>
+
+
+/**
+ * Handle for a GET /orders operation.
+ */
+struct TALER_MERCHANT_OrdersGetHandle
+{
+  /**
+   * The url for this request.
+   */
+  char *url;
+
+  /**
+   * Handle for the request.
+   */
+  struct GNUNET_CURL_Job *job;
+
+  /**
+   * Function to call with the result.
+   */
+  TALER_MERCHANT_OrdersGetCallback cb;
+
+  /**
+   * Closure for @a cb.
+   */
+  void *cb_cls;
+
+  /**
+   * Reference to the execution context.
+   */
+  struct GNUNET_CURL_Context *ctx;
+
+};
+
+
+/**
+ * Parse order information from @a ia.
+ *
+ * @param ia JSON array (or NULL!) with order data
+ * @param ogh operation handle
+ * @return #GNUNET_OK on success
+ */
+static int
+parse_orders (const json_t *ia,
+              struct TALER_MERCHANT_OrdersGetHandle *ogh)
+{
+  unsigned int oes_len = json_array_size (ia);
+  struct TALER_MERCHANT_OrderEntry oes[oes_len];
+  size_t index;
+  json_t *value;
+  int ret;
+
+  ret = GNUNET_OK;
+  json_array_foreach (ia, index, value) {
+    struct TALER_MERCHANT_OrderEntry *ie = &oes[index];
+    struct GNUNET_JSON_Specification spec[] = {
+      GNUNET_JSON_spec_string ("order_id",
+                               &ie->order_id),
+      GNUNET_JSON_spec_end ()
+    };
+
+    if (GNUNET_OK !=
+        GNUNET_JSON_parse (value,
+                           spec,
+                           NULL, NULL))
+    {
+      GNUNET_break_op (0);
+      ret = GNUNET_SYSERR;
+      continue;
+    }
+    if (GNUNET_SYSERR == ret)
+      break;
+  }
+  if (GNUNET_OK == ret)
+  {
+    struct TALER_MERCHANT_HttpResponse hr = {
+      .http_status = MHD_HTTP_OK
+    };
+
+    ogh->cb (ogh->cb_cls,
+             &hr,
+             oes_len,
+             oes);
+    ogh->cb = NULL; /* just to be sure */
+  }
+  return ret;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /orders request.
+ *
+ * @param cls the `struct TALER_MERCHANT_OrdersGetHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param json response body, NULL if not in JSON
+ */
+static void
+handle_get_orders_finished (void *cls,
+                            long response_code,
+                            const void *response)
+{
+  struct TALER_MERCHANT_OrdersGetHandle *ogh = cls;
+  const json_t *json = response;
+  struct TALER_MERCHANT_HttpResponse hr = {
+    .http_status = (unsigned int) response_code,
+    .reply = json
+  };
+
+  ogh->job = NULL;
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Got /orders response with status code %u\n",
+              (unsigned int) response_code);
+  switch (response_code)
+  {
+  case MHD_HTTP_OK:
+    {
+      json_t *orders;
+      struct GNUNET_JSON_Specification spec[] = {
+        GNUNET_JSON_spec_json ("orders",
+                               &orders),
+        GNUNET_JSON_spec_end ()
+      };
+
+      if (GNUNET_OK !=
+          GNUNET_JSON_parse (json,
+                             spec,
+                             NULL, NULL))
+      {
+        hr.http_status = 0;
+        hr.ec = TALER_EC_INVALID_RESPONSE;
+      }
+      else
+      {
+        if ( (! json_is_array (orders)) ||
+             (GNUNET_OK ==
+              parse_orders (orders,
+                            ogh)) )
+        {
+          GNUNET_JSON_parse_free (spec);
+          TALER_MERCHANT_orders_get_cancel (ogh);
+          return;
+        }
+        else
+        {
+          hr.http_status = 0;
+          hr.ec = TALER_EC_INVALID_RESPONSE;
+        }
+      }
+      GNUNET_JSON_parse_free (spec);
+      break;
+    }
+  default:
+    /* unexpected response code */
+    hr.ec = TALER_JSON_get_error_code (json);
+    hr.hint = TALER_JSON_get_error_hint (json);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected response code %u/%d\n",
+                (unsigned int) response_code,
+                (int) hr.ec);
+    break;
+  }
+  ogh->cb (ogh->cb_cls,
+           &hr,
+           0,
+           NULL);
+  TALER_MERCHANT_orders_get_cancel (ogh);
+}
+
+
+/**
+ * Make a GET /orders request.
+ *
+ * @param ctx the context
+ * @param backend_url HTTP base URL for the backend
+ * @param cb function to call with the backend's inventory information
+ * @param cb_cls closure for @a cb
+ * @return the request handle; NULL upon error
+ */
+struct TALER_MERCHANT_OrdersGetHandle *
+TALER_MERCHANT_orders_get (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  TALER_MERCHANT_OrdersGetCallback cb,
+  void *cb_cls)
+{
+  return TALER_MERCHANT_orders_get2 (ctx,
+                                     backend_url,
+                                     TALER_MERCHANT_YNA_ALL,
+                                     TALER_MERCHANT_YNA_ALL,
+                                     TALER_MERCHANT_YNA_ALL,
+                                     GNUNET_TIME_UNIT_FOREVER_ABS,
+                                     UINT64_MAX,
+                                     -20, /* default is most recent 20 entries */
+                                     GNUNET_TIME_UNIT_ZERO,
+                                     cb,
+                                     cb_cls);
+}
+
+
+/**
+ * Make a GET /orders request with filters.
+ *
+ * @param ctx the context
+ * @param backend_url HTTP base URL for the backend
+ * @param paid filter on payment status
+ * @param refunded filter on refund status
+ * @param wired filter on wire transfer status
+ * @param date range limit by date
+ * @param start_row range limit by order table row
+ * @param delta range from which @a date and @a start_row apply, positive
+ *              to return delta items after the given limit(s), negative to
+ *              return delta items before the given limit(s)
+ * @param timeout how long to wait (long polling) of zero results match the query
+ * @param cb function to call with the backend's inventory information
+ * @param cb_cls closure for @a cb
+ * @return the request handle; NULL upon error
+ */
+struct TALER_MERCHANT_OrdersGetHandle *
+TALER_MERCHANT_orders_get2 (
+  struct GNUNET_CURL_Context *ctx,
+  const char *backend_url,
+  enum TALER_MERCHANT_YesNoAll paid,
+  enum TALER_MERCHANT_YesNoAll refunded,
+  enum TALER_MERCHANT_YesNoAll wired,
+  struct GNUNET_TIME_Absolute date,
+  uint64_t start_row,
+  int64_t delta,
+  struct GNUNET_TIME_Relative timeout,
+  TALER_MERCHANT_OrdersGetCallback cb,
+  void *cb_cls)
+{
+  struct TALER_MERCHANT_OrdersGetHandle *ogh;
+  CURL *eh;
+  unsigned int timeout_ms = timeout.rel_value_us
+                            / GNUNET_TIME_UNIT_MILLISECONDS.rel_value_us;
+
+  GNUNET_assert (NULL != backend_url);
+  if (0 == delta)
+  {
+    GNUNET_break (0);
+    return NULL;
+  }
+  ogh = GNUNET_new (struct TALER_MERCHANT_OrdersGetHandle);
+  ogh->ctx = ctx;
+  ogh->cb = cb;
+  ogh->cb_cls = cb_cls;
+
+  /* build ogh->url with the various optional arguments */
+  {
+    struct GNUNET_Buffer buf = { 0 };
+    bool first = true;
+    /**
+     * Macro to append @a a and @a b to @a buf, using
+     * the right separators between key (@a a) and
+     * value (@a b). Uses "first" to decide between
+     * using "?" and "&" as the separator.
+     *
+     * @param a a key
+     * @param b a value
+     */
+#define APPEND(a,b)                             \
+  do { \
+    if (first) \
+      GNUNET_buffer_write_str (&buf, \
+                               "?");            \
+    else \
+      GNUNET_buffer_write_str (&buf, \
+                               "&"); \
+    first = false; \
+    GNUNET_buffer_write_str (&buf, (a)); \
+    GNUNET_buffer_write_str (&buf, "="); \
+    GNUNET_buffer_write_str (&buf, (b)); \
+  } while (0)
+
+    {
+      char *url;
+
+      url = TALER_url_join (backend_url,
+                            "private/orders",
+                            NULL);
+      if (NULL == url)
+        goto finished;
+      GNUNET_buffer_write_str (&buf,
+                               url);
+      GNUNET_free (url);
+    }
+    if (TALER_MERCHANT_YNA_ALL != paid)
+      APPEND ("paid",
+              (TALER_MERCHANT_YNA_YES == paid) ? "yes" : "no");
+    if (TALER_MERCHANT_YNA_ALL != refunded)
+      APPEND ("refunded",
+              (TALER_MERCHANT_YNA_YES == refunded) ? "yes" : "no");
+    if (TALER_MERCHANT_YNA_ALL != wired)
+      APPEND ("wired",
+              (TALER_MERCHANT_YNA_YES == wired) ? "yes" : "no");
+    if (delta > 0)
+    {
+      if (0 != date.abs_value_us)
+      {
+        const char *str;
+
+        str = GNUNET_STRINGS_absolute_time_to_string (date);
+        APPEND ("date",
+                str);
+      }
+      if (0 != start_row)
+      {
+        char cbuf[30];
+
+        GNUNET_snprintf (cbuf,
+                         sizeof (cbuf),
+                         "%llu",
+                         (unsigned long long) start_row);
+        APPEND ("start",
+                cbuf);
+      }
+    }
+    else
+    {
+      if (GNUNET_TIME_UNIT_FOREVER_ABS.abs_value_us != date.abs_value_us)
+      {
+        const char *str;
+
+        str = GNUNET_STRINGS_absolute_time_to_string (date);
+        APPEND ("date",
+                str);
+      }
+      if (UINT64_MAX != start_row)
+      {
+        char cbuf[30];
+
+        GNUNET_snprintf (cbuf,
+                         sizeof (cbuf),
+                         "%llu",
+                         (unsigned long long) start_row);
+        APPEND ("start",
+                cbuf);
+      }
+    }
+    if (-20 != delta)
+    {
+      char cbuf[30];
+
+      GNUNET_snprintf (cbuf,
+                       sizeof (cbuf),
+                       "%lld",
+                       (long long) delta);
+      APPEND ("delta",
+              cbuf);
+    }
+    if (0 != timeout_ms)
+    {
+      char cbuf[30];
+
+      GNUNET_snprintf (cbuf,
+                       sizeof (cbuf),
+                       "%llu",
+                       (unsigned long long) timeout_ms);
+      APPEND ("timeout_ms",
+              cbuf);
+    }
+    ogh->url = GNUNET_buffer_reap_str (&buf);
+#undef APPEND
+  }
+
+finished:
+  if (NULL == ogh->url)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Could not construct request URL.\n");
+    GNUNET_free (ogh);
+    return NULL;
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Requesting URL '%s'\n",
+              ogh->url);
+  eh = curl_easy_init ();
+  GNUNET_assert (CURLE_OK ==
+                 curl_easy_setopt (eh,
+                                   CURLOPT_URL,
+                                   ogh->url));
+  ogh->job = GNUNET_CURL_job_add (ctx,
+                                  eh,
+                                  GNUNET_YES,
+                                  &handle_get_orders_finished,
+                                  ogh);
+  return ogh;
+}
+
+
+/**
+ * Cancel /orders request.  Must not be called by clients after
+ * the callback was invoked.
+ *
+ * @param ogh request to cancel.
+ */
+void
+TALER_MERCHANT_orders_get_cancel (
+  struct TALER_MERCHANT_OrdersGetHandle *ogh)
+{
+  if (NULL != ogh->job)
+    GNUNET_CURL_job_cancel (ogh->job);
+  GNUNET_free (ogh->url);
+  GNUNET_free (ogh);
+}