add support for multi-backend multi-currency deployments

1 files changed, 244 insertions, 173 deletions

diff --git a/src/main.c b/src/main.c
index 42da955..b2c5891 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,6 +1,6 @@
 /*
  This file is part of TALER
- Copyright (C) 2019, 2020 Taler Systems SA
+ Copyright (C) 2019, 2020, 2022 Taler Systems SA
 
  TALER is free software; you can redistribute it and/or modify it under the
  terms of the GNU General Public License as published by the Free Software
@@ -58,6 +58,11 @@ along with
 /* for adafruit pitft display */
 #include <linux/fb.h>
 
+#ifndef EXIT_NOTCONFIGURED
+#define EXIT_NOTCONFIGURED 6
+#endif
+
+
 /* Constants */
 #define MAX_SIZE_RX_BUFFER 256
 
@@ -292,6 +297,11 @@ struct Product
   char *description;
 
   /**
+   * Authorization to header to use for this @e instance.
+   */
+  char *auth_header;
+
+  /**
    * Which instance should be used for billing?  Full URL, replaces
    * the default base URL for orders involving this product.  NULL if
    * we should use the #backend_base_url.
@@ -313,7 +323,7 @@ struct Product
    * Set to #GNUNET_YES if this product was found
    * to have been sold out (VEND failure).
    */
-  int sold_out;
+  bool sold_out;
 
   /**
    * Key for the product (optional, needed to test the application without vending machine)
@@ -328,6 +338,17 @@ struct Product
  */
 struct PaymentActivity
 {
+
+  /**
+   * Curl context for communication with taler backend
+   */
+  struct GNUNET_CURL_Context *ctx;
+
+  /**
+   * Closure for #GNUNET_CURL_gnunet_scheduler_reschedule().
+   */
+  struct GNUNET_CURL_RescheduleContext *rc;
+
   /**
    * Handle to a POST /orders operation
    */
@@ -390,16 +411,15 @@ struct PaymentActivity
 
   /**
    * Member to see if the wallet already received a uri
-   * GNUNET_YES, GNUNET_NO
-   * If yes, tunneling can be offered to the wallet
+   * If true, tunneling can be offered to the wallet.
    */
-  int wallet_has_uri;
+  bool wallet_has_uri;
 
   /**
-   * Set to #GNUNET_YES once the product has been paid
+   * Set to true once the product has been paid
    * (and we are in the process of yielding the product).
    */
-  int paid;
+  bool paid;
 };
 
 
@@ -468,7 +488,7 @@ struct MdbHandle
   /**
    * Indicates if a vend session is running or not
    */
-  int session_running;
+  bool session_running;
 
   /**
    * File descriptor to the UART device file
@@ -542,6 +562,16 @@ struct Refund
   struct Refund *prev;
 
   /**
+   * Curl context for communication with taler backend
+   */
+  struct GNUNET_CURL_Context *ctx;
+
+  /**
+   * Closure for #GNUNET_CURL_gnunet_scheduler_reschedule().
+   */
+  struct GNUNET_CURL_RescheduleContext *rc;
+
+  /**
    * Handle to the ongoing operation.
    */
   struct TALER_MERCHANT_OrderRefundHandle *orh;
@@ -578,7 +608,7 @@ static int in_shutdown;
  * Flag set to remember that MDB needs shutdown
  * (because we were actually able to talk to MDB).
  */
-static int mdb_active;
+static bool mdb_active;
 
 /**
  * Reference to the keyboard task
@@ -591,21 +621,6 @@ static struct GNUNET_SCHEDULER_Task *keyboard_task;
 static struct GNUNET_SCHEDULER_Task *cancelbutton_task;
 
 /**
- * Curl context for communication with taler backend
- */
-static struct GNUNET_CURL_Context *ctx;
-
-/**
- * Closure for #GNUNET_CURL_gnunet_scheduler_reschedule().
- */
-static struct GNUNET_CURL_RescheduleContext *rc;
-
-/**
- * Currency read from configuration file
- */
-static char *currency;
-
-/**
  * Taler Backend url read from configuration file
  */
 static char *backend_base_url;
@@ -616,11 +631,6 @@ static char *backend_base_url;
 static char *fulfillment_msg;
 
 /**
- * Authorization for the taler backend
- */
-static char *authorization;
-
-/**
  * ESSID of a WLAN network offered by the snack system, or NULL.
  */
 static char *essid;
@@ -756,6 +766,11 @@ static int disable_tty;
 static int sold_out_enabled;
 
 /**
+ * True if we have the 'reset' button on GPIO.
+ */
+static bool have_gpio;
+
+/**
  * Taler wallet application identifier
  */
 static const uint8_t taler_aid[] = { 0xF0, 0x00, 0x54, 0x41, 0x4c, 0x45, 0x52 };
@@ -915,6 +930,25 @@ run_mdb_event_loop (void);
 
 
 /**
+ * Runs asynchronous cleanup part for freeing a
+ * payment activity.
+ *
+ * @param[in] cls a `struct PaymentActivity` to clean up
+ */
+static void
+async_pa_cleanup_job (void *cls)
+{
+  struct PaymentActivity *pa = cls;
+
+  if (NULL != pa->ctx)
+    GNUNET_CURL_fini (pa->ctx);
+  if (NULL != pa->rc)
+    GNUNET_CURL_gnunet_rc_destroy (pa->rc);
+  GNUNET_free (pa);
+}
+
+
+/**
  * @brief Cleanup all the data when a order has succeeded or got cancelled
  *
  * @param pa the payment activity to clean up
@@ -928,15 +962,12 @@ cleanup_payment (struct PaymentActivity *pa)
     nfc_close (pa->pnd);
   }
   if (NULL != cancelbutton_task)
-  {
     GNUNET_SCHEDULER_cancel (cancelbutton_task);
-    cancelbutton_task = NULL;
-  }
   if (NULL != pa->po)
     TALER_MERCHANT_orders_post_cancel (pa->po);
   if (NULL != pa->ogh)
     TALER_MERCHANT_merchant_order_get_cancel (pa->ogh);
-  GNUNET_CURL_gnunet_scheduler_reschedule (&rc);
+  GNUNET_CURL_gnunet_scheduler_reschedule (&pa->rc);
   if (NULL != pa->task)
     GNUNET_SCHEDULER_cancel (pa->task);
   if (NULL != pa->delay_task)
@@ -959,7 +990,8 @@ cleanup_payment (struct PaymentActivity *pa)
     GNUNET_free (pa->taler_pay_uri);
   }
   GNUNET_free (pa->order_id);
-  GNUNET_free (pa);
+  GNUNET_SCHEDULER_add_now (&async_pa_cleanup_job,
+                            pa);
 }
 
 
@@ -1047,19 +1079,8 @@ shutdown_task (void *cls)
   /* last ditch saying nicely goodbye to MDB */
   in_shutdown = GNUNET_YES;
   mdb.cmd = &endSession;
-  run_mdb_event_loop ();
-
-  if (NULL != ctx)
-  {
-    GNUNET_CURL_fini (ctx);
-    ctx = NULL;
-  }
-  if (NULL != rc)
-  {
-    GNUNET_CURL_gnunet_rc_destroy (rc);
-    rc = NULL;
-  }
-
+  if (-1 != mdb.uartfd)
+    run_mdb_event_loop ();
   if ( (MAP_FAILED != qrDisplay.memory) &&
        (NULL != qrDisplay.memory) )
   {
@@ -1082,12 +1103,13 @@ shutdown_task (void *cls)
       GNUNET_break (0 == close (qrDisplay.backlightfd));
     qrDisplay.backlightfd = -1;
   }
-  if (0 < cancel_button.cancelbuttonfd)
+  if (-1 != cancel_button.cancelbuttonfd)
   {
-    GNUNET_break (0 == close (cancel_button.cancelbuttonfd));
+    GNUNET_break (0 ==
+                  close (cancel_button.cancelbuttonfd));
     cancel_button.cancelbuttonfd = open ("/sys/class/gpio/unexport",
                                          O_WRONLY);
-    if (0 > cancel_button.cancelbuttonfd)
+    if (-1 == cancel_button.cancelbuttonfd)
     {
       GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                   "Unable to open /gpio/unexport for cancel button\n");
@@ -1104,6 +1126,7 @@ shutdown_task (void *cls)
 
       }
       GNUNET_break (0 == close (cancel_button.cancelbuttonfd));
+      cancel_button.cancelbuttonfd = -1;
     }
   }
   /* free the allocated productes read from config file */
@@ -1112,6 +1135,7 @@ shutdown_task (void *cls)
     for (unsigned int i = 0; i < products_length; i++)
     {
       GNUNET_free (products[i].description);
+      GNUNET_free (products[i].auth_header);
       GNUNET_free (products[i].instance);
       GNUNET_free (products[i].preview);
     }
@@ -1186,7 +1210,7 @@ wallet_transmit_uri (void *cls)
   }
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "'PUT DATA' command sent successfully via NFC\n");
-  pa->wallet_has_uri = GNUNET_YES;
+  pa->wallet_has_uri = true;
   /* FIXME: or just offer Internet service here? */
 
   /* transmit the uri again later, there can be many external failures,
@@ -1406,7 +1430,7 @@ check_payment_cb (void *cls,
   if (TALER_MERCHANT_OSC_PAID == osr->status)
   {
     mdb.cmd = &cmd_approve_vend;
-    payment_activity->paid = GNUNET_YES;
+    payment_activity->paid = true;
     run_mdb_event_loop ();
     if ((disable_mdb) && (! disable_tty))
     {
@@ -1463,7 +1487,7 @@ check_payment_again (void *cls)
 
   pa->delay_pay_task = NULL;
   GNUNET_assert (NULL == pa->ogh);
-  pa->ogh = TALER_MERCHANT_merchant_order_get (ctx,
+  pa->ogh = TALER_MERCHANT_merchant_order_get (pa->ctx,
                                                pa->base_url,
                                                pa->order_id,
                                                NULL /* snack machine, no Web crap */,
@@ -1509,7 +1533,7 @@ proposal_cb (void *cls,
               "Backend successfully created order `%s'\n",
               por->details.ok.order_id);
   pa->order_id = GNUNET_strdup (por->details.ok.order_id);
-  pa->ogh = TALER_MERCHANT_merchant_order_get (ctx,
+  pa->ogh = TALER_MERCHANT_merchant_order_get (pa->ctx,
                                                pa->base_url,
                                                pa->order_id,
                                                NULL /* snack machine, no Web crap */,
@@ -1523,6 +1547,7 @@ proposal_cb (void *cls,
 static void
 start_read_cancel_button (void);
 
+
 /**
  * @brief Launch a new order
  *
@@ -1601,13 +1626,19 @@ launch_payment (struct Product *product)
               ? backend_base_url
               : product->instance);
   pa = GNUNET_new (struct PaymentActivity);
+  pa->ctx = GNUNET_CURL_init (&GNUNET_CURL_gnunet_scheduler_reschedule,
+                              &pa->rc);
+  pa->rc = GNUNET_CURL_gnunet_rc_create (pa->ctx);
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CURL_append_header (pa->ctx,
+                                            product->auth_header));
   pa->product = product;
   pa->amount = product->price;
   /* put the order on the merchant's backend */
   pa->base_url = (NULL == product->instance)
                  ? backend_base_url
                  : product->instance;
-  pa->po = TALER_MERCHANT_orders_post2 (ctx,
+  pa->po = TALER_MERCHANT_orders_post2 (pa->ctx,
                                         pa->base_url,
                                         orderReq,
                                         MAX_REFUND_DELAY,
@@ -1624,11 +1655,11 @@ launch_payment (struct Product *product)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                 "TALER_MERCHANT_order_put failed (out of memory?)\n");
-    GNUNET_free (pa);
+    cleanup_payment (pa);
     return NULL;
   }
   /* Start to read the button on the VM to cancel this payment */
-  if (0 < cancel_button.cancelbuttonfd)
+  if (-1 != cancel_button.cancelbuttonfd)
     start_read_cancel_button ();
   return pa;
 }
@@ -1652,6 +1683,25 @@ vend_success ()
 
 
 /**
+ * Runs asynchronous cleanup part for freeing a
+ * refund activity.
+ *
+ * @param[in] cls a `struct Refund` to clean up
+ */
+static void
+async_refund_cleanup_job (void *cls)
+{
+  struct Refund *r = cls;
+
+  if (NULL != r->ctx)
+    GNUNET_CURL_fini (r->ctx);
+  if (NULL != r->rc)
+    GNUNET_CURL_gnunet_rc_destroy (r->rc);
+  GNUNET_free (r);
+}
+
+
+/**
  * @brief Callback to process a POST /refund request
  *
  * @param cls closure
@@ -1680,7 +1730,8 @@ refund_complete_cb (void *cls,
   GNUNET_CONTAINER_DLL_remove (refund_head,
                                refund_tail,
                                r);
-  GNUNET_free (r);
+  GNUNET_SCHEDULER_add_now (&async_refund_cleanup_job,
+                            r);
 }
 
 
@@ -1702,11 +1753,17 @@ vend_failure (void)
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Received MDB vend failure for `%s', refunding customer\n",
               p->description);
-  p->sold_out = GNUNET_YES;
+  p->sold_out = true;
   mdb.cmd = &endSession;
-  mdb.session_running = GNUNET_NO;
+  mdb.session_running = false;
   r = GNUNET_new (struct Refund);
-  r->orh = TALER_MERCHANT_post_order_refund (ctx,
+  r->ctx = GNUNET_CURL_init (&GNUNET_CURL_gnunet_scheduler_reschedule,
+                             &r->rc);
+  r->rc = GNUNET_CURL_gnunet_rc_create (r->ctx);
+  GNUNET_assert (GNUNET_OK ==
+                 GNUNET_CURL_append_header (r->ctx,
+                                            p->auth_header));
+  r->orh = TALER_MERCHANT_post_order_refund (r->ctx,
                                              (NULL == p->instance)
                                              ? backend_base_url
                                              : p->instance,
@@ -1766,14 +1823,14 @@ read_keyboard_command (void *cls)
       else
       {
         mdb.cmd = &endSession;
-        mdb.session_running = GNUNET_NO;
+        mdb.session_running = false;
       }
       run_mdb_event_loop ();
       cleanup_payment (payment_activity);
       payment_activity = NULL;
       break;
     case 'a':
-      payment_activity->paid = GNUNET_YES;
+      payment_activity->paid = true;
       mdb.cmd = &cmd_approve_vend;
       run_mdb_event_loop ();
       break;
@@ -1819,7 +1876,7 @@ read_keyboard_command (void *cls)
     if (((char) input) == products[i].key)
     {
       if ( (sold_out_enabled) &&
-           (GNUNET_YES == products[i].sold_out) )
+           (products[i].sold_out) )
       {
         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                     "Product %s sold out, denying vend\n",
@@ -1885,7 +1942,7 @@ cancel_button_pressed (void *cls)
         /* The order was paid and if we know this, then it is also yielded,
          * just end the current session */
         mdb.cmd = &endSession;
-        mdb.session_running = GNUNET_NO;
+        mdb.session_running = false;
       }
       run_mdb_event_loop ();
       cleanup_payment (payment_activity);
@@ -1944,7 +2001,9 @@ start_read_keyboard ()
 static void
 start_read_cancel_button ()
 {
-  struct GNUNET_DISK_FileHandle fh = { cancel_button.cancelbuttonfd };
+  struct GNUNET_DISK_FileHandle fh = {
+    cancel_button.cancelbuttonfd
+  };
 
   GNUNET_assert (NULL == cancelbutton_task);
   cancelbutton_task = GNUNET_SCHEDULER_add_read_file (
@@ -2071,10 +2130,10 @@ static void
 handle_ack ()
 {
   if (&cmd_begin_session == mdb.last_cmd)
-    mdb.session_running = GNUNET_YES;
+    mdb.session_running = true;
   if (&cmd_deny_vend == mdb.last_cmd)
   {
-    mdb.session_running = GNUNET_NO;
+    mdb.session_running = false;
     mdb.cmd = &endSession;
   }
   if (&cmd_reader_display_sold_out == mdb.last_cmd)
@@ -2190,7 +2249,7 @@ handle_command (const char *hex,
           }
           unsigned int product;
 
-          GNUNET_break (GNUNET_YES == mdb.session_running);
+          GNUNET_break (mdb.session_running);
           /* NOTE: hex[4..7] contain the price */
           if (12 > hex_len)
           {
@@ -2216,7 +2275,7 @@ handle_command (const char *hex,
                           "Product %u selected on MDB\n",
                           product);
               if ( (sold_out_enabled) &&
-                   (GNUNET_YES == products[i].sold_out) )
+                   (products[i].sold_out) )
               {
                 GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                             "Product %s sold out, denying vend\n",
@@ -2236,12 +2295,12 @@ handle_command (const char *hex,
           break;
         }
       case VMC_VEND_SUCCESS:
-        GNUNET_break (GNUNET_YES == mdb.session_running);
+        GNUNET_break (mdb.session_running);
         vend_success ();
         break;
       case VMC_VEND_FAILURE:
         {
-          GNUNET_break (GNUNET_YES == mdb.session_running);
+          GNUNET_break (mdb.session_running);
           vend_failure ();
           break;
         }
@@ -2249,7 +2308,7 @@ handle_command (const char *hex,
         {
           GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                       "Received MDB session complete\n");
-          mdb.session_running = GNUNET_NO;
+          mdb.session_running = false;
           mdb.cmd = &endSession;
           if (NULL != payment_activity)
           {
@@ -2389,7 +2448,7 @@ handle_command (const char *hex,
       case VMC_READER_DISABLE:
         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                     "Received Reader Disable via MDB\n");
-        mdb.session_running = GNUNET_NO;
+        mdb.session_running = false;
         if (NULL != payment_activity)
         {
           cleanup_payment (payment_activity);
@@ -2400,23 +2459,23 @@ handle_command (const char *hex,
           if ( (sold_out_enabled) &&
                (0 != strcmp (products[i].description,
                              "empty")) &&
-               (GNUNET_YES == products[i].sold_out) )
+               (products[i].sold_out) )
           {
             GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                         "Resetting sold out state of product %s\n",
                         products[i].description);
-            products[i].sold_out = GNUNET_NO;
+            products[i].sold_out = false;
           }
         }
         break;
       case VMC_READER_ENABLE:
         GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                     "Received Reader Enable via MDB\n");
-        mdb.session_running = GNUNET_NO;
+        mdb.session_running = false;
         break;
       case VMC_READER_CANCEL:
         mdb.cmd = &cmd_reader_cancelled;
-        mdb.session_running = GNUNET_NO;
+        mdb.session_running = false;
         break;
       default:
         GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
@@ -2441,7 +2500,7 @@ handle_command (const char *hex,
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Received command out of sequence from MDB (for command `%s')\n",
                 (NULL != mdb.last_cmd) ? mdb.last_cmd->name : "?");
-    mdb.session_running = GNUNET_NO;
+    mdb.session_running = false;
     if (mdb.last_cmd != &endSession)
       mdb.cmd = &endSession;
     else
@@ -2496,7 +2555,7 @@ read_mdb_command (void *cls)
 
   while (mdb.rx_off > 0)
   {
-    mdb_active = GNUNET_YES;
+    mdb_active = true;
     /* find beginning of command */
     for (cmdStartIdx = 0; cmdStartIdx < mdb.rx_off; cmdStartIdx++)
       if (VMC_CMD_START == mdb.rxBuffer[cmdStartIdx])
@@ -2555,7 +2614,7 @@ run_mdb_event_loop ()
   struct GNUNET_DISK_FileHandle fh = { mdb.uartfd };
 
   /* begin session if no cmd waits for sending and no cmd is received from the VMC */
-  if ( (GNUNET_NO == mdb.session_running) &&
+  if ( (! mdb.session_running) &&
        (NULL == mdb.cmd) &&
        (NULL == mdb.last_cmd) )
   {
@@ -2609,6 +2668,7 @@ static void
 read_products (void *cls,
                const char *section)
 {
+  const struct GNUNET_CONFIGURATION_Handle *cfg = cls;
   struct Product tmpProduct;
   char *tmpKey;
   char *thumbnail_fn;
@@ -2620,7 +2680,7 @@ read_products (void *cls,
     return;
   /* the current section is a product, parse its specifications and store it in a temporary product */
   if (GNUNET_OK !=
-      GNUNET_CONFIGURATION_get_value_string (cls,
+      GNUNET_CONFIGURATION_get_value_string (cfg,
                                              section,
                                              "description",
                                              &tmpProduct.description))
@@ -2635,15 +2695,15 @@ read_products (void *cls,
     if (0 == strcmp (tmpProduct.description,
                      "empty"))
     {
-      tmpProduct.sold_out = GNUNET_YES;
+      tmpProduct.sold_out = true;
     }
     else
     {
-      tmpProduct.sold_out = GNUNET_NO;
+      tmpProduct.sold_out = false;
     }
   }
   if (GNUNET_OK !=
-      TALER_config_get_amount (cls,
+      TALER_config_get_amount (cfg,
                                section,
                                "price",
                                &tmpProduct.price))
@@ -2654,18 +2714,8 @@ read_products (void *cls,
     GNUNET_free (tmpProduct.description);
     return;
   }
-  if (0 != strcasecmp (currency,
-                       tmpProduct.price.currency))
-  {
-    GNUNET_log_config_invalid (GNUNET_ERROR_TYPE_ERROR,
-                               section,
-                               "price",
-                               "currency mismatch");
-    GNUNET_free (tmpProduct.description);
-    return;
-  }
   if (GNUNET_OK ==
-      GNUNET_CONFIGURATION_get_value_string (cls,
+      GNUNET_CONFIGURATION_get_value_string (cfg,
                                              section,
                                              "key",
                                              &tmpKey))
@@ -2679,14 +2729,14 @@ read_products (void *cls,
     tmpProduct.key = '\0';
   }
   if (GNUNET_OK !=
-      GNUNET_CONFIGURATION_get_value_string (cls,
+      GNUNET_CONFIGURATION_get_value_string (cfg,
                                              section,
                                              "instance",
                                              &tmpProduct.instance))
     tmpProduct.instance = NULL;
   tmpProduct.preview = NULL;
   if (GNUNET_OK ==
-      GNUNET_CONFIGURATION_get_value_string (cls,
+      GNUNET_CONFIGURATION_get_value_string (cfg,
                                              section,
                                              "thumbnail",
                                              &thumbnail_fn))
@@ -2778,7 +2828,7 @@ read_products (void *cls,
     GNUNET_free (thumbnail_fn);
   }
   if (GNUNET_OK !=
-      GNUNET_CONFIGURATION_get_value_number (cls,
+      GNUNET_CONFIGURATION_get_value_number (cfg,
                                              section,
                                              "number",
                                              &tmpProduct.number))
@@ -2791,6 +2841,35 @@ read_products (void *cls,
     GNUNET_free (tmpProduct.preview);
     return;
   }
+
+  {
+    char *auth;
+
+    if ( (GNUNET_OK !=
+          GNUNET_CONFIGURATION_get_value_string (cfg,
+                                                 section,
+                                                 "BACKEND-AUTHORIZATION",
+                                                 &auth)) &&
+         (GNUNET_OK !=
+          GNUNET_CONFIGURATION_get_value_string (cfg,
+                                                 "taler-mdb",
+                                                 "BACKEND-AUTHORIZATION",
+                                                 &auth)) )
+    {
+      GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
+                                 section,
+                                 "BACKEND-AUTHORIZATION");
+      GNUNET_free (tmpProduct.description);
+      GNUNET_free (tmpProduct.instance);
+      GNUNET_free (tmpProduct.preview);
+      return;
+    }
+    GNUNET_asprintf (&tmpProduct.auth_header,
+                     "%s: %s",
+                     MHD_HTTP_HEADER_AUTHORIZATION,
+                     auth);
+    GNUNET_free (auth);
+  }
   /* append the temporary product to the existing products */
   GNUNET_array_append (products,
                        products_length,
@@ -2800,8 +2879,10 @@ read_products (void *cls,
 
 /**
  * @brief Initialise the uart device to send mdb commands
+ *
+ * @return #GNUNET_OK on success
  */
-static int
+static enum GNUNET_GenericReturnValue
 mdb_init ()
 {
   struct termios uart_opts_raw;
@@ -2823,7 +2904,8 @@ mdb_init ()
     return GNUNET_SYSERR;
   }
 
-  if (0 != tcgetattr (mdb.uartfd, &mdb.uart_opts_backup))
+  if (0 != tcgetattr (mdb.uartfd,
+                      &mdb.uart_opts_backup))
   {
     GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR,
                          "tcgetattr");
@@ -2886,14 +2968,6 @@ run (void *cls,
   (void) args;
   (void) cfgfile;
 
-  /* parse the configuration file */
-  if (GNUNET_OK !=
-      TALER_config_get_currency (cfg,
-                                 &currency))
-  {
-    global_ret = EXIT_FAILURE;
-    return;
-  }
   /* parse the devices, if no config entry is found, a standard is used */
   if (GNUNET_OK !=
       GNUNET_CONFIGURATION_get_value_filename (cfg,
@@ -2943,28 +3017,6 @@ run (void *cls,
     return;
   }
   {
-    char *auth;
-
-    if (GNUNET_OK !=
-        GNUNET_CONFIGURATION_get_value_string (cfg,
-                                               "taler-mdb",
-                                               "backend-authorization",
-                                               &auth))
-    {
-      GNUNET_log_config_missing (GNUNET_ERROR_TYPE_ERROR,
-                                 "taler-mdb",
-                                 "backend-authorization");
-      global_ret = EXIT_FAILURE;
-      return;
-    }
-    /* concat the authorization e.g. Authorization: ApiKey sandbox */
-    GNUNET_asprintf (&authorization,
-                     "%s: %s",
-                     MHD_HTTP_HEADER_AUTHORIZATION,
-                     auth);
-    GNUNET_free (auth);
-  }
-  {
     if (GNUNET_OK !=
         GNUNET_CONFIGURATION_get_value_string (cfg,
                                                "taler-mdb",
@@ -2992,7 +3044,13 @@ run (void *cls,
   GNUNET_CONFIGURATION_iterate_sections (cfg,
                                          &read_products,
                                          (void *) cfg);
-  GNUNET_assert (NULL != products);
+  if (NULL == products)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "No valid products configured\n");
+    global_ret = EXIT_NOTCONFIGURED;
+    return;
+  }
 
   GNUNET_SCHEDULER_add_shutdown (&shutdown_task,
                                  NULL);
@@ -3011,22 +3069,13 @@ run (void *cls,
   nfc_init (&context);
   if (NULL == context)
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                 "Unable to initialize NFC (nfc_init() failed)\n");
     global_ret = EXIT_FAILURE;
     GNUNET_SCHEDULER_shutdown ();
     return;
   }
 
-  /* initialize HTTP client */
-  ctx = GNUNET_CURL_init (&GNUNET_CURL_gnunet_scheduler_reschedule,
-                          &rc);
-  rc = GNUNET_CURL_gnunet_rc_create (ctx);
-  /* setup authorization */
-  GNUNET_assert (GNUNET_OK ==
-                 GNUNET_CURL_append_header (ctx,
-                                            authorization));
-
   /* open gpio pin for cancel button */
   {
     int efd;
@@ -3035,20 +3084,31 @@ run (void *cls,
                 O_WRONLY);
     if (-1 == efd)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                   "Unable to open /gpio/export for cancel button\n");
-      global_ret = EXIT_FAILURE;
-      GNUNET_SCHEDULER_shutdown ();
-      return;
+      have_gpio = false;
+    }
+    else
+    {
+      if (2 != write (efd,
+                      "23",
+                      2))
+      {
+        GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
+                                  "write",
+                                  "/sys/class/gpio/export");
+        have_gpio = false;
+      }
+      else
+      {
+        have_gpio = true;
+      }
+      GNUNET_assert (0 == close (efd));
     }
-    if (2 != write (efd, "23", 2))
-      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
-                                "write",
-                                "/sys/class/gpio/export");
-    GNUNET_assert (0 == close (efd));
   }
 
   /* set direction: input */
+  if (have_gpio)
   {
     int dfd;
 
@@ -3056,29 +3116,40 @@ run (void *cls,
                 O_WRONLY);
     if (-1 == dfd)
     {
-      GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
                   "Unable to open /gpio/gpio23/direction for cancel button\n");
-      global_ret = EXIT_FAILURE;
-      GNUNET_SCHEDULER_shutdown ();
-      return;
+      have_gpio = false;
+    }
+    else
+    {
+      if (2 != write (dfd,
+                      "in",
+                      2))
+      {
+        GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
+                                  "write",
+                                  "/sys/class/gpio/gpio23/direction");
+        have_gpio = false;
+      }
     }
-    if (2 != write (dfd, "in", 2))
-      GNUNET_log_strerror_file (GNUNET_ERROR_TYPE_WARNING,
-                                "write",
-                                "/sys/class/gpio/gpio23/direction");
     GNUNET_assert (0 == close (dfd));
   }
 
-  /* actually open fd for reading the state */
-  cancel_button.cancelbuttonfd = open ("/sys/class/gpio/gpio23/value",
-                                       O_RDONLY);
-  if (-1 == cancel_button.cancelbuttonfd)
+  if (have_gpio)
   {
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
-                "Unable to open /gpio/gpio23/value for cancel button\n");
-    global_ret = EXIT_FAILURE;
-    GNUNET_SCHEDULER_shutdown ();
-    return;
+    /* actually open fd for reading the state */
+    cancel_button.cancelbuttonfd = open ("/sys/class/gpio/gpio23/value",
+                                         O_RDONLY);
+    if (-1 == cancel_button.cancelbuttonfd)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Unable to open /gpio/gpio23/value for cancel button\n");
+      have_gpio = false;
+    }
+  }
+  else
+  {
+    cancel_button.cancelbuttonfd = -1;
   }
 
 
@@ -3121,11 +3192,11 @@ run (void *cls,
     }
 
     /* get pointer onto frame buffer */
-    qrDisplay.memory =  mmap (NULL,
-                              qrDisplay.fix_info.smem_len,
-                              PROT_READ | PROT_WRITE, MAP_SHARED,
-                              qrDisplay.devicefd,
-                              0);
+    qrDisplay.memory = mmap (NULL,
+                             qrDisplay.fix_info.smem_len,
+                             PROT_READ | PROT_WRITE, MAP_SHARED,
+                             qrDisplay.devicefd,
+                             0);
     if (MAP_FAILED == qrDisplay.memory)
     {
       GNUNET_log_strerror (GNUNET_ERROR_TYPE_WARNING,