merging /keys and /wire API in the exchange

17 files changed, 680 insertions, 800 deletions

diff --git a/src/backend/taler-merchant-httpd.c b/src/backend/taler-merchant-httpd.c
index be0140e1..d8be1edc 100644
--- a/src/backend/taler-merchant-httpd.c
+++ b/src/backend/taler-merchant-httpd.c
@@ -303,6 +303,7 @@ static void
 do_shutdown (void *cls)
 {
   (void) cls;
+  TMH_force_orders_resume ();
   TMH_force_reward_resume ();
   TMH_force_ac_resume ();
   TMH_force_pc_resume ();
@@ -1666,8 +1667,8 @@ url_handler (void *cls,
        (! hc->rh->skip_instance) )
   {
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                "Instance `%s' not known\n",
-                hc->infix);
+                "Instance for `%s' not known\n",
+                hc->url);
     return TALER_MHD_reply_with_error (connection,
                                        MHD_HTTP_NOT_FOUND,
                                        TALER_EC_MERCHANT_GENERIC_INSTANCE_UNKNOWN,
diff --git a/src/backend/taler-merchant-httpd_exchanges.c b/src/backend/taler-merchant-httpd_exchanges.c
index 5fca3c34..7e99704c 100644
--- a/src/backend/taler-merchant-httpd_exchanges.c
+++ b/src/backend/taler-merchant-httpd_exchanges.c
@@ -32,19 +32,6 @@
 #define MAX_RETRIES 3
 
 /**
- * Minimum delay after which we'll re-fetch key information from the exchange.
- */
-#define MIN_RELOAD_DELAY GNUNET_TIME_relative_multiply ( \
-    GNUNET_TIME_UNIT_MINUTES, 2)
-
-/**
- * Delay after which we'll allow clients to force us to re-fetch key
- * information from the exchange if we don't know the denomination key.
- */
-#define FORCED_RELOAD_DELAY GNUNET_TIME_relative_multiply ( \
-    GNUNET_TIME_UNIT_MINUTES, 15)
-
-/**
  * Threshold after which exponential backoff should not increase.
  */
 #define RETRY_BACKOFF_THRESHOLD GNUNET_TIME_relative_multiply ( \
@@ -52,19 +39,6 @@
 
 
 /**
- * Perform our exponential back-off calculation, starting at 1 ms
- * and then going by a factor of 2 up unto a maximum of RETRY_BACKOFF_THRESHOLD.
- *
- * @param r current backoff time, initially zero
- */
-#define RETRY_BACKOFF(r) GNUNET_TIME_relative_min (RETRY_BACKOFF_THRESHOLD, \
-                                                   GNUNET_TIME_relative_multiply ( \
-                                                     GNUNET_TIME_relative_max ( \
-                                                       GNUNET_TIME_UNIT_MILLISECONDS, \
-                                                       (r)), 2));
-
-
-/**
  * Information we keep for a pending #MMH_EXCHANGES_keys4exchange() operation.
  */
 struct TMH_EXCHANGES_KeysOperation
@@ -105,46 +79,6 @@ struct TMH_EXCHANGES_KeysOperation
 
 
 /**
- * Information we keep for a pending #MMH_EXCHANGES_wire4exchange() operation.
- */
-struct TMH_EXCHANGES_WireOperation
-{
-
-  /**
-   * Kept in a DLL.
-   */
-  struct TMH_EXCHANGES_WireOperation *next;
-
-  /**
-   * Kept in a DLL.
-   */
-  struct TMH_EXCHANGES_WireOperation *prev;
-
-  /**
-   * Function to call with the result.
-   */
-  TMH_EXCHANGES_WireContinuation fc;
-
-  /**
-   * Closure for @e fc.
-   */
-  void *fc_cls;
-
-  /**
-   * Exchange we wait for the /wire for.
-   */
-  struct TMH_Exchange *my_exchange;
-
-  /**
-   * Task scheduled to asynchronously return the result to
-   * the find continuation.
-   */
-  struct GNUNET_SCHEDULER_Task *at;
-
-};
-
-
-/**
  * Information about wire transfer fees of an exchange, by wire method.
  */
 struct FeesByWireMethod
@@ -281,21 +215,6 @@ struct TMH_Exchange
   struct TMH_EXCHANGES_KeysOperation *keys_tail;
 
   /**
-   * Head of /wire pending for this exchange.
-   */
-  struct TMH_EXCHANGES_WireOperation *w_head;
-
-  /**
-   * Tail of /wire pending for this exchange.
-   */
-  struct TMH_EXCHANGES_WireOperation *w_tail;
-
-  /**
-   * Request to /keys needed for our /wire operation.
-   */
-  struct TMH_EXCHANGES_KeysOperation *ko;
-
-  /**
    * Head of accounts of this exchange.
    */
   struct ExchangeAccount *acc_head;
@@ -321,16 +240,6 @@ struct TMH_Exchange
   struct TALER_EXCHANGE_Keys *keys;
 
   /**
-   * Active /wire request to the exchange, or NULL.
-   */
-  struct TALER_EXCHANGE_WireHandle *wire_request;
-
-  /**
-   * Task to re-run /wire after some delay.
-   */
-  struct GNUNET_SCHEDULER_Task *wire_task;
-
-  /**
    * Head of wire fees from /wire request.
    */
   struct FeesByWireMethod *wire_fees_head;
@@ -372,25 +281,6 @@ struct TMH_Exchange
    */
   bool trusted;
 
-  /**
-   * true if this exchange did return to use the
-   * response from /wire.
-   */
-  bool have_wire;
-
-};
-
-
-/**
- * Opaque wire details abstraction returned to a client after successfully
- * obtaining /wire.
- */
-struct TMH_ExchangeWireDetails
-{
-  /**
-   * Internal representation of the exchange
-   */
-  struct TMH_Exchange *exchange;
 };
 
 
@@ -418,6 +308,16 @@ static struct GNUNET_DB_EventHandler *keys_eh;
 static int trusted_exchange_count;
 
 
+const struct TALER_MasterPublicKeyP *
+TMH_EXCHANGES_get_master_pub (
+  const struct TMH_Exchange *exchange)
+{
+  GNUNET_break ( (exchange->trusted) ||
+                 (NULL != exchange->keys) );
+  return &exchange->master_pub;
+}
+
+
 /**
  * Free data structures within @a ea, but not @a ea
  * pointer itself.
@@ -590,37 +490,17 @@ keys_mgmt_cb (
  * the callback.
  *
  * @param exchange the exchange to check for pending find operations
- * @return true if we need /wire data from @a exchange
  */
-static bool
+static void
 process_find_operations (struct TMH_Exchange *exchange)
 {
-  struct TMH_EXCHANGES_KeysOperation *fn2;
-  struct TMH_EXCHANGES_WireOperation *wn;
   struct GNUNET_TIME_Timestamp now;
 
-  fn2 = NULL;
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "Processing find operations for `%s'\n",
-              exchange->url);
-  for (struct TMH_EXCHANGES_KeysOperation *fo = exchange->keys_head;
-       NULL != fo;
-       fo = fn2)
-  {
-    fn2 = fo->next;
-    fo->fc (fo->fc_cls,
-            exchange->keys);
-    TMH_EXCHANGES_keys4exchange_cancel (fo);
-  }
-  if (! exchange->have_wire)
-    return true;
   now = GNUNET_TIME_timestamp_get ();
   for (struct FeesByWireMethod *fbw = exchange->wire_fees_head;
        NULL != fbw;
        fbw = fbw->next)
   {
-    bool removed = false;
-
     while ( (NULL != fbw->af) &&
             (GNUNET_TIME_timestamp_cmp (fbw->af->end_date,
                                         <,
@@ -630,7 +510,6 @@ process_find_operations (struct TMH_Exchange *exchange)
 
       fbw->af = af->next;
       GNUNET_free (af);
-      removed = true;
     }
     if (NULL == fbw->af)
     {
@@ -638,15 +517,10 @@ process_find_operations (struct TMH_Exchange *exchange)
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
                   "Exchange has no wire fees configured for `%s' wire method\n",
                   fbw->wire_method);
-      if (removed)
-      {
-        exchange->have_wire = false;
-        return true; /* We just removed previous fees, try fetching update */
-      }
     }
-    if (GNUNET_TIME_timestamp_cmp (fbw->af->start_date,
-                                   >,
-                                   now))
+    else if (GNUNET_TIME_timestamp_cmp (fbw->af->start_date,
+                                        >,
+                                        now))
     {
       /* Disagreement on the current time */
       GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
@@ -656,45 +530,30 @@ process_find_operations (struct TMH_Exchange *exchange)
                       fbw->af->start_date.abs_time),
                     true));
     }
-  }
+  } /* for all wire methods */
 
-  if (! exchange->have_wire)
-    return true; /* need /wire response to continue */
   {
-    struct TMH_ExchangeWireDetails wd = {
-      .exchange = exchange
-    };
+    struct TMH_EXCHANGES_KeysOperation *kon;
 
-    wn = NULL;
-    for (struct TMH_EXCHANGES_WireOperation *w = exchange->w_head;
-         NULL != w;
-         w = wn)
+    kon = NULL;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "Processing find operations for `%s'\n",
+                exchange->url);
+    for (struct TMH_EXCHANGES_KeysOperation *ko = exchange->keys_head;
+         NULL != ko;
+         ko = kon)
     {
-      wn = w->next;
-      w->fc (w->fc_cls,
-             &wd);
-      TMH_EXCHANGES_wire4exchange_cancel (w);
+      kon = ko->next;
+      ko->fc (ko->fc_cls,
+              exchange->keys,
+              exchange);
+      TMH_EXCHANGES_keys4exchange_cancel (ko);
     }
   }
-  return false;
 }
 
 
 /**
- * Check if we have any remaining pending requests for the
- * given @a exchange, and if we have the required data, call
- * the callback.  If requests without /wire data remain,
- * retry the /wire request after some delay.
- *
- * Must only be called if 'exchange->keys' is non-NULL.
- *
- * @param cls a `struct TMH_Exchange` to check
- */
-static void
-wire_task_cb (void *cls);
-
-
-/**
  * Function called with information about the wire fees for each wire method.
  * Stores the wire fees with the exchange for later use.
  *
@@ -994,99 +853,6 @@ outer:;
 
 
 /**
- * Callbacks of this type are used to serve the result of submitting a
- * wire format inquiry request to a exchange.
- *
- * If the request fails to generate a valid response from the
- * exchange, @a http_status will also be zero.
- *
- * Must only be called if 'exchange->keys' is non-NULL.
- *
- * @param cls closure, a `struct TMH_Exchange`
- * @param wr response details
- */
-static void
-handle_wire_data (void *cls,
-                  const struct TALER_EXCHANGE_WireResponse *wr)
-{
-  struct TMH_Exchange *exchange = cls;
-  const struct TALER_EXCHANGE_Keys *keys;
-  enum TALER_ErrorCode ecx;
-
-  exchange->wire_request = NULL;
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "Received /wire response\n");
-  if (MHD_HTTP_OK != wr->hr.http_status)
-  {
-    struct TMH_EXCHANGES_WireOperation *w;
-
-    exchange->have_wire = false;
-    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                "Failed to obtain /wire details from `%s': %u/%d\n",
-                exchange->url,
-                wr->hr.http_status,
-                wr->hr.ec);
-    while (NULL != (w = exchange->w_head))
-    {
-      w->fc (w->fc_cls,
-             NULL);
-      TMH_EXCHANGES_wire4exchange_cancel (w);
-    }
-    return;
-  }
-  keys = exchange->keys;
-  GNUNET_assert (NULL != keys);
-  ecx = process_wire_accounts (exchange,
-                               &keys->master_pub,
-                               wr->details.ok.accounts_len,
-                               wr->details.ok.accounts);
-  if (TALER_EC_NONE == ecx)
-    ecx = process_wire_fees (exchange,
-                             &keys->master_pub,
-                             wr->details.ok.fees_len,
-                             wr->details.ok.fees);
-  if (TALER_EC_NONE != ecx)
-  {
-    /* Report hard failure to all callbacks! */
-    struct TMH_EXCHANGES_KeysOperation *keys;
-
-    GNUNET_break_op (0);
-    exchange->have_wire = false;
-    while (NULL != (keys = exchange->keys_head))
-    {
-      keys->fc (keys->fc_cls,
-                NULL);
-      TMH_EXCHANGES_keys4exchange_cancel (keys);
-    }
-    return;
-  }
-  exchange->have_wire = true;
-  if ( (process_find_operations (exchange)) &&
-       (NULL == exchange->wire_task) &&
-       (NULL == exchange->wire_request) )
-  {
-    /* need to run /wire again. But as we DID get a successful reply,
-       and as the exchange is unlikely to offer new wire methods very
-       frequently, start with some significant delay */
-    exchange->wire_retry_delay
-      = GNUNET_TIME_relative_max (GNUNET_TIME_UNIT_MINUTES,
-                                  exchange->wire_retry_delay);
-    exchange->wire_retry_delay = RETRY_BACKOFF (exchange->wire_retry_delay);
-    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                "Need %s/wire, next download attempt in %s\n",
-                exchange->url,
-                GNUNET_STRINGS_relative_time_to_string (
-                  exchange->wire_retry_delay,
-                  true));
-    exchange->wire_task
-      = GNUNET_SCHEDULER_add_delayed (exchange->wire_retry_delay,
-                                      &wire_task_cb,
-                                      exchange);
-  }
-}
-
-
-/**
  * Retry getting keys from the given exchange in the closure.
  *
  * @param cls the `struct TMH_Exchange *`
@@ -1096,46 +862,13 @@ retry_exchange (void *cls)
 {
   struct TMH_Exchange *exchange = cls;
 
-  /* might be a scheduled reload and not our first attempt */
   exchange->retry_task = NULL;
-  if (NULL != exchange->conn)
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "Already trying /keys\n");
-    return; /* already trying */
-  }
-  if ( (NULL != exchange->keys) &&
-       (GNUNET_TIME_absolute_is_future (
-          exchange->keys->key_data_expiration.abs_time)) )
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "Already have valid /keys\n");
-    if ( (process_find_operations (exchange)) &&
-         (NULL == exchange->wire_request) &&
-         (NULL == exchange->wire_task) )
-    {
-      GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                  "Got key data, but also need wire data. Will request /wire now\n");
-      exchange->wire_request
-        = TALER_EXCHANGE_wire (
-            TMH_curl_ctx,
-            exchange->url,
-            exchange->keys,
-            &handle_wire_data,
-            exchange);
-    }
-    return; /* still have a valid reply */
-  }
-  /* increment exponential-backoff */
+  GNUNET_assert (NULL == exchange->conn);
   exchange->retry_delay
-    = RETRY_BACKOFF (exchange->retry_delay);
-  /* No download until both backoff and #FORCED_RELOAD_DELAY
-     are satisfied again */
+    = GNUNET_TIME_randomized_backoff (exchange->retry_delay,
+                                      RETRY_BACKOFF_THRESHOLD);
   exchange->first_retry
-    = GNUNET_TIME_relative_to_absolute (
-        GNUNET_TIME_relative_max (
-          exchange->retry_delay,
-          FORCED_RELOAD_DELAY));
+    = GNUNET_TIME_relative_to_absolute (exchange->retry_delay);
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Fetching /keys from exchange %s in retry_exchange()\n",
               exchange->url);
@@ -1174,6 +907,7 @@ return_keys (void *cls)
 struct TMH_EXCHANGES_KeysOperation *
 TMH_EXCHANGES_keys4exchange (
   const char *chosen_exchange,
+  bool force_download,
   TMH_EXCHANGES_Find2Continuation fc,
   void *fc_cls)
 {
@@ -1197,6 +931,7 @@ TMH_EXCHANGES_keys4exchange (
                                exchange->keys_tail,
                                fo);
   if ( (NULL != exchange->keys) &&
+       (! force_download) &&
        (GNUNET_TIME_absolute_is_future (
           exchange->keys->key_data_expiration.abs_time)) )
   {
@@ -1257,7 +992,7 @@ TMH_EXCHANGES_keys4exchange_cancel (
  * @return NULL if we do not have fees for this method yet
  */
 static const struct FeesByWireMethod *
-get_wire_fees (struct TMH_Exchange *exchange,
+get_wire_fees (const struct TMH_Exchange *exchange,
                struct GNUNET_TIME_Timestamp now,
                const char *wire_method)
 {
@@ -1289,26 +1024,6 @@ get_wire_fees (struct TMH_Exchange *exchange,
 }
 
 
-static void
-wire_task_cb (void *cls)
-{
-  struct TMH_Exchange *exchange = cls;
-
-  exchange->wire_task = NULL;
-  if (! process_find_operations (exchange))
-    return; /* no more need */
-  GNUNET_assert (NULL == exchange->wire_request);
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "Initiating /wire download\n");
-  exchange->wire_request
-    = TALER_EXCHANGE_wire (TMH_curl_ctx,
-                           exchange->url,
-                           exchange->keys,
-                           &handle_wire_data,
-                           exchange);
-}
-
-
 /**
  * Free @a exchange.
  *
@@ -1319,6 +1034,10 @@ free_exchange_entry (struct TMH_Exchange *exchange)
 {
   struct FeesByWireMethod *f;
 
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Releasing %s exchange %s\n",
+              exchange->trusted ? "trusted" : "untrusted",
+              exchange->url);
   GNUNET_CONTAINER_DLL_remove (exchange_head,
                                exchange_tail,
                                exchange);
@@ -1338,16 +1057,6 @@ free_exchange_entry (struct TMH_Exchange *exchange)
     GNUNET_free (f->wire_method);
     GNUNET_free (f);
   }
-  if (NULL != exchange->wire_request)
-  {
-    TALER_EXCHANGE_wire_cancel (exchange->wire_request);
-    exchange->wire_request = NULL;
-  }
-  if (NULL != exchange->wire_task)
-  {
-    GNUNET_SCHEDULER_cancel (exchange->wire_task);
-    exchange->wire_task = NULL;
-  }
   if (NULL != exchange->conn)
   {
     TALER_EXCHANGE_get_keys_cancel (exchange->conn);
@@ -1362,8 +1071,6 @@ free_exchange_entry (struct TMH_Exchange *exchange)
   }
   GNUNET_assert (NULL == exchange->keys_head);
   GNUNET_assert (NULL == exchange->keys_tail);
-  GNUNET_assert (NULL == exchange->w_head);
-  GNUNET_assert (NULL == exchange->w_tail);
   GNUNET_free (exchange->url);
   GNUNET_free (exchange);
 }
@@ -1379,31 +1086,17 @@ static void
 fail_and_retry (struct TMH_Exchange *exchange)
 {
   struct TMH_EXCHANGES_KeysOperation *keys;
-  struct TMH_EXCHANGES_WireOperation *w;
 
-  if (NULL != exchange->wire_request)
-  {
-    TALER_EXCHANGE_wire_cancel (exchange->wire_request);
-    exchange->wire_request = NULL;
-  }
-  if (NULL != exchange->wire_task)
-  {
-    GNUNET_SCHEDULER_cancel (exchange->wire_task);
-    exchange->wire_task = NULL;
-  }
   while (NULL != (keys = exchange->keys_head))
   {
     keys->fc (keys->fc_cls,
-              NULL);
+              NULL,
+              exchange);
     TMH_EXCHANGES_keys4exchange_cancel (keys);
   }
-  while (NULL != (w = exchange->w_head))
-  {
-    w->fc (w->fc_cls,
-           NULL);
-    TMH_EXCHANGES_wire4exchange_cancel (w);
-  }
-  exchange->retry_delay = RETRY_BACKOFF (exchange->retry_delay);
+  exchange->retry_delay
+    = GNUNET_TIME_randomized_backoff (exchange->retry_delay,
+                                      RETRY_BACKOFF_THRESHOLD);
   GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
               "Failed to fetch /keys from `%s'; retrying in %s\n",
               exchange->url,
@@ -1435,6 +1128,31 @@ keys_mgmt_cb (void *cls,
     fail_and_retry (exchange);
     return;
   }
+
+  /* store exchange online signing keys in our DB */
+  for (unsigned int i = 0; i<keys->num_sign_keys; i++)
+  {
+    struct TALER_EXCHANGE_SigningPublicKey *sign_key = &keys->sign_keys[i];
+    enum GNUNET_DB_QueryStatus qs;
+
+    TMH_db->preflight (TMH_db->cls);
+    qs = TMH_db->insert_exchange_signkey (
+      TMH_db->cls,
+      &keys->master_pub,
+      &sign_key->key,
+      sign_key->valid_from,
+      sign_key->valid_until,
+      sign_key->valid_legal,
+      &sign_key->master_sig);
+    /* 0 is OK, we may already have the key in the DB! */
+    if (0 > qs)
+    {
+      GNUNET_break (0);
+      fail_and_retry (exchange);
+      return;
+    }
+  }
+
   qs = TMH_db->insert_exchange_keys (TMH_db->cls,
                                      keys);
   TALER_EXCHANGE_keys_decref (keys);
@@ -1450,129 +1168,20 @@ keys_mgmt_cb (void *cls,
                           &es,
                           exchange->url,
                           strlen (exchange->url) + 1);
+    exchange->retry_delay = GNUNET_TIME_UNIT_ZERO;
   }
 }
 
 
-/**
- * Task to return find operation result asynchronously to caller.
- *
- * @param cls a `struct TMH_EXCHANGES_WireOperation`
- */
-static void
-return_wire_result (void *cls)
-{
-  struct TMH_EXCHANGES_WireOperation *w = cls;
-  struct TMH_Exchange *exchange = w->my_exchange;
-
-  w->at = NULL;
-  process_find_operations (exchange);
-}
-
-
-struct TMH_EXCHANGES_WireOperation *
-TMH_EXCHANGES_wire4exchange (
-  const char *chosen_exchange,
-  TMH_EXCHANGES_WireContinuation fc,
-  void *fc_cls)
-{
-  struct TMH_Exchange *exchange;
-  struct TMH_EXCHANGES_WireOperation *w;
-
-  if (NULL == TMH_curl_ctx)
-  {
-    GNUNET_break (0);
-    return NULL;
-  }
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-              "Trying to find chosen exchange `%s'\n",
-              chosen_exchange);
-  exchange = lookup_exchange (chosen_exchange);
-  w = GNUNET_new (struct TMH_EXCHANGES_WireOperation);
-  w->fc = fc;
-  w->fc_cls = fc_cls;
-  w->my_exchange = exchange;
-  GNUNET_CONTAINER_DLL_insert (exchange->w_head,
-                               exchange->w_tail,
-                               w);
-  if (exchange->have_wire)
-  {
-    /* We are not currently waiting for a reply, immediately
-       return result */
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "The exchange `%s' is ready\n",
-                exchange->url);
-    GNUNET_assert (NULL == w->at);
-    w->at = GNUNET_SCHEDULER_add_now (&return_wire_result,
-                                      w);
-    return w;
-  }
-  if (NULL != exchange->wire_request)
-    return w; /* /wire request is active, do nothing */
-  if ( (NULL != exchange->keys) &&
-       (GNUNET_TIME_absolute_is_future (
-          exchange->keys->key_data_expiration.abs_time)) )
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "Requesting /wire from `%s'\n",
-                exchange->url);
-    exchange->wire_request
-      = TALER_EXCHANGE_wire (TMH_curl_ctx,
-                             exchange->url,
-                             exchange->keys,
-                             &handle_wire_data,
-                             exchange);
-    return w;
-  }
-  if ( (NULL == exchange->keys) &&
-       ( (NULL != exchange->conn) ||
-         (NULL != exchange->retry_task) ) )
-    return w; /* /keys request active, do nothing */
-
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "No valid keys, fetching /keys at %s\n",
-              GNUNET_TIME_absolute2s (exchange->first_retry));
-  exchange->retry_task
-    = GNUNET_SCHEDULER_add_at (exchange->first_retry,
-                               &retry_exchange,
-                               exchange);
-  return w;
-}
-
-
-void
-TMH_EXCHANGES_wire4exchange_cancel (
-  struct TMH_EXCHANGES_WireOperation *w)
-{
-  struct TMH_Exchange *exchange = w->my_exchange;
-
-  if (NULL != w->at)
-  {
-    GNUNET_SCHEDULER_cancel (w->at);
-    w->at = NULL;
-  }
-  GNUNET_CONTAINER_DLL_remove (exchange->w_head,
-                               exchange->w_tail,
-                               w);
-  GNUNET_free (w);
-}
-
-
 enum GNUNET_GenericReturnValue
 TMH_EXCHANGES_lookup_wire_fee (
-  const struct TMH_ExchangeWireDetails *wd,
+  const struct TMH_Exchange *exchange,
   const char *wire_method,
   struct TALER_Amount *wire_fee)
 {
-  struct TMH_Exchange *exchange = wd->exchange;
   const struct FeesByWireMethod *fbm;
   const struct TALER_EXCHANGE_WireAggregateFees *af;
 
-  if (! exchange->have_wire)
-  {
-    GNUNET_break (0);
-    return GNUNET_SYSERR;
-  }
   fbm = get_wire_fees (exchange,
                        GNUNET_TIME_timestamp_get (),
                        wire_method);
@@ -1586,11 +1195,17 @@ TMH_EXCHANGES_lookup_wire_fee (
 
 enum GNUNET_GenericReturnValue
 TMH_exchange_check_debit (
-  const struct TMH_ExchangeWireDetails *wd,
+  const struct TMH_Exchange *exchange,
   const struct TMH_WireMethod *wm)
 {
-  struct TMH_Exchange *ex = wd->exchange;
-  for (struct ExchangeAccount *acc = ex->acc_head;
+  if (NULL == exchange->acc_head)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                "No accounts available for %s\n",
+                exchange->url);
+    return GNUNET_SYSERR;
+  }
+  for (struct ExchangeAccount *acc = exchange->acc_head;
        NULL != acc;
        acc = acc->next)
   {
@@ -1632,48 +1247,25 @@ TMH_exchange_check_debit (
 }
 
 
-json_t *
-TMH_exchange_get_acceptable (const struct TMH_WireMethod *wm)
+void
+TMH_exchange_get_trusted (TMH_ExchangeCallback cb,
+                          void *cb_cls)
 {
-  json_t *te = json_array ();
-
-  GNUNET_assert (NULL != te);
-  for (struct TMH_Exchange *exchange = exchange_head;
+  for (const struct TMH_Exchange *exchange = exchange_head;
        NULL != exchange;
        exchange = exchange->next)
   {
-    json_t *j_exchange;
-    unsigned int priority;
-
     if (! exchange->trusted)
-      continue;
-    priority = 512; /* medium */
-    if (exchange->have_wire)
     {
-      struct TMH_ExchangeWireDetails wd = {
-        .exchange = exchange
-      };
-
-      if (GNUNET_OK ==
-          TMH_exchange_check_debit (&wd,
-                                    wm))
-        priority = 1024; /* high */
-      else
-        priority = 0; /* negative response */
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  "Exchange %s not trusted, skipping!\n",
+                  exchange->url);
+      continue;
     }
-    j_exchange = GNUNET_JSON_PACK (
-      GNUNET_JSON_pack_string ("url",
-                               exchange->url),
-      GNUNET_JSON_pack_uint64 ("priority",
-                               priority),
-      GNUNET_JSON_pack_data_auto ("master_pub",
-                                  &exchange->master_pub));
-    GNUNET_assert (NULL != j_exchange);
-    GNUNET_assert (0 ==
-                   json_array_append_new (te,
-                                          j_exchange));
+    cb (cb_cls,
+        exchange->url,
+        exchange);
   }
-  return te;
 }
 
 
@@ -1762,6 +1354,10 @@ accept_exchanges (void *cls,
                 "MASTER_KEY missing in section '%s', not trusting exchange\n",
                 section);
   }
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Setup exchange %s as %s\n",
+              exchange->url,
+              exchange->trusted ? "trusted" : "untrusted");
   GNUNET_assert (NULL == exchange->retry_task);
   exchange->retry_task
     = GNUNET_SCHEDULER_add_now (&retry_exchange,
@@ -1785,7 +1381,7 @@ update_exchange_keys (void *cls,
   const char *url = extra;
   struct TMH_Exchange *exchange;
   struct TALER_EXCHANGE_Keys *keys;
-  struct GNUNET_TIME_Relative delay;
+  enum TALER_ErrorCode ecx;
 
   if ( (NULL == extra) ||
        (0 == extra_len) )
@@ -1810,11 +1406,35 @@ update_exchange_keys (void *cls,
     GNUNET_break (0);
     return;
   }
-  TALER_EXCHANGE_keys_decref (exchange->keys);
-  exchange->keys = keys;
+
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Loaded /keys from database with %u accounts\n",
+              keys->accounts_len);
+  // FIXME: split into parsing part (do here)
+  // and DB part (do when receiving /keys!)
+  ecx = process_wire_accounts (exchange,
+                               &keys->master_pub,
+                               keys->accounts_len,
+                               keys->accounts);
+  if (TALER_EC_NONE == ecx)
+    ecx = process_wire_fees (exchange,
+                             &keys->master_pub,
+                             keys->fees_len,
+                             keys->fees);
+  if (TALER_EC_NONE != ecx)
+  {
+    /* Report hard failure to all callbacks! */
+    GNUNET_break_op (0);
+    fail_and_retry (exchange);
+    TALER_EXCHANGE_keys_decref (keys);
+    return;
+  }
+
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
               "Reloaded /keys of %s from database\n",
               url);
+  TALER_EXCHANGE_keys_decref (exchange->keys);
+  exchange->keys = keys;
   if ( (exchange->trusted) &&
        (0 != GNUNET_memcmp (&exchange->master_pub,
                             &keys->master_pub)) )
@@ -1843,62 +1463,7 @@ update_exchange_keys (void *cls,
     }
   }
 
-  /* store exchange online signing keys in our DB */
-  for (unsigned int i = 0; i<keys->num_sign_keys; i++)
-  {
-    struct TALER_EXCHANGE_SigningPublicKey *sign_key = &keys->sign_keys[i];
-    enum GNUNET_DB_QueryStatus qs;
-
-    TMH_db->preflight (TMH_db->cls);
-    qs = TMH_db->insert_exchange_signkey (
-      TMH_db->cls,
-      &keys->master_pub,
-      &sign_key->key,
-      sign_key->valid_from,
-      sign_key->valid_until,
-      sign_key->valid_legal,
-      &sign_key->master_sig);
-    /* 0 is OK, we may already have the key in the DB! */
-    if (0 > qs)
-    {
-      GNUNET_break (0);
-      fail_and_retry (exchange);
-      return;
-    }
-  }
-
-  exchange->first_retry
-    = GNUNET_TIME_relative_to_absolute (MIN_RELOAD_DELAY);
-  delay = GNUNET_TIME_absolute_get_remaining (
-    keys->key_data_expiration.abs_time);
-  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "/keys response expires at %s! Retrying at that time!\n",
-              GNUNET_TIME_absolute2s (
-                keys->key_data_expiration.abs_time));
-  delay = GNUNET_TIME_relative_max (delay,
-                                    MIN_RELOAD_DELAY);
-  exchange->retry_delay = GNUNET_TIME_UNIT_ZERO;
-  if (NULL != exchange->retry_task)
-    GNUNET_SCHEDULER_cancel (exchange->retry_task);
-  exchange->retry_task
-    = GNUNET_SCHEDULER_add_delayed (delay,
-                                    &retry_exchange,
-                                    exchange);
-
-  if ( (process_find_operations (exchange)) &&
-       (NULL == exchange->wire_request) &&
-       (NULL == exchange->wire_task) )
-  {
-    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
-                "Got key data, but also need wire data. Will request /wire now\n");
-    exchange->wire_request
-      = TALER_EXCHANGE_wire (
-          TMH_curl_ctx,
-          exchange->url,
-          exchange->keys,
-          &handle_wire_data,
-          exchange);
-  }
+  process_find_operations (exchange);
 }
 
 
diff --git a/src/backend/taler-merchant-httpd_exchanges.h b/src/backend/taler-merchant-httpd_exchanges.h
index 89e5deee..b0f2d879 100644
--- a/src/backend/taler-merchant-httpd_exchanges.h
+++ b/src/backend/taler-merchant-httpd_exchanges.h
@@ -37,19 +37,6 @@ struct TMH_Exchange;
 
 
 /**
- * Return the list of exchanges we would find
- * acceptable for a payment given the @a wire_method.
- *
- * @param wm wire method the payment should be
- *        made with
- * @return list of exchanges we accept for @a wire_method
- *   (and that would accept our bank account)
- */
-json_t *
-TMH_exchange_get_acceptable (const struct TMH_WireMethod *wm);
-
-
-/**
  * Parses "trusted" exchanges listed in the configuration.
  *
  * @param cfg the configuration
@@ -73,30 +60,13 @@ TMH_EXCHANGES_done (void);
  *
  * @param cls closure
  * @param keys the keys of the exchange
+ * @param exchange representation of the exchange
  */
 typedef void
 (*TMH_EXCHANGES_Find2Continuation)(
   void *cls,
-  struct TALER_EXCHANGE_Keys *keys);
-
-
-/**
- * Abstraction of wire knowledge returned internally.
- */
-struct TMH_ExchangeWireDetails;
-
-
-/**
- * Function called with the result of a #TMH_EXCHANGES_wire4exchange()
- * operation.
- *
- * @param cls closure
- * @param wire the wire data of the exchange
- */
-typedef void
-(*TMH_EXCHANGES_WireContinuation)(
-  void *cls,
-  const struct TMH_ExchangeWireDetails *wire);
+  struct TALER_EXCHANGE_Keys *keys,
+  struct TMH_Exchange *exchange);
 
 
 /**
@@ -104,22 +74,19 @@ typedef void
  */
 struct TMH_EXCHANGES_KeysOperation;
 
-/**
- * Information we keep for a pending #MMH_EXCHANGES_wire4exchange() operation.
- */
-struct TMH_EXCHANGES_WireOperation;
-
 
 /**
  * Get /keys of the given @a exchange.
  *
  * @param exchange URL of the exchange we would like to talk to
+ * @param force_download force /keys download now
  * @param fc function to call with the handles for the exchange
  * @param fc_cls closure for @a fc
  */
 struct TMH_EXCHANGES_KeysOperation *
 TMH_EXCHANGES_keys4exchange (
   const char *exchange,
+  bool force_download,
   TMH_EXCHANGES_Find2Continuation fc,
   void *fc_cls);
 
@@ -134,34 +101,47 @@ TMH_EXCHANGES_keys4exchange_cancel (struct TMH_EXCHANGES_KeysOperation *fo);
 
 
 /**
- * Get /wire of the given @a exchange.
+ * Callback on an exchange known to us. Does not warrant
+ * that the "keys" information is actually available for
+ * @a exchange.
  *
- * @param exchange URL of the exchange we would like to talk to
- * @param fc function to call with the handles for the exchange
- * @param fc_cls closure for @a fc
+ * @param cls closure
+ * @param url base URL of the exchange
+ * @param exchange internal handle for the exchange
  */
-struct TMH_EXCHANGES_WireOperation *
-TMH_EXCHANGES_wire4exchange (
-  const char *exchange,
-  TMH_EXCHANGES_WireContinuation fc,
-  void *fc_cls);
+typedef void
+(*TMH_ExchangeCallback)(void *cls,
+                        const char *url,
+                        const struct TMH_Exchange *exchange);
 
 
 /**
- * Abort pending wire details lookup operation.
+ * Return all trusted exchanges to @a cb.
  *
- * @param fo handle to operation to abort
+ * @param cb function to call
+ * @param cb_cls closure for @a cb
  */
 void
-TMH_EXCHANGES_wire4exchange_cancel (
-  struct TMH_EXCHANGES_WireOperation *fo);
+TMH_exchange_get_trusted (TMH_ExchangeCallback cb,
+                          void *cb_cls);
 
+/**
+ * Return the master public key of the given @a exchange.
+ * Will be returned from configuration for trusted
+ * exchanges.
+ *
+ * @param exchange exchange to get master public key for
+ * @return the master public key of @a exchange
+ */
+const struct TALER_MasterPublicKeyP *
+TMH_EXCHANGES_get_master_pub (
+  const struct TMH_Exchange *exchange);
 
 /**
  * Lookup current wire fee by @a exchange_url and
  * @a wire_method.
  *
- * @param wd wire details of the exchange
+ * @param exchange the exchange to check
  * @param wire_method wire method to lookup fee by
  * @param[out] wire_fee set to the wire fee
  * @return #GNUNET_OK on success
@@ -170,7 +150,7 @@ TMH_EXCHANGES_wire4exchange_cancel (
  */
 enum GNUNET_GenericReturnValue
 TMH_EXCHANGES_lookup_wire_fee (
-  const struct TMH_ExchangeWireDetails *wd,
+  const struct TMH_Exchange *exchange,
   const char *wire_method,
   struct TALER_Amount *wire_fee);
 
@@ -181,13 +161,13 @@ TMH_EXCHANGES_lookup_wire_fee (
  * is trusted and that @a ex allows wire transfers
  * into the account given in @a wm.
  *
- * @param wd the wire details of the exchange to check
+ * @param exchange the exchange to check
  * @param wm the wire method to check with
  * @return #GNUNET_OK if such a debit can happen
  */
 enum GNUNET_GenericReturnValue
 TMH_exchange_check_debit (
-  const struct TMH_ExchangeWireDetails *wd,
+  const struct TMH_Exchange *exchange,
   const struct TMH_WireMethod *wm);
 
 
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-abort.c b/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
index f63404b4..09ac8acb 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-abort.c
@@ -497,13 +497,16 @@ refund_cb (void *cls,
  *
  * @param cls the `struct AbortContext`
  * @param keys keys of the exchange
+ * @param exchange representation of the exchange
  */
 static void
 process_abort_with_exchange (void *cls,
-                             struct TALER_EXCHANGE_Keys *keys)
+                             struct TALER_EXCHANGE_Keys *keys,
+                             struct TMH_Exchange *exchange)
 {
   struct AbortContext *ac = cls;
 
+  (void) exchange;
   ac->fo = NULL;
   GNUNET_assert (GNUNET_YES == ac->suspended);
   if (NULL == keys)
@@ -584,6 +587,7 @@ find_next_exchange (struct AbortContext *ac)
     {
       ac->current_exchange = rdi->exchange_url;
       ac->fo = TMH_EXCHANGES_keys4exchange (ac->current_exchange,
+                                            false,
                                             &process_abort_with_exchange,
                                             ac);
       if (NULL == ac->fo)
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-pay.c b/src/backend/taler-merchant-httpd_post-orders-ID-pay.c
index 75bc4345..d4e620bd 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-pay.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-pay.c
@@ -176,13 +176,6 @@ struct ExchangeGroup
   struct TMH_EXCHANGES_KeysOperation *fo;
 
   /**
-   * Handle for operation to lookup /wire from
-   * the exchange used for this transaction; NULL if no operation is
-   * pending.
-   */
-  struct TMH_EXCHANGES_WireOperation *gwo;
-
-  /**
    * URL of the exchange that issued this coin. Aliases
    * the exchange URL of one of the coins, do not free!
    */
@@ -692,8 +685,6 @@ pay_context_cleanup (void *cls)
 
     if (NULL != eg->fo)
       TMH_EXCHANGES_keys4exchange_cancel (eg->fo);
-    if (NULL != eg->gwo)
-      TMH_EXCHANGES_wire4exchange_cancel (eg->gwo);
     GNUNET_free (eg);
   }
   GNUNET_free (pc->egs);
@@ -785,14 +776,17 @@ deposit_get_callback (
  *
  * @param cls the `struct KycContext`
  * @param keys NULL if exchange was not found to be acceptable
+ * @param exchange representation of the exchange
  */
 static void
 process_kyc_with_exchange (
   void *cls,
-  struct TALER_EXCHANGE_Keys *keys)
+  struct TALER_EXCHANGE_Keys *keys,
+  struct TMH_Exchange *exchange)
 {
   struct KycContext *kc = cls;
 
+  (void) exchange;
   kc->fo = NULL;
   if (NULL == keys)
   {
@@ -922,9 +916,11 @@ check_kyc (struct PayContext *pc,
   GNUNET_CONTAINER_DLL_insert (kc_head,
                                kc_tail,
                                kc);
-  kc->fo = TMH_EXCHANGES_keys4exchange (kc->exchange_url,
-                                        &process_kyc_with_exchange,
-                                        kc);
+  kc->fo = TMH_EXCHANGES_keys4exchange (
+    kc->exchange_url,
+    false,
+    &process_kyc_with_exchange,
+    kc);
   if (NULL == kc->fo)
   {
     GNUNET_break (0);
@@ -1146,15 +1142,26 @@ batch_deposit_cb (
 
 
 /**
+ * Force re-downloading keys for @a eg.
+ *
+ * @param[in,out] eg group to re-download keys for
+ */
+static void
+force_keys (struct ExchangeGroup *eg);
+
+
+/**
  * Function called with the result of our exchange keys lookup.
  *
  * @param cls the `struct ExchangeGroup`
  * @param keys the keys of the exchange
+ * @param exchange representation of the exchange
  */
 static void
 process_pay_with_keys (
   void *cls,
-  struct TALER_EXCHANGE_Keys *keys)
+  struct TALER_EXCHANGE_Keys *keys,
+  struct TMH_Exchange *exchange)
 {
   struct ExchangeGroup *eg = cls;
   struct PayContext *pc = eg->pc;
@@ -1178,6 +1185,62 @@ process_pay_with_keys (
     return;
   }
 
+  if (GNUNET_OK !=
+      TMH_exchange_check_debit (exchange,
+                                pc->wm))
+  {
+    if (eg->tried_force_keys)
+    {
+      GNUNET_break_op (0);
+      pc->pending_at_eg--;
+      resume_pay_with_error (
+        pc,
+        TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_WIRE_METHOD_UNSUPPORTED,
+        NULL);
+      return;
+    }
+    eg->tried_force_keys = true;
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "Forcing /keys download (once) as wire method seems unsupported for debit\n");
+    eg->fo = TMH_EXCHANGES_keys4exchange (
+      eg->exchange_url,
+      true,
+      &process_pay_with_keys,
+      eg);
+    if (NULL == eg->fo)
+    {
+      GNUNET_break (0);
+      pc->pending_at_eg--;
+      resume_pay_with_error (pc,
+                             TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_EXCHANGE_LOOKUP_FAILED,
+                             "Failed to lookup exchange by URL");
+      return;
+    }
+    return;
+  }
+
+  if (GNUNET_OK !=
+      TMH_EXCHANGES_lookup_wire_fee (exchange,
+                                     pc->wm->wire_method,
+                                     &eg->wire_fee))
+  {
+    if (eg->tried_force_keys)
+    {
+      pc->pending_at_eg--;
+      GNUNET_break_op (0);
+      resume_pay_with_error (
+        pc,
+        TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_WIRE_METHOD_UNSUPPORTED,
+        pc->wm->wire_method);
+      return;
+    }
+    force_keys (eg);
+    return;
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Got wire data for %s\n",
+              eg->exchange_url);
+
   /* Initiate /batch-deposit operation for all coins of
      the current exchange (!) */
   group_size = 0;
@@ -1198,19 +1261,25 @@ process_pay_with_keys (
                                                      &dc->cdd.h_denom_pub);
     if (NULL == denom_details)
     {
-      pc->pending_at_eg--;
-      resume_pay_with_response (
-        pc,
-        MHD_HTTP_BAD_REQUEST,
-        TALER_MHD_MAKE_JSON_PACK (
-          TALER_JSON_pack_ec (
-            TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_DENOMINATION_KEY_NOT_FOUND),
-          GNUNET_JSON_pack_data_auto ("h_denom_pub",
-                                      &dc->cdd.h_denom_pub),
-          GNUNET_JSON_pack_allow_null (
-            GNUNET_JSON_pack_object_steal (
-              "exchange_keys",
-              TALER_EXCHANGE_keys_to_json (keys)))));
+      if (eg->tried_force_keys)
+      {
+        GNUNET_break_op (0);
+        pc->pending_at_eg--;
+        resume_pay_with_response (
+          pc,
+          MHD_HTTP_BAD_REQUEST,
+          TALER_MHD_MAKE_JSON_PACK (
+            TALER_JSON_pack_ec (
+              TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_DENOMINATION_KEY_NOT_FOUND),
+            GNUNET_JSON_pack_data_auto ("h_denom_pub",
+                                        &dc->cdd.h_denom_pub),
+            GNUNET_JSON_pack_allow_null (
+              GNUNET_JSON_pack_object_steal (
+                "exchange_keys",
+                TALER_EXCHANGE_keys_to_json (keys)))));
+        return;
+      }
+      force_keys (eg);
       return;
     }
     dc->deposit_fee = denom_details->fees.deposit;
@@ -1270,6 +1339,7 @@ process_pay_with_keys (
 AGE_FAIL:
       if (0 < code)
       {
+        GNUNET_break_op (0);
         pc->pending_at_eg--;
         GNUNET_free (dc->age_commitment.keys);
         resume_pay_with_response (
@@ -1383,73 +1453,21 @@ AGE_FAIL:
 }
 
 
-/**
- * Function called with the result of our exchange lookup.
- *
- * @param cls the `struct ExchangeGroup`
- * @param keys the keys of the exchange
- */
 static void
-process_pay_with_wire (
-  void *cls,
-  const struct TMH_ExchangeWireDetails *wire)
+force_keys (struct ExchangeGroup *eg)
 {
-  struct ExchangeGroup *eg = cls;
-  struct PayContext *pc = eg->pc;
-  struct TMH_HandlerContext *hc = pc->hc;
-  enum GNUNET_GenericReturnValue ret;
-
-  eg->gwo = NULL;
-  GNUNET_SCHEDULER_begin_async_scope (&hc->async_scope_id);
-  if (NULL == wire)
-  {
-    GNUNET_break_op (0);
-    pc->pending_at_eg--;
-    /* FIXME: define more specific error code... */
-    resume_pay_with_error (
-      pc,
-      TALER_EC_MERCHANT_GENERIC_EXCHANGE_CONNECT_FAILURE,
-      NULL);
-    return;
-  }
-  if (GNUNET_OK !=
-      TMH_exchange_check_debit (wire,
-                                pc->wm))
-  {
-    GNUNET_break_op (0);
-    pc->pending_at_eg--;
-    resume_pay_with_error (
-      pc,
-      TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_WIRE_METHOD_UNSUPPORTED,
-      NULL);
-    return;
-  }
-  ret = TMH_EXCHANGES_lookup_wire_fee (wire,
-                                       pc->wm->wire_method,
-                                       &eg->wire_fee);
-  if (GNUNET_OK != ret)
-  {
-    enum TALER_ErrorCode ec;
-
-    ec = (GNUNET_NO == ret)
-      ? TALER_EC_MERCHANT_POST_ORDERS_ID_PAY_WIRE_METHOD_UNSUPPORTED
-      : TALER_EC_MERCHANT_GENERIC_EXCHANGE_WIRE_REQUEST_FAILED;
-    pc->pending_at_eg--;
-    GNUNET_break_op (0);
-    resume_pay_with_error (
-      pc,
-      ec,
-      pc->wm->wire_method);
-    return;
-  }
+  eg->tried_force_keys = true;
   GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-              "Got /wire for %s, now going for /keys\n",
-              eg->exchange_url);
-  eg->fo = TMH_EXCHANGES_keys4exchange (eg->exchange_url,
-                                        &process_pay_with_keys,
-                                        eg);
+              "Forcing /keys download (once) as wire fees are unknown\n");
+  eg->fo = TMH_EXCHANGES_keys4exchange (
+    eg->exchange_url,
+    true,
+    &process_pay_with_keys,
+    eg);
   if (NULL == eg->fo)
   {
+    struct PayContext *pc = eg->pc;
+
     GNUNET_break (0);
     pc->pending_at_eg--;
     resume_pay_with_error (pc,
@@ -1489,12 +1507,14 @@ start_batch_deposits (struct PayContext *pc)
     if (! have_coins)
       continue; /* no coins left to deposit at this exchange */
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
-                "Getting /wire details for %s\n",
+                "Getting /keys for %s\n",
                 eg->exchange_url);
-    eg->gwo = TMH_EXCHANGES_wire4exchange (eg->exchange_url,
-                                           &process_pay_with_wire,
-                                           eg);
-    if (NULL == eg->gwo)
+    eg->fo = TMH_EXCHANGES_keys4exchange (
+      eg->exchange_url,
+      false,
+      &process_pay_with_keys,
+      eg);
+    if (NULL == eg->fo)
     {
       GNUNET_break (0);
       resume_pay_with_error (pc,
diff --git a/src/backend/taler-merchant-httpd_post-orders-ID-refund.c b/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
index ded6ff9d..f71eb17e 100644
--- a/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
+++ b/src/backend/taler-merchant-httpd_post-orders-ID-refund.c
@@ -439,14 +439,17 @@ refund_cb (void *cls,
  *
  * @param cls a `struct CoinRefund *`
  * @param keys keys of exchange, NULL on error
+ * @param exchange representation of the exchange
  */
 static void
 exchange_found_cb (void *cls,
-                   struct TALER_EXCHANGE_Keys *keys)
+                   struct TALER_EXCHANGE_Keys *keys,
+                   struct TMH_Exchange *exchange)
 {
   struct CoinRefund *cr = cls;
   struct PostRefundData *prd = cr->prd;
 
+  (void) exchange;
   cr->fo = NULL;
   if (NULL == keys)
   {
@@ -707,6 +710,7 @@ TMH_post_orders_ID_refund (const struct TMH_RequestHandler *rh,
       {
         /* We need to talk to the exchange */
         cr->fo = TMH_EXCHANGES_keys4exchange (cr->exchange_url,
+                                              false,
                                               &exchange_found_cb,
                                               cr);
       }
diff --git a/src/backend/taler-merchant-httpd_post-rewards-ID-pickup.c b/src/backend/taler-merchant-httpd_post-rewards-ID-pickup.c
index b7aa31e1..05347c9f 100644
--- a/src/backend/taler-merchant-httpd_post-rewards-ID-pickup.c
+++ b/src/backend/taler-merchant-httpd_post-rewards-ID-pickup.c
@@ -384,14 +384,17 @@ withdraw_cb (void *cls,
  *
  * @param cls closure, with our `struct PlanchetOperation *`
  * @param keys keys for the exchange
+ * @param exchange representation of the exchange
  */
 static void
 do_withdraw (void *cls,
-             struct TALER_EXCHANGE_Keys *keys)
+             struct TALER_EXCHANGE_Keys *keys,
+             struct TMH_Exchange *exchange)
 {
   struct PlanchetOperation *po = cls;
   struct PickupContext *pc = po->pc;
 
+  (void) exchange;
   po->fo = NULL;
   TMH_db->preflight (TMH_db->cls);
   if (NULL == keys)
@@ -443,6 +446,7 @@ try_withdraw (struct PickupContext *pc,
   po->pd = *planchet;
   po->offset = offset;
   po->fo = TMH_EXCHANGES_keys4exchange (pc->exchange_url,
+                                        false,
                                         &do_withdraw,
                                         po);
   GNUNET_assert (NULL != po->fo);
@@ -484,13 +488,16 @@ do_timeout (void *cls)
  *
  * @param cls closure, with our `struct PickupContext *`
  * @param keys the keys of the exchange
+ * @param exchange representation of the exchange
  */
 static void
 compute_total_requested (void *cls,
-                         struct TALER_EXCHANGE_Keys *keys)
+                         struct TALER_EXCHANGE_Keys *keys,
+                         struct TMH_Exchange *exchange)
 {
   struct PickupContext *pc = cls;
 
+  (void) exchange;
   pc->fo = NULL;
   stop_operations (pc); /* stops timeout job */
   if (NULL == keys)
@@ -727,6 +734,7 @@ TMH_post_rewards_ID_pickup (const struct TMH_RequestHandler *rh,
                                            &do_timeout,
                                            pc);
     pc->fo = TMH_EXCHANGES_keys4exchange (pc->exchange_url,
+                                          false,
                                           &compute_total_requested,
                                           pc);
     return MHD_YES;
diff --git a/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c b/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
index eda0aaa8..d269402b 100644
--- a/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
+++ b/src/backend/taler-merchant-httpd_private-get-instances-ID-kyc.c
@@ -650,15 +650,18 @@ exchange_check_cb (void *cls,
  *
  * @param cls closure with our `struct ExchangeKycRequest *`
  * @param keys keys of the exchange context
+ * @param exchange representation of the exchange
  */
 static void
 kyc_with_exchange (void *cls,
-                   struct TALER_EXCHANGE_Keys *keys)
+                   struct TALER_EXCHANGE_Keys *keys,
+                   struct TMH_Exchange *exchange)
 {
   struct ExchangeKycRequest *ekr = cls;
   struct KycContext *kc = ekr->kc;
   struct TALER_PaytoHashP h_payto;
 
+  (void) exchange;
   ekr->fo = NULL;
   if (NULL == keys)
   {
@@ -738,6 +741,7 @@ kyc_status_cb (void *cls,
   ekr->last_check = last_check;
   ekr->kc = kc;
   ekr->fo = TMH_EXCHANGES_keys4exchange (exchange_url,
+                                         false,
                                          &kyc_with_exchange,
                                          ekr);
 }
diff --git a/src/backend/taler-merchant-httpd_private-get-orders-ID.c b/src/backend/taler-merchant-httpd_private-get-orders-ID.c
index 710194f8..f732dc84 100644
--- a/src/backend/taler-merchant-httpd_private-get-orders-ID.c
+++ b/src/backend/taler-merchant-httpd_private-get-orders-ID.c
@@ -591,14 +591,17 @@ deposit_get_cb (void *cls,
  *
  * @param cls closure with a `struct GetOrderRequestContext *`
  * @param keys keys of the exchange
+ * @param exchange representation of the exchange
  */
 static void
 exchange_found_cb (void *cls,
-                   struct TALER_EXCHANGE_Keys *keys)
+                   struct TALER_EXCHANGE_Keys *keys,
+                   struct TMH_Exchange *exchange)
 {
   struct TransferQuery *tq = cls;
   struct GetOrderRequestContext *gorc = tq->gorc;
 
+  (void) exchange;
   tq->fo = NULL;
   if (NULL == keys)
   {
@@ -678,6 +681,7 @@ deposit_cb (void *cls,
   tq->amount_with_fee = *amount_with_fee;
   tq->deposit_fee = *deposit_fee;
   tq->fo = TMH_EXCHANGES_keys4exchange (exchange_url,
+                                        false,
                                         &exchange_found_cb,
                                         tq);
   if (NULL == tq->fo)
diff --git a/src/backend/taler-merchant-httpd_private-post-orders.c b/src/backend/taler-merchant-httpd_private-post-orders.c
index 5646af4d..66cf71a5 100644
--- a/src/backend/taler-merchant-httpd_private-post-orders.c
+++ b/src/backend/taler-merchant-httpd_private-post-orders.c
@@ -94,6 +94,40 @@ struct InventoryProduct
 
 
 /**
+ * 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;
+
+};
+
+
+/**
  * Information we keep per order we are processing.
  */
 struct OrderContext
@@ -105,6 +139,16 @@ struct OrderContext
   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;
@@ -132,6 +176,12 @@ struct OrderContext
   json_t *order;
 
   /**
+   * Array of exchanges we find acceptable for this
+   * order.
+   */
+  json_t *exchanges;
+
+  /**
    * RFC8905 payment target type to find a matching merchant account
    */
   const char *payment_target;
@@ -143,6 +193,18 @@ struct OrderContext
   const struct TMH_WireMethod *wm;
 
   /**
+   * 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;
+
+  /**
    * Claim token for the request.
    */
   struct TALER_ClaimTokenP claim_token;
@@ -158,14 +220,19 @@ struct OrderContext
   struct InventoryProduct *inventory_products;
 
   /**
-   * Length of the @e uuids array.
+   * array of UUIDs used to reserve products from @a inventory_products.
    */
-  unsigned int uuids_length;
+  struct GNUNET_Uuid *uuids;
 
   /**
-   * array of UUIDs used to reserve products from @a inventory_products.
+   * Shared key to use with @e pos_algorithm.
    */
-  struct GNUNET_Uuid *uuids;
+  const char *pos_key;
+
+  /**
+   * Our order ID. Pointer into @e order.
+   */
+  const char *order_id;
 
   /**
    * which product (by offset) is out of stock, UINT_MAX if all were in-stock
@@ -173,14 +240,14 @@ struct OrderContext
   unsigned int out_of_stock_index;
 
   /**
-   * Shared key to use with @e pos_algorithm.
+   * Length of the @e uuids array.
    */
-  const char *pos_key;
+  unsigned int uuids_length;
 
   /**
-   * Our order ID. Pointer into @e order.
+   * #GNUNET_YES if suspended.
    */
-  const char *order_id;
+  enum GNUNET_GenericReturnValue suspended;
 
   /**
    * Selected algorithm (by template) when we are to
@@ -212,10 +279,50 @@ struct OrderContext
     ORDER_PHASE_FINISHED_MHD_NO
   } phase;
 
+  /**
+   * Set to true once we are sure that we have at
+   * least one good exchange.
+   */
+  bool exchange_good;
+
+  /**
+   * 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;
+
 };
 
 
 /**
+ * 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);
+  }
+}
+
+
+/**
  * Update the phase of @a oc based on @a mret.
  *
  * @param[in,out] oc order to update phase for
@@ -285,7 +392,22 @@ static void
 clean_order (void *cls)
 {
   struct OrderContext *oc = cls;
+  struct RekeyExchange *rx;
 
+  while (NULL != (rx = oc->pending_reload_head))
+  {
+    GNUNET_CONTAINER_DLL_remove (oc->pending_reload_head,
+                                 oc->pending_reload_tail,
+                                 rx);
+    TMH_EXCHANGES_keys4exchange_cancel (rx->fo);
+    GNUNET_free (rx->url);
+    GNUNET_free (rx);
+  }
+  if (NULL != oc->exchanges)
+  {
+    json_decref (oc->exchanges);
+    oc->exchanges = NULL;
+  }
   GNUNET_array_grow (oc->inventory_products,
                      oc->inventory_products_length,
                      0);
@@ -734,38 +856,196 @@ check_contract (struct OrderContext *oc)
 
 
 /**
- * Set list of acceptable exchanges in @a oc.
+ * Compute the set of exchanges that would be acceptable
+ * for this order.
  *
- * @param[in,out] oc order context
+ * @param cls our `struct OrderContext`
+ * @param url base URL of an exchange (not used)
+ * @param exchange internal handle for the exchange
  */
 static void
-set_exchanges (struct OrderContext *oc)
+get_acceptable (void *cls,
+                const char *url,
+                const struct TMH_Exchange *exchange)
 {
-  json_t *exchanges;
+  struct OrderContext *oc = cls;
+  unsigned int priority;
+  json_t *j_exchange;
+  enum GNUNET_GenericReturnValue res;
 
-  exchanges = TMH_exchange_get_acceptable (oc->wm);
-  if (0 == json_array_size (exchanges))
+  res = TMH_exchange_check_debit (exchange,
+                                  oc->wm);
+  switch (res)
+  {
+  case GNUNET_OK:
+    priority = 1024;   /* high */
+    oc->exchange_good = true;
+    break;
+  case GNUNET_NO:
+    if (oc->forced_reload)
+      priority = 0;   /* fresh negative response */
+    else
+      priority = 512; /* stale negative response */
+    break;
+  case GNUNET_SYSERR:
+    if (oc->forced_reload)
+      priority = 256;   /* fresh, no accounts yet */
+    else
+      priority = 768;  /* stale, no accounts yet */
+    break;
+  }
+  j_exchange = GNUNET_JSON_PACK (
+    GNUNET_JSON_pack_string ("url",
+                             url),
+    GNUNET_JSON_pack_uint64 ("priority",
+                             priority),
+    GNUNET_JSON_pack_data_auto ("master_pub",
+                                TMH_EXCHANGES_get_master_pub (exchange)));
+  GNUNET_assert (NULL != j_exchange);
+  GNUNET_assert (0 ==
+                 json_array_append_new (oc->exchanges,
+                                        j_exchange));
+}
+
+
+/**
+ * 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_forced (
+  void *cls,
+  struct TALER_EXCHANGE_Keys *keys,
+  struct TMH_Exchange *exchange)
+{
+  struct RekeyExchange *rx = cls;
+  struct OrderContext *oc = rx->oc;
+
+  rx->fo = NULL;
+  GNUNET_CONTAINER_DLL_remove (oc->pending_reload_head,
+                               oc->pending_reload_tail,
+                               rx);
+  if (NULL == keys)
   {
-    json_decref (exchanges);
-    /* FIXME: maybe there are exchanges for which we simply
-       did not yet get /wire replies. We should *try* to
-       run find_exchange() or something to give those
-       exchanges a chance to respond => need to suspend! */
     GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
-                "Cannot create order: lacking trusted exchanges for wire method `%s'\n",
-                oc->wm->wire_method);
-    reply_with_error (
-      oc,
-      MHD_HTTP_CONFLICT,
-      TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_EXCHANGES_FOR_WIRE_METHOD,
-      oc->wm->wire_method);
+                "Failed to download %s/keys\n",
+                rx->url);
+  }
+  get_acceptable (oc,
+                  rx->url,
+                  exchange);
+  GNUNET_free (rx->url);
+  GNUNET_free (rx);
+  if (NULL != oc->pending_reload_head)
     return;
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Resuming order processing after /keys downloads (now have %u accounts)\n",
+              (unsigned int) json_array_size (oc->exchanges));
+  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 */
+}
+
+
+/**
+ * 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
+rekey_exchanges (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->pending_reload_head,
+                               oc->pending_reload_tail,
+                               rx);
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Forcing download of %s/keys\n",
+              url);
+  rx->fo = TMH_EXCHANGES_keys4exchange (url,
+                                        true,
+                                        &keys_forced,
+                                        rx);
+}
+
+
+/**
+ * Set list of acceptable exchanges in @a oc.
+ *
+ * @param[in,out] oc order context
+ * @return true to suspend execution
+ */
+static bool
+set_exchanges (struct OrderContext *oc)
+{
+  /* Note: re-building 'oc->exchanges' every time here might be a tad
+     expensive; could likely consider caching the result if it starts to
+     matter. */
+  if (NULL == oc->exchanges)
+    oc->exchanges = json_array ();
+  TMH_exchange_get_trusted (&get_acceptable,
+                            oc);
+  if (! oc->exchange_good)
+  {
+    if (! oc->forced_reload)
+    {
+      oc->forced_reload = true;
+      GNUNET_assert (0 ==
+                     json_array_clear (oc->exchanges));
+      TMH_exchange_get_trusted (&rekey_exchanges,
+                                oc);
+    }
+    if (NULL != oc->pending_reload_head)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  "Still trying to re-load /keys\n");
+      MHD_suspend_connection (oc->connection);
+      oc->suspended = GNUNET_YES;
+      GNUNET_CONTAINER_DLL_insert (oc_head,
+                                   oc_tail,
+                                   oc);
+      return true; /* reloads pending */
+    }
+    if (0 == json_array_size (oc->exchanges))
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  "Cannot create order: lacking trusted exchanges\n");
+      reply_with_error (
+        oc,
+        MHD_HTTP_CONFLICT,
+        TALER_EC_MERCHANT_PRIVATE_POST_ORDERS_NO_EXCHANGES_FOR_WIRE_METHOD,
+        oc->wm->wire_method);
+      return false;
+    }
+    GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                "Creating order, but possibly without usable trusted exchanges\n");
   }
+  /* 'set' is correct here: reference in oc->exchanges released in cleanup_order() */
   GNUNET_assert (0 ==
-                 json_object_set_new (oc->order,
-                                      "exchanges",
-                                      exchanges));
+                 json_object_set (oc->order,
+                                  "exchanges",
+                                  oc->exchanges));
   oc->phase++;
+  return false;
 }
 
 
@@ -1603,7 +1883,8 @@ TMH_private_post_orders_with_pos_secrets (
       patch_order (oc);
       break;
     case ORDER_PHASE_SET_EXCHANGES:
-      set_exchanges (oc);
+      if (set_exchanges (oc))
+        return MHD_YES;
       break;
     case ORDER_PHASE_CHECK_CONTRACT:
       check_contract (oc);
@@ -1625,9 +1906,10 @@ TMH_private_post_orders_with_pos_secrets (
 
 
 MHD_RESULT
-TMH_private_post_orders (const struct TMH_RequestHandler *rh,
-                         struct MHD_Connection *connection,
-                         struct TMH_HandlerContext *hc)
+TMH_private_post_orders (
+  const struct TMH_RequestHandler *rh,
+  struct MHD_Connection *connection,
+  struct TMH_HandlerContext *hc)
 {
   return TMH_private_post_orders_with_pos_secrets (rh,
                                                    connection,
diff --git a/src/backend/taler-merchant-httpd_private-post-orders.h b/src/backend/taler-merchant-httpd_private-post-orders.h
index 9d7b1841..cbbb59c0 100644
--- a/src/backend/taler-merchant-httpd_private-post-orders.h
+++ b/src/backend/taler-merchant-httpd_private-post-orders.h
@@ -23,6 +23,14 @@
 
 #include "taler-merchant-httpd.h"
 
+
+/**
+ * Force resuming all suspended orders on shutdown.
+ */
+void
+TMH_force_orders_resume (void);
+
+
 /**
  * Generate an order.  We add the fields 'exchanges', 'merchant_pub', and
  * 'H_wire' to the order gotten from the frontend, as well as possibly other
diff --git a/src/backend/taler-merchant-httpd_private-post-reserves.c b/src/backend/taler-merchant-httpd_private-post-reserves.c
index c6641876..db40b017 100644
--- a/src/backend/taler-merchant-httpd_private-post-reserves.c
+++ b/src/backend/taler-merchant-httpd_private-post-reserves.c
@@ -89,11 +89,6 @@ struct PostReserveContext
   struct TMH_EXCHANGES_KeysOperation *fo;
 
   /**
-   * Handle for contacting the exchange for /wire.
-   */
-  struct TMH_EXCHANGES_WireOperation *wo;
-
-  /**
    * Master public key of the exchange matching
    * @e exchange_url.
    */
@@ -127,6 +122,11 @@ struct PostReserveContext
    * without a response due to shutdown.
    */
   enum GNUNET_GenericReturnValue suspended;
+
+  /**
+   * True if we already force reloaded /keys.
+   */
+  bool force_reload;
 };
 
 
@@ -168,11 +168,6 @@ TMH_force_rc_resume ()
       TMH_EXCHANGES_keys4exchange_cancel (rc->fo);
       rc->fo = NULL;
     }
-    if (NULL != rc->wo)
-    {
-      TMH_EXCHANGES_wire4exchange_cancel (rc->wo);
-      rc->wo = NULL;
-    }
   }
 }
 
@@ -216,49 +211,17 @@ resume_request (struct PostReserveContext *rc)
 
 
 /**
- * Function called once we go the /wire response from the exchange.
- *
- * @param cls a `struct PostReserveContext *`
- * @param wire exchange wire details
- */
-static void
-wire_cb (void *cls,
-         const struct TMH_ExchangeWireDetails *wire)
-{
-  struct PostReserveContext *rc = cls;
-
-  rc->wo = NULL;
-  rc->accounts = TMH_exchange_accounts_by_method (
-    &rc->master_pub,
-    rc->wire_method);
-  if (NULL == rc->accounts)
-  {
-    rc->ec = TALER_EC_GENERIC_DB_FETCH_FAILED;
-    rc->http_status = MHD_HTTP_CONFLICT;
-    resume_request (rc);
-    return;
-  }
-  if (0 == json_array_size (rc->accounts))
-  {
-    rc->ec = TALER_EC_MERCHANT_PRIVATE_POST_RESERVES_UNSUPPORTED_WIRE_METHOD;
-    rc->http_status = MHD_HTTP_CONFLICT;
-    resume_request (rc);
-    return;
-  }
-  resume_request (rc);
-}
-
-
-/**
  * Function called with the result of a #TMH_EXCHANGES_keys4exchange()
  * operation.
  *
  * @param cls closure with our `struct PostReserveContext *`
  * @param keys exchange keys
+ * @param exchange representation of the exchange
  */
 static void
 handle_exchange (void *cls,
-                 struct TALER_EXCHANGE_Keys *keys)
+                 struct TALER_EXCHANGE_Keys *keys,
+                 struct TMH_Exchange *exchange)
 {
   struct PostReserveContext *rc = cls;
 
@@ -273,6 +236,18 @@ handle_exchange (void *cls,
   }
   if (! keys->rewards_allowed)
   {
+    if (! rc->force_reload)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  "Forcing %s/keys reload (rewards not allowed)\n",
+                  rc->exchange_url);
+      rc->force_reload = true;
+      rc->fo = TMH_EXCHANGES_keys4exchange (rc->exchange_url,
+                                            true,
+                                            &handle_exchange,
+                                            rc);
+      return;
+    }
     rc->ec = TALER_EC_MERCHANT_PRIVATE_POST_RESERVES_REWARDS_NOT_ALLOWED;
     rc->http_status = MHD_HTTP_CONFLICT;
     resume_request (rc);
@@ -281,9 +256,33 @@ handle_exchange (void *cls,
   rc->master_pub = keys->master_pub;
   rc->reserve_expiration
     = GNUNET_TIME_relative_to_timestamp (keys->reserve_closing_delay);
-  rc->wo = TMH_EXCHANGES_wire4exchange (rc->exchange_url,
-                                        &wire_cb,
-                                        rc);
+  rc->accounts = TMH_exchange_accounts_by_method (
+    &rc->master_pub,
+    rc->wire_method);
+  if ( (NULL == rc->accounts) ||
+       (0 == json_array_size (rc->accounts)) )
+  {
+    if (! rc->force_reload)
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                  "Forcing %s/keys reload (no accounts)\n",
+                  rc->exchange_url);
+      rc->force_reload = true;
+      rc->fo = TMH_EXCHANGES_keys4exchange (rc->exchange_url,
+                                            true,
+                                            &handle_exchange,
+                                            rc);
+      return;
+    }
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "Wire method `%s' not supported\n",
+                rc->wire_method);
+    rc->ec = TALER_EC_MERCHANT_PRIVATE_POST_RESERVES_UNSUPPORTED_WIRE_METHOD;
+    rc->http_status = MHD_HTTP_CONFLICT;
+    resume_request (rc);
+    return;
+  }
+  resume_request (rc);
 }
 
 
@@ -326,6 +325,7 @@ TMH_private_post_reserves (const struct TMH_RequestHandler *rh,
                : MHD_NO;
     }
     rc->fo = TMH_EXCHANGES_keys4exchange (rc->exchange_url,
+                                          false,
                                           &handle_exchange,
                                           rc);
     rc->suspended = GNUNET_YES;
diff --git a/src/lib/merchant_api_post_order_pay.c b/src/lib/merchant_api_post_order_pay.c
index e48b7cd3..24c1cf61 100644
--- a/src/lib/merchant_api_post_order_pay.c
+++ b/src/lib/merchant_api_post_order_pay.c
@@ -329,6 +329,10 @@ parse_conflict (struct TALER_MERCHANT_OrderPayHandle *oph,
     break;
   default:
     GNUNET_break_op (0);
+    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+                "Unexpected error code %d: %s\n",
+                ec,
+                TALER_ErrorCode_get_hint (ec));
     return GNUNET_SYSERR;
   }
 
diff --git a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_1/1688579204 b/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_1/1688579204
deleted file mode 100644
index 413ac682..00000000
--- a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_1/1688579204
+++ /dev/null
diff --git a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_5/1688579204 b/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_5/1688579204
deleted file mode 100644
index 56735a35..00000000
--- a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_5/1688579204
+++ /dev/null
@@ -1,2 +0,0 @@
- 0c©ô
bL
-n#vìïœãpŒap¡¦(Kó°ÕáC
\ No newline at end of file
diff --git a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_1/1688579204 b/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_1/1688579204
deleted file mode 100644
index 9378dd7b..00000000
--- a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_1/1688579204
+++ /dev/null
@@ -1 +0,0 @@
-º|žÑ
’Óå‹xjÄÕfóß4­½¤3ØÞÜ€òƒ)

\ No newline at end of file
diff --git a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_10/1688579204 b/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_10/1688579204
deleted file mode 100644
index 5388599c..00000000
--- a/src/testing/test_merchant_api_home/taler/exchange-secmod-cs/keys/coin_eur_ct_10/1688579204
+++ /dev/null
@@ -1 +0,0 @@
-P^ÛÃ(‘0B"ijL´u1ðÌɯä?@dÄÿ±
\ No newline at end of file