fix #9197: wait at most 250ms for /keys from exchanges before giving up

2 files changed, 86 insertions, 0 deletions

diff --git a/src/backend/taler-merchant-httpd_private-post-orders.c b/src/backend/taler-merchant-httpd_private-post-orders.c
index 7053ac70..c1583791 100644
--- a/src/backend/taler-merchant-httpd_private-post-orders.c
+++ b/src/backend/taler-merchant-httpd_private-post-orders.c
@@ -68,6 +68,14 @@
  */
 #define STANDARD_LABEL_MERCHANT_ADDRESS "_ma"
 
+/**
+ * How long do we wait at most for /keys from the exchange(s)?
+ * Ensures that we do not block forever just because some exchange
+ * fails to respond *or* because our taler-merchant-keyscheck
+ * refuses a forced download.
+ */
+#define MAX_KEYS_WAIT \
+        GNUNET_TIME_relative_multiply (GNUNET_TIME_UNIT_MILLISECONDS, 250)
 
 /**
  * Generate the base URL for the given merchant instance.
@@ -449,6 +457,17 @@ struct OrderContext
      * order creation requests exceeds legal limits.
      */
     struct TALER_Amount total_exchange_limit;
+
+    /**
+     * How long do we wait at most until giving up on getting keys?
+     */
+    struct GNUNET_TIME_Absolute keys_timeout;
+
+    /**
+     * Task to wake us up on @e keys_timeout.
+     */
+    struct GNUNET_SCHEDULER_Task *wakeup_task;
+
   } set_exchanges;
 
   /**
@@ -664,6 +683,11 @@ clean_order (void *cls)
     GNUNET_free (rx->url);
     GNUNET_free (rx);
   }
+  if (NULL != oc->set_exchanges.wakeup_task)
+  {
+    GNUNET_SCHEDULER_cancel (oc->set_exchanges.wakeup_task);
+    oc->set_exchanges.wakeup_task = NULL;
+  }
   if (NULL != oc->set_exchanges.exchanges)
   {
     json_decref (oc->set_exchanges.exchanges);
@@ -2105,6 +2129,28 @@ notify_kyc_required (const struct OrderContext *oc)
 
 
 /**
+ * Task run when we are timing out on /keys and will just
+ * proceed with what we got.
+ *
+ * @param cls our `struct OrderContext *` to resume
+ */
+static void
+wakeup_timeout (void *cls)
+{
+  struct OrderContext *oc = cls;
+
+  oc->set_exchanges.wakeup_task = NULL;
+  GNUNET_assert (GNUNET_YES == oc->suspended);
+  GNUNET_CONTAINER_DLL_remove (oc_head,
+                               oc_tail,
+                               oc);
+  MHD_resume_connection (oc->connection);
+  oc->suspended = GNUNET_NO;
+  TALER_MHD_daemon_trigger (); /* we resumed, kick MHD */
+}
+
+
+/**
  * Set list of acceptable exchanges in @a oc. Upon success, continue
  * processing with set_max_fee().
  *
@@ -2114,6 +2160,11 @@ notify_kyc_required (const struct OrderContext *oc)
 static bool
 set_exchanges (struct OrderContext *oc)
 {
+  if (NULL != oc->set_exchanges.wakeup_task)
+  {
+    GNUNET_SCHEDULER_cancel (oc->set_exchanges.wakeup_task);
+    oc->set_exchanges.wakeup_task = NULL;
+  }
   if (TALER_amount_is_zero (&oc->parse_order.brutto))
   {
     /* Total amount is zero, so we don't actually need exchanges! */
@@ -2127,6 +2178,8 @@ set_exchanges (struct OrderContext *oc)
      matter. */
   if (NULL == oc->set_exchanges.exchanges)
   {
+    oc->set_exchanges.keys_timeout
+      = GNUNET_TIME_relative_to_absolute (MAX_KEYS_WAIT);
     oc->set_exchanges.exchanges = json_array ();
     GNUNET_assert (NULL != oc->set_exchanges.exchanges);
     GNUNET_assert (
@@ -2147,11 +2200,29 @@ set_exchanges (struct OrderContext *oc)
                                 oc);
     }
   }
+  if (GNUNET_TIME_absolute_is_past (oc->set_exchanges.keys_timeout))
+  {
+    struct RekeyExchange *rx;
+
+    while (NULL != (rx = oc->set_exchanges.pending_reload_head))
+    {
+      GNUNET_CONTAINER_DLL_remove (oc->set_exchanges.pending_reload_head,
+                                   oc->set_exchanges.pending_reload_tail,
+                                   rx);
+      TMH_EXCHANGES_keys4exchange_cancel (rx->fo);
+      GNUNET_free (rx->url);
+      GNUNET_free (rx);
+    }
+  }
   if (NULL != oc->set_exchanges.pending_reload_head)
   {
     GNUNET_log (GNUNET_ERROR_TYPE_INFO,
                 "Still trying to (re)load %skeys\n",
                 oc->set_exchanges.pending_reload_head->url);
+    oc->set_exchanges.wakeup_task
+      = GNUNET_SCHEDULER_add_at (oc->set_exchanges.keys_timeout,
+                                 &wakeup_timeout,
+                                 oc);
     MHD_suspend_connection (oc->connection);
     oc->suspended = GNUNET_YES;
     GNUNET_CONTAINER_DLL_insert (oc_head,
diff --git a/src/include/taler_merchant_service.h b/src/include/taler_merchant_service.h
index 05ea273b..0ad7dc75 100644
--- a/src/include/taler_merchant_service.h
+++ b/src/include/taler_merchant_service.h
@@ -3239,6 +3239,21 @@ struct TALER_MERCHANT_PayResponse
     // TODO: might want to return further details on errors,
     // especially refund signatures on double-pay conflict.
 
+    struct
+    {
+
+      /**
+       * Array of exchange URLs which had legal problems.
+       */
+      const char **exchanges;
+
+      /**
+       * Length of the @e exchanges array.
+       */
+      unsigned int num_exchanges;
+
+    } unavailable_for_legal_reasons;
+
   } details;
 
 };