[taler-merchant] 02/02: make taler-merchant-reconciliation use keys via taler-merchant-exchangekeysupdate

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grothoff pushed a commit to branch master
in repository merchant.

commit aa29da994abd4b4dcb0648e67484589db7351ae9
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Sun Sep 8 13:55:12 2024 +0200

    make taler-merchant-reconciliation use keys via 
taler-merchant-exchangekeysupdate
---
 src/backend/taler-merchant-reconciliation.c | 224 ++++++++++++----------------
 1 file changed, 97 insertions(+), 127 deletions(-)

diff --git a/src/backend/taler-merchant-reconciliation.c 
b/src/backend/taler-merchant-reconciliation.c
index 23c9a926..8bb88849 100644
--- a/src/backend/taler-merchant-reconciliation.c
+++ b/src/backend/taler-merchant-reconciliation.c
@@ -1,6 +1,6 @@
 /*
   This file is part of TALER
-  Copyright (C) 2023 Taler Systems SA
+  Copyright (C) 2023-2024 Taler Systems SA
 
   TALER is free software; you can redistribute it and/or modify it under the
   terms of the GNU Affero General Public License as published by the Free 
Software
@@ -82,49 +82,22 @@ struct Exchange
    */
   char *exchange_url;
 
-  /**
-   * A connection to this exchange
-   */
-  struct TALER_EXCHANGE_GetKeysHandle *conn;
-
   /**
    * The keys of this exchange
    */
   struct TALER_EXCHANGE_Keys *keys;
 
-  /**
-   * Task where we retry fetching /keys from the exchange.
-   */
-  struct GNUNET_SCHEDULER_Task *retry_task;
-
   /**
    * How many active inquiries do we have right now with this exchange.
    */
   unsigned int exchange_inquiries;
 
-  /**
-   * How soon can may we, at the earliest, re-download /keys?
-   */
-  struct GNUNET_TIME_Absolute first_retry;
-
-  /**
-   * How long should we wait between the next retry?
-   */
-  struct GNUNET_TIME_Relative retry_delay;
-
   /**
    * How long should we wait between requests
    * for transfer details?
    */
   struct GNUNET_TIME_Relative transfer_delay;
 
-  /**
-   * False to indicate that there is an ongoing
-   * /keys transfer we are waiting for;
-   * true to indicate that /keys data is up-to-date.
-   */
-  bool ready;
-
 };
 
 
@@ -232,6 +205,12 @@ static struct GNUNET_SCHEDULER_Task *task;
  */
 static struct GNUNET_DB_EventHandler *eh;
 
+/**
+ * Event handler to learn that there may be new exchange
+ * keys to check.
+ */
+static struct GNUNET_DB_EventHandler *eh_keys;
+
 /**
  * How many active inquiries do we have right now.
  */
@@ -296,91 +275,6 @@ launch_inquiries_at_exchange (struct Exchange *e)
 }
 
 
-/**
- * Function that initiates a /keys download.
- *
- * @param cls a `struct Exchange *`
- */
-static void
-download_keys (void *cls);
-
-
-/**
- * Function called with information about who is auditing
- * a particular exchange and what keys the exchange is using.
- *
- * @param cls closure with a `struct Exchange *`
- * @param kr response data
- * @param[in] keys the keys of the exchange
- */
-static void
-cert_cb (
-  void *cls,
-  const struct TALER_EXCHANGE_KeysResponse *kr,
-  struct TALER_EXCHANGE_Keys *keys)
-{
-  struct Exchange *e = cls;
-  struct GNUNET_TIME_Absolute n;
-
-  e->conn = NULL;
-  switch (kr->hr.http_status)
-  {
-  case MHD_HTTP_OK:
-    e->ready = true;
-    TALER_EXCHANGE_keys_decref (e->keys);
-    e->keys = keys;
-    launch_inquiries_at_exchange (e);
-    /* Reset back-off */
-    e->retry_delay = GNUNET_TIME_UNIT_ZERO;
-    /* Success: rate limit at once per minute */
-    e->first_retry = GNUNET_TIME_relative_to_absolute (
-      GNUNET_TIME_UNIT_MINUTES);
-    n = GNUNET_TIME_absolute_max (e->first_retry,
-                                  keys->key_data_expiration.abs_time);
-    if (NULL != e->retry_task)
-      GNUNET_SCHEDULER_cancel (e->retry_task);
-    e->retry_task = GNUNET_SCHEDULER_add_at (n,
-                                             &download_keys,
-                                             e);
-    break;
-  default:
-    e->retry_delay
-      = GNUNET_TIME_STD_BACKOFF (e->retry_delay);
-    e->first_retry
-      = GNUNET_TIME_relative_to_absolute (e->retry_delay);
-    if (NULL != e->retry_task)
-      GNUNET_SCHEDULER_cancel (e->retry_task);
-    e->retry_task = GNUNET_SCHEDULER_add_delayed (e->retry_delay,
-                                                  &download_keys,
-                                                  e);
-    break;
-  }
-}
-
-
-static void
-download_keys (void *cls)
-{
-  struct Exchange *e = cls;
-  struct GNUNET_TIME_Relative n;
-
-  /* If we do not hear back again soon, try again automatically */
-  n = GNUNET_TIME_STD_BACKOFF (e->retry_delay);
-  n = GNUNET_TIME_relative_max (n,
-                                GNUNET_TIME_UNIT_MINUTES);
-  e->retry_task = GNUNET_SCHEDULER_add_delayed (n,
-                                                &download_keys,
-                                                e);
-  if ( (NULL == e->keys) ||
-       (GNUNET_TIME_absolute_is_past (e->keys->key_data_expiration.abs_time)) )
-    e->conn = TALER_EXCHANGE_get_keys (ctx,
-                                       e->exchange_url,
-                                       e->keys,
-                                       &cert_cb,
-                                       e);
-}
-
-
 /**
  * Updates the transaction status for inquiry @a w to the given values.
  *
@@ -418,6 +312,37 @@ update_transaction_status (const struct Inquiry *w,
 }
 
 
+/**
+ * Interact with the database to get the current set
+ * of exchange keys known to us.
+ *
+ * @param e the exchange to check
+ */
+static void
+sync_keys (struct Exchange *e)
+{
+  enum GNUNET_DB_QueryStatus qs;
+  struct TALER_EXCHANGE_Keys *keys;
+
+  qs = db_plugin->select_exchange_keys (db_plugin->cls,
+                                        e->exchange_url,
+                                        &keys);
+  if (qs < 0)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
+  {
+    GNUNET_break (0);
+    return;
+  }
+  TALER_EXCHANGE_keys_decref (e->keys);
+  e->keys = keys;
+  launch_inquiries_at_exchange (e);
+}
+
+
 /**
  * Lookup our internal data structure for the given
  * @a exchange_url or create one if we do not yet have
@@ -440,8 +365,7 @@ find_exchange (const char *exchange_url)
   GNUNET_CONTAINER_DLL_insert (e_head,
                                e_tail,
                                e);
-  e->retry_task = GNUNET_SCHEDULER_add_now (&download_keys,
-                                            e);
+  sync_keys (e);
   return e;
 }
 
@@ -522,21 +446,11 @@ shutdown_task (void *cls)
       end_inquiry (w);
     }
     GNUNET_free (e->exchange_url);
-    if (NULL != e->conn)
-    {
-      TALER_EXCHANGE_get_keys_cancel (e->conn);
-      e->conn = NULL;
-    }
     if (NULL != e->keys)
     {
       TALER_EXCHANGE_keys_decref (e->keys);
       e->keys = NULL;
     }
-    if (NULL != e->retry_task)
-    {
-      GNUNET_SCHEDULER_cancel (e->retry_task);
-      e->retry_task = NULL;
-    }
     GNUNET_CONTAINER_DLL_remove (e_head,
                                  e_tail,
                                  e);
@@ -547,6 +461,11 @@ shutdown_task (void *cls)
     db_plugin->event_listen_cancel (eh);
     eh = NULL;
   }
+  if (NULL != eh_keys)
+  {
+    db_plugin->event_listen_cancel (eh_keys);
+    eh_keys = NULL;
+  }
   if (NULL != task)
   {
     GNUNET_SCHEDULER_cancel (task);
@@ -1007,7 +926,8 @@ exchange_request (void *cls)
   struct Exchange *e = w->exchange;
 
   w->task = NULL;
-  GNUNET_assert (e->ready);
+  if (NULL == e->keys)
+    return;
   w->wdh = TALER_EXCHANGE_transfers_get (
     ctx,
     e->exchange_url,
@@ -1099,7 +1019,7 @@ start_inquiry (
                                e->w_tail,
                                w);
   w->exchange = e;
-  if (w->exchange->ready)
+  if (NULL != w->exchange->keys)
     w->task = GNUNET_SCHEDULER_add_now (&exchange_request,
                                         w);
   /* Wait at least 1 minute for /keys */
@@ -1193,6 +1113,42 @@ transfer_added (void *cls,
 }
 
 
+/**
+ * Function called when keys were channged in the
+ * merchant database. Updates ours.
+ *
+ * @param cls closure (NULL)
+ * @param extra additional event data provided
+ * @param extra_size number of bytes in @a extra
+ */
+static void
+keys_changed (void *cls,
+              const void *extra,
+              size_t extra_size)
+{
+  const char *url = extra;
+  struct Exchange *e;
+
+  (void) cls;
+  if ( (NULL == extra) ||
+       (0 == extra_size) )
+  {
+    GNUNET_break (0);
+    return;
+  }
+  if ('\0' != url[extra_size - 1])
+  {
+    GNUNET_break (0);
+    return;
+  }
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              "Received keys change notification: reload `%s'\n",
+              url);
+  e = find_exchange (url);
+  sync_keys (e);
+}
+
+
 /**
  * First task.
  *
@@ -1253,6 +1209,20 @@ run (void *cls,
                                   &transfer_added,
                                   NULL);
   }
+  {
+    struct GNUNET_DB_EventHeaderP es = {
+      .size = htons (sizeof (es)),
+      .type = htons (TALER_DBEVENT_MERCHANT_EXCHANGE_KEYS)
+    };
+
+    eh_keys
+      = db_plugin->event_listen (db_plugin->cls,
+                                 &es,
+                                 GNUNET_TIME_UNIT_FOREVER_REL,
+                                 &keys_changed,
+                                 NULL);
+  }
+
   GNUNET_assert (NULL == task);
   task = GNUNET_SCHEDULER_add_now (&find_work,
                                    NULL);

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