implement DB plugin function to obtain reserve information, migrate logic to simplified API spec (#3887); use plugin API in /payback DB implementation

11 files changed, 245 insertions, 90 deletions

diff --git a/src/exchange-lib/exchange_api_payback.c b/src/exchange-lib/exchange_api_payback.c
index 600e0d682..b08fe3b68 100644
--- a/src/exchange-lib/exchange_api_payback.c
+++ b/src/exchange-lib/exchange_api_payback.c
@@ -95,14 +95,13 @@ verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph,
   struct TALER_ExchangeSignatureP exchange_sig;
   struct TALER_Amount amount;
   struct GNUNET_TIME_Absolute deadline;
-  const char *wire_subject;
   const struct TALER_EXCHANGE_Keys *key_state;
   struct GNUNET_JSON_Specification spec[] = {
     GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
     GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
     TALER_JSON_spec_amount ("amount", &amount),
     GNUNET_JSON_spec_absolute_time ("payback_deadline", &deadline),
-    GNUNET_JSON_spec_string ("wire_subject", &wire_subject),
+    GNUNET_JSON_spec_fixed_auto ("reserve_pub", &pc.reserve_pub),
     GNUNET_JSON_spec_end()
   };
 
@@ -128,9 +127,6 @@ verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph,
   TALER_amount_hton (&pc.payback_amount,
                      &amount);
   pc.coin_pub = ph->coin_pub;
-  GNUNET_CRYPTO_hash (wire_subject,
-                      strlen (wire_subject),
-                      &pc.h_wire_subject);
   if (GNUNET_OK !=
       GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK,
                                   &pc.purpose,
@@ -145,7 +141,7 @@ verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph,
 	  TALER_EC_NONE,
           &amount,
           deadline,
-          wire_subject,
+          &pc.reserve_pub,
           json);
   return GNUNET_OK;
 }
diff --git a/src/exchange/taler-exchange-httpd_db.c b/src/exchange/taler-exchange-httpd_db.c
index eb7058bb2..fe417663d 100644
--- a/src/exchange/taler-exchange-httpd_db.c
+++ b/src/exchange/taler-exchange-httpd_db.c
@@ -2269,6 +2269,7 @@ TEH_DB_execute_track_transaction (struct MHD_Connection *connection,
  * @param coin information about the coin
  * @param value how much are coins of the @a coin's denomination worth?
  * @param h_blind blinded coin to use for the lookup
+ * @param coin_blind blinding factor used (for later verification by the auditor)
  * @param coin_sig signature of the coin (to be stored)
  * @return MHD result code
  */
@@ -2277,13 +2278,13 @@ TEH_DB_execute_payback (struct MHD_Connection *connection,
                         const struct TALER_CoinPublicInfo *coin,
                         const struct TALER_Amount *value,
                         const struct GNUNET_HashCode *h_blind,
+                        const struct TALER_DenominationBlindingKeyP *coin_blind,
                         const struct TALER_CoinSpendSignatureP *coin_sig)
 {
   int ret;
   struct TALER_EXCHANGEDB_Session *session;
   struct TALER_EXCHANGEDB_TransactionList *tl;
-  struct TALER_EXCHANGEDB_CollectableBlindcoin collectable;
-  char wire_subject[42]; // FIXME: size? (#3887)
+  struct TALER_ReservePublicKeyP reserve_pub;
   struct TALER_Amount amount;
   struct TALER_Amount spent;
   struct GNUNET_TIME_Absolute payback_deadline;
@@ -2297,12 +2298,12 @@ TEH_DB_execute_payback (struct MHD_Connection *connection,
 
   START_TRANSACTION (session, connection);
 
-  /* FIXME (#3887): not _exactly_ the right call, we need to get the
-     reserve's incoming wire transfer data, not 'collectable' */
-  ret = TEH_plugin->get_withdraw_info (TEH_plugin->cls,
-                                       session,
-                                       h_blind,
-                                       &collectable);
+  /* Check whether a payback is allowed, and if so, to which
+     reserve / account the money should go */
+  ret = TEH_plugin->get_reserve_by_h_blind (TEH_plugin->cls,
+                                            session,
+                                            h_blind,
+                                            &reserve_pub);
   if (GNUNET_SYSERR == ret)
   {
     GNUNET_break (0);
@@ -2358,8 +2359,16 @@ TEH_DB_execute_payback (struct MHD_Connection *connection,
   TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
                                           tl);
 
-  /* FIXME: add coin to list of wire transfers for payback */
-  // ret = TEH_plugin->(); // #3887
+  /* add coin to list of wire transfers for payback */
+  ret = TEH_plugin->insert_payback_request (TEH_plugin->cls,
+                                            session,
+                                            &reserve_pub,
+                                            coin,
+                                            coin_sig,
+                                            coin_blind,
+                                            h_blind,
+                                            &amount,
+                                            &payback_deadline);
   if (GNUNET_SYSERR == ret)
   {
     TALER_LOG_WARNING ("Failed to store /payback information in database\n");
@@ -2373,7 +2382,7 @@ TEH_DB_execute_payback (struct MHD_Connection *connection,
 
   return TEH_RESPONSE_reply_payback_success (connection,
                                              &coin->coin_pub,
-                                             wire_subject,
+                                             &reserve_pub,
                                              &amount,
                                              payback_deadline);
 }
diff --git a/src/exchange/taler-exchange-httpd_db.h b/src/exchange/taler-exchange-httpd_db.h
index 520a6f59e..d2a0168db 100644
--- a/src/exchange/taler-exchange-httpd_db.h
+++ b/src/exchange/taler-exchange-httpd_db.h
@@ -246,6 +246,7 @@ TEH_DB_execute_track_transaction (struct MHD_Connection *connection,
  * @param coin information about the coin
  * @param value how much are coins of the @a coin's denomination worth?
  * @param h_blind blinded coin to use for the lookup
+ * @param coin_blind blinding factor used (for later verification by the auditor)
  * @param coin_sig signature of the coin
  * @return MHD result code
  */
@@ -254,6 +255,7 @@ TEH_DB_execute_payback (struct MHD_Connection *connection,
                         const struct TALER_CoinPublicInfo *coin,
                         const struct TALER_Amount *value,
                         const struct GNUNET_HashCode *h_blind,
+                        const struct TALER_DenominationBlindingKeyP *coin_blind,
                         const struct TALER_CoinSpendSignatureP *coin_sig);
 
 
diff --git a/src/exchange/taler-exchange-httpd_payback.c b/src/exchange/taler-exchange-httpd_payback.c
index 31235729e..b4b664f94 100644
--- a/src/exchange/taler-exchange-httpd_payback.c
+++ b/src/exchange/taler-exchange-httpd_payback.c
@@ -134,6 +134,7 @@ verify_and_execute_payback (struct MHD_Connection *connection,
                                  coin,
                                  &value,
                                  &h_blind,
+                                 coin_bks,
                                  coin_sig);
 }
 
diff --git a/src/exchange/taler-exchange-httpd_responses.c b/src/exchange/taler-exchange-httpd_responses.c
index efe3ee091..96587c4d1 100644
--- a/src/exchange/taler-exchange-httpd_responses.c
+++ b/src/exchange/taler-exchange-httpd_responses.c
@@ -1320,7 +1320,8 @@ TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
  * A wallet asked for /payback, return the successful response.
  *
  * @param connection connection to the client
- * @param wire_subject the wire subject we will use for the pay back operation
+ * @param coin_pub coin for which we are processing the payback request
+ * @param reserve_pub public key of the reserve that will receive the payback
  * @param amount the amount we will wire back
  * @param payback_deadline deadline by which the exchange promises to pay
  * @return MHD result code
@@ -1328,7 +1329,7 @@ TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
 int
 TEH_RESPONSE_reply_payback_success (struct MHD_Connection *connection,
                                     const struct TALER_CoinSpendPublicKeyP *coin_pub,
-                                    const char *wire_subject,
+                                    const struct TALER_ReservePublicKeyP *reserve_pub,
                                     const struct TALER_Amount *amount,
                                     struct GNUNET_TIME_Absolute payback_deadline)
 {
@@ -1342,16 +1343,14 @@ TEH_RESPONSE_reply_payback_success (struct MHD_Connection *connection,
   TALER_amount_hton (&pc.payback_amount,
                      amount);
   pc.coin_pub = *coin_pub;
-  GNUNET_CRYPTO_hash (wire_subject,
-                      strlen (wire_subject),
-                      &pc.h_wire_subject);
+  pc.reserve_pub = *reserve_pub;
   TEH_KS_sign (&pc.purpose,
                &pub,
                &sig);
   return TEH_RESPONSE_reply_json_pack (connection,
                                        MHD_HTTP_OK,
-                                       "{s:s, s:o, s:o, s:o, s:o}",
-                                       "wire_subject", wire_subject,
+                                       "{s:o, s:o, s:o, s:o, s:o}",
+                                       "reserve_pub", GNUNET_JSON_from_data_auto (reserve_pub),
                                        "payback_deadline", GNUNET_JSON_from_time_abs (payback_deadline),
                                        "amount", TALER_JSON_from_amount (amount),
                                        "exchange_sig", GNUNET_JSON_from_data_auto (&sig),
diff --git a/src/exchange/taler-exchange-httpd_responses.h b/src/exchange/taler-exchange-httpd_responses.h
index e12229565..6b68949e5 100644
--- a/src/exchange/taler-exchange-httpd_responses.h
+++ b/src/exchange/taler-exchange-httpd_responses.h
@@ -577,7 +577,7 @@ TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
  *
  * @param connection connection to the client
  * @param coin_pub coin for which we are processing the payback request
- * @param wire_subject the wire subject we will use for the pay back operation
+ * @param reserve_pub public key of the reserve that will receive the payback
  * @param amount the amount we will wire back
  * @param payback_deadline deadline by which the exchange promises to pay
  * @return MHD result code
@@ -585,7 +585,7 @@ TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
 int
 TEH_RESPONSE_reply_payback_success (struct MHD_Connection *connection,
                                     const struct TALER_CoinSpendPublicKeyP *coin_pub,
-                                    const char *wire_subject,
+                                    const struct TALER_ReservePublicKeyP *reserve_pub,
                                     const struct TALER_Amount *amount,
                                     struct GNUNET_TIME_Absolute payback_deadline);
 
diff --git a/src/exchangedb/plugin_exchangedb_common.c b/src/exchangedb/plugin_exchangedb_common.c
index 1aa77a481..7b29b1d85 100644
--- a/src/exchangedb/plugin_exchangedb_common.c
+++ b/src/exchangedb/plugin_exchangedb_common.c
@@ -39,6 +39,7 @@ common_free_reserve_history (void *cls,
     switch(rh->type)
     {
     case TALER_EXCHANGEDB_RO_BANK_TO_EXCHANGE:
+    case TALER_EXCHANGEDB_RO_EXCHANGE_TO_BANK:
       bt = rh->details.bank;
       if (NULL != bt->sender_account_details)
         json_decref (bt->sender_account_details);
@@ -52,6 +53,9 @@ common_free_reserve_history (void *cls,
       GNUNET_CRYPTO_rsa_public_key_free (cbc->denom_pub.rsa_public_key);
       GNUNET_free (cbc);
       break;
+    case TALER_EXCHANGEDB_RO_PAYBACK_COIN:
+      GNUNET_free (rh->details.payback);
+      break;
     }
     backref = rh;
     rh = rh->next;
@@ -125,6 +129,9 @@ common_free_coin_transaction_list (void *cls,
         GNUNET_CRYPTO_rsa_signature_free (list->details.refund->coin.denom_sig.rsa_signature);
       GNUNET_free (list->details.refund);
       break;
+    case TALER_EXCHANGEDB_TT_PAYBACK:
+      GNUNET_free (list->details.payback);
+      break;
     }
     GNUNET_free (list);
     list = next;
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c
index 1bb49df99..a01b93fbf 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -1383,6 +1383,15 @@ postgres_prepare (PGconn *db_conn)
            " ORDER BY wireout_uuid ASC",
            1, NULL);
 
+  /* Used in #postgres_get_reserve_by_h_blind() */
+  PREPARE ("reserve_by_h_blind",
+           "SELECT"
+           " reserve_pub"
+           " FROM reserves_out"
+           " WHERE h_blind_ev=$1"
+           " LIMIT 1;",
+           1, NULL);
+
   PREPARE ("gc_denominations",
            "DELETE"
            " FROM denominations"
@@ -5401,6 +5410,107 @@ postgres_select_wire_out_above_serial_id (void *cls,
 
 
 /**
+ * Function called to add a request for an emergency payback for a
+ * coin.  The funds are to be added back to the reserve.  The function
+ * should return the @a deadline by which the exchange will trigger a
+ * wire transfer back to the customer's account for the reserve.
+ *
+ * @param cls closure
+ * @param session database connection
+ * @param reserve_pub public key of the reserve that is being refunded
+ * @param coin information about the coin
+ * @param coin_sig signature of the coin of type #TALER_SIGNATURE_WALLET_COIN_PAYBACK
+ * @param coin_blind blinding key of the coin
+ * @param h_blind_ev blinded envelope, as calculated by the exchange
+ * @param amount total amount to be paid back
+ * @param receiver_account_details who should receive the funds
+ * @param[out] deadline set to absolute time by when the exchange plans to pay it back
+ * @return #GNUNET_OK on success,
+ *         #GNUNET_SYSERR on DB errors
+ */
+static int
+postgres_insert_payback_request (void *cls,
+                                 struct TALER_EXCHANGEDB_Session *session,
+                                 const struct TALER_ReservePublicKeyP *reserve_pub,
+                                 const struct TALER_CoinPublicInfo *coin,
+                                 const struct TALER_CoinSpendSignatureP *coin_sig,
+                                 const struct TALER_DenominationBlindingKeyP *coin_blind,
+                                 const struct GNUNET_HashCode *h_blinded_ev,
+                                 const struct TALER_Amount *amount,
+                                 struct GNUNET_TIME_Absolute *deadline)
+{
+  GNUNET_break (0);
+  return GNUNET_SYSERR;
+}
+
+
+/**
+ * Obtain information about which reserve a coin was generated
+ * from given the hash of the blinded coin.
+ *
+ * @param cls closure
+ * @param session a session
+ * @param h_blind_ev hash of the blinded coin
+ * @param[out] reserve_pub set to information about the reserve (on success only)
+ * @return #GNUNET_OK on success,
+ *         #GNUNET_NO if there are no entries,
+ *         #GNUNET_SYSERR on DB errors
+ */
+static int
+postgres_get_reserve_by_h_blind (void *cls,
+                                 struct TALER_EXCHANGEDB_Session *session,
+                                 const struct GNUNET_HashCode *h_blind_ev,
+                                 struct TALER_ReservePublicKeyP *reserve_pub)
+{
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (h_blind_ev),
+    GNUNET_PQ_query_param_end
+  };
+  PGresult *result;
+
+  result = GNUNET_PQ_exec_prepared (session->conn,
+                                    "reserve_by_h_blind",
+                                    params);
+  if (PGRES_TUPLES_OK !=
+      PQresultStatus (result))
+  {
+    BREAK_DB_ERR (result, session->conn);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+  int nrows;
+
+  nrows = PQntuples (result);
+  if (0 == nrows)
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+                "reserve_by_h_blind() returned 0 matching rows\n");
+    PQclear (result);
+    return GNUNET_NO;
+  }
+  {
+    struct GNUNET_PQ_ResultSpec rs[] = {
+      GNUNET_PQ_result_spec_auto_from_type ("reserve_pub",
+                                            reserve_pub),
+      GNUNET_PQ_result_spec_end
+    };
+
+    if (GNUNET_OK !=
+        GNUNET_PQ_extract_result (result,
+                                  rs,
+                                  0))
+    {
+      GNUNET_break (0);
+      PQclear (result);
+      return GNUNET_SYSERR;
+    }
+  }
+  PQclear (result);
+  return GNUNET_OK;
+}
+
+
+/**
  * Initialize Postgres database subsystem.
  *
  * @param cls a configuration instance
@@ -5500,6 +5610,8 @@ libtaler_plugin_exchangedb_postgres_init (void *cls)
   plugin->select_reserves_in_above_serial_id = &postgres_select_reserves_in_above_serial_id;
   plugin->select_reserves_out_above_serial_id = &postgres_select_reserves_out_above_serial_id;
   plugin->select_wire_out_above_serial_id = &postgres_select_wire_out_above_serial_id;
+  plugin->insert_payback_request = &postgres_insert_payback_request;
+  plugin->get_reserve_by_h_blind = &postgres_get_reserve_by_h_blind;
   return plugin;
 }
 
diff --git a/src/include/taler_exchange_service.h b/src/include/taler_exchange_service.h
index c69b33e8a..39aa96d11 100644
--- a/src/include/taler_exchange_service.h
+++ b/src/include/taler_exchange_service.h
@@ -1345,7 +1345,7 @@ struct TALER_EXCHANGE_PaybackHandle;
  * @param ec taler-specific error code, #TALER_EC_NONE on success
  * @param amount amount the exchange will wire back for this coin
  * @param deadline by when will the exchange wire the funds?
- * @param wire_subject which wire subject will the exchange use?
+ * @param reserve_pub public key of the reserve receiving the payback
  * @param full_response full response from the exchange (for logging, in case of errors)
  */
 typedef void
@@ -1354,7 +1354,7 @@ typedef void
                                          enum TALER_ErrorCode ec,
                                          const struct TALER_Amount *amount,
                                          struct GNUNET_TIME_Absolute deadline,
-                                         const char *wire_subject,
+                                         const struct TALER_ReservePublicKeyP *reserve_pub,
                                          const json_t *full_response);
 
 
diff --git a/src/include/taler_exchangedb_plugin.h b/src/include/taler_exchangedb_plugin.h
index 9db748050..332c668de 100644
--- a/src/include/taler_exchangedb_plugin.h
+++ b/src/include/taler_exchangedb_plugin.h
@@ -28,13 +28,14 @@
 
 
 /**
- * @brief Information we keep on bank transfer(s) that established a reserve.
+ * @brief Information we keep on bank transfer(s) that established or
+ * closed a reserve.
  */
 struct TALER_EXCHANGEDB_BankTransfer
 {
 
   /**
-   * Public key of the reserve that was filled.
+   * Public key of the reserve that was filled or depleted.
    */
   struct TALER_ReservePublicKeyP reserve_pub;
 
@@ -51,7 +52,7 @@ struct TALER_EXCHANGEDB_BankTransfer
   struct GNUNET_TIME_Absolute execution_date;
 
   /**
-   * Detailed wire information about the sending account.
+   * Detailed wire information about the sending (or receiving) account.
    */
   json_t *sender_account_details;
 
@@ -145,21 +146,69 @@ struct TALER_EXCHANGEDB_CollectableBlindcoin
 };
 
 
+/**
+ * Information the exchange records about a /payback request.
+ */
+struct TALER_EXCHANGEDB_Payback
+{
+
+  /**
+   * Which coin was paid back?
+   */
+  struct TALER_CoinPublicInfo coin;
+
+  /**
+   * How much was the coin still worth at this time?
+   */
+  struct TALER_Amount value;
+
+  /**
+   * Blinding factor supplied to prove to the exchange that
+   * the coin came from this reserve.
+   */
+  struct TALER_DenominationBlindingKeyP coin_blind;
+
+  /**
+   * Signature of the coin of type
+   * #TALER_SIGNATURE_WALLET_COIN_PAYBACK.
+   */
+  struct TALER_CoinSpendSignatureP coin_sig;
+
+  /**
+   * Public key of the reserve the coin was paid back into.
+   */
+  struct TALER_ReservePublicKeyP reserve_pub;
+
+};
+
 
 /**
- * @brief Types of operations on a reserved.
+ * @brief Types of operations on a reserve.
  */
 enum TALER_EXCHANGEDB_ReserveOperation
 {
   /**
    * Money was deposited into the reserve via a bank transfer.
+   * This is how customers establish a reserve at the exchange.
    */
   TALER_EXCHANGEDB_RO_BANK_TO_EXCHANGE = 0,
 
   /**
    * A Coin was withdrawn from the reserve using /withdraw.
    */
-  TALER_EXCHANGEDB_RO_WITHDRAW_COIN = 1
+  TALER_EXCHANGEDB_RO_WITHDRAW_COIN = 1,
+
+  /**
+   * A coin was returned to the reserve using /payback.
+   */
+  TALER_EXCHANGEDB_RO_PAYBACK_COIN = 2,
+
+  /**
+   * The exchange send inactive funds back from the reserve to the
+   * customer's bank account.  This happens when the exchange
+   * closes a reserve with a non-zero amount left in it.
+   */
+  TALER_EXCHANGEDB_RO_EXCHANGE_TO_BANK = 3
 };
 
 
@@ -189,7 +238,9 @@ struct TALER_EXCHANGEDB_ReserveHistory
   {
 
     /**
-     * Details about a bank transfer to the exchange.
+     * Details about a bank transfer to the exchange (reserve
+     * was established) or from the exchange (reserve was
+     * closed).
      */
     struct TALER_EXCHANGEDB_BankTransfer *bank;
 
@@ -198,6 +249,11 @@ struct TALER_EXCHANGEDB_ReserveHistory
      */
     struct TALER_EXCHANGEDB_CollectableBlindcoin *withdraw;
 
+    /**
+     * Details about a /payback operation.
+     */
+    struct TALER_EXCHANGEDB_Payback *payback;
+
   } details;
 
 };
@@ -485,7 +541,12 @@ enum TALER_EXCHANGEDB_TransactionType
   /**
    * /refund operation.
    */
-  TALER_EXCHANGEDB_TT_REFUND = 2
+  TALER_EXCHANGEDB_TT_REFUND = 2,
+
+  /**
+   * /payback operation.
+   */
+  TALER_EXCHANGEDB_TT_PAYBACK = 3
 
 };
 
@@ -527,6 +588,11 @@ struct TALER_EXCHANGEDB_TransactionList
      */
     struct TALER_EXCHANGEDB_Refund *refund;
 
+    /**
+     * Details if transaction was a /payback operation.
+     */
+    struct TALER_EXCHANGEDB_Payback *payback;
+
   } details;
 
 };
@@ -1863,25 +1929,21 @@ struct TALER_EXCHANGEDB_Plugin
 
 
   /**
-   * Function called to add a request for an emergency payback for a coin.
-   * Note that this function must check if there is an aggregation for the
-   * respective reserve, if not create one, and return the identifiers for
-   * the aggregate in @a wire_subject and @a deadline.  The
-   * @a acceptable_delay will be constant for an exchange, so if an
-   * aggregate exists it must either be past the deadline or be usable,
-   * in which case this function should update the aggregate's total amount.
-   *
-   * If no aggregate exists, a fresh @a wire_subject is picked at random.
+   * Function called to add a request for an emergency payback for a
+   * coin.  The funds are to be added back to the reserve.  The
+   * function should return the @a deadline by which the exchange will
+   * trigger a wire transfer back to the customer's account for the
+   * reserve.
    *
    * @param cls closure
    * @param session database connection
+   * @param reserve_pub public key of the reserve that is being refunded
    * @param coin information about the coin
    * @param coin_sig signature of the coin of type #TALER_SIGNATURE_WALLET_COIN_PAYBACK
    * @param coin_blind blinding key of the coin
    * @param h_blind_ev blinded envelope, as calculated by the exchange
    * @param amount total amount to be paid back
-   * @param acceptable_delay how long could a wire transfer be delayed
-   * @param[out] wire_subject wire subject the database selected for the transfer
+   * @param receiver_account_details who should receive the funds
    * @param[out] deadline set to absolute time by when the exchange plans to pay it back
    * @return #GNUNET_OK on success,
    *         #GNUNET_SYSERR on DB errors
@@ -1889,64 +1951,32 @@ struct TALER_EXCHANGEDB_Plugin
   int
   (*insert_payback_request)(void *cls,
                             struct TALER_EXCHANGEDB_Session *session,
+                            const struct TALER_ReservePublicKeyP *reserve_pub,
                             const struct TALER_CoinPublicInfo *coin,
                             const struct TALER_CoinSpendSignatureP *coin_sig,
                             const struct TALER_DenominationBlindingKeyP *coin_blind,
                             const struct GNUNET_HashCode *h_blinded_ev,
                             const struct TALER_Amount *amount,
-                            struct GNUNET_TIME_Relative acceptable_delay,
-                            struct TALER_WireTransferIdentifierRawP *wire_subject,
                             struct GNUNET_TIME_Absolute *deadline);
 
 
   /**
-   * Return all (already aggregated!) payback payments due between @e
-   * start_time and @e end_time.  To be used by the special
-   * 'emergency' aggregator to make the paybacks (which presumably
-   * only runs if there are paybacks to be made, and which is
-   * restricted to only accept paybacks for approved denomination
-   * keys).
-   *
-   * @param cls closure
-   * @param session database connection
-   * @param start_time beginning of selection range, inclusive
-   * @param end_time end of selection range, exclusive
-   * @param cb function to call on each required payback operation
-   * @param cb_cls closure for @a cb
-   * @return #GNUNET_OK on success,
-   *         #GNUNET_NO if there are no entries,
-   *         #GNUNET_SYSERR on DB errors
-   */
-  int
-  (*select_payback_requests)(void *cls,
-                             struct TALER_EXCHANGEDB_Session *session,
-                             struct GNUNET_TIME_Absolute start_time,
-                             struct GNUNET_TIME_Absolute end_time,
-                             TALER_EXCHANGEDB_PaybackCallback cb,
-                             void *cb_cls);
-
-
-  /**
-   * Obtain the individual payback requests that justified the aggregate
-   * wire transfer.  Usually used by the auditor to verify losses from
-   * paybacks.
+   * Obtain information about which reserve a coin was generated
+   * from given the hash of the blinded coin.
    *
    * @param cls closure
    * @param session a session
-   * @param wire_subject wire subject of the payback wire transfer
-   * @param cb callback to call with the justification
-   * @param cb_cls closure for @a cb
+   * @param h_blind_ev hash of the blinded coin
+   * @param[out] reserve_pub set to information about the reserve (on success only)
    * @return #GNUNET_OK on success,
    *         #GNUNET_NO if there are no entries,
    *         #GNUNET_SYSERR on DB errors
    */
   int
-  (*get_payback_justification)(void *cls,
-                               struct TALER_EXCHANGEDB_Session *session,
-                               const struct TALER_WireTransferIdentifierRawP *wire_subject,
-                               // ? add constraints like h_wire of receiver?
-                               TALER_EXCHANGEDB_PaybackJustificationCallback cb,
-                               void *cb_cls);
+  (*get_reserve_by_h_blind)(void *cls,
+                            struct TALER_EXCHANGEDB_Session *session,
+                            const struct GNUNET_HashCode *h_blind_ev,
+                            struct TALER_ReservePublicKeyP *reserve_pub);
 
 };
 
diff --git a/src/include/taler_signatures.h b/src/include/taler_signatures.h
index c514a9430..2d0e8bb37 100644
--- a/src/include/taler_signatures.h
+++ b/src/include/taler_signatures.h
@@ -1192,10 +1192,9 @@ struct TALER_PaybackConfirmationPS
   struct TALER_CoinSpendPublicKeyP coin_pub;
 
   /**
-   * Hash (!) of the wire transfer subject that the exchange
-   * will use.  Hash excludes the 0-terminator.
+   * Public key of the reserve that will receive the payback.
    */
-  struct GNUNET_HashCode h_wire_subject;
+  struct TALER_ReservePublicKeyP reserve_pub;
 };