Added appropriate response on contract-conflict during deposit

In case of a detected conflict during deposit, because
(merchant_pub, h_contract_terms) already existed, with different other
field values, we now provide the client an error response that contains
the h_wire.  This way, the client can retrieve further details about the
conflicting transaction via
/deposits/$H_WIRE/$MERCHANT_PUB/$H_CONTRACT_TERMS/$COIN_PUB

Fixes #8002

1 files changed, 81 insertions, 0 deletions

diff --git a/src/exchangedb/pg_get_wire_hash_for_contract.c b/src/exchangedb/pg_get_wire_hash_for_contract.c
new file mode 100644
index 000000000..5ff092a6c
--- /dev/null
+++ b/src/exchangedb/pg_get_wire_hash_for_contract.c
@@ -0,0 +1,81 @@
+/*
+   This file is part of TALER
+   Copyright (C) 2023 Taler Systems SA
+
+   TALER is free software; you can redistribute it and/or modify it under the
+   terms of the GNU General Public License as published by the Free Software
+   Foundation; either version 3, or (at your option) any later version.
+
+   TALER is distributed in the hope that it will be useful, but WITHOUT ANY
+   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License along with
+   TALER; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
+ */
+/**
+ * @file exchangedb/pg_get_wire_hash_for_contract.c
+ * @brief Implementation of the get_wire_hash_for_contract function for Postgres
+ * @author Özgür Kesim
+ */
+#include "platform.h"
+#include "taler_error_codes.h"
+#include "taler_dbevents.h"
+#include "taler_exchangedb_plugin.h"
+#include "taler_pq_lib.h"
+#include "pg_get_wire_hash_for_contract.h"
+#include "pg_helper.h"
+
+
+enum GNUNET_DB_QueryStatus
+TEH_PG_get_wire_hash_for_contract (
+  void *cls,
+  const struct TALER_MerchantPublicKeyP *merchant_pub,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  struct TALER_MerchantWireHashP *h_wire)
+{
+  struct PostgresClosure *pg = cls;
+  enum GNUNET_DB_QueryStatus qs;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (merchant_pub),
+    GNUNET_PQ_query_param_auto_from_type (h_contract_terms),
+    GNUNET_PQ_query_param_end
+  };
+  char *payto_uri;
+  struct TALER_WireSaltP wire_salt;
+  struct GNUNET_PQ_ResultSpec rs[] = {
+    GNUNET_PQ_result_spec_auto_from_type ("wire_salt",
+                                          &wire_salt),
+    GNUNET_PQ_result_spec_string ("payto_uri",
+                                  &payto_uri),
+    GNUNET_PQ_result_spec_end
+  };
+
+  /* check if the necessary records exist and get them */
+  PREPARE (pg,
+           "get_wire_hash_for_contract",
+           "SELECT"
+           "bdep.wire_salt"
+           ",wt.payto_uri"
+           " FROM coin_deposits"
+           "    JOIN batch_deposits bdep"
+           "      USING (batch_deposit_serial_id)"
+           "    JOIN wire_targets wt"
+           "      USING (wire_target_h_payto)"
+           " WHERE bdep.merchant_pub=$1"
+           "   AND bdep.h_contract_terms=$2");
+  /* NOTE: above query might be more efficient if we computed the shard
+     from the merchant_pub and included that in the query */
+  qs = GNUNET_PQ_eval_prepared_singleton_select (pg->conn,
+                                                 "get_wire_hash_for_contract",
+                                                 params,
+                                                 rs);
+  if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
+  {
+    TALER_merchant_wire_signature_hash (payto_uri,
+                                        &wire_salt,
+                                        h_wire);
+    GNUNET_PQ_cleanup_result (rs);
+  }
+  return qs;
+}