[wip, #7267] more refined denomination conflict response during deposit

If a coin was known but with a different denomination, return to the
client an error response that contains the denomination's public key and
the corresponding signature of the provided coin.

4 files changed, 118 insertions, 8 deletions

diff --git a/src/exchangedb/Makefile.am b/src/exchangedb/Makefile.am
index 84bd53018..847f2d880 100644
--- a/src/exchangedb/Makefile.am
+++ b/src/exchangedb/Makefile.am
@@ -126,6 +126,7 @@ libtaler_plugin_exchangedb_postgres_la_SOURCES = \
   pg_count_known_coins.h pg_count_known_coins.c \
   pg_ensure_coin_known.h pg_ensure_coin_known.c \
   pg_get_known_coin.h pg_get_known_coin.c \
+  pg_get_signature_for_known_coin.h pg_get_signature_for_known_coin.c \
   pg_get_coin_denomination.h pg_get_coin_denomination.c \
   pg_have_deposit2.h pg_have_deposit2.c \
   pg_aggregate.h pg_aggregate.c \
diff --git a/src/exchangedb/pg_get_signature_for_known_coin.c b/src/exchangedb/pg_get_signature_for_known_coin.c
new file mode 100644
index 000000000..06074312f
--- /dev/null
+++ b/src/exchangedb/pg_get_signature_for_known_coin.c
@@ -0,0 +1,63 @@
+/*
+   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_signature_for_known_coin.c
+ * @brief Implementation of the get_signature_for_known_coin function for Postgres
+ * @author Özgür Kesim
+ */
+#include "platform.h"
+#include "taler_error_codes.h"
+#include "taler_dbevents.h"
+#include "taler_pq_lib.h"
+#include "pg_get_signature_for_known_coin.h"
+#include "pg_helper.h"
+
+enum GNUNET_DB_QueryStatus
+TEH_PG_get_signature_for_known_coin (
+  void *cls,
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  struct TALER_DenominationPublicKey *denom_pub,
+  struct TALER_DenominationSignature *denom_sig)
+{
+  struct PostgresClosure *pg = cls;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (coin_pub),
+    GNUNET_PQ_query_param_end
+  };
+  struct GNUNET_PQ_ResultSpec rs[] = {
+    TALER_PQ_result_spec_denom_pub ("denom_pub",
+                                    denom_pub),
+    TALER_PQ_result_spec_denom_sig ("denom_sig",
+                                    denom_sig),
+    GNUNET_PQ_result_spec_end
+  };
+
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Getting denomination and signature for (potentially) known coin %s\n",
+              TALER_B2S (coin_pub));
+  PREPARE (pg,
+           "get_signature_for_known_coin",
+           "SELECT"
+           " denominations.denom_pub"
+           ",denom_sig"
+           " FROM known_coins"
+           " JOIN denominations USING (denominations_serial)"
+           " WHERE coin_pub=$1;");
+  return GNUNET_PQ_eval_prepared_singleton_select (pg->conn,
+                                                   "get_signature_for_known_coin",
+                                                   params,
+                                                   rs);
+}
diff --git a/src/exchangedb/pg_get_signature_for_known_coin.h b/src/exchangedb/pg_get_signature_for_known_coin.h
new file mode 100644
index 000000000..ec389176b
--- /dev/null
+++ b/src/exchangedb/pg_get_signature_for_known_coin.h
@@ -0,0 +1,43 @@
+/*
+   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_signature_for_known_coin.h
+ * @brief implementation of the get_signature_for_known_coin function for Postgres
+ * @author Özgür Kesim
+ */
+#ifndef PG_GET_SIGNATURE_FOR_KNOWN_COIN_H
+#define PG_GET_SIGNATURE_FOR_KNOWN_COIN_H
+
+#include "taler_util.h"
+#include "taler_json_lib.h"
+#include "taler_exchangedb_plugin.h"
+/**
+ * Retrieve the denomination and the corresponding signature for a known coin.
+ *
+ * @param cls the plugin closure
+ * @param coin_pub the public key of the coin to search for
+ * @param[out] denom_pub the denomination of the public key, if coin was present
+ * @param[out] denom_sig the signature with the denomination key of the coin, if coin was present
+ * @return transaction status code
+ */
+enum GNUNET_DB_QueryStatus
+TEH_PG_get_signature_for_known_coin (
+  void *cls,
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  struct TALER_DenominationPublicKey *denom_pub,
+  struct TALER_DenominationSignature *denom_sig);
+
+#endif
diff --git a/src/exchangedb/plugin_exchangedb_postgres.c b/src/exchangedb/plugin_exchangedb_postgres.c
index 51dbea659..7d9044a1e 100644
--- a/src/exchangedb/plugin_exchangedb_postgres.c
+++ b/src/exchangedb/plugin_exchangedb_postgres.c
@@ -130,6 +130,7 @@
 #include "pg_count_known_coins.h"
 #include "pg_ensure_coin_known.h"
 #include "pg_get_known_coin.h"
+#include "pg_get_signature_for_known_coin.h"
 #include "pg_get_coin_denomination.h"
 #include "pg_have_deposit2.h"
 #include "pg_aggregate.h"
@@ -232,14 +233,14 @@
  * @param conn SQL connection that was used
  */
 #define BREAK_DB_ERR(result,conn) do {                                  \
-    GNUNET_break (0);                                                   \
-    GNUNET_log (GNUNET_ERROR_TYPE_ERROR,                                \
-                "Database failure: %s/%s/%s/%s/%s",                     \
-                PQresultErrorField (result, PG_DIAG_MESSAGE_PRIMARY),   \
-                PQresultErrorField (result, PG_DIAG_MESSAGE_DETAIL),    \
-                PQresultErrorMessage (result),                          \
-                PQresStatus (PQresultStatus (result)),                  \
-                PQerrorMessage (conn));                                 \
+          GNUNET_break (0);                                                   \
+          GNUNET_log (GNUNET_ERROR_TYPE_ERROR,                                \
+                      "Database failure: %s/%s/%s/%s/%s",                     \
+                      PQresultErrorField (result, PG_DIAG_MESSAGE_PRIMARY),   \
+                      PQresultErrorField (result, PG_DIAG_MESSAGE_DETAIL),    \
+                      PQresultErrorMessage (result),                          \
+                      PQresStatus (PQresultStatus (result)),                  \
+                      PQerrorMessage (conn));                                 \
 } while (0)
 
 
@@ -601,6 +602,8 @@ libtaler_plugin_exchangedb_postgres_init (void *cls)
     = &TEH_PG_ensure_coin_known;
   plugin->get_known_coin
     = &TEH_PG_get_known_coin;
+  plugin->get_signature_for_known_coin
+    = &TEH_PG_get_signature_for_known_coin;
   plugin->get_coin_denomination
     = &TEH_PG_get_coin_denomination;
   plugin->have_deposit2