[taler-merchant] branch master updated: consider refunds when checking exchange transfer claims

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grothoff pushed a commit to branch master
in repository merchant.

The following commit(s) were added to refs/heads/master by this push:
     new e6a45456 consider refunds when checking exchange transfer claims
e6a45456 is described below

commit e6a4545620933a325b1e7e0d122c2281468bef62
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Mon Apr 1 21:05:45 2024 +0200

    consider refunds when checking exchange transfer claims
---
 .../pg_lookup_deposits_by_contract_and_coin.c      | 135 ++++++++++++++++++++-
 src/backenddb/pg_lookup_refunds.h                  |  12 +-
 src/backenddb/pg_lookup_refunds_detailed.h         |  11 +-
 3 files changed, 141 insertions(+), 17 deletions(-)

diff --git a/src/backenddb/pg_lookup_deposits_by_contract_and_coin.c 
b/src/backenddb/pg_lookup_deposits_by_contract_and_coin.c
index 9bf46d0c..29ff3926 100644
--- a/src/backenddb/pg_lookup_deposits_by_contract_and_coin.c
+++ b/src/backenddb/pg_lookup_deposits_by_contract_and_coin.c
@@ -45,6 +45,11 @@ struct LookupDepositsByCnCContext
    */
   struct PostgresClosure *pg;
 
+  /**
+   * Total amount refunded on this coin and contract.
+   */
+  struct TALER_Amount refund_total;
+
   /**
    * Transaction result.
    */
@@ -52,6 +57,51 @@ struct LookupDepositsByCnCContext
 };
 
 
+/**
+ * Function to be called with the results of a SELECT statement
+ * that has returned @a num_results results.
+ *
+ * @param cls of type `struct LookupDepositsByCnCContext *`
+ * @param result the postgres result
+ * @param num_results the number of results in @a result
+ */
+static void
+lookup_refunds_cb (void *cls,
+                   PGresult *result,
+                   unsigned int num_results)
+{
+  struct LookupDepositsByCnCContext *ldcc = cls;
+
+  for (unsigned int i = 0; i<num_results; i++)
+  {
+    struct TALER_Amount refund_amount;
+    struct GNUNET_PQ_ResultSpec rs[] = {
+      TALER_PQ_result_spec_amount_with_currency ("refund_amount",
+                                                 &refund_amount),
+      GNUNET_PQ_result_spec_end
+    };
+
+    if (GNUNET_OK !=
+        GNUNET_PQ_extract_result (result,
+                                  rs,
+                                  i))
+    {
+      GNUNET_break (0);
+      ldcc->qs = GNUNET_DB_STATUS_HARD_ERROR;
+      return;
+    }
+    if (0 == i)
+      ldcc->refund_total = refund_amount;
+    else
+      GNUNET_assert (0 <=
+                     TALER_amount_add (&ldcc->refund_total,
+                                       &ldcc->refund_total,
+                                       &refund_amount));
+    GNUNET_PQ_cleanup_result (rs); /* technically useless here */
+  }
+}
+
+
 /**
  * Function to be called with the results of a SELECT statement
  * that has returned @a num_results results.
@@ -112,6 +162,50 @@ lookup_deposits_by_contract_and_coin_cb (void *cls,
       ldcc->qs = GNUNET_DB_STATUS_HARD_ERROR;
       return;
     }
+    if (TALER_amount_is_valid (&ldcc->refund_total))
+    {
+      if (1 ==
+          TALER_amount_cmp (&ldcc->refund_total,
+                            &amount_with_fee))
+      {
+        /* Refunds exceeded total deposit? not OK! */
+        GNUNET_break (0);
+        ldcc->qs = GNUNET_DB_STATUS_HARD_ERROR;
+        return;
+      }
+      if (0 ==
+          TALER_amount_cmp (&ldcc->refund_total,
+                            &amount_with_fee))
+      {
+        /* refund_total == amount_with_fee;
+           in this case, the total contributed to the
+           wire transfer is zero (as are fees) */
+        GNUNET_assert (GNUNET_OK ==
+                       TALER_amount_set_zero (ldcc->refund_total.currency,
+                                              &amount_with_fee));
+        GNUNET_assert (GNUNET_OK ==
+                       TALER_amount_set_zero (ldcc->refund_total.currency,
+                                              &deposit_fee));
+
+      }
+      else
+      {
+        /* Compute deposit value by subtracting refunds */
+        GNUNET_assert (0 <
+                       TALER_amount_subtract (&amount_with_fee,
+                                              &amount_with_fee,
+                                              &ldcc->refund_total));
+        if (-1 ==
+            TALER_amount_cmp (&amount_with_fee,
+                              &deposit_fee))
+        {
+          /* amount_with_fee < deposit_fee, so after refunds less than
+             the deposit fee remains; reduce deposit fee to
+             the remaining value of the coin */
+          deposit_fee = amount_with_fee;
+        }
+      }
+    }
     ldcc->cb (ldcc->cb_cls,
               exchange_url,
               &amount_with_fee,
@@ -128,13 +222,15 @@ lookup_deposits_by_contract_and_coin_cb (void *cls,
   ldcc->qs = num_results;
 }
 
+
 enum GNUNET_DB_QueryStatus
-TMH_PG_lookup_deposits_by_contract_and_coin (void *cls,
-                                             const char *instance_id,
-                                             const struct 
TALER_PrivateContractHashP *h_contract_terms,
-                                             const struct 
TALER_CoinSpendPublicKeyP *coin_pub,
-                                             
TALER_MERCHANTDB_CoinDepositCallback cb,
-                                             void *cb_cls)
+TMH_PG_lookup_deposits_by_contract_and_coin (
+  void *cls,
+  const char *instance_id,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  const struct TALER_CoinSpendPublicKeyP *coin_pub,
+  TALER_MERCHANTDB_CoinDepositCallback cb,
+  void *cb_cls)
 {
   struct PostgresClosure *pg = cls;
   struct GNUNET_PQ_QueryParam params[] = {
@@ -151,6 +247,33 @@ TMH_PG_lookup_deposits_by_contract_and_coin (void *cls,
   enum GNUNET_DB_QueryStatus qs;
 
   check_connection (pg);
+  /* no preflight check here, run in transaction by caller! */
+  TALER_LOG_DEBUG ("Looking for refund of h_contract_terms %s at `%s'\n",
+                   GNUNET_h2s (&h_contract_terms->hash),
+                   instance_id);
+  check_connection (pg);
+  PREPARE (pg,
+           "lookup_refunds_by_coin_and_contract",
+           "SELECT"
+           " refund_amount"
+           " FROM merchant_refunds"
+           " WHERE coin_pub=$3"
+           "  AND order_serial="
+           "  (SELECT order_serial"
+           "     FROM merchant_contract_terms"
+           "    WHERE h_contract_terms=$2"
+           "      AND merchant_serial="
+           "        (SELECT merchant_serial"
+           "           FROM merchant_instances"
+           "          WHERE merchant_id=$1))");
+  qs = GNUNET_PQ_eval_prepared_multi_select (pg->conn,
+                                             
"lookup_refunds_by_coin_and_contract",
+                                             params,
+                                             &lookup_refunds_cb,
+                                             &ldcc);
+  if (0 > qs)
+    return qs;
+
   PREPARE (pg,
            "lookup_deposits_by_contract_and_coin",
            "SELECT"
diff --git a/src/backenddb/pg_lookup_refunds.h 
b/src/backenddb/pg_lookup_refunds.h
index 2b047019..20f44e9d 100644
--- a/src/backenddb/pg_lookup_refunds.h
+++ b/src/backenddb/pg_lookup_refunds.h
@@ -36,11 +36,11 @@
  * @return transaction status
  */
 enum GNUNET_DB_QueryStatus
-TMH_PG_lookup_refunds (void *cls,
-                       const char *instance_id,
-                       const struct
-                       TALER_PrivateContractHashP *h_contract_terms,
-                       TALER_MERCHANTDB_RefundCallback rc,
-                       void *rc_cls);
+TMH_PG_lookup_refunds (
+  void *cls,
+  const char *instance_id,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  TALER_MERCHANTDB_RefundCallback rc,
+  void *rc_cls);
 
 #endif
diff --git a/src/backenddb/pg_lookup_refunds_detailed.h 
b/src/backenddb/pg_lookup_refunds_detailed.h
index c2531446..665f06cf 100644
--- a/src/backenddb/pg_lookup_refunds_detailed.h
+++ b/src/backenddb/pg_lookup_refunds_detailed.h
@@ -36,10 +36,11 @@
  * @return transaction status
  */
 enum GNUNET_DB_QueryStatus
-TMH_PG_lookup_refunds_detailed (void *cls,
-                                const char *instance_id,
-                                const struct TALER_PrivateContractHashP 
*h_contract_terms,
-                                TALER_MERCHANTDB_RefundDetailCallback rc,
-                                void *rc_cls);
+TMH_PG_lookup_refunds_detailed (
+  void *cls,
+  const char *instance_id,
+  const struct TALER_PrivateContractHashP *h_contract_terms,
+  TALER_MERCHANTDB_RefundDetailCallback rc,
+  void *rc_cls);
 
 #endif

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