-handle withdraw CS nonce reuse more nicely

src/exchange/taler-exchange-httpd_withdraw.c

@@ -97,6 +97,7 @@ withdraw_transaction (void *cls,
   enum GNUNET_DB_QueryStatus qs;
   bool found = false;
   bool balance_ok = false;
+  bool nonce_ok = false;
   struct GNUNET_TIME_Timestamp now;
   uint64_t ruuid;
   const struct TALER_CsNonce *nonce;
@@ -108,16 +109,13 @@ withdraw_transaction (void *cls,
     (TALER_DENOMINATION_CS == bp->cipher)
     ? &bp->details.cs_blinded_planchet.nonce
     : NULL;
-  // FIXME: what error is returned on nonce reuse?
-  // Should expand function to return this error
-  // specifically, and then we should return a
-  // TALER_EC_EXCHANGE_WITHDRAW_NONCE_REUSE,
   qs = TEH_plugin->do_withdraw (TEH_plugin->cls,
                                 nonce,
                                 &wc->collectable,
                                 now,
                                 &found,
                                 &balance_ok,
+                                &nonce_ok,
                                 &wc->kyc,
                                 &ruuid);
   if (0 > qs)
@@ -146,6 +144,15 @@ withdraw_transaction (void *cls,
       &wc->collectable.reserve_pub);
     return GNUNET_DB_STATUS_HARD_ERROR;
   }
+  if (! nonce_ok)
+  {
+    TEH_plugin->rollback (TEH_plugin->cls);
+    *mhd_ret = TALER_MHD_reply_with_error (connection,
+                                           MHD_HTTP_CONFLICT,
+                                           TALER_EC_EXCHANGE_WITHDRAW_NONCE_REUSE,
+                                           NULL);
+    return GNUNET_DB_STATUS_HARD_ERROR;
+  }
   if ( (TEH_KYC_NONE != TEH_kyc_config.mode) &&
        (! wc->kyc.ok) &&
        (TALER_EXCHANGEDB_KYC_W2W == wc->kyc.type) )

src/exchangedb/exchange-0001-part.sql

@@ -1422,6 +1422,7 @@ CREATE OR REPLACE FUNCTION exchange_do_withdraw(
   IN min_reserve_gc INT8,
   OUT reserve_found BOOLEAN,
   OUT balance_ok BOOLEAN,
+  OUT nonce_ok BOOLEAN,
   OUT kycok BOOLEAN,
   OUT account_uuid INT8,
   OUT ruuid INT8)
@@ -1478,6 +1479,7 @@ THEN
   -- reserve unknown
   reserve_found=FALSE;
   balance_ok=FALSE;
+  nonce_ok=TRUE;
   kycok=FALSE;
   account_uuid=0;
   ruuid=2;
@@ -1511,6 +1513,7 @@ THEN
   -- idempotent query, all constraints must be satisfied
   reserve_found=TRUE;
   balance_ok=TRUE;
+  nonce_ok=TRUE;
   kycok=TRUE;
   account_uuid=0;
   RETURN;
@@ -1534,6 +1537,7 @@ ELSE
     reserve_frac=reserve_frac - amount_frac;
   ELSE
     reserve_found=TRUE;
+    nonce_ok=TRUE; -- we do not really know
     balance_ok=FALSE;
     kycok=FALSE; -- we do not really know or care
     account_uuid=0;
@@ -1585,10 +1589,12 @@ THEN
       balance_ok=FALSE;
       kycok=FALSE;
       account_uuid=0;
-      ruuid=1; -- FIXME: return error message more nicely!
+      nonce_ok=FALSE;
-      ASSERT false, 'nonce reuse attempted by client';
+      RETURN;
     END IF;
   END IF;
+ELSE
+  nonce_ok=TRUE; -- no nonce, hence OK!
 END IF;
 
 

src/exchangedb/plugin_exchangedb_postgres.c

@@ -827,6 +827,7 @@ prepare_statements (struct PostgresClosure *pg)
       "SELECT "
       " reserve_found"
       ",balance_ok"
+      ",nonce_ok"
       ",kycok AS kyc_ok"
       ",account_uuid AS payment_target_uuid"
       ",ruuid"
@@ -5906,6 +5907,7 @@ postgres_get_withdraw_info (
  * @param now current time (rounded)
  * @param[out] found set to true if the reserve was found
  * @param[out] balance_ok set to true if the balance was sufficient
+ * @param[out] nonce_ok set to false if the nonce was reused
  * @param[out] kyc set to true if the kyc status of the reserve is satisfied
  * @param[out] ruuid set to the reserve's UUID (reserves table row)
  * @return query execution status
@@ -5918,6 +5920,7 @@ postgres_do_withdraw (
   struct GNUNET_TIME_Timestamp now,
   bool *found,
   bool *balance_ok,
+  bool *nonce_ok,
   struct TALER_EXCHANGEDB_KycStatus *kyc,
   uint64_t *ruuid)
 {
@@ -5944,6 +5947,8 @@ postgres_do_withdraw (
                                 balance_ok),
     GNUNET_PQ_result_spec_bool ("kyc_ok",
                                 &kyc->ok),
+    GNUNET_PQ_result_spec_bool ("nonce_ok",
+                                nonce_ok),
     GNUNET_PQ_result_spec_uint64 ("payment_target_uuid",
                                   &kyc->payment_target_uuid),
     GNUNET_PQ_result_spec_uint64 ("ruuid",

src/include/taler_exchangedb_plugin.h

@@ -3171,6 +3171,7 @@ struct TALER_EXCHANGEDB_Plugin
    * @param now current time (rounded)
    * @param[out] found set to true if the reserve was found
    * @param[out] balance_ok set to true if the balance was sufficient
+   * @param[out] nonce_ok set to false if the nonce was reused
    * @param[out] kyc set to the KYC status of the reserve
    * @param[out] ruuid set to the reserve's UUID (reserves table row)
    * @return query execution status
@@ -3183,6 +3184,7 @@ struct TALER_EXCHANGEDB_Plugin
     struct GNUNET_TIME_Timestamp now,
     bool *found,
     bool *balance_ok,
+    bool *nonce_ok,
     struct TALER_EXCHANGEDB_KycStatus *kyc_ok,
     uint64_t *ruuid);