add idempotency checks for /refresh/reveal, fixing #4793

ChangeLog

@@ -1,3 +1,6 @@
+Thu Nov 17 16:37:22 CET 2016
+	Added missing idempotency checks for /refresh/reveal. -CG
+
 Thu Nov 17 11:37:56 CET 2016
 	Fixed a few cases of missing database rollbacks, causing the
 	exchange to be stuck. -CG

src/exchange-lib/test_exchange_api.c

@@ -1710,6 +1710,9 @@ interpreter_run (void *cls)
     fail (is);
     return;
   }
+  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+              "Running command `%s'\n",
+              cmd->label);
   switch (cmd->oc)
   {
   case OC_END:
@@ -2836,6 +2839,12 @@ run (void *cls)
       .expected_response_code = MHD_HTTP_OK,
       .details.refresh_reveal.melt_ref = "refresh-melt-1" },
 
+    /* do it again to check idempotency */
+    { .oc = OC_REFRESH_REVEAL,
+      .label = "refresh-reveal-1-idempotency",
+      .expected_response_code = MHD_HTTP_OK,
+      .details.refresh_reveal.melt_ref = "refresh-melt-1" },
+
     /* Test that /refresh/link works */
     { .oc = OC_REFRESH_LINK,
       .label = "refresh-link-1",
@@ -2849,7 +2858,7 @@ run (void *cls)
       .label = "refresh-deposit-refreshed-1a",
       .expected_response_code = MHD_HTTP_OK,
       .details.deposit.amount = "EUR:1",
-      .details.deposit.coin_ref = "refresh-reveal-1",
+      .details.deposit.coin_ref = "refresh-reveal-1-idempotency",
       .details.deposit.coin_idx = 0,
       .details.deposit.wire_details = "{ \"type\":\"test\", \"bank_uri\":\"http://localhost:8082/\", \"account_number\":42  }",
       .details.deposit.contract = "{ \"items\": [ { \"name\":\"ice cream\", \"value\":3 } ] }",
@@ -3072,12 +3081,6 @@ main (int argc,
   enum GNUNET_OS_ProcessStatusType type;
   unsigned long code;
 
-  GNUNET_log_setup ("test-exchange-api",
-                    "DEBUG",
-                    "/tmp/logs");
-  GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "test log\n");
-  return 0;
-
   /* These might get in the way... */
   unsetenv ("XDG_DATA_HOME");
   unsetenv ("XDG_CONFIG_HOME");

src/exchange/taler-exchange-httpd_db.c

@@ -1280,6 +1280,18 @@ refresh_exchange_coin (struct MHD_Connection *connection,
     ev_sig.rsa_signature = NULL;
     return ev_sig;
   }
+  if (GNUNET_OK ==
+      TEH_plugin->get_refresh_out (TEH_plugin->cls,
+                                   session,
+                                   session_hash,
+                                   coin_off,
+                                   &ev_sig))
+  {
+    GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+                "Returning cashed reply for /refresh/reveal signature\n");
+    return ev_sig;
+  }
+
   ev_sig.rsa_signature
     = GNUNET_CRYPTO_rsa_sign_blinded (dki->denom_priv.rsa_private_key,
                                       commit_coin->coin_ev,
@@ -1289,7 +1301,7 @@ refresh_exchange_coin (struct MHD_Connection *connection,
     GNUNET_break (0);
     return ev_sig;
   }
-  if (GNUNET_OK !=
+  if (GNUNET_SYSERR ==
       TEH_plugin->insert_refresh_out (TEH_plugin->cls,
                                       session,
                                       session_hash,
@@ -1300,6 +1312,7 @@ refresh_exchange_coin (struct MHD_Connection *connection,
     GNUNET_CRYPTO_rsa_signature_free (ev_sig.rsa_signature);
     ev_sig.rsa_signature = NULL;
   }
+
   return ev_sig;
 }
 

src/exchange/taler-exchange-httpd_responses.c

@@ -318,7 +318,7 @@ TEH_RESPONSE_reply_internal_db_error (struct MHD_Connection *connection,
 {
   return TEH_RESPONSE_reply_internal_error (connection,
 					    ec,
-                                            "Failed to connect to database");
+                                            "Failure in database interaction");
 }
 
 

src/exchangedb/plugin_exchangedb_postgres.c

@@ -1154,6 +1154,15 @@ postgres_prepare (PGconn *db_conn)
            "($1, $2, $3)",
            3, NULL);
 
+  /* Used in #postgres_get_refresh_out() to test if the
+     generated signature(s) already exists */
+  PREPARE ("get_refresh_out",
+           "SELECT ev_sig"
+           " FROM refresh_out"
+           " WHERE session_hash=$1"
+           " AND newcoin_index=$2",
+           2, NULL);
+
   /* Used in #postgres_get_link_data_list().  We use the session_hash
      to obtain the "noreveal_index" for that session, and then select the
      corresponding signatures (ev_sig) and the denomination keys from
@@ -3431,6 +3440,67 @@ postgres_get_refresh_transfer_public_key (void *cls,
 }
 
 
+/**
+ * Insert signature of a new coin generated during refresh into
+ * the database indexed by the refresh session and the index
+ * of the coin.  This data is later used should an old coin
+ * be used to try to obtain the private keys during "/refresh/link".
+ *
+ * @param cls the `struct PostgresClosure` with the plugin-specific state
+ * @param session database connection
+ * @param session_hash hash to identify refresh session
+ * @param newcoin_index coin index
+ * @param ev_sig coin signature
+ * @return #GNUNET_OK on success, #GNUNET_NO if we have no such result
+ *         #GNUNET_SYSERR on error
+ */
+static int
+postgres_get_refresh_out (void *cls,
+                          struct TALER_EXCHANGEDB_Session *session,
+                          const struct GNUNET_HashCode *session_hash,
+                          uint16_t newcoin_index,
+                          struct TALER_DenominationSignature *ev_sig)
+{
+  PGresult *result;
+  struct GNUNET_PQ_QueryParam params[] = {
+    GNUNET_PQ_query_param_auto_from_type (session_hash),
+    GNUNET_PQ_query_param_uint16 (&newcoin_index),
+    GNUNET_PQ_query_param_end
+  };
+  struct GNUNET_PQ_ResultSpec rs[] = {
+    GNUNET_PQ_result_spec_rsa_signature ("ev_sig",
+                                         &ev_sig->rsa_signature),
+    GNUNET_PQ_result_spec_end
+  };
+
+  result = GNUNET_PQ_exec_prepared (session->conn,
+                                    "get_refresh_out",
+                                    params);
+  if (PGRES_TUPLES_OK != PQresultStatus (result))
+  {
+    BREAK_DB_ERR (result);
+    PQclear (result);
+    return GNUNET_SYSERR;
+  }
+  if (1 != PQntuples (result))
+  {
+    PQclear (result);
+    return GNUNET_NO;
+  }
+  if (GNUNET_OK !=
+      GNUNET_PQ_extract_result (result,
+                                rs,
+                                0))
+  {
+    PQclear (result);
+    GNUNET_break (0);
+    return GNUNET_SYSERR;
+  }
+  PQclear (result);
+  return GNUNET_OK;
+}
+
+
 /**
  * Insert signature of a new coin generated during refresh into
  * the database indexed by the refresh session and the index
@@ -3443,6 +3513,7 @@ postgres_get_refresh_transfer_public_key (void *cls,
  * @param newcoin_index coin index
  * @param ev_sig coin signature
  * @return #GNUNET_OK on success
+ *         #GNUNET_SYSERR on error
  */
 static int
 postgres_insert_refresh_out (void *cls,
@@ -5050,6 +5121,7 @@ libtaler_plugin_exchangedb_postgres_init (void *cls)
   plugin->free_refresh_commit_coins = &postgres_free_refresh_commit_coins;
   plugin->insert_refresh_transfer_public_key = &postgres_insert_refresh_transfer_public_key;
   plugin->get_refresh_transfer_public_key = &postgres_get_refresh_transfer_public_key;
+  plugin->get_refresh_out = &postgres_get_refresh_out;
   plugin->insert_refresh_out = &postgres_insert_refresh_out;
   plugin->get_link_data_list = &postgres_get_link_data_list;
   plugin->free_link_data_list = &common_free_link_data_list;

src/include/taler_exchangedb_plugin.h

@@ -1359,6 +1359,27 @@ struct TALER_EXCHANGEDB_Plugin
                                       struct TALER_TransferPublicKeyP *tp);
 
 
+  /**
+   * Get signature of a new coin generated during refresh into
+   * the database indexed by the refresh session and the index
+   * of the coin.
+   *
+   * @param cls the @e cls of this struct with the plugin-specific state
+   * @param session database connection
+   * @param session_hash hash to identify refresh session
+   * @param newcoin_index coin index
+   * @param[out] ev_sig coin signature
+   * @return #GNUNET_OK on success, #GNUNET_NO if we have no such entry,
+   *         #GNUNET_SYSERR on error
+   */
+  int
+  (*get_refresh_out) (void *cls,
+                      struct TALER_EXCHANGEDB_Session *session,
+                      const struct GNUNET_HashCode *session_hash,
+                      uint16_t newcoin_index,
+                      struct TALER_DenominationSignature *ev_sig);
+
+
   /**
    * Insert signature of a new coin generated during refresh into
    * the database indexed by the refresh session and the index
@@ -1371,6 +1392,7 @@ struct TALER_EXCHANGEDB_Plugin
    * @param newcoin_index coin index
    * @param ev_sig coin signature
    * @return #GNUNET_OK on success
+   *         #GNUNET_SYSERR on error
    */
   int
   (*insert_refresh_out) (void *cls,