first sketch at db module implementation for #3887

src/exchange/taler-exchange-httpd_db.c

@@ -242,6 +242,8 @@ TEH_DB_execute_deposit (struct MHD_Connection *connection,
                                                &deposit->merchant_pub,
                                                &amount_without_fee);
   }
+
+  /* FIXME: move the 'mks'-logic outside of _db.c? */
   mks = TEH_KS_acquire ();
   dki = TEH_KS_denomination_key_lookup (mks,
                                         &deposit->coin.denom_pub,
@@ -250,7 +252,7 @@ TEH_DB_execute_deposit (struct MHD_Connection *connection,
   {
     TEH_KS_release (mks);
     return TEH_RESPONSE_reply_internal_db_error (connection,
-					   TALER_EC_DEPOSIT_DB_DENOMINATION_KEY_UNKNOWN);
+                                                 TALER_EC_DEPOSIT_DB_DENOMINATION_KEY_UNKNOWN);
   }
   TALER_amount_ntoh (&value,
                      &dki->issue.properties.value);
@@ -283,8 +285,9 @@ TEH_DB_execute_deposit (struct MHD_Connection *connection,
   {
     TEH_plugin->rollback (TEH_plugin->cls,
                           session);
-    ret = TEH_RESPONSE_reply_deposit_insufficient_funds (connection,
+    ret = TEH_RESPONSE_reply_coin_insufficient_funds (connection,
-                                                         tl);
+                                                      TALER_EC_DEPOSIT_INSUFFICIENT_FUNDS,
+                                                      tl);
     TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
                                             tl);
     return ret;
@@ -2264,18 +2267,114 @@ TEH_DB_execute_track_transaction (struct MHD_Connection *connection,
  *
  * @param connection the MHD connection to handle
  * @param coin information about the coin
- * @param coin_bks blinding data of the coin (to be checked)
+ * @param value how much are coins of the @a coin's denomination worth?
- * @param coin_sig signature of the coin
+ * @param h_blind blinded coin to use for the lookup
+ * @param coin_sig signature of the coin (to be stored)
  * @return MHD result code
  */
 int
 TEH_DB_execute_payback (struct MHD_Connection *connection,
                         const struct TALER_CoinPublicInfo *coin,
-                        const struct TALER_DenominationBlindingKeyP *coin_bks,
+                        const struct TALER_Amount *value,
+                        const struct GNUNET_HashCode *h_blind,
                         const struct TALER_CoinSpendSignatureP *coin_sig)
 {
-  GNUNET_break (0); /* not implemented (#3887) */
+  int ret;
-  return MHD_NO;
+  struct TALER_EXCHANGEDB_Session *session;
+  struct TALER_EXCHANGEDB_TransactionList *tl;
+  struct TALER_EXCHANGEDB_CollectableBlindcoin collectable;
+  char wire_subject[42]; // FIXME: size? (#3887)
+  struct TALER_Amount amount;
+  struct TALER_Amount spent;
+  struct GNUNET_TIME_Absolute payback_deadline;
+
+  if (NULL == (session = TEH_plugin->get_session (TEH_plugin->cls)))
+  {
+    GNUNET_break (0);
+    return TEH_RESPONSE_reply_internal_db_error (connection,
+						 TALER_EC_DB_SETUP_FAILED);
+  }
+
+  START_TRANSACTION (session, connection);
+
+  /* FIXME (#3887): not _exactly_ the right call, we need to get the
+     reserve's incoming wire transfer data, not 'collectable' */
+  ret = TEH_plugin->get_withdraw_info (TEH_plugin->cls,
+                                       session,
+                                       h_blind,
+                                       &collectable);
+  if (GNUNET_SYSERR == ret)
+  {
+    GNUNET_break (0);
+    TEH_plugin->rollback (TEH_plugin->cls,
+                          session);
+    return TEH_RESPONSE_reply_internal_db_error (connection,
+						 TALER_EC_PAYBACK_DB_FETCH_FAILED);
+  }
+  if (GNUNET_NO == ret)
+  {
+    GNUNET_break_op (0);
+    TEH_plugin->rollback (TEH_plugin->cls,
+                          session);
+    return TEH_RESPONSE_reply_payback_unknown (connection,
+                                               TALER_EC_PAYBACK_WITHDRAW_NOT_FOUND);
+  }
+
+  /* Calculate remaining balance. */
+  tl = TEH_plugin->get_coin_transactions (TEH_plugin->cls,
+                                          session,
+                                          &coin->coin_pub);
+  TALER_amount_get_zero (value->currency,
+                         &spent);
+  if (GNUNET_OK !=
+      calculate_transaction_list_totals (tl,
+                                         &spent,
+                                         &spent))
+  {
+    GNUNET_break (0);
+    TEH_plugin->rollback (TEH_plugin->cls,
+                          session);
+    TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
+                                            tl);
+    return TEH_RESPONSE_reply_internal_db_error (connection,
+						 TALER_EC_PAYBACK_HISTORY_DB_ERROR);
+  }
+  TALER_amount_subtract (&amount,
+                         value,
+                         &spent);
+  if ( (0 == amount.fraction) &&
+       (0 == amount.value) )
+  {
+    GNUNET_break_op (0);
+    TEH_plugin->rollback (TEH_plugin->cls,
+                          session);
+    ret = TEH_RESPONSE_reply_coin_insufficient_funds (connection,
+                                                      TALER_EC_PAYBACK_COIN_BALANCE_ZERO,
+                                                      tl);
+    TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
+                                            tl);
+    return ret;
+  }
+  TEH_plugin->free_coin_transaction_list (TEH_plugin->cls,
+                                          tl);
+
+  /* FIXME: add coin to list of wire transfers for payback */
+  // ret = TEH_plugin->(); // #3887
+  if (GNUNET_SYSERR == ret)
+  {
+    TALER_LOG_WARNING ("Failed to store /payback information in database\n");
+    TEH_plugin->rollback (TEH_plugin->cls,
+                          session);
+    return TEH_RESPONSE_reply_internal_db_error (connection,
+						 TALER_EC_PAYBACK_DB_PUT_FAILED);
+  }
+
+  COMMIT_TRANSACTION(session, connection);
+
+  return TEH_RESPONSE_reply_payback_success (connection,
+                                             wire_subject,
+                                             &amount,
+                                             payback_deadline);
 }
 
 

src/exchange/taler-exchange-httpd_db.h

@@ -244,14 +244,16 @@ TEH_DB_execute_track_transaction (struct MHD_Connection *connection,
  *
  * @param connection the MHD connection to handle
  * @param coin information about the coin
- * @param coin_bks blinding data of the coin (to be checked)
+ * @param value how much are coins of the @a coin's denomination worth?
+ * @param h_blind blinded coin to use for the lookup
  * @param coin_sig signature of the coin
  * @return MHD result code
  */
 int
 TEH_DB_execute_payback (struct MHD_Connection *connection,
                         const struct TALER_CoinPublicInfo *coin,
-                        const struct TALER_DenominationBlindingKeyP *coin_bks,
+                        const struct TALER_Amount *value,
+                        const struct GNUNET_HashCode *h_blind,
                         const struct TALER_CoinSpendSignatureP *coin_sig);
 
 

src/exchange/taler-exchange-httpd_payback.c

@@ -56,7 +56,11 @@ verify_and_execute_payback (struct MHD_Connection *connection,
   struct TEH_KS_StateHandle *key_state;
   const struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dki;
   struct TALER_PaybackRequestPS pr;
-
+  struct TALER_Amount value;
+  struct GNUNET_HashCode h_blind;
+  struct GNUNET_HashCode c_hash;
+  char *coin_ev;
+  size_t coin_ev_size;
 
   /* check denomination exists and is in payback mode */
   key_state = TEH_KS_acquire ();
@@ -71,6 +75,8 @@ verify_and_execute_payback (struct MHD_Connection *connection,
 					   TALER_EC_PAYBACK_DENOMINATION_KEY_UNKNOWN,
                                            "denom_pub");
   }
+  TALER_amount_ntoh (&value,
+                     &dki->issue.properties.value);
 
   /* check denomination signature */
   if (GNUNET_YES !=
@@ -104,9 +110,30 @@ verify_and_execute_payback (struct MHD_Connection *connection,
                                                  "coin_sig");
   }
 
+  GNUNET_CRYPTO_hash (&coin->coin_pub.eddsa_pub,
+                      sizeof (struct GNUNET_CRYPTO_EcdsaPublicKey),
+                      &c_hash);
+  if (GNUNET_YES !=
+      GNUNET_CRYPTO_rsa_blind (&c_hash,
+                               &coin_bks->bks,
+                               coin->denom_pub.rsa_public_key,
+                               &coin_ev,
+                               &coin_ev_size))
+  {
+    GNUNET_break (0);
+    return TEH_RESPONSE_reply_internal_error (connection,
+                                              TALER_EC_PAYBACK_BLINDING_FAILED,
+                                              "coin_bks");
+  }
+  GNUNET_CRYPTO_hash (coin_ev,
+                      coin_ev_size,
+                      &h_blind);
+  GNUNET_free (coin_ev);
+
   return TEH_DB_execute_payback (connection,
                                  coin,
-                                 coin_bks,
+                                 &value,
+                                 &h_blind,
                                  coin_sig);
 }
 

src/exchange/taler-exchange-httpd_responses.c

@@ -436,6 +436,11 @@ compile_transaction_history (const struct TALER_EXCHANGEDB_TransactionList *tl)
   const struct TALER_EXCHANGEDB_TransactionList *pos;
 
   history = json_array ();
+  if (NULL == history)
+  {
+    GNUNET_break (0); /* out of memory!? */
+    return NULL;
+  }
   for (pos = tl; NULL != pos; pos = pos->next)
   {
     switch (pos->type)
@@ -562,29 +567,33 @@ compile_transaction_history (const struct TALER_EXCHANGEDB_TransactionList *tl)
 
 
 /**
- * Send proof that a /deposit request is invalid to client.  This
+ * Send proof that a request is invalid to client because of
- * function will create a message with all of the operations affecting
+ * insufficient funds.  This function will create a message with all
- * the coin that demonstrate that the coin has insufficient value.
+ * of the operations affecting the coin that demonstrate that the coin
+ * has insufficient value.
  *
  * @param connection connection to the client
+ * @param ec error code to return
  * @param tl transaction list to use to build reply
  * @return MHD result code
  */
 int
-TEH_RESPONSE_reply_deposit_insufficient_funds (struct MHD_Connection *connection,
+TEH_RESPONSE_reply_coin_insufficient_funds (struct MHD_Connection *connection,
-                                               const struct TALER_EXCHANGEDB_TransactionList *tl)
+                                            enum TALER_ErrorCode ec,
+                                            const struct TALER_EXCHANGEDB_TransactionList *tl)
 {
   json_t *history;
 
   history = compile_transaction_history (tl);
   if (NULL == history)
-    return TEH_RESPONSE_reply_internal_db_error (connection,
+    return TEH_RESPONSE_reply_internal_error (connection,
-						 TALER_EC_DEPOSIT_HISTORY_DB_ERROR_INSUFFICIENT_FUNDS);
+                                              TALER_EC_COIN_HISTORY_DB_ERROR_INSUFFICIENT_FUNDS,
+                                              "failed to convert transaction history to JSON");
   return TEH_RESPONSE_reply_json_pack (connection,
                                        MHD_HTTP_FORBIDDEN,
                                        "{s:s, s:I, s:o}",
                                        "error", "insufficient funds",
-				       "code", (json_int_t) TALER_EC_DEPOSIT_INSUFFICIENT_FUNDS,
+				       "code", (json_int_t) ec,
                                        "history", history);
 }
 
@@ -1286,4 +1295,44 @@ TEH_RESPONSE_reply_track_transfer_details (struct MHD_Connection *connection,
 }
 
 
+
+/**
+ * A wallet asked for /payback, but we do not know anything
+ * about the original withdraw operation given. Generates a
+ * 404 reply.
+ *
+ * @param connection connection to the client
+ * @param ec Taler error code
+ * @return MHD result code
+ */
+int
+TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
+                                    enum TALER_ErrorCode ec)
+{
+  GNUNET_break (0); /* #3887 */
+  return MHD_NO;
+}
+
+
+/**
+ * A wallet asked for /payback, return the successful response.
+ *
+ * @param connection connection to the client
+ * @param wire_subject the wire subject we will use for the pay back operation
+ * @param amount the amount we will wire back
+ * @param payback_deadline deadline by which the exchange promises to pay
+ * @return MHD result code
+ */
+int
+TEH_RESPONSE_reply_payback_success (struct MHD_Connection *connection,
+                                    const char *wire_subject,
+                                    const struct TALER_Amount *amount,
+                                    struct GNUNET_TIME_Absolute payback_deadline)
+{
+  GNUNET_break (0); /* #3887 */
+  return MHD_NO;
+}
+
+
+
 /* end of taler-exchange-httpd_responses.c */

src/exchange/taler-exchange-httpd_responses.h

@@ -250,17 +250,20 @@ TEH_RESPONSE_reply_deposit_success (struct MHD_Connection *connection,
 
 
 /**
- * Send proof that a /deposit request is invalid to client.  This
+ * Send proof that a request is invalid to client because of
- * function will create a message with all of the operations affecting
+ * insufficient funds.  This function will create a message with all
- * the coin that demonstrate that the coin has insufficient value.
+ * of the operations affecting the coin that demonstrate that the coin
+ * has insufficient value.
  *
  * @param connection connection to the client
+ * @param ec error code to return
  * @param tl transaction list to use to build reply
  * @return MHD result code
  */
 int
-TEH_RESPONSE_reply_deposit_insufficient_funds (struct MHD_Connection *connection,
+TEH_RESPONSE_reply_coin_insufficient_funds (struct MHD_Connection *connection,
-                                               const struct TALER_EXCHANGEDB_TransactionList *tl);
+                                            enum TALER_ErrorCode ec,
+                                            const struct TALER_EXCHANGEDB_TransactionList *tl);
 
 
 /**
@@ -556,4 +559,34 @@ TEH_RESPONSE_reply_refresh_link_success (struct MHD_Connection *connection,
                                          const struct TEH_RESPONSE_LinkSessionInfo *sessions);
 
 
+/**
+ * A wallet asked for /payback, but we do not know anything
+ * about the original withdraw operation given. Generates a
+ * 404 reply.
+ *
+ * @param connection connection to the client
+ * @param ec Taler error code
+ * @return MHD result code
+ */
+int
+TEH_RESPONSE_reply_payback_unknown (struct MHD_Connection *connection,
+                                    enum TALER_ErrorCode ec);
+
+
+/**
+ * A wallet asked for /payback, return the successful response.
+ *
+ * @param connection connection to the client
+ * @param wire_subject the wire subject we will use for the pay back operation
+ * @param amount the amount we will wire back
+ * @param payback_deadline deadline by which the exchange promises to pay
+ * @return MHD result code
+ */
+int
+TEH_RESPONSE_reply_payback_success (struct MHD_Connection *connection,
+                                    const char *wire_subject,
+                                    const struct TALER_Amount *amount,
+                                    struct GNUNET_TIME_Absolute payback_deadline);
+
+
 #endif

src/include/taler_error_codes.h

@@ -128,6 +128,17 @@ enum TALER_ErrorCode
    */
   TALER_EC_PARAMETER_MALFORMED = 1009,
 
+  /**
+   * The exchange failed to obtain the transaction history of the
+   * given coin from the database while generating an insufficient
+   * funds errors.  This can happen during /deposit or /payback requests.
+   * This response is provided with HTTP status code
+   * MHD_HTTP_INTERNAL_SERVER_ERROR.
+   */
+  TALER_EC_COIN_HISTORY_DB_ERROR_INSUFFICIENT_FUNDS = 1010,
+
+
+
   /* ********** request-specific error codes ************* */
 
   /**
@@ -230,7 +241,7 @@ enum TALER_ErrorCode
   /**
    * The exchange failed to obtain the transaction history of the
    * given reserve from the database while generating an insufficient
-   * funds errors.
+   * funds error.
    * This response is provided with HTTP status code
    * MHD_HTTP_INTERNAL_SERVER_ERROR.
    */
@@ -349,15 +360,6 @@ enum TALER_ErrorCode
    */
   TALER_EC_DEPOSIT_INVALID_WIRE_FORMAT_CONTRACT_HASH_CONFLICT = 1211,
 
-  /**
-   * The exchange failed to obtain the transaction history of the
-   * given coin from the database while generating an insufficient
-   * funds errors.
-   * This response is provided with HTTP status code
-   * MHD_HTTP_INTERNAL_SERVER_ERROR.
-   */
-  TALER_EC_DEPOSIT_HISTORY_DB_ERROR_INSUFFICIENT_FUNDS = 1212,
-
   /**
    * The exchange detected that the given account number
    * is invalid for the selected wire format type.
@@ -852,6 +854,49 @@ enum TALER_ErrorCode
    */
   TALER_EC_PAYBACK_DENOMINATION_SIGNATURE_INVALID = 1852,
 
+  /**
+   * The exchange failed to access its own database about reserves.
+   * This response is provided with HTTP status code
+   * MHD_HTTP_INTERNAL_SERVER_ERROR.
+   */
+  TALER_EC_PAYBACK_DB_FETCH_FAILED = 1853,
+
+  /**
+   * The exchange could not find the corresponding withdraw operation.
+   * The request is denied.  This response is provided with an HTTP
+   * status code of MHD_HTTP_NOT_FOUND.
+   */
+  TALER_EC_PAYBACK_WITHDRAW_NOT_FOUND = 1854,
+
+  /**
+   * The exchange obtained an internally inconsistent transaction
+   * history for the given coin. This response is provided with HTTP
+   * status code MHD_HTTP_INTERNAL_SERVER_ERROR.
+   */
+  TALER_EC_PAYBACK_HISTORY_DB_ERROR = 1855,
+
+  /**
+   * The exchange failed to store information about the payback to be
+   * performed in the database. This response is provided with HTTP
+   * status code MHD_HTTP_INTERNAL_SERVER_ERROR.
+   */
+  TALER_EC_PAYBACK_DB_PUT_FAILED = 1856,
+
+  /**
+   * The coin's remaining balance is zero.  The request is denied.
+   * This response is provided with an HTTP status code of
+   * MHD_HTTP_FORBIDDEN.
+   */
+  TALER_EC_PAYBACK_COIN_BALANCE_ZERO = 1857,
+
+  /**
+   * The exchange failed to reproduce the coin's blinding.
+   * This response is provided with an HTTP status code of
+   * MHD_HTTP_INTERNAL_SERVER_ERROR.
+   */
+  TALER_EC_PAYBACK_BLINDING_FAILED = 1858,
+
+
 
   /* *********** Merchant backend error codes ********* */