298 lines
9.2 KiB
C
298 lines
9.2 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2015, 2016 Inria & GNUnet e.V.
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TALER is free software; you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation; either version 3, or (at your option) any later version.
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TALER is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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A PARTICULAR PURPOSE. See the GNU General Public License for more details.
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You should have received a copy of the GNU General Public License along with
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TALER; see the file COPYING. If not, If not, see
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<http://www.gnu.org/licenses/>
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*/
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/**
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* @file exchange-lib/exchange_api_common.c
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* @brief common functions for the exchange API
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* @author Christian Grothoff
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*/
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#include "platform.h"
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#include "exchange_api_common.h"
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#include "taler_json_lib.h"
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#include <gnunet/gnunet_curl_lib.h>
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#include "exchange_api_handle.h"
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#include "taler_signatures.h"
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/**
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* Verify a coins transaction history as returned by the exchange.
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*
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* @param currency expected currency for the coin
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* @param coin_pub public key of the coin
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* @param history history of the coin in json encoding
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* @param[out] total how much of the coin has been spent according to @a history
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* @return #GNUNET_OK if @a history is valid, #GNUNET_SYSERR if not
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*/
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int
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TALER_EXCHANGE_verify_coin_history (const char *currency,
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const struct TALER_CoinSpendPublicKeyP *coin_pub,
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json_t *history,
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struct TALER_Amount *total)
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{
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size_t len;
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size_t off;
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int add;
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struct TALER_Amount rtotal;
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if (NULL == history)
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{
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GNUNET_break_op (0);
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return GNUNET_SYSERR;
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}
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len = json_array_size (history);
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if (0 == len)
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{
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GNUNET_break_op (0);
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return GNUNET_SYSERR;
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}
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TALER_amount_get_zero (currency,
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total);
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TALER_amount_get_zero (currency,
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&rtotal);
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for (off=0;off<len;off++)
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{
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json_t *transaction;
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struct TALER_Amount amount;
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struct TALER_CoinSpendSignatureP sig;
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void *details;
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size_t details_size;
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const char *type;
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struct GNUNET_JSON_Specification spec[] = {
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TALER_JSON_spec_amount ("amount",
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&amount),
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GNUNET_JSON_spec_string ("type",
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&type),
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GNUNET_JSON_spec_fixed_auto ("signature",
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&sig),
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GNUNET_JSON_spec_varsize ("details",
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&details,
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&details_size),
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GNUNET_JSON_spec_end()
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};
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transaction = json_array_get (history,
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off);
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if (GNUNET_OK !=
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GNUNET_JSON_parse (transaction,
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spec,
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NULL, NULL))
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{
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GNUNET_break_op (0);
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return GNUNET_SYSERR;
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}
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add = GNUNET_SYSERR;
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if (0 == strcasecmp (type,
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"DEPOSIT"))
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{
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const struct TALER_DepositRequestPS *dr;
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struct TALER_Amount dr_amount;
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if (details_size != sizeof (struct TALER_DepositRequestPS))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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dr = (const struct TALER_DepositRequestPS *) details;
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if (details_size != ntohl (dr->purpose.size))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_DEPOSIT,
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&dr->purpose,
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&sig.eddsa_signature,
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&coin_pub->eddsa_pub))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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TALER_amount_ntoh (&dr_amount,
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&dr->amount_with_fee);
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if (0 != TALER_amount_cmp (&dr_amount,
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&amount))
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{
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GNUNET_break (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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add = GNUNET_YES;
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}
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else if (0 == strcasecmp (type,
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"MELT"))
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{
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const struct TALER_RefreshMeltCoinAffirmationPS *rm;
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struct TALER_Amount rm_amount;
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if (details_size != sizeof (struct TALER_RefreshMeltCoinAffirmationPS))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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rm = (const struct TALER_RefreshMeltCoinAffirmationPS *) details;
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if (details_size != ntohl (rm->purpose.size))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_MELT,
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&rm->purpose,
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&sig.eddsa_signature,
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&coin_pub->eddsa_pub))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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TALER_amount_ntoh (&rm_amount,
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&rm->amount_with_fee);
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if (0 != TALER_amount_cmp (&rm_amount,
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&amount))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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add = GNUNET_YES;
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}
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else if (0 == strcasecmp (type,
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"REFUND"))
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{
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const struct TALER_RefundRequestPS *rr;
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struct TALER_Amount rr_amount;
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struct TALER_Amount rr_fee;
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struct TALER_Amount rr_delta;
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if (details_size != sizeof (struct TALER_RefundRequestPS))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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rr = (const struct TALER_RefundRequestPS *) details;
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if (details_size != ntohl (rr->purpose.size))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_MERCHANT_REFUND,
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&rr->purpose,
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&sig.eddsa_signature,
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&rr->merchant.eddsa_pub))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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TALER_amount_ntoh (&rr_amount,
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&rr->refund_amount);
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TALER_amount_ntoh (&rr_fee,
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&rr->refund_fee);
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if (GNUNET_OK !=
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TALER_amount_subtract (&rr_delta,
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&rr_amount,
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&rr_fee))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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if (0 != TALER_amount_cmp (&rr_delta,
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&amount))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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/* NOTE/FIXME: theoretically, we could also check that the given
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transaction_id and merchant_pub and h_contract appear in the
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history under deposits. However, there is really no benefit
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for the exchange to lie here, so not checking is probably OK
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(an auditor ought to check, though). Then again, we similarly
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had no reason to check the merchant's signature (other than a
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well-formendess check). */
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add = GNUNET_NO;
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}
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else
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{
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/* signature not supported, new version on server? */
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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if (GNUNET_YES == add)
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{
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/* This amount should be added to the total */
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if (GNUNET_OK !=
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TALER_amount_add (total,
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total,
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&amount))
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{
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/* overflow in history already!? inconceivable! Bad exchange! */
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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}
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else
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{
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/* This amount should be subtracted from the total.
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However, for the implementation, we first *add* up all of
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these negative amounts, as we might get refunds before
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deposits from a semi-evil exchange. Then, at the end, we do
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the subtraction by calculating "total = total - rtotal" */
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GNUNET_assert (GNUNET_NO == add);
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if (GNUNET_OK !=
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TALER_amount_add (&rtotal,
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&rtotal,
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&amount))
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{
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/* overflow in refund history? inconceivable! Bad exchange! */
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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}
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GNUNET_JSON_parse_free (spec);
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}
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/* Finally, subtract 'rtotal' from total to handle the subtractions */
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if (GNUNET_OK !=
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TALER_amount_subtract (total,
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total,
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&rtotal))
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{
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/* underflow in history? inconceivable! Bad exchange! */
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GNUNET_break_op (0);
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return GNUNET_SYSERR;
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}
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return GNUNET_OK;
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}
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/* end of exchange_api_common.c */
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