405 lines
14 KiB
C
405 lines
14 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2015-2017 Taler Systems SA
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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, see
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<http://www.gnu.org/licenses/>
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*/
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/**
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* @file 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 "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 dk fee structure for the coin, NULL to skip verifying fees
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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 struct
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TALER_EXCHANGE_DenomPublicKey *dk,
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const char *currency,
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const struct
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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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struct TALER_Amount rtotal;
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struct TALER_Amount fee;
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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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GNUNET_assert (GNUNET_OK ==
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TALER_amount_get_zero (currency,
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total));
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GNUNET_assert (GNUNET_OK ==
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TALER_amount_get_zero (currency,
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&rtotal));
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for (size_t off = 0; off<len; off++)
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{
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int add;
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json_t *transaction;
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struct TALER_Amount amount;
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const char *type;
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struct GNUNET_JSON_Specification spec_glob[] = {
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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_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_glob,
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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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struct TALER_DepositRequestPS dr;
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struct TALER_CoinSpendSignatureP sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_fixed_auto ("coin_sig",
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&sig),
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GNUNET_JSON_spec_fixed_auto ("h_contract_terms",
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&dr.h_contract_terms),
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GNUNET_JSON_spec_fixed_auto ("h_wire",
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&dr.h_wire),
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GNUNET_JSON_spec_absolute_time_nbo ("timestamp",
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&dr.timestamp),
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GNUNET_JSON_spec_absolute_time_nbo ("refund_deadline",
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&dr.refund_deadline),
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TALER_JSON_spec_amount_nbo ("deposit_fee",
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&dr.deposit_fee),
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GNUNET_JSON_spec_fixed_auto ("merchant_pub",
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&dr.merchant),
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GNUNET_JSON_spec_end ()
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};
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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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dr.purpose.size = htonl (sizeof (dr));
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dr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_DEPOSIT);
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TALER_amount_hton (&dr.amount_with_fee,
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&amount);
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dr.coin_pub = *coin_pub;
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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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return GNUNET_SYSERR;
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}
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if (NULL != dk)
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{
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/* check that deposit fee matches our expectations from /keys! */
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TALER_amount_ntoh (&fee,
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&dr.deposit_fee);
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if ( (GNUNET_YES !=
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TALER_amount_cmp_currency (&fee,
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&dk->fee_deposit)) ||
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(0 !=
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TALER_amount_cmp (&fee,
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&dk->fee_deposit)) )
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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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}
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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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struct TALER_RefreshMeltCoinAffirmationPS rm;
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struct TALER_CoinSpendSignatureP sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_fixed_auto ("coin_sig",
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&sig),
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GNUNET_JSON_spec_fixed_auto ("rc",
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&rm.rc),
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TALER_JSON_spec_amount_nbo ("melt_fee",
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&rm.melt_fee),
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GNUNET_JSON_spec_end ()
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};
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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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rm.purpose.size = htonl (sizeof (rm));
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rm.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_MELT);
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TALER_amount_hton (&rm.amount_with_fee,
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&amount);
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rm.coin_pub = *coin_pub;
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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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return GNUNET_SYSERR;
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}
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if (NULL != dk)
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{
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/* check that melt fee matches our expectations from /keys! */
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TALER_amount_ntoh (&fee,
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&rm.melt_fee);
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if ( (GNUNET_YES !=
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TALER_amount_cmp_currency (&fee,
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&dk->fee_refresh)) ||
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(0 !=
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TALER_amount_cmp (&fee,
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&dk->fee_refresh)) )
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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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}
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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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struct TALER_RefundRequestPS rr;
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struct TALER_MerchantSignatureP sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_fixed_auto ("merchant_sig",
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&sig),
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GNUNET_JSON_spec_fixed_auto ("h_contract_terms",
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&rr.h_contract_terms),
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GNUNET_JSON_spec_fixed_auto ("merchant_pub",
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&rr.merchant),
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GNUNET_JSON_spec_uint64 ("rtransaction_id",
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&rr.rtransaction_id),
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TALER_JSON_spec_amount_nbo ("refund_fee",
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&rr.refund_fee),
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GNUNET_JSON_spec_end ()
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};
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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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rr.purpose.size = htonl (sizeof (rr));
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rr.purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_REFUND);
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rr.coin_pub = *coin_pub;
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TALER_amount_hton (&rr.refund_amount,
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&amount);
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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_sig,
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&rr.merchant.eddsa_pub))
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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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/* NOTE: theoretically, we could also check that the given
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merchant_pub and h_contract_terms 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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/* check that refund fee matches our expectations from /keys! */
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if (NULL != dk)
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{
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TALER_amount_ntoh (&fee,
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&rr.refund_fee);
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if ( (GNUNET_YES !=
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TALER_amount_cmp_currency (&fee,
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&dk->fee_refund)) ||
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(0 !=
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TALER_amount_cmp (&fee,
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&dk->fee_refund)) )
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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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}
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add = GNUNET_NO;
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}
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else if (0 == strcasecmp (type,
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"PAYBACK"))
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{
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struct TALER_PaybackConfirmationPS pc;
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struct TALER_ExchangePublicKeyP exchange_pub;
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struct TALER_ExchangeSignatureP exchange_sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_fixed_auto ("exchange_sig",
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&exchange_sig),
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GNUNET_JSON_spec_fixed_auto ("exchange_pub",
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&exchange_pub),
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GNUNET_JSON_spec_fixed_auto ("reserve_pub",
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&pc.reserve_pub),
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GNUNET_JSON_spec_absolute_time_nbo ("timestamp",
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&pc.timestamp),
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GNUNET_JSON_spec_end ()
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};
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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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pc.purpose.size = htonl (sizeof (pc));
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pc.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK);
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pc.coin_pub = *coin_pub;
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TALER_amount_hton (&pc.payback_amount,
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&amount);
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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK,
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&pc.purpose,
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&exchange_sig.eddsa_signature,
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&exchange_pub.eddsa_pub))
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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_YES;
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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_assert (GNUNET_SYSERR == add);
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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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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" */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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return GNUNET_SYSERR;
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}
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}
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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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/**
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* Obtain meta data about an exchange (online) signing
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* key.
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*
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* @param keys from where to obtain the meta data
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* @param exchange_pub public key to lookup
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* @return NULL on error (@a exchange_pub not known)
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*/
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const struct TALER_EXCHANGE_SigningPublicKey *
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TALER_EXCHANGE_get_exchange_signing_key_info (const struct
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TALER_EXCHANGE_Keys *keys,
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const struct
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TALER_ExchangePublicKeyP *
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exchange_pub)
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{
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for (unsigned int i = 0; i<keys->num_sign_keys; i++)
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{
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const struct TALER_EXCHANGE_SigningPublicKey *spk;
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spk = &keys->sign_keys[i];
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if (0 == GNUNET_memcmp (exchange_pub,
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&spk->key))
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return spk;
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}
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return NULL;
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}
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/* end of exchange_api_common.c */
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