diff options
Diffstat (limited to 'src/lib/merchant_api_pay_abort.c')
| -rw-r--r-- | src/lib/merchant_api_pay_abort.c | 499 |
1 files changed, 499 insertions, 0 deletions
diff --git a/src/lib/merchant_api_pay_abort.c b/src/lib/merchant_api_pay_abort.c new file mode 100644 index 00000000..76163743 --- /dev/null +++ b/src/lib/merchant_api_pay_abort.c @@ -0,0 +1,499 @@ +/* + This file is part of TALER + Copyright (C) 2014, 2015, 2016 GNUnet e.V. and INRIA + + TALER is free software; you can redistribute it and/or modify it under the + terms of the GNU Lesser General Public License as published by the Free Software + Foundation; either version 2.1, or (at your option) any later version. + + TALER is distributed in the hope that it will be useful, but WITHOUT ANY + WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR + A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License along with + TALER; see the file COPYING.LGPL. If not, see + <http://www.gnu.org/licenses/> +*/ +/** + * @file lib/merchant_api_pay.c + * @brief Implementation of the /pay request of the merchant's HTTP API + * @author Christian Grothoff + */ +#include "platform.h" +#include <curl/curl.h> +#include <jansson.h> +#include <microhttpd.h> /* just for HTTP status codes */ +#include <gnunet/gnunet_util_lib.h> +#include <gnunet/gnunet_curl_lib.h> +#include "taler_merchant_service.h" +#include <taler/taler_json_lib.h> +#include <taler/taler_signatures.h> +#include <taler/taler_exchange_service.h> +#include "merchant_api_common.h" + + +/** + * @brief A Pay Handle + */ +struct TALER_MERCHANT_Pay +{ + + /** + * The url for this request. + */ + char *url; + + /** + * JSON encoding of the request to POST. + */ + char *json_enc; + + /** + * Handle for the request. + */ + struct GNUNET_CURL_Job *job; + + /** + * Function to call with the result. + */ + TALER_MERCHANT_PayCallback cb; + + /** + * Closure for @a cb. + */ + void *cb_cls; + + /** + * Reference to the execution context. + */ + struct GNUNET_CURL_Context *ctx; + + /** + * Number of @e coins we are paying with. + */ + unsigned int num_coins; + + /** + * The coins we are paying with. + */ + struct TALER_MERCHANT_PaidCoin *coins; + +}; + + +/** + * We got a 403 response back from the exchange (or the merchant). + * Now we need to check the provided cryptographic proof that the + * coin was actually already spent! + * + * @param pc handle of the original coin we paid with + * @param json cryptographic proof of coin's transaction history as + * was returned by the exchange/merchant + * @return #GNUNET_OK if proof checks out + */ +static int +check_coin_history (const struct TALER_MERCHANT_PaidCoin *pc, + json_t *json) +{ + struct TALER_Amount spent; + struct TALER_Amount spent_plus_contrib; + + if (GNUNET_OK != + TALER_EXCHANGE_verify_coin_history (pc->amount_with_fee.currency, + &pc->coin_pub, + json, + &spent)) + { + /* Exchange's history fails to verify */ + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + if (GNUNET_OK != + TALER_amount_add (&spent_plus_contrib, + &spent, + &pc->amount_with_fee)) + { + /* We got an integer overflow? Bad application! */ + GNUNET_break (0); + return GNUNET_SYSERR; + } + if (-1 != TALER_amount_cmp (&pc->denom_value, + &spent_plus_contrib)) + { + /* according to our calculations, the transaction should + have still worked, exchange error! */ + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + GNUNET_log (GNUNET_ERROR_TYPE_INFO, + "Accepting proof of double-spending\n"); + return GNUNET_OK; +} + + +/** + * We got a 403 response back from the exchange (or the merchant). + * Now we need to check the provided cryptographic proof that the + * coin was actually already spent! + * + * @param ph handle of the original pay operation + * @param json cryptographic proof returned by the exchange/merchant + * @return #GNUNET_OK if proof checks out + */ +static int +check_forbidden (struct TALER_MERCHANT_Pay *ph, + const json_t *json) +{ + json_t *history; + struct TALER_CoinSpendPublicKeyP coin_pub; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_json ("history", &history), + GNUNET_JSON_spec_fixed_auto ("coin_pub", &coin_pub), + GNUNET_JSON_spec_end() + }; + int ret; + + if (GNUNET_OK != + GNUNET_JSON_parse (json, + spec, + NULL, NULL)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + for (unsigned int i=0;i<ph->num_coins;i++) + { + if (0 == memcmp (&ph->coins[i].coin_pub, + &coin_pub, + sizeof (struct TALER_CoinSpendPublicKeyP))) + { + ret = check_coin_history (&ph->coins[i], + history); + GNUNET_JSON_parse_free (spec); + return ret; + } + } + GNUNET_break_op (0); /* complaint is not about any of the coins + that we actually paid with... */ + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; +} + + +/** + * Function called when we're done processing the + * HTTP /pay request. + * + * @param cls the `struct TALER_MERCHANT_Pay` + * @param response_code HTTP response code, 0 on error + * @param json response body, NULL if not in JSON + */ +static void +handle_pay_finished (void *cls, + long response_code, + const json_t *json) +{ + struct TALER_MERCHANT_Pay *ph = cls; + + ph->job = NULL; + switch (response_code) + { + case 0: + break; + case MHD_HTTP_OK: + break; + case MHD_HTTP_BAD_REQUEST: + /* This should never happen, either us or the merchant is buggy + (or API version conflict); just pass JSON reply to the application */ + break; + case MHD_HTTP_FORBIDDEN: + if (GNUNET_OK != check_forbidden (ph, + json)) + { + GNUNET_break_op (0); + response_code = 0; + } + break; + case MHD_HTTP_UNAUTHORIZED: + /* Nothing really to verify, merchant says one of the signatures is + invalid; as we checked them, this should never happen, we + should pass the JSON reply to the application */ + break; + case MHD_HTTP_NOT_FOUND: + /* Nothing really to verify, this should never + happen, we should pass the JSON reply to the application */ + break; + case MHD_HTTP_INTERNAL_SERVER_ERROR: + /* Server had an internal issue; we should retry, but this API + leaves this to the application */ + break; + default: + /* unexpected response code */ + GNUNET_log (GNUNET_ERROR_TYPE_ERROR, + "Unexpected response code %u\n", + (unsigned int) response_code); + GNUNET_break (0); + response_code = 0; + break; + } + GNUNET_log (GNUNET_ERROR_TYPE_INFO, + "/pay completed with response code %u\n", + (unsigned int) response_code); + ph->cb (ph->cb_cls, + response_code, + TALER_JSON_get_error_code (json), + json); + TALER_MERCHANT_pay_cancel (ph); +} + + +/** + * Pay a merchant. API for wallets that have the coin's private keys. + * _NOTE_: this function does NOT calculate each coin amount in order + * to match the contract total price. This calculation is to be made + * by the logic using this library. + * + * @param ctx the execution loop context + * @param merchant_uri base URI of the merchant's backend + * @param instance which merchant instance will receive this payment + * @param h_contract_terms hashcode of the proposal being paid + * @param amount total value of the contract to be paid to the merchant + * @param max_fee maximum fee covered by the merchant (according to the contract) + * @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests) + * @param merchant_sig signature from the merchant over the original contract + * @param timestamp timestamp when the contract was finalized, must match approximately the current time of the merchant + * @param refund_deadline date until which the merchant can issue a refund to the customer via the merchant (can be zero if refunds are not allowed) + * @param pay_deadline maximum time limit to pay for this contract + * @param h_wire hash of the merchant’s account details + * @param order_id order id of the proposal being paid + * @param num_coins number of coins used to pay + * @param coins array of coins we use to pay + * @param pay_cb the callback to call when a reply for this request is available + * @param pay_cb_cls closure for @a pay_cb + * @return a handle for this request + */ +struct TALER_MERCHANT_Pay * +TALER_MERCHANT_pay_wallet (struct GNUNET_CURL_Context *ctx, + const char *merchant_uri, + const char *instance, + const struct GNUNET_HashCode *h_contract_terms, + const struct TALER_Amount *amount, + const struct TALER_Amount *max_fee, + const struct TALER_MerchantPublicKeyP *merchant_pub, + const struct TALER_MerchantSignatureP *merchant_sig, + struct GNUNET_TIME_Absolute timestamp, + struct GNUNET_TIME_Absolute refund_deadline, + struct GNUNET_TIME_Absolute pay_deadline, + const struct GNUNET_HashCode *h_wire, + const char *order_id, + unsigned int num_coins, + const struct TALER_MERCHANT_PayCoin *coins, + TALER_MERCHANT_PayCallback pay_cb, + void *pay_cb_cls) +{ + struct TALER_DepositRequestPS dr; + struct TALER_MERCHANT_PaidCoin pc[num_coins]; + struct TALER_MERCHANT_Pay *ph; + json_t *pay_obj; + json_t *j_coins; + CURL *eh; + struct TALER_Amount total_fee; + struct TALER_Amount total_amount; + + (void) GNUNET_TIME_round_abs (×tamp); + (void) GNUNET_TIME_round_abs (&pay_deadline); + (void) GNUNET_TIME_round_abs (&refund_deadline); + + if (GNUNET_YES != + TALER_amount_cmp_currency (amount, + max_fee)) + { + GNUNET_break (0); + return NULL; + } + + dr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_DEPOSIT); + dr.purpose.size = htonl (sizeof (struct TALER_DepositRequestPS)); + dr.h_contract_terms = *h_contract_terms; + dr.h_wire = *h_wire; + dr.timestamp = GNUNET_TIME_absolute_hton (timestamp); + dr.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline); + dr.merchant = *merchant_pub; + for (unsigned int i=0;i<num_coins;i++) + { + const struct TALER_MERCHANT_PayCoin *coin = &coins[i]; + struct TALER_MERCHANT_PaidCoin *p = &pc[i]; + struct TALER_Amount fee; + + /* prepare 'dr' for this coin to generate coin signature */ + GNUNET_CRYPTO_eddsa_key_get_public (&coin->coin_priv.eddsa_priv, + &dr.coin_pub.eddsa_pub); + TALER_amount_hton (&dr.amount_with_fee, + &coin->amount_with_fee); + if (GNUNET_SYSERR == + TALER_amount_subtract (&fee, + &coin->amount_with_fee, + &coin->amount_without_fee)) + { + /* Integer underflow, fee larger than total amount? + This should not happen (client violated API!) */ + GNUNET_break (0); + return NULL; + } + TALER_amount_hton (&dr.deposit_fee, + &fee); + { + TALER_LOG_DEBUG ("... amount_with_fee was %s\n", + TALER_amount2s (&coin->amount_with_fee)); + TALER_LOG_DEBUG ("... fee was %s\n", + TALER_amount2s (&fee)); + } + + GNUNET_CRYPTO_eddsa_sign (&coin->coin_priv.eddsa_priv, + &dr.purpose, + &p->coin_sig.eddsa_signature); + p->denom_pub = coin->denom_pub; + p->denom_sig = coin->denom_sig; + p->denom_value = coin->denom_value; + p->coin_pub = dr.coin_pub; + p->amount_with_fee = coin->amount_with_fee; + p->amount_without_fee = coin->amount_without_fee; + p->exchange_url = coin->exchange_url; + } + + j_coins = json_array (); + for (unsigned int i=0;i<num_coins;i++) + { + json_t *j_coin; + const struct TALER_MERCHANT_PaidCoin *pc = &coins[i]; + struct TALER_Amount fee; + + if (GNUNET_SYSERR == + TALER_amount_subtract (&fee, + &pc->amount_with_fee, + &pc->amount_without_fee)) + { + /* Integer underflow, fee larger than total amount? + This should not happen (client violated API!) */ + GNUNET_break (0); + json_decref (j_coins); + return NULL; + } + if (0 == i) + { + total_fee = fee; + total_amount = pc->amount_with_fee; + } + else + { + if ( (GNUNET_OK != + TALER_amount_add (&total_fee, + &total_fee, + &fee)) || + (GNUNET_OK != + TALER_amount_add (&total_amount, + &total_amount, + &pc->amount_with_fee)) ) + { + /* integer overflow */ + GNUNET_break (0); + json_decref (j_coins); + return NULL; + } + } + + /* create JSON for this coin */ + j_coin = json_pack ("{s:o, s:o," /* contribution/coin_pub */ + " s:s, s:o," /* exchange_url / denom_pub */ + " s:o, s:o}", /* ub_sig / coin_sig */ + "contribution", TALER_JSON_from_amount (&pc->amount_with_fee), + "coin_pub", GNUNET_JSON_from_data_auto (&pc->coin_pub), + "exchange_url", pc->exchange_url, + "denom_pub", GNUNET_JSON_from_rsa_public_key (pc->denom_pub.rsa_public_key), + "ub_sig", GNUNET_JSON_from_rsa_signature (pc->denom_sig.rsa_signature), + "coin_sig", GNUNET_JSON_from_data_auto (&pc->coin_sig) + ); + if (0 != + json_array_append_new (j_coins, + j_coin)) + { + GNUNET_break (0); + json_decref (j_coins); + return NULL; + } + } + + pay_obj = json_pack ("{" + " s:o," /* coins */ + " s:s," /* order_id */ + " s:o," /* merchant_pub */ + "}", + "coins", j_coins, + "order_id", order_id, + "merchant_pub", GNUNET_JSON_from_data_auto (merchant_pub)); + if (NULL == pay_obj) + { + GNUNET_break (0); + return NULL; + } + ph = GNUNET_new (struct TALER_MERCHANT_Pay); + ph->ctx = ctx; + ph->cb = pay_cb; + ph->cb_cls = pay_cb_cls; + ph->url = MAH_path_to_url_ (merchant_uri, + "/pay"); + ph->num_coins = num_coins; + ph->coins = GNUNET_new_array (num_coins, + struct TALER_MERCHANT_PaidCoin); + memcpy (ph->coins, + coins, + num_coins * sizeof (struct TALER_MERCHANT_PaidCoin)); + + eh = curl_easy_init (); + GNUNET_assert (NULL != (ph->json_enc = + json_dumps (pay_obj, + JSON_COMPACT))); + json_decref (pay_obj); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_URL, + ph->url)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_POSTFIELDS, + ph->json_enc)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_POSTFIELDSIZE, + strlen (ph->json_enc))); + ph->job = GNUNET_CURL_job_add (ctx, + eh, + GNUNET_YES, + &handle_pay_finished, + ph); + return ph; +} + + +/** + * Cancel a pay permission request. This function cannot be used + * on a request handle if a response is already served for it. + * + * @param pay the pay permission request handle + */ +void +TALER_MERCHANT_pay_cancel (struct TALER_MERCHANT_Pay *pay) +{ + if (NULL != pay->job) + { + GNUNET_CURL_job_cancel (pay->job); + pay->job = NULL; + } + GNUNET_free (pay->coins); + GNUNET_free (pay->url); + GNUNET_free (pay->json_enc); + GNUNET_free (pay); +} + + +/* end of merchant_api_pay.c */ |