From 5aebc70da6524d3b27ad4f93a66ba70dbe64fab1 Mon Sep 17 00:00:00 2001 From: Christian Grothoff Date: Wed, 29 Mar 2017 15:45:18 +0200 Subject: implement /payback-functions in libtalerexchange.so (new C file) --- src/exchange-lib/exchange_api_payback.c | 338 ++++++++++++++++++++++++++++++++ 1 file changed, 338 insertions(+) create mode 100644 src/exchange-lib/exchange_api_payback.c (limited to 'src') diff --git a/src/exchange-lib/exchange_api_payback.c b/src/exchange-lib/exchange_api_payback.c new file mode 100644 index 000000000..7546605d1 --- /dev/null +++ b/src/exchange-lib/exchange_api_payback.c @@ -0,0 +1,338 @@ +/* + This file is part of TALER + Copyright (C) 2017 GNUnet e.V. and Inria + + TALER is free software; you can redistribute it and/or modify it under the + terms of the GNU General Public License as published by the Free Software + Foundation; either version 3, 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 General Public License for more details. + + You should have received a copy of the GNU General Public License along with + TALER; see the file COPYING. If not, see + +*/ +/** + * @file exchange-lib/exchange_api_payback.c + * @brief Implementation of the /payback request of the exchange's HTTP API + * @author Christian Grothoff + */ +#include "platform.h" +#include +#include +#include /* just for HTTP status codes */ +#include +#include +#include +#include "taler_json_lib.h" +#include "taler_exchange_service.h" +#include "exchange_api_handle.h" +#include "taler_signatures.h" + + +/** + * @brief A Payback Handle + */ +struct TALER_EXCHANGE_PaybackHandle +{ + + /** + * The connection to exchange this request handle will use + */ + struct TALER_EXCHANGE_Handle *exchange; + + /** + * 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_EXCHANGE_PaybackResultCallback cb; + + /** + * Closure for @a cb. + */ + void *cb_cls; + + /** + * Public key of the coin we are trying to get paid back. + */ + struct TALER_CoinSpendPublicKeyP coin_pub; + +}; + + +/** + * Verify that the signature on the "200 OK" response + * from the exchange is valid. If it is, call the + * callback. + * + * @param ph payback handle + * @param json json reply with the signature + * @return #GNUNET_OK if the signature is valid and we called the callback; + * #GNUNET_SYSERR if not (callback must still be called) + */ +static int +verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph, + const json_t *json) +{ + struct TALER_PaybackConfirmationPS pc; + struct TALER_ExchangePublicKeyP exchange_pub; + struct TALER_ExchangeSignatureP exchange_sig; + struct TALER_Amount amount; + struct GNUNET_TIME_Absolute deadline; + const char *wire_subject; + const struct TALER_EXCHANGE_Keys *key_state; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_fixed_auto ("eddsa_sig", &exchange_sig), + GNUNET_JSON_spec_fixed_auto ("eddsa_pub", &exchange_pub), + TALER_JSON_spec_amount ("amount", &amount), + GNUNET_JSON_spec_absolute_time ("payback_deadline", &deadline), + GNUNET_JSON_spec_string ("wire_subject", &wire_subject), + GNUNET_JSON_spec_end() + }; + + if (GNUNET_OK != + GNUNET_JSON_parse (json, + spec, + NULL, NULL)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + key_state = TALER_EXCHANGE_get_keys (ph->exchange); + if (GNUNET_OK != + TALER_EXCHANGE_test_signing_key (key_state, + &exchange_pub)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + pc.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK); + pc.purpose.size = htonl (sizeof (pc)); + pc.payback_deadline = GNUNET_TIME_absolute_hton (deadline); + TALER_amount_hton (&pc.payback_amount, + &amount); + pc.coin_pub = ph->coin_pub; + GNUNET_CRYPTO_hash (wire_subject, + strlen (wire_subject), + &pc.h_wire_subject); + if (GNUNET_OK != + GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK, + &pc.purpose, + &exchange_sig.eddsa_signature, + &exchange_pub.eddsa_pub)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + ph->cb (ph->cb_cls, + MHD_HTTP_OK, + TALER_EC_NONE, + &amount, + deadline, + wire_subject, + json); + return GNUNET_OK; +} + + +/** + * Function called when we're done processing the + * HTTP /payback request. + * + * @param cls the `struct TALER_EXCHANGE_PaybackHandle` + * @param response_code HTTP response code, 0 on error + * @param json parsed JSON result, NULL on error + */ +static void +handle_payback_finished (void *cls, + long response_code, + const json_t *json) +{ + struct TALER_EXCHANGE_PaybackHandle *ph = cls; + + ph->job = NULL; + switch (response_code) + { + case 0: + break; + case MHD_HTTP_OK: + if (GNUNET_OK != + verify_payback_signature_ok (ph, + json)) + { + GNUNET_break_op (0); + response_code = 0; + } + TALER_EXCHANGE_payback_cancel (ph); + return; + case MHD_HTTP_BAD_REQUEST: + /* This should never happen, either us or the exchange is buggy + (or API version conflict); just pass JSON reply to the application */ + break; + case MHD_HTTP_UNAUTHORIZED: + /* Nothing really to verify, exchange 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_GONE: + /* Kind of normal: the money was already sent to the merchant + (it was too late for the refund). */ + 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; + } + ph->cb (ph->cb_cls, + response_code, + TALER_JSON_get_error_code (json), + NULL, + GNUNET_TIME_UNIT_FOREVER_ABS, + NULL, + json); + TALER_EXCHANGE_payback_cancel (ph); +} + + +/** + * Ask the exchange to pay back a coin due to the exchange triggering + * the emergency payback protocol for a given denomination. The value + * of the coin will be refunded to the original customer (without fees). + * + * @param exchange the exchange handle; the exchange must be ready to operate + * @param pk kind of coin to pay back + * @param denom_sig signature over the coin by the exchange using @a pk + * @param coin_priv the coin's private key, + * @param blinding_key where to fetch the coin's blinding key + * @param payback_cb the callback to call when the final result for this request is available + * @param payback_cb_cls closure for @a payback_cb + * @return NULL + * if the inputs are invalid (i.e. denomination key not with this exchange). + * In this case, the callback is not called. + */ +struct TALER_EXCHANGE_PaybackHandle * +TALER_EXCHANGE_payback (struct TALER_EXCHANGE_Handle *exchange, + const struct TALER_EXCHANGE_DenomPublicKey *pk, + const struct TALER_DenominationSignature *denom_sig, + const struct TALER_CoinSpendPrivateKeyP *coin_priv, + const struct TALER_DenominationBlindingKeyP *blinding_key, + TALER_EXCHANGE_PaybackResultCallback payback_cb, + void *payback_cb_cls) +{ + struct TALER_EXCHANGE_PaybackHandle *ph; + struct GNUNET_CURL_Context *ctx; + struct TALER_PaybackRequestPS pr; + struct TALER_CoinSpendSignatureP coin_sig; + json_t *payback_obj; + CURL *eh; + + GNUNET_assert (GNUNET_YES == + MAH_handle_is_ready (exchange)); + pr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_PAYBACK); + pr.purpose.size = htonl (sizeof (struct TALER_PaybackRequestPS)); + GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv, + &pr.coin_pub.eddsa_pub); + pr.h_denom_pub = pk->h_key; + pr.coin_blind = *blinding_key; + GNUNET_assert (GNUNET_OK == + GNUNET_CRYPTO_eddsa_sign (&coin_priv->eddsa_priv, + &pr.purpose, + &coin_sig.eddsa_signature)); + + payback_obj = json_pack ("{s:o, s:o," /* denom pub/sig */ + " s:o, s:o," /* coin pub/sig */ + " s:o}", /* coin_bks */ + "denom_pub", GNUNET_JSON_from_rsa_public_key (pk->key.rsa_public_key), + "denom_sig", GNUNET_JSON_from_rsa_signature (denom_sig->rsa_signature), + "coin_pub", GNUNET_JSON_from_data_auto (&pr.coin_pub), + "coin_sig", GNUNET_JSON_from_data_auto (&coin_sig), + "coin_blind_key_secret", GNUNET_JSON_from_data_auto (blinding_key) + ); + GNUNET_assert (NULL != payback_obj); + + ph = GNUNET_new (struct TALER_EXCHANGE_PaybackHandle); + ph->coin_pub = pr.coin_pub; + ph->exchange = exchange; + ph->cb = payback_cb; + ph->cb_cls = payback_cb_cls; + ph->url = MAH_path_to_url (exchange, "/payback"); + + eh = curl_easy_init (); + GNUNET_assert (NULL != (ph->json_enc = + json_dumps (payback_obj, + JSON_COMPACT))); + json_decref (payback_obj); + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, + "URL for payback: `%s'\n", + ph->url); + 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))); + ctx = MAH_handle_to_context (exchange); + ph->job = GNUNET_CURL_job_add (ctx, + eh, + GNUNET_YES, + &handle_payback_finished, + ph); + return ph; +} + + +/** + * Cancel a payback request. This function cannot be used on a + * request handle if the callback was already invoked. + * + * @param ph the payback handle + */ +void +TALER_EXCHANGE_payback_cancel (struct TALER_EXCHANGE_PaybackHandle *ph) +{ + if (NULL != ph->job) + { + GNUNET_CURL_job_cancel (ph->job); + ph->job = NULL; + } + GNUNET_free (ph->url); + GNUNET_free (ph->json_enc); + GNUNET_free (ph); +} + + +/* end of exchange_api_payback.c */ -- cgit v1.2.3