370 lines
11 KiB
C
370 lines
11 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2017 GNUnet e.V. and Inria
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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 exchange-lib/exchange_api_payback.c
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* @brief Implementation of the /payback request of the exchange's HTTP API
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* @author Christian Grothoff
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*/
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#include "platform.h"
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#include <curl/curl.h>
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#include <jansson.h>
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#include <microhttpd.h> /* just for HTTP status codes */
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#include <gnunet/gnunet_util_lib.h>
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#include <gnunet/gnunet_json_lib.h>
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#include <gnunet/gnunet_curl_lib.h>
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#include "taler_json_lib.h"
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#include "taler_exchange_service.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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* @brief A Payback Handle
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*/
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struct TALER_EXCHANGE_PaybackHandle
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{
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/**
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* The connection to exchange this request handle will use
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*/
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struct TALER_EXCHANGE_Handle *exchange;
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/**
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* The url for this request.
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*/
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char *url;
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/**
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* JSON encoding of the request to POST.
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*/
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char *json_enc;
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/**
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* Denomination key of the coin.
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*/
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const struct TALER_EXCHANGE_DenomPublicKey *pk;
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/**
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* Handle for the request.
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*/
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struct GNUNET_CURL_Job *job;
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/**
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* Function to call with the result.
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*/
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TALER_EXCHANGE_PaybackResultCallback cb;
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/**
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* Closure for @a cb.
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*/
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void *cb_cls;
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/**
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* Public key of the coin we are trying to get paid back.
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*/
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struct TALER_CoinSpendPublicKeyP coin_pub;
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};
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/**
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* Verify that the signature on the "200 OK" response
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* from the exchange is valid. If it is, call the
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* callback.
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*
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* @param ph payback handle
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* @param json json reply with the signature
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* @return #GNUNET_OK if the signature is valid and we called the callback;
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* #GNUNET_SYSERR if not (callback must still be called)
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*/
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static int
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verify_payback_signature_ok (const struct TALER_EXCHANGE_PaybackHandle *ph,
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const json_t *json)
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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 TALER_Amount amount;
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struct GNUNET_TIME_Absolute timestamp;
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const struct TALER_EXCHANGE_Keys *key_state;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
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GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
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TALER_JSON_spec_amount ("amount", &amount),
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GNUNET_JSON_spec_absolute_time ("timestamp", ×tamp),
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GNUNET_JSON_spec_fixed_auto ("reserve_pub", &pc.reserve_pub),
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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 (json,
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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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key_state = TALER_EXCHANGE_get_keys (ph->exchange);
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if (GNUNET_OK !=
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TALER_EXCHANGE_test_signing_key (key_state,
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&exchange_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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pc.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_PAYBACK);
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pc.purpose.size = htonl (sizeof (pc));
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pc.timestamp = GNUNET_TIME_absolute_hton (timestamp);
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TALER_amount_hton (&pc.payback_amount,
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&amount);
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pc.coin_pub = ph->coin_pub;
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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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ph->cb (ph->cb_cls,
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MHD_HTTP_OK,
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TALER_EC_NONE,
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&amount,
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timestamp,
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&pc.reserve_pub,
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json);
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return GNUNET_OK;
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}
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/**
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* Function called when we're done processing the
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* HTTP /payback request.
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*
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* @param cls the `struct TALER_EXCHANGE_PaybackHandle`
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* @param response_code HTTP response code, 0 on error
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* @param json parsed JSON result, NULL on error
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*/
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static void
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handle_payback_finished (void *cls,
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long response_code,
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const json_t *json)
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{
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struct TALER_EXCHANGE_PaybackHandle *ph = cls;
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ph->job = NULL;
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switch (response_code)
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{
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case 0:
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break;
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case MHD_HTTP_OK:
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if (GNUNET_OK !=
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verify_payback_signature_ok (ph,
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json))
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{
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GNUNET_break_op (0);
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response_code = 0;
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}
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TALER_EXCHANGE_payback_cancel (ph);
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return;
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case MHD_HTTP_BAD_REQUEST:
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/* This should never happen, either us or the exchange is buggy
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(or API version conflict); just pass JSON reply to the application */
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break;
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case MHD_HTTP_FORBIDDEN:
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{
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/* Insufficient funds, proof attached */
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json_t *history;
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struct TALER_Amount total;
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const struct TALER_EXCHANGE_DenomPublicKey *dki;
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dki = ph->pk;
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history = json_object_get (json,
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"history");
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if (GNUNET_OK !=
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TALER_EXCHANGE_verify_coin_history (dki->fee_deposit.currency,
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&ph->coin_pub,
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history,
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&total))
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{
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GNUNET_break_op (0);
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response_code = 0;
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}
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ph->cb (ph->cb_cls,
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response_code,
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TALER_JSON_get_error_code (json),
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&total,
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GNUNET_TIME_UNIT_FOREVER_ABS,
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NULL,
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json);
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TALER_EXCHANGE_payback_cancel (ph);
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return;
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}
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case MHD_HTTP_UNAUTHORIZED:
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/* Nothing really to verify, exchange says one of the signatures is
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invalid; as we checked them, this should never happen, we
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should pass the JSON reply to the application */
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break;
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case MHD_HTTP_NOT_FOUND:
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/* Nothing really to verify, this should never
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happen, we should pass the JSON reply to the application */
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break;
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case MHD_HTTP_GONE:
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/* Kind of normal: the money was already sent to the merchant
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(it was too late for the refund). */
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break;
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case MHD_HTTP_INTERNAL_SERVER_ERROR:
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/* Server had an internal issue; we should retry, but this API
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leaves this to the application */
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break;
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default:
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/* unexpected response code */
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GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
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"Unexpected response code %u\n",
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(unsigned int) response_code);
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GNUNET_break (0);
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response_code = 0;
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break;
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}
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ph->cb (ph->cb_cls,
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response_code,
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TALER_JSON_get_error_code (json),
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NULL,
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GNUNET_TIME_UNIT_FOREVER_ABS,
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NULL,
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json);
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TALER_EXCHANGE_payback_cancel (ph);
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}
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/**
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* Ask the exchange to pay back a coin due to the exchange triggering
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* the emergency payback protocol for a given denomination. The value
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* of the coin will be refunded to the original customer (without fees).
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*
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* @param exchange the exchange handle; the exchange must be ready to operate
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* @param pk kind of coin to pay back
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* @param denom_sig signature over the coin by the exchange using @a pk
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* @param coin_priv the coin's private key,
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* @param blinding_key where to fetch the coin's blinding key
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* @param payback_cb the callback to call when the final result for this request is available
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* @param payback_cb_cls closure for @a payback_cb
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* @return NULL
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* if the inputs are invalid (i.e. denomination key not with this exchange).
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* In this case, the callback is not called.
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*/
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struct TALER_EXCHANGE_PaybackHandle *
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TALER_EXCHANGE_payback (struct TALER_EXCHANGE_Handle *exchange,
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const struct TALER_EXCHANGE_DenomPublicKey *pk,
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const struct TALER_DenominationSignature *denom_sig,
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const struct TALER_CoinSpendPrivateKeyP *coin_priv,
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const struct TALER_DenominationBlindingKeyP *blinding_key,
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TALER_EXCHANGE_PaybackResultCallback payback_cb,
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void *payback_cb_cls)
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{
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struct TALER_EXCHANGE_PaybackHandle *ph;
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struct GNUNET_CURL_Context *ctx;
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struct TALER_PaybackRequestPS pr;
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struct TALER_CoinSpendSignatureP coin_sig;
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json_t *payback_obj;
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CURL *eh;
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GNUNET_assert (GNUNET_YES ==
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MAH_handle_is_ready (exchange));
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pr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_PAYBACK);
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pr.purpose.size = htonl (sizeof (struct TALER_PaybackRequestPS));
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GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
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&pr.coin_pub.eddsa_pub);
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pr.h_denom_pub = pk->h_key;
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pr.coin_blind = *blinding_key;
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GNUNET_assert (GNUNET_OK ==
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GNUNET_CRYPTO_eddsa_sign (&coin_priv->eddsa_priv,
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&pr.purpose,
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&coin_sig.eddsa_signature));
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payback_obj = json_pack ("{s:o, s:o," /* denom pub/sig */
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" s:o, s:o," /* coin pub/sig */
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" s:o}", /* coin_bks */
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"denom_pub", GNUNET_JSON_from_rsa_public_key (pk->key.rsa_public_key),
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"denom_sig", GNUNET_JSON_from_rsa_signature (denom_sig->rsa_signature),
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"coin_pub", GNUNET_JSON_from_data_auto (&pr.coin_pub),
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"coin_sig", GNUNET_JSON_from_data_auto (&coin_sig),
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"coin_blind_key_secret", GNUNET_JSON_from_data_auto (blinding_key)
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);
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GNUNET_assert (NULL != payback_obj);
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ph = GNUNET_new (struct TALER_EXCHANGE_PaybackHandle);
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ph->coin_pub = pr.coin_pub;
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ph->exchange = exchange;
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ph->pk = pk;
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ph->cb = payback_cb;
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ph->cb_cls = payback_cb_cls;
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ph->url = MAH_path_to_url (exchange, "/payback");
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eh = curl_easy_init ();
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GNUNET_assert (NULL != (ph->json_enc =
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json_dumps (payback_obj,
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JSON_COMPACT)));
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json_decref (payback_obj);
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GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
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"URL for payback: `%s'\n",
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ph->url);
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GNUNET_assert (CURLE_OK ==
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curl_easy_setopt (eh,
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CURLOPT_URL,
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ph->url));
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GNUNET_assert (CURLE_OK ==
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curl_easy_setopt (eh,
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CURLOPT_POSTFIELDS,
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ph->json_enc));
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GNUNET_assert (CURLE_OK ==
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curl_easy_setopt (eh,
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CURLOPT_POSTFIELDSIZE,
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strlen (ph->json_enc)));
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ctx = MAH_handle_to_context (exchange);
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ph->job = GNUNET_CURL_job_add (ctx,
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eh,
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GNUNET_YES,
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&handle_payback_finished,
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ph);
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return ph;
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}
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/**
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* Cancel a payback request. This function cannot be used on a
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* request handle if the callback was already invoked.
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*
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* @param ph the payback handle
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*/
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void
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TALER_EXCHANGE_payback_cancel (struct TALER_EXCHANGE_PaybackHandle *ph)
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{
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if (NULL != ph->job)
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{
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GNUNET_CURL_job_cancel (ph->job);
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ph->job = NULL;
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}
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GNUNET_free (ph->url);
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GNUNET_free (ph->json_enc);
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GNUNET_free (ph);
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}
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/* end of exchange_api_payback.c */
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