sketching out refund API implementation
This commit is contained in:
Christian Grothoff
parent
edd31c7415
commit
77e9e3a7f6
335
src/exchange-lib/exchange_api_refund.c
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335
src/exchange-lib/exchange_api_refund.c
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/*
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This file is part of TALER
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Copyright (C) 2014, 2015, 2016 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_refund.c
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* @brief Implementation of the /refund request of the exchange's HTTP API
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* @author Sree Harsha Totakura <sreeharsha@totakura.in>
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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_common.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 Refund Handle
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*/
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struct TALER_EXCHANGE_RefundHandle
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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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* 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_RefundResultCallback 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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* Information the exchange should sign in response.
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*/
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struct TALER_RefundConfirmationPS depconf;
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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.
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*
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* @param rh refund handle
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* @param json json reply with the signature
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* @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
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*/
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static int
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verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
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const json_t *json)
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{
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struct TALER_ExchangeSignatureP exchange_sig;
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struct TALER_ExchangePublicKeyP exchange_pub;
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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 ("sig", &exchange_sig),
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GNUNET_JSON_spec_fixed_auto ("pub", &exchange_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 (rh->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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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND,
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&rh->depconf.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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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 /refund request.
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*
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* @param cls the `struct TALER_EXCHANGE_RefundHandle`
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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_refund_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_RefundHandle *rh = cls;
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rh->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_refund_signature_ok (rh,
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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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break;
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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_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_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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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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rh->cb (rh->cb_cls,
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response_code,
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json);
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TALER_EXCHANGE_refund_cancel (rh);
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}
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/**
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* Submit a refund request to the exchange and get the exchange's
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* response. This API is used by a merchant. Note that
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* while we return the response verbatim to the caller for further
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* processing, we do already verify that the response is well-formed
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* (i.e. that signatures included in the response are all valid). If
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* the exchange's reply is not well-formed, we return an HTTP status code
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* of zero to @a cb.
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*
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* The @a exchange must be ready to operate (i.e. have
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* finished processing the /keys reply). If this check fails, we do
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* NOT initiate the transaction with the exchange and instead return NULL.
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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 amount the amount to be refunded; must be larger than the refund fee
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* (as that fee is still being subtracted), and smaller than the amount
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* (with deposit fee) of the original deposit contribution of this coin
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* @param refund_fee fee applicable to this coin for the refund
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* @param h_contract hash of the contact of the merchant with the customer that is being refunded
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* @param transaction_id transaction id for the transaction being refunded, must match @a h_contract
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* @param coin_pub coin’s public key of the coin from the original deposit operation
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* @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
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* this is needed as we may first do a partial refund and later a full refund. If both
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* refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
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* refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
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* @param merchant_priv the private key of the merchant, used to generate signature for refund request
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* @param cb the callback to call when a reply for this request is available
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* @param cb_cls closure for the above callback
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* @return a handle for this request; NULL if the inputs are invalid (i.e.
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* signatures fail to verify). In this case, the callback is not called.
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*/
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struct TALER_EXCHANGE_RefundHandle *
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TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
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const struct TALER_Amount *amount,
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const struct TALER_Amount *refund_fee,
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const struct GNUNET_HashCode *h_contract,
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const struct TALER_CoinSpendPublicKeyP *coin_pub,
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uint64_t rtransaction_id,
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const struct TALER_MerchantPrivateKeyP *merchant_priv,
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TALER_EXCHANGE_RefundResultCallback cb,
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void *cb_cls)
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{
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struct TALER_EXCHANGE_RefundHandle *rh;
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struct GNUNET_CURL_Context *ctx;
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struct TALER_MerchantSignatureP merchant_sig;
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struct TALER_MerchantPublicKeyP merchant_pub;
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json_t *refund_obj;
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CURL *eh;
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if (GNUNET_YES !=
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MAH_handle_is_ready (exchange))
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{
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GNUNET_break (0);
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return NULL;
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}
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/* FIXME: create signature! */
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refund_obj = json_pack ("{s:o, s:o," /* amount/fee */
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" s:o, s:o," /* H_contract, coin_pub */
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" s:I, s:I," /* transaction id, rtransaction id */
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" s:o, s:o}", /* merchant_pub, merchant_sig */
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"amount", TALER_JSON_from_amount (amount),
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"fee", TALER_JSON_from_amount (amount),
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"H_contract", GNUNET_JSON_from_data (h_contract,
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sizeof (struct GNUNET_HashCode)),
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"coin_pub", GNUNET_JSON_from_data (coin_pub,
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sizeof (*coin_pub)),
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"transaction_id", (json_int_t) transaction_id,
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"rtransaction_id", (json_int_t) rtransaction_id,
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"merchant_pub", GNUNET_JSON_from_data (&merchant_pub,
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sizeof (merchant_pub)),
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"merchant_sig", GNUNET_JSON_from_data (&merchant_sig,
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sizeof (merchant_sig))
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);
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rh = GNUNET_new (struct TALER_EXCHANGE_RefundHandle);
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rh->exchange = exchange;
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rh->cb = cb;
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rh->cb_cls = cb_cls;
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rh->url = MAH_path_to_url (exchange, "/refund");
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rh->depconf.purpose.size = htonl (sizeof (struct TALER_RefundConfirmationPS));
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rh->depconf.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND);
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rh->depconf.h_contract = *h_contract;
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rh->depconf.transaction_id = GNUNET_htonll (transaction_id);
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rh->depconf.rtransaction_id = GNUNET_htonll (rtransaction_id);
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TALER_amount_hton (&rh->depconf.refund_amount,
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amount);
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TALER_amount_hton (&rh->depconf.refund_fee,
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refund_fee);
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rh->depconf.coin_pub = *coin_pub;
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rh->depconf.merchant = *merchant_pub;
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eh = curl_easy_init ();
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GNUNET_assert (NULL != (rh->json_enc =
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json_dumps (refund_obj,
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JSON_COMPACT)));
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json_decref (refund_obj);
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GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
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"URL for refund: `%s'\n",
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rh->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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rh->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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rh->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 (rh->json_enc)));
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ctx = MAH_handle_to_context (exchange);
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rh->job = GNUNET_CURL_job_add (ctx,
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eh,
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GNUNET_YES,
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&handle_refund_finished,
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rh);
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return rh;
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}
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/**
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* Cancel a refund permission request. This function cannot be used
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* on a request handle if a response is already served for it.
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*
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* @param refund the refund permission request handle
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*/
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void
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TALER_EXCHANGE_refund_cancel (struct TALER_EXCHANGE_RefundHandle *refund)
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{
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if (NULL != refund->job)
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{
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GNUNET_CURL_job_cancel (refund->job);
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refund->job = NULL;
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}
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GNUNET_free (refund->url);
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GNUNET_free (refund->json_enc);
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GNUNET_free (refund);
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}
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/* end of exchange_api_refund.c */
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@ -506,6 +506,7 @@ typedef void
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* @param amount the amount to be refunded; must be larger than the refund fee
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* (as that fee is still being subtracted), and smaller than the amount
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* (with deposit fee) of the original deposit contribution of this coin
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* @param refund_fee fee applicable to this coin for the refund
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* @param h_contract hash of the contact of the merchant with the customer that is being refunded
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* @param transaction_id transaction id for the transaction being refunded, must match @a h_contract
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* @param coin_pub coin’s public key of the coin from the original deposit operation
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@ -522,6 +523,7 @@ typedef void
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struct TALER_EXCHANGE_RefundHandle *
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TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
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const struct TALER_Amount *amount,
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const struct TALER_Amount *refund_fee,
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const struct GNUNET_HashCode *h_contract,
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const struct TALER_CoinSpendPublicKeyP *coin_pub,
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uint64_t rtransaction_id,
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