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/*
This file is part of TALER
Copyright (C) 2014, 2015, 2016 GNUnet e.V.
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, If not, see
<http://www.gnu.org/licenses/>
*/
/**
* @file exchange-lib/exchange_api_refund.c
* @brief Implementation of the /refund request of the exchange'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_json_lib.h>
#include <gnunet/gnunet_curl_lib.h>
#include "taler_json_lib.h"
#include "taler_exchange_service.h"
#include "exchange_api_common.h"
#include "exchange_api_handle.h"
#include "taler_signatures.h"
/**
* @brief A Refund Handle
*/
struct TALER_EXCHANGE_RefundHandle
{
/**
* 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_RefundResultCallback cb;
/**
* Closure for @a cb.
*/
void *cb_cls;
/**
* Information the exchange should sign in response.
*/
struct TALER_RefundConfirmationPS depconf;
};
/**
* Verify that the signature on the "200 OK" response
* from the exchange is valid.
*
* @param rh refund handle
* @param json json reply with the signature
* @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
*/
static int
verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
const json_t *json)
{
struct TALER_ExchangeSignatureP exchange_sig;
struct TALER_ExchangePublicKeyP exchange_pub;
const struct TALER_EXCHANGE_Keys *key_state;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
GNUNET_JSON_spec_fixed_auto ("pub", &exchange_pub),
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 (rh->exchange);
if (GNUNET_OK !=
TALER_EXCHANGE_test_signing_key (key_state,
&exchange_pub))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
if (GNUNET_OK !=
GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND,
&rh->depconf.purpose,
&exchange_sig.eddsa_signature,
&exchange_pub.eddsa_pub))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
return GNUNET_OK;
}
/**
* Function called when we're done processing the
* HTTP /refund request.
*
* @param cls the `struct TALER_EXCHANGE_RefundHandle`
* @param response_code HTTP response code, 0 on error
* @param json parsed JSON result, NULL on error
*/
static void
handle_refund_finished (void *cls,
long response_code,
const json_t *json)
{
struct TALER_EXCHANGE_RefundHandle *rh = cls;
rh->job = NULL;
switch (response_code)
{
case 0:
break;
case MHD_HTTP_OK:
if (GNUNET_OK !=
verify_refund_signature_ok (rh,
json))
{
GNUNET_break_op (0);
response_code = 0;
}
break;
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_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",
response_code);
GNUNET_break (0);
response_code = 0;
break;
}
rh->cb (rh->cb_cls,
response_code,
json);
TALER_EXCHANGE_refund_cancel (rh);
}
/**
* Submit a refund request to the exchange and get the exchange's
* response. This API is used by a merchant. Note that
* while we return the response verbatim to the caller for further
* processing, we do already verify that the response is well-formed
* (i.e. that signatures included in the response are all valid). If
* the exchange's reply is not well-formed, we return an HTTP status code
* of zero to @a cb.
*
* The @a exchange must be ready to operate (i.e. have
* finished processing the /keys reply). If this check fails, we do
* NOT initiate the transaction with the exchange and instead return NULL.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param amount the amount to be refunded; must be larger than the refund fee
* (as that fee is still being subtracted), and smaller than the amount
* (with deposit fee) of the original deposit contribution of this coin
* @param refund_fee fee applicable to this coin for the refund
* @param h_contract hash of the contact of the merchant with the customer that is being refunded
* @param transaction_id transaction id for the transaction being refunded, must match @a h_contract
* @param coin_pub coin’s public key of the coin from the original deposit operation
* @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
* this is needed as we may first do a partial refund and later a full refund. If both
* refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
* refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
* @param merchant_priv the private key of the merchant, used to generate signature for refund request
* @param cb the callback to call when a reply for this request is available
* @param cb_cls closure for the above callback
* @return a handle for this request; NULL if the inputs are invalid (i.e.
* signatures fail to verify). In this case, the callback is not called.
*/
struct TALER_EXCHANGE_RefundHandle *
TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_Amount *amount,
const struct TALER_Amount *refund_fee,
const struct GNUNET_HashCode *h_contract,
uint64_t transaction_id,
const struct TALER_CoinSpendPublicKeyP *coin_pub,
uint64_t rtransaction_id,
const struct TALER_MerchantPrivateKeyP *merchant_priv,
TALER_EXCHANGE_RefundResultCallback cb,
void *cb_cls)
{
struct TALER_EXCHANGE_RefundHandle *rh;
struct GNUNET_CURL_Context *ctx;
struct TALER_RefundRequestPS rr;
struct TALER_MerchantSignatureP merchant_sig;
json_t *refund_obj;
CURL *eh;
if (GNUNET_YES !=
MAH_handle_is_ready (exchange))
{
GNUNET_break (0);
return NULL;
}
rr.purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_REFUND);
rr.purpose.size = htonl (sizeof (struct TALER_RefundRequestPS));
rr.h_contract = *h_contract;
rr.transaction_id = GNUNET_htonll (transaction_id);
rr.coin_pub = *coin_pub;
GNUNET_CRYPTO_eddsa_key_get_public (&merchant_priv->eddsa_priv,
&rr.merchant.eddsa_pub);
rr.rtransaction_id = GNUNET_htonll (rtransaction_id);
TALER_amount_hton (&rr.refund_amount,
amount);
TALER_amount_hton (&rr.refund_fee,
refund_fee);
GNUNET_assert (GNUNET_OK ==
GNUNET_CRYPTO_eddsa_sign (&merchant_priv->eddsa_priv,
&rr.purpose,
&merchant_sig.eddsa_sig));
refund_obj = json_pack ("{s:o, s:o," /* amount/fee */
" s:o, s:o," /* H_contract, coin_pub */
" s:I, s:I," /* transaction id, rtransaction id */
" s:o, s:o}", /* merchant_pub, merchant_sig */
"amount", TALER_JSON_from_amount (amount),
"fee", TALER_JSON_from_amount (amount),
"H_contract", GNUNET_JSON_from_data (h_contract,
sizeof (struct GNUNET_HashCode)),
"coin_pub", GNUNET_JSON_from_data (coin_pub,
sizeof (*coin_pub)),
"transaction_id", (json_int_t) transaction_id,
"rtransaction_id", (json_int_t) rtransaction_id,
"merchant_pub", GNUNET_JSON_from_data (&rr.merchant,
sizeof (struct TALER_MerchantPublicKeyP)),
"merchant_sig", GNUNET_JSON_from_data (&merchant_sig,
sizeof (merchant_sig))
);
rh = GNUNET_new (struct TALER_EXCHANGE_RefundHandle);
rh->exchange = exchange;
rh->cb = cb;
rh->cb_cls = cb_cls;
rh->url = MAH_path_to_url (exchange, "/refund");
rh->depconf.purpose.size = htonl (sizeof (struct TALER_RefundConfirmationPS));
rh->depconf.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND);
rh->depconf.h_contract = *h_contract;
rh->depconf.transaction_id = GNUNET_htonll (transaction_id);
rh->depconf.coin_pub = *coin_pub;
rh->depconf.merchant = rr.merchant;
rh->depconf.rtransaction_id = GNUNET_htonll (rtransaction_id);
TALER_amount_hton (&rh->depconf.refund_amount,
amount);
TALER_amount_hton (&rh->depconf.refund_fee,
refund_fee);
eh = curl_easy_init ();
GNUNET_assert (NULL != (rh->json_enc =
json_dumps (refund_obj,
JSON_COMPACT)));
json_decref (refund_obj);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"URL for refund: `%s'\n",
rh->url);
GNUNET_assert (CURLE_OK ==
curl_easy_setopt (eh,
CURLOPT_URL,
rh->url));
GNUNET_assert (CURLE_OK ==
curl_easy_setopt (eh,
CURLOPT_POSTFIELDS,
rh->json_enc));
GNUNET_assert (CURLE_OK ==
curl_easy_setopt (eh,
CURLOPT_POSTFIELDSIZE,
strlen (rh->json_enc)));
ctx = MAH_handle_to_context (exchange);
rh->job = GNUNET_CURL_job_add (ctx,
eh,
GNUNET_YES,
&handle_refund_finished,
rh);
return rh;
}
/**
* Cancel a refund permission request. This function cannot be used
* on a request handle if a response is already served for it.
*
* @param refund the refund permission request handle
*/
void
TALER_EXCHANGE_refund_cancel (struct TALER_EXCHANGE_RefundHandle *refund)
{
if (NULL != refund->job)
{
GNUNET_CURL_job_cancel (refund->job);
refund->job = NULL;
}
GNUNET_free (refund->url);
GNUNET_free (refund->json_enc);
GNUNET_free (refund);
}
/* end of exchange_api_refund.c */
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