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/*
This file is part of TALER
Copyright (C) 2017-2022 Taler Systems SA
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
<http://www.gnu.org/licenses/>
*/
/**
* @file lib/exchange_api_recoup.c
* @brief Implementation of the /recoup request of the exchange's HTTP API
* @author Christian Grothoff
*/
#include "platform.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"
#include "exchange_api_curl_defaults.h"
/**
* @brief A Recoup Handle
*/
struct TALER_EXCHANGE_RecoupHandle
{
/**
* The connection to exchange this request handle will use
*/
struct TALER_EXCHANGE_Handle *exchange;
/**
* The url for this request.
*/
char *url;
/**
* Context for #TEH_curl_easy_post(). Keeps the data that must
* persist for Curl to make the upload.
*/
struct TALER_CURL_PostContext ctx;
/**
* Denomination key of the coin.
*/
struct TALER_EXCHANGE_DenomPublicKey pk;
/**
* Our signature requesting the recoup.
*/
struct TALER_CoinSpendSignatureP coin_sig;
/**
* Handle for the request.
*/
struct GNUNET_CURL_Job *job;
/**
* Function to call with the result.
*/
TALER_EXCHANGE_RecoupResultCallback 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;
};
/**
* Parse a recoup response. If it is valid, call the callback.
*
* @param ph recoup 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 enum GNUNET_GenericReturnValue
process_recoup_response (const struct TALER_EXCHANGE_RecoupHandle *ph,
const json_t *json)
{
struct TALER_ReservePublicKeyP reserve_pub;
struct GNUNET_JSON_Specification spec_withdraw[] = {
GNUNET_JSON_spec_fixed_auto ("reserve_pub",
&reserve_pub),
GNUNET_JSON_spec_end ()
};
struct TALER_EXCHANGE_HttpResponse hr = {
.reply = json,
.http_status = MHD_HTTP_OK
};
if (GNUNET_OK !=
GNUNET_JSON_parse (json,
spec_withdraw,
NULL, NULL))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
ph->cb (ph->cb_cls,
&hr,
&reserve_pub);
return GNUNET_OK;
}
/**
* Function called when we're done processing the
* HTTP /recoup request.
*
* @param cls the `struct TALER_EXCHANGE_RecoupHandle`
* @param response_code HTTP response code, 0 on error
* @param response parsed JSON result, NULL on error
*/
static void
handle_recoup_finished (void *cls,
long response_code,
const void *response)
{
struct TALER_EXCHANGE_RecoupHandle *ph = cls;
const json_t *j = response;
struct TALER_EXCHANGE_HttpResponse hr = {
.reply = j,
.http_status = (unsigned int) response_code
};
const struct TALER_EXCHANGE_Keys *keys;
ph->job = NULL;
keys = TALER_EXCHANGE_get_keys (ph->exchange);
switch (response_code)
{
case 0:
hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
break;
case MHD_HTTP_OK:
if (GNUNET_OK !=
process_recoup_response (ph,
j))
{
GNUNET_break_op (0);
hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
hr.http_status = 0;
break;
}
TALER_EXCHANGE_recoup_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 */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
break;
case MHD_HTTP_CONFLICT:
{
struct TALER_Amount min_key;
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
if (GNUNET_OK !=
TALER_EXCHANGE_get_min_denomination_ (keys,
&min_key))
{
GNUNET_break (0);
hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
hr.http_status = 0;
break;
}
if (GNUNET_OK !=
TALER_EXCHANGE_check_coin_conflict_ (
keys,
j,
&ph->pk,
&ph->coin_pub,
&ph->coin_sig,
&min_key))
{
GNUNET_break (0);
hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
hr.http_status = 0;
break;
}
break;
}
case MHD_HTTP_FORBIDDEN:
/* 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 */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
break;
case MHD_HTTP_NOT_FOUND:
/* Nothing really to verify, this should never
happen, we should pass the JSON reply to the application */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
break;
case MHD_HTTP_GONE:
/* Kind of normal: the money was already sent to the merchant
(it was too late for the refund). */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
break;
case MHD_HTTP_INTERNAL_SERVER_ERROR:
/* Server had an internal issue; we should retry, but this API
leaves this to the application */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
break;
default:
/* unexpected response code */
hr.ec = TALER_JSON_get_error_code (j);
hr.hint = TALER_JSON_get_error_hint (j);
GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
"Unexpected response code %u/%d for exchange recoup\n",
(unsigned int) response_code,
(int) hr.ec);
GNUNET_break (0);
break;
}
ph->cb (ph->cb_cls,
&hr,
NULL);
TALER_EXCHANGE_recoup_cancel (ph);
}
struct TALER_EXCHANGE_RecoupHandle *
TALER_EXCHANGE_recoup (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_EXCHANGE_DenomPublicKey *pk,
const struct TALER_DenominationSignature *denom_sig,
const struct TALER_ExchangeWithdrawValues *exchange_vals,
const struct TALER_PlanchetMasterSecretP *ps,
TALER_EXCHANGE_RecoupResultCallback recoup_cb,
void *recoup_cb_cls)
{
struct TALER_EXCHANGE_RecoupHandle *ph;
struct GNUNET_CURL_Context *ctx;
struct TALER_DenominationHashP h_denom_pub;
json_t *recoup_obj;
CURL *eh;
char arg_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2 + 32];
struct TALER_CoinSpendPrivateKeyP coin_priv;
union TALER_DenominationBlindingKeyP bks;
GNUNET_assert (GNUNET_YES ==
TEAH_handle_is_ready (exchange));
ph = GNUNET_new (struct TALER_EXCHANGE_RecoupHandle);
TALER_planchet_setup_coin_priv (ps,
exchange_vals,
&coin_priv);
TALER_planchet_blinding_secret_create (ps,
exchange_vals,
&bks);
GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv.eddsa_priv,
&ph->coin_pub.eddsa_pub);
TALER_denom_pub_hash (&pk->key,
&h_denom_pub);
TALER_wallet_recoup_sign (&h_denom_pub,
&bks,
&coin_priv,
&ph->coin_sig);
recoup_obj = GNUNET_JSON_PACK (
GNUNET_JSON_pack_data_auto ("denom_pub_hash",
&h_denom_pub),
TALER_JSON_pack_denom_sig ("denom_sig",
denom_sig),
TALER_JSON_pack_exchange_withdraw_values ("ewv",
exchange_vals),
GNUNET_JSON_pack_data_auto ("coin_sig",
&ph->coin_sig),
GNUNET_JSON_pack_data_auto ("coin_blind_key_secret",
&bks));
if (TALER_DENOMINATION_CS == denom_sig->cipher)
{
struct TALER_CsNonce nonce;
// FIXME: add this to the spec!
/* NOTE: this is not elegant, and as per the note in TALER_coin_ev_hash()
it is not strictly clear that the nonce is needed. Best case would be
to find a way to include it more 'naturally' somehow, for example with
the variant union version of bks! */
TALER_cs_withdraw_nonce_derive (ps,
&nonce);
GNUNET_assert (
0 ==
json_object_set_new (recoup_obj,
"cs_nonce",
GNUNET_JSON_from_data_auto (
&nonce)));
}
{
char pub_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2];
char *end;
end = GNUNET_STRINGS_data_to_string (
&ph->coin_pub,
sizeof (struct TALER_CoinSpendPublicKeyP),
pub_str,
sizeof (pub_str));
*end = '\0';
GNUNET_snprintf (arg_str,
sizeof (arg_str),
"/coins/%s/recoup",
pub_str);
}
ph->exchange = exchange;
ph->pk = *pk;
memset (&ph->pk.key,
0,
sizeof (ph->pk.key)); /* zero out, as lifetime cannot be warranted */
ph->cb = recoup_cb;
ph->cb_cls = recoup_cb_cls;
ph->url = TEAH_path_to_url (exchange,
arg_str);
if (NULL == ph->url)
{
json_decref (recoup_obj);
GNUNET_free (ph);
return NULL;
}
eh = TALER_EXCHANGE_curl_easy_get_ (ph->url);
if ( (NULL == eh) ||
(GNUNET_OK !=
TALER_curl_easy_post (&ph->ctx,
eh,
recoup_obj)) )
{
GNUNET_break (0);
if (NULL != eh)
curl_easy_cleanup (eh);
json_decref (recoup_obj);
GNUNET_free (ph->url);
GNUNET_free (ph);
return NULL;
}
json_decref (recoup_obj);
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"URL for recoup: `%s'\n",
ph->url);
ctx = TEAH_handle_to_context (exchange);
ph->job = GNUNET_CURL_job_add2 (ctx,
eh,
ph->ctx.headers,
&handle_recoup_finished,
ph);
return ph;
}
void
TALER_EXCHANGE_recoup_cancel (struct TALER_EXCHANGE_RecoupHandle *ph)
{
if (NULL != ph->job)
{
GNUNET_CURL_job_cancel (ph->job);
ph->job = NULL;
}
GNUNET_free (ph->url);
TALER_curl_easy_post_finished (&ph->ctx);
GNUNET_free (ph);
}
/* end of exchange_api_recoup.c */
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