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exchange/src/exchange-lib/exchange_api_refresh_link.c

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/*
This file is part of TALER
Copyright (C) 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, see
<http://www.gnu.org/licenses/>
*/
/**
* @file exchange-lib/exchange_api_refresh_link.c
* @brief Implementation of the /refresh/link request of the exchange's HTTP API
* @author Christian Grothoff
*/
#include "platform.h"
#include <curl/curl.h>
#include <microhttpd.h> /* just for HTTP status codes */
#include <gnunet/gnunet_util_lib.h>
#include <gnunet/gnunet_curl_lib.h>
#include "taler_exchange_service.h"
#include "taler_json_lib.h"
#include "exchange_api_handle.h"
#include "taler_signatures.h"
/**
* @brief A /refresh/link Handle
*/
struct TALER_EXCHANGE_RefreshLinkHandle
{
/**
* The connection to exchange this request handle will use
*/
struct TALER_EXCHANGE_Handle *exchange;
/**
* The url for this request.
*/
char *url;
/**
* Handle for the request.
*/
struct GNUNET_CURL_Job *job;
/**
* Function to call with the result.
*/
TALER_EXCHANGE_RefreshLinkCallback link_cb;
/**
* Closure for @e cb.
*/
void *link_cb_cls;
/**
* Private key of the coin, required to decode link information.
*/
struct TALER_CoinSpendPrivateKeyP coin_priv;
};
/**
* Parse the provided linkage data from the "200 OK" response
* for one of the coins.
*
* @param rlh refresh link handle
* @param json json reply with the data for one coin
* @param coin_num number of the coin to decode
* @param trans_pub our transfer public key
* @param[out] coin_priv where to return private coin key
* @param[out] sig where to return private coin signature
* @param[out] pub where to return the public key for the coin
* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
*/
static int
parse_refresh_link_coin (const struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
const json_t *json,
unsigned int coin_num,
const struct TALER_TransferPublicKeyP *trans_pub,
struct TALER_CoinSpendPrivateKeyP *coin_priv,
struct TALER_DenominationSignature *sig,
struct TALER_DenominationPublicKey *pub)
{
struct GNUNET_CRYPTO_RsaSignature *bsig;
struct GNUNET_CRYPTO_RsaPublicKey *rpub;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_rsa_public_key ("denom_pub", &rpub),
GNUNET_JSON_spec_rsa_signature ("ev_sig", &bsig),
GNUNET_JSON_spec_end()
};
struct TALER_TransferSecretP secret;
struct TALER_FreshCoinP fc;
/* parse reply */
if (GNUNET_OK !=
GNUNET_JSON_parse (json,
spec,
NULL, NULL))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
TALER_link_recover_transfer_secret (trans_pub,
&rlh->coin_priv,
&secret);
TALER_setup_fresh_coin (&secret,
coin_num,
&fc);
/* extract coin and signature */
*coin_priv = fc.coin_priv;
sig->rsa_signature
= GNUNET_CRYPTO_rsa_unblind (bsig,
&fc.blinding_key.bks,
rpub);
/* clean up */
pub->rsa_public_key = GNUNET_CRYPTO_rsa_public_key_dup (rpub);
GNUNET_JSON_parse_free (spec);
return GNUNET_OK;
}
/**
* Parse the provided linkage data from the "200 OK" response
* for one of the coins.
*
* @param[in,out] rlh refresh link handle (callback may be zero'ed out)
* @param json json reply with the data for one coin
* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
*/
static int
parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh,
const json_t *json)
{
unsigned int session;
unsigned int num_coins;
int ret;
if (! json_is_array (json))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
num_coins = 0;
/* Theoretically, a coin may have been melted repeatedly
into different sessions; so the response is an array
which contains information by melting session. That
array contains another array. However, our API returns
a single 1d array, so we flatten the 2d array that is
returned into a single array. Note that usually a coin
is melted at most once, and so we'll only run this
loop once for 'session=0' in most cases.
num_coins tracks the size of the 1d array we return,
whilst 'i' and 'session' track the 2d array. */
for (session=0;session<json_array_size (json); session++)
{
json_t *jsona;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_json ("new_coins", &jsona),
GNUNET_JSON_spec_end()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (json_array_get (json,
session),
spec,
NULL, NULL))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
if (! json_is_array (jsona))
{
GNUNET_break_op (0);
GNUNET_JSON_parse_free (spec);
return GNUNET_SYSERR;
}
/* count all coins over all sessions */
num_coins += json_array_size (jsona);
GNUNET_JSON_parse_free (spec);
}
/* Now that we know how big the 1d array is, allocate
and fill it. */
{
unsigned int off_coin; /* index into 1d array */
unsigned int i;
struct TALER_CoinSpendPrivateKeyP coin_privs[num_coins];
struct TALER_DenominationSignature sigs[num_coins];
struct TALER_DenominationPublicKey pubs[num_coins];
memset (sigs, 0, sizeof (sigs));
memset (pubs, 0, sizeof (pubs));
off_coin = 0;
for (session=0;session<json_array_size (json); session++)
{
json_t *jsona;
struct TALER_TransferPublicKeyP trans_pub;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_json ("new_coins", &jsona),
GNUNET_JSON_spec_fixed_auto ("transfer_pub", &trans_pub),
GNUNET_JSON_spec_end()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (json_array_get (json,
session),
spec,
NULL, NULL))
{
GNUNET_break_op (0);
return GNUNET_SYSERR;
}
if (! json_is_array (jsona))
{
GNUNET_break_op (0);
GNUNET_JSON_parse_free (spec);
return GNUNET_SYSERR;
}
/* decode all coins */
for (i=0;i<json_array_size (jsona);i++)
{
if (GNUNET_OK !=
parse_refresh_link_coin (rlh,
json_array_get (jsona,
i),
i,
&trans_pub,
&coin_privs[i+off_coin],
&sigs[i+off_coin],
&pubs[i+off_coin]))
{
GNUNET_break_op (0);
break;
}
}
/* check if we really got all, then invoke callback */
off_coin += i;
if (i != json_array_size (jsona))
{
GNUNET_break_op (0);
ret = GNUNET_SYSERR;
GNUNET_JSON_parse_free (spec);
break;
}
GNUNET_JSON_parse_free (spec);
} /* end of for (session) */
if (off_coin == num_coins)
{
rlh->link_cb (rlh->link_cb_cls,
MHD_HTTP_OK,
num_coins,
coin_privs,
sigs,
pubs,
json);
rlh->link_cb = NULL;
ret = GNUNET_OK;
}
else
{
GNUNET_break_op (0);
ret = GNUNET_SYSERR;
}
/* clean up */
for (i=0;i<off_coin;i++)
{
if (NULL != sigs[i].rsa_signature)
GNUNET_CRYPTO_rsa_signature_free (sigs[i].rsa_signature);
if (NULL != pubs[i].rsa_public_key)
GNUNET_CRYPTO_rsa_public_key_free (pubs[i].rsa_public_key);
}
}
return ret;
}
/**
* Function called when we're done processing the
* HTTP /refresh/link request.
*
* @param cls the `struct TALER_EXCHANGE_RefreshLinkHandle`
* @param response_code HTTP response code, 0 on error
* @param json parsed JSON result, NULL on error
*/
static void
handle_refresh_link_finished (void *cls,
long response_code,
const json_t *json)
{
struct TALER_EXCHANGE_RefreshLinkHandle *rlh = cls;
rlh->job = NULL;
switch (response_code)
{
case 0:
break;
case MHD_HTTP_OK:
if (GNUNET_OK !=
parse_refresh_link_ok (rlh,
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_NOT_FOUND:
/* Nothing really to verify, exchange says this coin was not melted; 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",
(unsigned int) response_code);
GNUNET_break (0);
response_code = 0;
break;
}
if (NULL != rlh->link_cb)
rlh->link_cb (rlh->link_cb_cls,
response_code,
0, NULL, NULL, NULL,
json);
TALER_EXCHANGE_refresh_link_cancel (rlh);
}
/**
* Submit a link request to the exchange and get the exchange's response.
*
* This API is typically not used by anyone, it is more a threat
* against those trying to receive a funds transfer by abusing the
* /refresh protocol.
*
* @param exchange the exchange handle; the exchange must be ready to operate
* @param coin_priv private key to request link data for
* @param link_cb the callback to call with the useful result of the
* refresh operation the @a coin_priv was involved in (if any)
* @param link_cb_cls closure for @a link_cb
* @return a handle for this request
*/
struct TALER_EXCHANGE_RefreshLinkHandle *
TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange,
const struct TALER_CoinSpendPrivateKeyP *coin_priv,
TALER_EXCHANGE_RefreshLinkCallback link_cb,
void *link_cb_cls)
{
struct TALER_EXCHANGE_RefreshLinkHandle *rlh;
CURL *eh;
struct GNUNET_CURL_Context *ctx;
struct TALER_CoinSpendPublicKeyP coin_pub;
char *pub_str;
char *arg_str;
if (GNUNET_YES !=
MAH_handle_is_ready (exchange))
{
GNUNET_break (0);
return NULL;
}
GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
&coin_pub.eddsa_pub);
pub_str = GNUNET_STRINGS_data_to_string_alloc (&coin_pub,
sizeof (struct TALER_CoinSpendPublicKeyP));
GNUNET_asprintf (&arg_str,
"/refresh/link?coin_pub=%s",
pub_str);
GNUNET_free (pub_str);
rlh = GNUNET_new (struct TALER_EXCHANGE_RefreshLinkHandle);
rlh->exchange = exchange;
rlh->link_cb = link_cb;
rlh->link_cb_cls = link_cb_cls;
rlh->coin_priv = *coin_priv;
rlh->url = MAH_path_to_url (exchange, arg_str);
GNUNET_free (arg_str);
eh = curl_easy_init ();
GNUNET_assert (CURLE_OK ==
curl_easy_setopt (eh,
CURLOPT_URL,
rlh->url));
ctx = MAH_handle_to_context (exchange);
rlh->job = GNUNET_CURL_job_add (ctx,
eh,
GNUNET_YES,
&handle_refresh_link_finished,
rlh);
return rlh;
}
/**
* Cancel a refresh link request. This function cannot be used
* on a request handle if the callback was already invoked.
*
* @param rlh the refresh link handle
*/
void
TALER_EXCHANGE_refresh_link_cancel (struct TALER_EXCHANGE_RefreshLinkHandle *rlh)
{
if (NULL != rlh->job)
{
GNUNET_CURL_job_cancel (rlh->job);
rlh->job = NULL;
}
GNUNET_free (rlh->url);
GNUNET_free (rlh);
}
/* end of exchange_api_refresh_link.c */
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