515 lines
15 KiB
C
515 lines
15 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2015-2020 Taler Systems SA
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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 lib/exchange_api_link.c
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* @brief Implementation of the /coins/$COIN_PUB/link request
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* @author Christian Grothoff
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*/
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#include "platform.h"
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#include <microhttpd.h> /* just for HTTP status codes */
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#include <gnunet/gnunet_util_lib.h>
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#include <gnunet/gnunet_curl_lib.h>
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#include "taler_exchange_service.h"
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#include "taler_json_lib.h"
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#include "exchange_api_handle.h"
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#include "taler_signatures.h"
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#include "exchange_api_curl_defaults.h"
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/**
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* @brief A /coins/$COIN_PUB/link Handle
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*/
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struct TALER_EXCHANGE_LinkHandle
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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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* 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_LinkCallback link_cb;
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/**
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* Closure for @e cb.
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*/
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void *link_cb_cls;
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/**
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* Private key of the coin, required to decode link information.
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*/
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struct TALER_CoinSpendPrivateKeyP coin_priv;
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};
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/**
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* Parse the provided linkage data from the "200 OK" response
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* for one of the coins.
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*
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* @param lh link handle
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* @param json json reply with the data for one coin
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* @param coin_num number of the coin to decode
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* @param trans_pub our transfer public key
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* @param[out] coin_priv where to return private coin key
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* @param[out] sig where to return private coin signature
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* @param[out] pub where to return the public key for the coin
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* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
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*/
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static int
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parse_link_coin (const struct TALER_EXCHANGE_LinkHandle *lh,
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const json_t *json,
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unsigned int coin_num,
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const struct TALER_TransferPublicKeyP *trans_pub,
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struct TALER_CoinSpendPrivateKeyP *coin_priv,
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struct TALER_DenominationSignature *sig,
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struct TALER_DenominationPublicKey *pub)
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{
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struct GNUNET_CRYPTO_RsaSignature *bsig;
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struct GNUNET_CRYPTO_RsaPublicKey *rpub;
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struct TALER_CoinSpendSignatureP link_sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_rsa_public_key ("denom_pub", &rpub),
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GNUNET_JSON_spec_rsa_signature ("ev_sig", &bsig),
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GNUNET_JSON_spec_fixed_auto ("link_sig", &link_sig),
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GNUNET_JSON_spec_end ()
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};
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struct TALER_TransferSecretP secret;
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struct TALER_PlanchetSecretsP fc;
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/* parse reply */
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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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TALER_link_recover_transfer_secret (trans_pub,
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&lh->coin_priv,
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&secret);
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TALER_planchet_setup_refresh (&secret,
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coin_num,
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&fc);
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/* extract coin and signature */
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*coin_priv = fc.coin_priv;
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sig->rsa_signature
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= GNUNET_CRYPTO_rsa_unblind (bsig,
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&fc.blinding_key.bks,
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rpub);
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/* verify link_sig */
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{
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struct TALER_PlanchetDetail pd;
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struct GNUNET_HashCode c_hash;
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struct TALER_LinkDataPS ldp = {
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.purpose.size = htonl (sizeof (ldp)),
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.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_LINK),
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.transfer_pub = *trans_pub
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};
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GNUNET_CRYPTO_eddsa_key_get_public (&lh->coin_priv.eddsa_priv,
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&ldp.old_coin_pub.eddsa_pub);
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pub->rsa_public_key = rpub;
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if (GNUNET_OK !=
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TALER_planchet_prepare (pub,
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&fc,
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&c_hash,
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&pd))
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{
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GNUNET_break (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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ldp.h_denom_pub = pd.denom_pub_hash;
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GNUNET_CRYPTO_hash (pd.coin_ev,
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pd.coin_ev_size,
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&ldp.coin_envelope_hash);
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GNUNET_free (pd.coin_ev);
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if (GNUNET_OK !=
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GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_LINK,
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&ldp,
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&link_sig.eddsa_signature,
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&ldp.old_coin_pub.eddsa_pub))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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}
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/* clean up */
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pub->rsa_public_key = GNUNET_CRYPTO_rsa_public_key_dup (rpub);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_OK;
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}
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/**
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* Parse the provided linkage data from the "200 OK" response
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* for one of the coins.
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*
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* @param[in,out] lh link handle (callback may be zero'ed out)
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* @param json json reply with the data for one coin
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* @return #GNUNET_OK on success, #GNUNET_SYSERR on error
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*/
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static int
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parse_link_ok (struct TALER_EXCHANGE_LinkHandle *lh,
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const json_t *json)
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{
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unsigned int session;
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unsigned int num_coins;
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int ret;
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struct TALER_EXCHANGE_HttpResponse hr = {
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.reply = json,
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.http_status = MHD_HTTP_OK
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};
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if (! json_is_array (json))
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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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num_coins = 0;
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/* Theoretically, a coin may have been melted repeatedly
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into different sessions; so the response is an array
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which contains information by melting session. That
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array contains another array. However, our API returns
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a single 1d array, so we flatten the 2d array that is
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returned into a single array. Note that usually a coin
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is melted at most once, and so we'll only run this
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loop once for 'session=0' in most cases.
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num_coins tracks the size of the 1d array we return,
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whilst 'i' and 'session' track the 2d array. *///
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for (session = 0; session<json_array_size (json); session++)
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{
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json_t *jsona;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_json ("new_coins", &jsona),
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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_array_get (json,
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session),
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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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if (! json_is_array (jsona))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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/* count all coins over all sessions */
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num_coins += json_array_size (jsona);
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GNUNET_JSON_parse_free (spec);
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}
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/* Now that we know how big the 1d array is, allocate
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and fill it. */
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{
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unsigned int off_coin; /* index into 1d array */
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unsigned int i;
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struct TALER_CoinSpendPrivateKeyP coin_privs[GNUNET_NZL (num_coins)];
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struct TALER_DenominationSignature sigs[GNUNET_NZL (num_coins)];
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struct TALER_DenominationPublicKey pubs[GNUNET_NZL (num_coins)];
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memset (sigs, 0, sizeof (sigs));
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memset (pubs, 0, sizeof (pubs));
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off_coin = 0;
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for (session = 0; session<json_array_size (json); session++)
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{
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json_t *jsona;
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struct TALER_TransferPublicKeyP trans_pub;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_json ("new_coins",
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&jsona),
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GNUNET_JSON_spec_fixed_auto ("transfer_pub",
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&trans_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_array_get (json,
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session),
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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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if (! json_is_array (jsona))
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{
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GNUNET_break_op (0);
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GNUNET_JSON_parse_free (spec);
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return GNUNET_SYSERR;
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}
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/* decode all coins */
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for (i = 0; i<json_array_size (jsona); i++)
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{
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GNUNET_assert (i + off_coin < num_coins);
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if (GNUNET_OK !=
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parse_link_coin (lh,
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json_array_get (jsona,
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i),
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i,
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&trans_pub,
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&coin_privs[i + off_coin],
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&sigs[i + off_coin],
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&pubs[i + off_coin]))
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{
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GNUNET_break_op (0);
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break;
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}
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}
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/* check if we really got all, then invoke callback */
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off_coin += i;
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if (i != json_array_size (jsona))
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{
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GNUNET_break_op (0);
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ret = GNUNET_SYSERR;
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GNUNET_JSON_parse_free (spec);
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break;
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}
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GNUNET_JSON_parse_free (spec);
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} /* end of for (session) */
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if (off_coin == num_coins)
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{
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lh->link_cb (lh->link_cb_cls,
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&hr,
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num_coins,
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coin_privs,
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sigs,
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pubs);
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lh->link_cb = NULL;
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ret = GNUNET_OK;
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}
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else
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{
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GNUNET_break_op (0);
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ret = GNUNET_SYSERR;
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}
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/* clean up */
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GNUNET_assert (off_coin <= num_coins);
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for (i = 0; i<off_coin; i++)
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{
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if (NULL != sigs[i].rsa_signature)
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GNUNET_CRYPTO_rsa_signature_free (sigs[i].rsa_signature);
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if (NULL != pubs[i].rsa_public_key)
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GNUNET_CRYPTO_rsa_public_key_free (pubs[i].rsa_public_key);
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}
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}
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return ret;
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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 /coins/$COIN_PUB/link request.
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*
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* @param cls the `struct TALER_EXCHANGE_LinkHandle`
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* @param response_code HTTP response code, 0 on error
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* @param response parsed JSON result, NULL on error
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*/
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static void
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handle_link_finished (void *cls,
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long response_code,
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const void *response)
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{
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struct TALER_EXCHANGE_LinkHandle *lh = cls;
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const json_t *j = response;
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struct TALER_EXCHANGE_HttpResponse hr = {
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.reply = j,
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.http_status = (unsigned int) response_code
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};
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lh->job = NULL;
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switch (response_code)
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{
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case 0:
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hr.ec = TALER_EC_INVALID_RESPONSE;
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break;
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case MHD_HTTP_OK:
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if (GNUNET_OK !=
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parse_link_ok (lh,
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j))
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{
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GNUNET_break_op (0);
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hr.http_status = 0;
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hr.ec = TALER_EC_LINK_REPLY_MALFORMED;
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break;
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}
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GNUNET_assert (NULL == lh->link_cb);
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TALER_EXCHANGE_link_cancel (lh);
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return;
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case MHD_HTTP_BAD_REQUEST:
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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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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_NOT_FOUND:
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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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/* Nothing really to verify, exchange says this coin was not melted; 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_INTERNAL_SERVER_ERROR:
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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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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_break_op (0);
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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
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"Unexpected response code %u/%d\n",
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(unsigned int) response_code,
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(int) hr.ec);
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break;
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}
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if (NULL != lh->link_cb)
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lh->link_cb (lh->link_cb_cls,
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&hr,
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0,
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NULL,
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NULL,
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NULL);
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TALER_EXCHANGE_link_cancel (lh);
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}
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/**
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* Submit a link request to the exchange and get the exchange's response.
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*
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* This API is typically not used by anyone, it is more a threat against those
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* trying to receive a funds transfer by abusing the refresh protocol.
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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 coin_priv private key to request link data for
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* @param link_cb the callback to call with the useful result of the
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* refresh operation the @a coin_priv was involved in (if any)
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* @param link_cb_cls closure for @a link_cb
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* @return a handle for this request
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*/
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struct TALER_EXCHANGE_LinkHandle *
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TALER_EXCHANGE_link (struct TALER_EXCHANGE_Handle *exchange,
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const struct TALER_CoinSpendPrivateKeyP *coin_priv,
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TALER_EXCHANGE_LinkCallback link_cb,
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void *link_cb_cls)
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{
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struct TALER_EXCHANGE_LinkHandle *lh;
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CURL *eh;
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struct GNUNET_CURL_Context *ctx;
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struct TALER_CoinSpendPublicKeyP coin_pub;
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char arg_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2 + 32];
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if (GNUNET_YES !=
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TEAH_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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GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv,
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&coin_pub.eddsa_pub);
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{
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char pub_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2];
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char *end;
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end = GNUNET_STRINGS_data_to_string (&coin_pub,
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sizeof (struct
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TALER_CoinSpendPublicKeyP),
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pub_str,
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sizeof (pub_str));
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*end = '\0';
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GNUNET_snprintf (arg_str,
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sizeof (arg_str),
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"/coins/%s/link",
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pub_str);
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}
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lh = GNUNET_new (struct TALER_EXCHANGE_LinkHandle);
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lh->exchange = exchange;
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lh->link_cb = link_cb;
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lh->link_cb_cls = link_cb_cls;
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lh->coin_priv = *coin_priv;
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lh->url = TEAH_path_to_url (exchange,
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arg_str);
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eh = TALER_EXCHANGE_curl_easy_get_ (lh->url);
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if (NULL == eh)
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{
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GNUNET_break (0);
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GNUNET_free (lh->url);
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GNUNET_free (lh);
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return NULL;
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}
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ctx = TEAH_handle_to_context (exchange);
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lh->job = GNUNET_CURL_job_add_with_ct_json (ctx,
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eh,
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&handle_link_finished,
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lh);
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return lh;
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}
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/**
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* Cancel a link request. This function cannot be used
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* on a request handle if the callback was already invoked.
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*
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* @param lh the link handle
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*/
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void
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TALER_EXCHANGE_link_cancel (struct TALER_EXCHANGE_LinkHandle *lh)
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{
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if (NULL != lh->job)
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{
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GNUNET_CURL_job_cancel (lh->job);
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lh->job = NULL;
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}
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GNUNET_free (lh->url);
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GNUNET_free (lh);
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}
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/* end of exchange_api_link.c */
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