509 lines
15 KiB
C
509 lines
15 KiB
C
/*
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This file is part of TALER
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Copyright (C) 2014-2020 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_withdraw2.c
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* @brief Implementation of /reserves/$RESERVE_PUB/withdraw requests without blinding/unblinding
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* @author Christian Grothoff
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*/
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#include "platform.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_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 Withdraw Handle
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*/
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struct TALER_EXCHANGE_Withdraw2Handle
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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_Withdraw2Callback 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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* Context for #TEH_curl_easy_post(). Keeps the data that must
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* persist for Curl to make the upload.
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*/
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struct TALER_CURL_PostContext post_ctx;
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/**
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* Total amount requested (value plus withdraw fee).
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*/
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struct TALER_Amount requested_amount;
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/**
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* Public key of the reserve we are withdrawing from.
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*/
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struct TALER_ReservePublicKeyP reserve_pub;
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};
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/**
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* We got a 200 OK response for the /reserves/$RESERVE_PUB/withdraw operation.
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* Extract the coin's signature and return it to the caller. The signature we
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* get from the exchange is for the blinded value. Thus, we first must
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* unblind it and then should verify its validity against our coin's hash.
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*
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* If everything checks out, we return the unblinded signature
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* to the application via the callback.
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*
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* @param wh operation handle
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* @param json reply from the exchange
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* @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
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*/
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static int
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reserve_withdraw_ok (struct TALER_EXCHANGE_Withdraw2Handle *wh,
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const json_t *json)
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{
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struct GNUNET_CRYPTO_RsaSignature *blind_sig;
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struct GNUNET_JSON_Specification spec[] = {
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GNUNET_JSON_spec_rsa_signature ("ev_sig",
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&blind_sig),
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GNUNET_JSON_spec_end ()
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};
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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 (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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/* signature is valid, return it to the application */
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wh->cb (wh->cb_cls,
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&hr,
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blind_sig);
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/* make sure callback isn't called again after return */
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wh->cb = NULL;
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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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* We got a 409 CONFLICT response for the /reserves/$RESERVE_PUB/withdraw operation.
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* Check the signatures on the withdraw transactions in the provided
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* history and that the balances add up. We don't do anything directly
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* with the information, as the JSON will be returned to the application.
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* However, our job is ensuring that the exchange followed the protocol, and
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* this in particular means checking all of the signatures in the history.
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*
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* @param wh operation handle
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* @param json reply from the exchange
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* @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
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*/
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static int
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reserve_withdraw_payment_required (
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struct TALER_EXCHANGE_Withdraw2Handle *wh,
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const json_t *json)
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{
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struct TALER_Amount balance;
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struct TALER_Amount balance_from_history;
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json_t *history;
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size_t len;
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struct GNUNET_JSON_Specification spec[] = {
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TALER_JSON_spec_amount ("balance", &balance),
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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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history = json_object_get (json,
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"history");
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if (NULL == history)
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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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/* go over transaction history and compute
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total incoming and outgoing amounts */
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len = json_array_size (history);
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{
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struct TALER_EXCHANGE_ReserveHistory *rhistory;
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/* Use heap allocation as "len" may be very big and thus this may
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not fit on the stack. Use "GNUNET_malloc_large" as a malicious
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exchange may theoretically try to crash us by giving a history
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that does not fit into our memory. */
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rhistory = GNUNET_malloc_large (sizeof (struct
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TALER_EXCHANGE_ReserveHistory)
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* len);
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if (NULL == rhistory)
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{
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GNUNET_break (0);
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return GNUNET_SYSERR;
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}
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if (GNUNET_OK !=
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TALER_EXCHANGE_parse_reserve_history (wh->exchange,
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history,
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&wh->reserve_pub,
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balance.currency,
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&balance_from_history,
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len,
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rhistory))
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{
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GNUNET_break_op (0);
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TALER_EXCHANGE_free_reserve_history (rhistory,
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len);
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return GNUNET_SYSERR;
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}
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TALER_EXCHANGE_free_reserve_history (rhistory,
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len);
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}
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if (0 !=
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TALER_amount_cmp (&balance_from_history,
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&balance))
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{
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/* exchange cannot add up balances!? */
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GNUNET_break_op (0);
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return GNUNET_SYSERR;
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}
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/* Check that funds were really insufficient */
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if (0 >= TALER_amount_cmp (&wh->requested_amount,
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&balance))
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{
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/* Requested amount is smaller or equal to reported balance,
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so this should not have failed. */
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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 /reserves/$RESERVE_PUB/withdraw request.
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*
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* @param cls the `struct TALER_EXCHANGE_WithdrawHandle`
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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_reserve_withdraw_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_Withdraw2Handle *wh = 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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wh->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_GENERIC_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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reserve_withdraw_ok (wh,
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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_GENERIC_REPLY_MALFORMED;
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break;
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}
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GNUNET_assert (NULL == wh->cb);
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TALER_EXCHANGE_withdraw2_cancel (wh);
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return;
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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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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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break;
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case MHD_HTTP_CONFLICT:
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/* The exchange says that the reserve has insufficient funds;
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check the signatures in the history... */
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if (GNUNET_OK !=
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reserve_withdraw_payment_required (wh,
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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_GENERIC_REPLY_MALFORMED;
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}
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else
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{
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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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}
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break;
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case MHD_HTTP_FORBIDDEN:
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GNUNET_break_op (0);
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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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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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break;
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case MHD_HTTP_NOT_FOUND:
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/* Nothing really to verify, the exchange basically just says
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that it doesn't know this reserve. Can happen if we
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query before the wire transfer went through.
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We should simply pass the JSON reply to the application. */
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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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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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hr.ec = TALER_JSON_get_error_code (j);
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hr.hint = TALER_JSON_get_error_hint (j);
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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 != wh->cb)
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{
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wh->cb (wh->cb_cls,
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&hr,
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NULL);
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wh->cb = NULL;
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}
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TALER_EXCHANGE_withdraw2_cancel (wh);
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}
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/**
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* Withdraw a coin from the exchange using a /reserve/withdraw
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* request. This API is typically used by a wallet to withdraw a tip
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* where the reserve's signature was created by the merchant already.
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*
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* Note that to ensure that no money is lost in case of hardware
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* failures, the caller must have committed (most of) the arguments to
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* disk before calling, and be ready to repeat the request with the
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* same arguments in case of failures.
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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 pd planchet details of the planchet to withdraw
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* @param reserve_priv private key of the reserve to withdraw from
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* @param res_cb the callback to call when the final result for this request is available
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* @param res_cb_cls closure for @a res_cb
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* @return NULL
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* if the inputs are invalid (i.e. denomination key not with this exchange).
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* In this case, the callback is not called.
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*/
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struct TALER_EXCHANGE_Withdraw2Handle *
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TALER_EXCHANGE_withdraw2 (
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struct TALER_EXCHANGE_Handle *exchange,
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const struct TALER_PlanchetDetail *pd,
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const struct TALER_ReservePrivateKeyP *reserve_priv,
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TALER_EXCHANGE_Withdraw2Callback res_cb,
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void *res_cb_cls)
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{
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struct TALER_EXCHANGE_Withdraw2Handle *wh;
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const struct TALER_EXCHANGE_Keys *keys;
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const struct TALER_EXCHANGE_DenomPublicKey *dk;
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struct TALER_ReserveSignatureP reserve_sig;
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char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
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keys = TALER_EXCHANGE_get_keys (exchange);
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if (NULL == keys)
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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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dk = TALER_EXCHANGE_get_denomination_key_by_hash (keys,
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&pd->denom_pub_hash);
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if (NULL == dk)
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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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wh = GNUNET_new (struct TALER_EXCHANGE_Withdraw2Handle);
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wh->exchange = exchange;
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wh->cb = res_cb;
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wh->cb_cls = res_cb_cls;
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/* Compute how much we expected to charge to the reserve */
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if (0 >
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TALER_amount_add (&wh->requested_amount,
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&dk->value,
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&dk->fee_withdraw))
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{
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/* Overflow here? Very strange, our CPU must be fried... */
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GNUNET_break (0);
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GNUNET_free (wh);
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return NULL;
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}
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GNUNET_CRYPTO_eddsa_key_get_public (&reserve_priv->eddsa_priv,
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&wh->reserve_pub.eddsa_pub);
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{
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char pub_str[sizeof (struct TALER_ReservePublicKeyP) * 2];
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char *end;
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end = GNUNET_STRINGS_data_to_string (
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&wh->reserve_pub,
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sizeof (struct TALER_ReservePublicKeyP),
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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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"/reserves/%s/withdraw",
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pub_str);
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}
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{
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struct TALER_WithdrawRequestPS req = {
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.purpose.size = htonl (sizeof (struct TALER_WithdrawRequestPS)),
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.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW),
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.reserve_pub = wh->reserve_pub,
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.h_denomination_pub = pd->denom_pub_hash
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};
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TALER_amount_hton (&req.amount_with_fee,
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&wh->requested_amount);
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GNUNET_CRYPTO_hash (pd->coin_ev,
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pd->coin_ev_size,
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&req.h_coin_envelope);
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GNUNET_CRYPTO_eddsa_sign (&reserve_priv->eddsa_priv,
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&req,
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&reserve_sig.eddsa_signature);
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}
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{
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json_t *withdraw_obj;
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withdraw_obj = json_pack ("{s:o, s:o, s:o}",
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"denom_pub_hash",
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GNUNET_JSON_from_data_auto (&pd->denom_pub_hash),
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"coin_ev",
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GNUNET_JSON_from_data (pd->coin_ev,
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pd->coin_ev_size),
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"reserve_sig",
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GNUNET_JSON_from_data_auto (&reserve_sig));
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if (NULL == withdraw_obj)
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{
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GNUNET_break (0);
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GNUNET_free (wh);
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return NULL;
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}
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GNUNET_log (GNUNET_ERROR_TYPE_INFO,
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"Attempting to withdraw from reserve %s\n",
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TALER_B2S (&wh->reserve_pub));
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wh->url = TEAH_path_to_url (exchange,
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arg_str);
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{
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CURL *eh;
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struct GNUNET_CURL_Context *ctx;
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ctx = TEAH_handle_to_context (exchange);
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eh = TALER_EXCHANGE_curl_easy_get_ (wh->url);
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if ( (NULL == eh) ||
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(GNUNET_OK !=
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TALER_curl_easy_post (&wh->post_ctx,
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eh,
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withdraw_obj)) )
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{
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GNUNET_break (0);
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if (NULL != eh)
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curl_easy_cleanup (eh);
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json_decref (withdraw_obj);
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GNUNET_free (wh->url);
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GNUNET_free (wh);
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return NULL;
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}
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json_decref (withdraw_obj);
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wh->job = GNUNET_CURL_job_add2 (ctx,
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eh,
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wh->post_ctx.headers,
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&handle_reserve_withdraw_finished,
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wh);
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}
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}
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return wh;
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}
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/**
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* Cancel a withdraw status 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 wh the withdraw sign request handle
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*/
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void
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TALER_EXCHANGE_withdraw2_cancel (struct TALER_EXCHANGE_Withdraw2Handle *wh)
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{
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if (NULL != wh->job)
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{
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GNUNET_CURL_job_cancel (wh->job);
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wh->job = NULL;
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}
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GNUNET_free (wh->url);
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TALER_curl_easy_post_finished (&wh->post_ctx);
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GNUNET_free (wh);
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}
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