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-rw-r--r--src/lib/exchange_api_withdraw2.c513
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diff --git a/src/lib/exchange_api_withdraw2.c b/src/lib/exchange_api_withdraw2.c
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+/*
+ This file is part of TALER
+ Copyright (C) 2014-2020 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_withdraw2.c
+ * @brief Implementation of /reserves/$RESERVE_PUB/withdraw requests without blinding/unblinding
+ * @author Christian Grothoff
+ */
+#include "platform.h"
+#include <jansson.h>
+#include <microhttpd.h> /* just for HTTP status codes */
+#include <gnunet/gnunet_util_lib.h>
+#include <gnunet/gnunet_json_lib.h>
+#include <gnunet/gnunet_curl_lib.h>
+#include "taler_exchange_service.h"
+#include "taler_json_lib.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+
+/**
+ * @brief A Withdraw Handle
+ */
+struct TALER_EXCHANGE_Withdraw2Handle
+{
+
+ /**
+ * The connection to exchange this request handle will use
+ */
+ struct TALER_EXCHANGE_Handle *exchange;
+
+ /**
+ * The url for this request.
+ */
+ char *url;
+
+ /**
+ * Handle for the request.
+ */
+ struct GNUNET_CURL_Job *job;
+
+ /**
+ * Function to call with the result.
+ */
+ TALER_EXCHANGE_Withdraw2Callback cb;
+
+ /**
+ * Closure for @a cb.
+ */
+ void *cb_cls;
+
+ /**
+ * Context for #TEH_curl_easy_post(). Keeps the data that must
+ * persist for Curl to make the upload.
+ */
+ struct TALER_CURL_PostContext post_ctx;
+
+ /**
+ * Total amount requested (value plus withdraw fee).
+ */
+ struct TALER_Amount requested_amount;
+
+ /**
+ * Public key of the reserve we are withdrawing from.
+ */
+ struct TALER_ReservePublicKeyP reserve_pub;
+
+};
+
+
+/**
+ * We got a 200 OK response for the /reserves/$RESERVE_PUB/withdraw operation.
+ * Extract the coin's signature and return it to the caller. The signature we
+ * get from the exchange is for the blinded value. Thus, we first must
+ * unblind it and then should verify its validity against our coin's hash.
+ *
+ * If everything checks out, we return the unblinded signature
+ * to the application via the callback.
+ *
+ * @param wh operation handle
+ * @param json reply from the exchange
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
+ */
+static int
+reserve_withdraw_ok (struct TALER_EXCHANGE_Withdraw2Handle *wh,
+ const json_t *json)
+{
+ struct GNUNET_CRYPTO_RsaSignature *blind_sig;
+ struct GNUNET_JSON_Specification spec[] = {
+ GNUNET_JSON_spec_rsa_signature ("ev_sig",
+ &blind_sig),
+ GNUNET_JSON_spec_end ()
+ };
+ struct TALER_EXCHANGE_HttpResponse hr = {
+ .reply = json,
+ .http_status = MHD_HTTP_OK
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_JSON_parse (json,
+ spec,
+ NULL, NULL))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* signature is valid, return it to the application */
+ wh->cb (wh->cb_cls,
+ &hr,
+ blind_sig);
+ /* make sure callback isn't called again after return */
+ wh->cb = NULL;
+ GNUNET_JSON_parse_free (spec);
+ return GNUNET_OK;
+}
+
+
+/**
+ * We got a 409 CONFLICT response for the /reserves/$RESERVE_PUB/withdraw operation.
+ * Check the signatures on the withdraw transactions in the provided
+ * history and that the balances add up. We don't do anything directly
+ * with the information, as the JSON will be returned to the application.
+ * However, our job is ensuring that the exchange followed the protocol, and
+ * this in particular means checking all of the signatures in the history.
+ *
+ * @param wh operation handle
+ * @param json reply from the exchange
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
+ */
+static int
+reserve_withdraw_payment_required (
+ struct TALER_EXCHANGE_Withdraw2Handle *wh,
+ const json_t *json)
+{
+ struct TALER_Amount balance;
+ struct TALER_Amount balance_from_history;
+ json_t *history;
+ size_t len;
+ struct GNUNET_JSON_Specification spec[] = {
+ TALER_JSON_spec_amount ("balance", &balance),
+ GNUNET_JSON_spec_end ()
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_JSON_parse (json,
+ spec,
+ NULL, NULL))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ history = json_object_get (json,
+ "history");
+ if (NULL == history)
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+
+ /* go over transaction history and compute
+ total incoming and outgoing amounts */
+ len = json_array_size (history);
+ {
+ struct TALER_EXCHANGE_ReserveHistory *rhistory;
+
+ /* Use heap allocation as "len" may be very big and thus this may
+ not fit on the stack. Use "GNUNET_malloc_large" as a malicious
+ exchange may theoretically try to crash us by giving a history
+ that does not fit into our memory. */
+ rhistory = GNUNET_malloc_large (sizeof (struct
+ TALER_EXCHANGE_ReserveHistory)
+ * len);
+ if (NULL == rhistory)
+ {
+ GNUNET_break (0);
+ return GNUNET_SYSERR;
+ }
+
+ if (GNUNET_OK !=
+ TALER_EXCHANGE_parse_reserve_history (wh->exchange,
+ history,
+ &wh->reserve_pub,
+ balance.currency,
+ &balance_from_history,
+ len,
+ rhistory))
+ {
+ GNUNET_break_op (0);
+ TALER_EXCHANGE_free_reserve_history (rhistory,
+ len);
+ return GNUNET_SYSERR;
+ }
+ TALER_EXCHANGE_free_reserve_history (rhistory,
+ len);
+ }
+
+ if (0 !=
+ TALER_amount_cmp (&balance_from_history,
+ &balance))
+ {
+ /* exchange cannot add up balances!? */
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ /* Check that funds were really insufficient */
+ if (0 >= TALER_amount_cmp (&wh->requested_amount,
+ &balance))
+ {
+ /* Requested amount is smaller or equal to reported balance,
+ so this should not have failed. */
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /reserves/$RESERVE_PUB/withdraw request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_WithdrawHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_reserve_withdraw_finished (void *cls,
+ long response_code,
+ const void *response)
+{
+ struct TALER_EXCHANGE_Withdraw2Handle *wh = cls;
+ const json_t *j = response;
+ struct TALER_EXCHANGE_HttpResponse hr = {
+ .reply = j,
+ .http_status = (unsigned int) response_code
+ };
+
+ wh->job = NULL;
+ switch (response_code)
+ {
+ case 0:
+ hr.ec = TALER_EC_INVALID_RESPONSE;
+ break;
+ case MHD_HTTP_OK:
+ if (GNUNET_OK !=
+ reserve_withdraw_ok (wh,
+ j))
+ {
+ GNUNET_break_op (0);
+ hr.http_status = 0;
+ hr.ec = TALER_EC_WITHDRAW_REPLY_MALFORMED;
+ break;
+ }
+ GNUNET_assert (NULL == wh->cb);
+ TALER_EXCHANGE_withdraw2_cancel (wh);
+ 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:
+ /* The exchange says that the reserve has insufficient funds;
+ check the signatures in the history... */
+ if (GNUNET_OK !=
+ reserve_withdraw_payment_required (wh,
+ j))
+ {
+ GNUNET_break_op (0);
+ hr.http_status = 0;
+ hr.ec = TALER_EC_WITHDRAW_REPLY_MALFORMED;
+ }
+ else
+ {
+ hr.ec = TALER_JSON_get_error_code (j);
+ hr.hint = TALER_JSON_get_error_hint (j);
+ }
+ break;
+ case MHD_HTTP_FORBIDDEN:
+ GNUNET_break_op (0);
+ /* 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, the exchange basically just says
+ that it doesn't know this reserve. Can happen if we
+ query before the wire transfer went through.
+ We should simply 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_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 */
+ GNUNET_break_op (0);
+ 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\n",
+ (unsigned int) response_code,
+ (int) hr.ec);
+ break;
+ }
+ if (NULL != wh->cb)
+ {
+ wh->cb (wh->cb_cls,
+ &hr,
+ NULL);
+ wh->cb = NULL;
+ }
+ TALER_EXCHANGE_withdraw2_cancel (wh);
+}
+
+
+/**
+ * Withdraw a coin from the exchange using a /reserve/withdraw
+ * request. This API is typically used by a wallet to withdraw a tip
+ * where the reserve's signature was created by the merchant already.
+ *
+ * Note that to ensure that no money is lost in case of hardware
+ * failures, the caller must have committed (most of) the arguments to
+ * disk before calling, and be ready to repeat the request with the
+ * same arguments in case of failures.
+ *
+ * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param pk kind of coin to create
+ * @param reserve_sig signature from the reserve authorizing the withdrawal
+ * @param reserve_pub public key of the reserve to withdraw from
+ * @param ps secrets of the planchet
+ * caller must have committed this value to disk before the call (with @a pk)
+ * @param res_cb the callback to call when the final result for this request is available
+ * @param res_cb_cls closure for @a res_cb
+ * @return NULL
+ * if the inputs are invalid (i.e. denomination key not with this exchange).
+ * In this case, the callback is not called.
+ */
+struct TALER_EXCHANGE_Withdraw2Handle *
+TALER_EXCHANGE_withdraw2 (
+ struct TALER_EXCHANGE_Handle *exchange,
+ const struct TALER_PlanchetDetail *pd,
+ const struct TALER_ReservePrivateKeyP *reserve_priv,
+ TALER_EXCHANGE_Withdraw2Callback res_cb,
+ void *res_cb_cls)
+{
+ struct TALER_EXCHANGE_Withdraw2Handle *wh;
+ const struct TALER_EXCHANGE_Keys *keys;
+ const struct TALER_EXCHANGE_DenomPublicKey *dk;
+ struct TALER_ReserveSignatureP reserve_sig;
+ char arg_str[sizeof (struct TALER_ReservePublicKeyP) * 2 + 32];
+
+ keys = TALER_EXCHANGE_get_keys (exchange);
+ if (NULL == keys)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+ dk = TALER_EXCHANGE_get_denomination_key_by_hash (keys,
+ &pd->denom_pub_hash);
+ if (NULL == dk)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+ wh = GNUNET_new (struct TALER_EXCHANGE_Withdraw2Handle);
+ wh->exchange = exchange;
+ wh->cb = res_cb;
+ wh->cb_cls = res_cb_cls;
+ /* Compute how much we expected to charge to the reserve */
+ if (0 >
+ TALER_amount_add (&wh->requested_amount,
+ &dk->value,
+ &dk->fee_withdraw))
+ {
+ /* Overflow here? Very strange, our CPU must be fried... */
+ GNUNET_break (0);
+ GNUNET_free (wh);
+ return NULL;
+ }
+
+ GNUNET_CRYPTO_eddsa_key_get_public (&reserve_priv->eddsa_priv,
+ &wh->reserve_pub.eddsa_pub);
+
+ {
+ char pub_str[sizeof (struct TALER_ReservePublicKeyP) * 2];
+ char *end;
+
+ end = GNUNET_STRINGS_data_to_string (
+ &wh->reserve_pub,
+ sizeof (struct TALER_ReservePublicKeyP),
+ pub_str,
+ sizeof (pub_str));
+ *end = '\0';
+ GNUNET_snprintf (arg_str,
+ sizeof (arg_str),
+ "/reserves/%s/withdraw",
+ pub_str);
+ }
+ {
+ struct TALER_WithdrawRequestPS req = {
+ .purpose.size = htonl (sizeof (struct TALER_WithdrawRequestPS)),
+ .purpose.purpose = htonl (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW),
+ .reserve_pub = wh->reserve_pub,
+ .h_denomination_pub = pd->denom_pub_hash
+ };
+
+ TALER_amount_hton (&req.amount_with_fee,
+ &wh->requested_amount);
+ TALER_amount_hton (&req.withdraw_fee,
+ &dk->fee_withdraw);
+ GNUNET_CRYPTO_hash (pd->coin_ev,
+ pd->coin_ev_size,
+ &req.h_coin_envelope);
+ GNUNET_CRYPTO_eddsa_sign (&reserve_priv->eddsa_priv,
+ &req,
+ &reserve_sig.eddsa_signature);
+ }
+
+ {
+ json_t *withdraw_obj;
+
+ withdraw_obj = json_pack ("{s:o, s:o, s:o}",
+ "denom_pub_hash",
+ GNUNET_JSON_from_data_auto (&pd->denom_pub_hash),
+ "coin_ev",
+ GNUNET_JSON_from_data (pd->coin_ev,
+ pd->coin_ev_size),
+ "reserve_sig",
+ GNUNET_JSON_from_data_auto (&reserve_sig));
+ if (NULL == withdraw_obj)
+ {
+ GNUNET_break (0);
+ GNUNET_free (wh);
+ return NULL;
+ }
+ GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+ "Attempting to withdraw from reserve %s\n",
+ TALER_B2S (&wh->reserve_pub));
+ wh->url = TEAH_path_to_url (exchange,
+ arg_str);
+ {
+ CURL *eh;
+ struct GNUNET_CURL_Context *ctx;
+
+ ctx = TEAH_handle_to_context (exchange);
+ eh = TALER_EXCHANGE_curl_easy_get_ (wh->url);
+ if ( (NULL == eh) ||
+ (GNUNET_OK !=
+ TALER_curl_easy_post (&wh->post_ctx,
+ eh,
+ withdraw_obj)) )
+ {
+ GNUNET_break (0);
+ if (NULL != eh)
+ curl_easy_cleanup (eh);
+ json_decref (withdraw_obj);
+ GNUNET_free (wh->url);
+ GNUNET_free (wh);
+ return NULL;
+ }
+ json_decref (withdraw_obj);
+ wh->job = GNUNET_CURL_job_add2 (ctx,
+ eh,
+ wh->post_ctx.headers,
+ &handle_reserve_withdraw_finished,
+ wh);
+ }
+ }
+ return wh;
+}
+
+
+/**
+ * Cancel a withdraw status request. This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param wh the withdraw sign request handle
+ */
+void
+TALER_EXCHANGE_withdraw2_cancel (struct TALER_EXCHANGE_Withdraw2Handle *wh)
+{
+ if (NULL != wh->job)
+ {
+ GNUNET_CURL_job_cancel (wh->job);
+ wh->job = NULL;
+ }
+ GNUNET_free (wh->url);
+ TALER_curl_easy_post_finished (&wh->post_ctx);
+ GNUNET_free (wh);
+}