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Diffstat (limited to 'src/lib/exchange_api_withdraw2.c')
| -rw-r--r-- | src/lib/exchange_api_withdraw2.c | 513 |
1 files changed, 513 insertions, 0 deletions
diff --git a/src/lib/exchange_api_withdraw2.c b/src/lib/exchange_api_withdraw2.c new file mode 100644 index 000000000..f9468927a --- /dev/null +++ b/src/lib/exchange_api_withdraw2.c @@ -0,0 +1,513 @@ +/* + 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); +} |