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-rw-r--r--src/lib/exchange_api_csr_withdraw.c281
1 files changed, 281 insertions, 0 deletions
diff --git a/src/lib/exchange_api_csr_withdraw.c b/src/lib/exchange_api_csr_withdraw.c
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+++ b/src/lib/exchange_api_csr_withdraw.c
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+/*
+ This file is part of TALER
+ Copyright (C) 2014-2022 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_csr_withdraw.c
+ * @brief Implementation of /csr-withdraw requests (get R in exchange used for Clause Schnorr withdraw and refresh)
+ * @author Lucien Heuzeveldt
+ * @author Gian Demarmels
+ */
+#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 Clause Schnorr R Handle
+ */
+struct TALER_EXCHANGE_CsRWithdrawHandle
+{
+ /**
+ * Function to call with the result.
+ */
+ TALER_EXCHANGE_CsRWithdrawCallback cb;
+
+ /**
+ * Closure for @a cb.
+ */
+ void *cb_cls;
+
+ /**
+ * The url for this request.
+ */
+ char *url;
+
+ /**
+ * Handle for the request.
+ */
+ struct GNUNET_CURL_Job *job;
+
+ /**
+ * Context for #TEH_curl_easy_post(). Keeps the data that must
+ * persist for Curl to make the upload.
+ */
+ struct TALER_CURL_PostContext post_ctx;
+};
+
+
+/**
+ * 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 csrh operation handle
+ * @param av reply from the exchange
+ * @param hr http response details
+ * @return #GNUNET_OK on success, #GNUNET_SYSERR on errors
+ */
+static enum GNUNET_GenericReturnValue
+csr_ok (struct TALER_EXCHANGE_CsRWithdrawHandle *csrh,
+ const json_t *av,
+ struct TALER_EXCHANGE_HttpResponse *hr)
+{
+ struct TALER_EXCHANGE_CsRWithdrawResponse csrr = {
+ .hr = *hr,
+ };
+ struct GNUNET_JSON_Specification spec[] = {
+ TALER_JSON_spec_exchange_withdraw_values (
+ "ewv",
+ &csrr.details.ok.alg_values),
+ GNUNET_JSON_spec_end ()
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_JSON_parse (av,
+ spec,
+ NULL, NULL))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ csrh->cb (csrh->cb_cls,
+ &csrr);
+ TALER_denom_ewv_free (&csrr.details.ok.alg_values);
+ return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the HTTP /csr request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_CsRWithdrawHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_csr_finished (void *cls,
+ long response_code,
+ const void *response)
+{
+ struct TALER_EXCHANGE_CsRWithdrawHandle *csrh = cls;
+ const json_t *j = response;
+ struct TALER_EXCHANGE_HttpResponse hr = {
+ .reply = j,
+ .http_status = (unsigned int) response_code
+ };
+ struct TALER_EXCHANGE_CsRWithdrawResponse csrr = {
+ .hr = hr
+ };
+
+ csrh->job = NULL;
+ switch (response_code)
+ {
+ case 0:
+ csrr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE;
+ break;
+ case MHD_HTTP_OK:
+ {
+ if (GNUNET_OK !=
+ csr_ok (csrh,
+ response,
+ &hr))
+ {
+ GNUNET_break_op (0);
+ csrr.hr.http_status = 0;
+ csrr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED;
+ break;
+ }
+ }
+ TALER_EXCHANGE_csr_withdraw_cancel (csrh);
+ 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 */
+ csrr.hr.ec = TALER_JSON_get_error_code (j);
+ csrr.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 the /csr endpoint or denomination.
+ Can happen if the exchange doesn't support Clause Schnorr.
+ We should simply pass the JSON reply to the application. */
+ csrr.hr.ec = TALER_JSON_get_error_code (j);
+ csrr.hr.hint = TALER_JSON_get_error_hint (j);
+ break;
+ case MHD_HTTP_GONE:
+ /* could happen if denomination was revoked */
+ /* Note: one might want to check /keys for revocation
+ signature here, alas tricky in case our /keys
+ is outdated => left to clients */
+ csrr.hr.ec = TALER_JSON_get_error_code (j);
+ csrr.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 */
+ csrr.hr.ec = TALER_JSON_get_error_code (j);
+ csrr.hr.hint = TALER_JSON_get_error_hint (j);
+ break;
+ default:
+ /* unexpected response code */
+ GNUNET_break_op (0);
+ csrr.hr.ec = TALER_JSON_get_error_code (j);
+ csrr.hr.hint = TALER_JSON_get_error_hint (j);
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Unexpected response code %u/%d for CS R request\n",
+ (unsigned int) response_code,
+ (int) hr.ec);
+ break;
+ }
+ csrh->cb (csrh->cb_cls,
+ &csrr);
+ csrh->cb = NULL;
+ TALER_EXCHANGE_csr_withdraw_cancel (csrh);
+}
+
+
+struct TALER_EXCHANGE_CsRWithdrawHandle *
+TALER_EXCHANGE_csr_withdraw (
+ struct GNUNET_CURL_Context *curl_ctx,
+ const char *exchange_url,
+ const struct TALER_EXCHANGE_DenomPublicKey *pk,
+ const struct GNUNET_CRYPTO_CsSessionNonce *nonce,
+ TALER_EXCHANGE_CsRWithdrawCallback res_cb,
+ void *res_cb_cls)
+{
+ struct TALER_EXCHANGE_CsRWithdrawHandle *csrh;
+
+ if (GNUNET_CRYPTO_BSA_CS !=
+ pk->key.bsign_pub_key->cipher)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+ csrh = GNUNET_new (struct TALER_EXCHANGE_CsRWithdrawHandle);
+ csrh->cb = res_cb;
+ csrh->cb_cls = res_cb_cls;
+ csrh->url = TALER_url_join (exchange_url,
+ "csr-withdraw",
+ NULL);
+ if (NULL == csrh->url)
+ {
+ GNUNET_free (csrh);
+ return NULL;
+ }
+
+ {
+ CURL *eh;
+ json_t *req;
+
+ req = GNUNET_JSON_PACK (
+ GNUNET_JSON_pack_data_varsize ("nonce",
+ nonce,
+ sizeof(*nonce)),
+ GNUNET_JSON_pack_data_varsize ("denom_pub_hash",
+ &pk->h_key,
+ sizeof(pk->h_key)));
+ GNUNET_assert (NULL != req);
+ eh = TALER_EXCHANGE_curl_easy_get_ (csrh->url);
+ if ( (NULL == eh) ||
+ (GNUNET_OK !=
+ TALER_curl_easy_post (&csrh->post_ctx,
+ eh,
+ req)) )
+ {
+ GNUNET_break (0);
+ if (NULL != eh)
+ curl_easy_cleanup (eh);
+ json_decref (req);
+ GNUNET_free (csrh->url);
+ GNUNET_free (csrh);
+ return NULL;
+ }
+ json_decref (req);
+ csrh->job = GNUNET_CURL_job_add2 (curl_ctx,
+ eh,
+ csrh->post_ctx.headers,
+ &handle_csr_finished,
+ csrh);
+ }
+ return csrh;
+}
+
+
+void
+TALER_EXCHANGE_csr_withdraw_cancel (
+ struct TALER_EXCHANGE_CsRWithdrawHandle *csrh)
+{
+ if (NULL != csrh->job)
+ {
+ GNUNET_CURL_job_cancel (csrh->job);
+ csrh->job = NULL;
+ }
+ GNUNET_free (csrh->url);
+ TALER_curl_easy_post_finished (&csrh->post_ctx);
+ GNUNET_free (csrh);
+}