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-rw-r--r--src/lib/exchange_api_recoup.c423
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diff --git a/src/lib/exchange_api_recoup.c b/src/lib/exchange_api_recoup.c
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+/*
+ This file is part of TALER
+ Copyright (C) 2017 GNUnet e.V. and Inria
+
+ 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_recoup.c
+ * @brief Implementation of the /recoup request of the exchange's HTTP API
+ * @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_json_lib.h"
+#include "taler_exchange_service.h"
+#include "exchange_api_handle.h"
+#include "taler_signatures.h"
+#include "exchange_api_curl_defaults.h"
+
+
+/**
+ * @brief A Recoup Handle
+ */
+struct TALER_EXCHANGE_RecoupHandle
+{
+
+ /**
+ * The connection to exchange this request handle will use
+ */
+ struct TALER_EXCHANGE_Handle *exchange;
+
+ /**
+ * The url for this request.
+ */
+ char *url;
+
+ /**
+ * Context for #TEH_curl_easy_post(). Keeps the data that must
+ * persist for Curl to make the upload.
+ */
+ struct TALER_CURL_PostContext ctx;
+
+ /**
+ * Denomination key of the coin.
+ */
+ struct TALER_EXCHANGE_DenomPublicKey pk;
+
+ /**
+ * Handle for the request.
+ */
+ struct GNUNET_CURL_Job *job;
+
+ /**
+ * Function to call with the result.
+ */
+ TALER_EXCHANGE_RecoupResultCallback cb;
+
+ /**
+ * Closure for @a cb.
+ */
+ void *cb_cls;
+
+ /**
+ * Public key of the coin we are trying to get paid back.
+ */
+ struct TALER_CoinSpendPublicKeyP coin_pub;
+
+ /**
+ * #GNUNET_YES if the coin was refreshed
+ */
+ int was_refreshed;
+
+};
+
+
+/**
+ * Verify that the signature on the "200 OK" response
+ * from the exchange is valid. If it is, call the
+ * callback.
+ *
+ * @param ph recoup handle
+ * @param json json reply with the signature
+ * @return #GNUNET_OK if the signature is valid and we called the callback;
+ * #GNUNET_SYSERR if not (callback must still be called)
+ */
+static int
+verify_recoup_signature_ok (const struct TALER_EXCHANGE_RecoupHandle *ph,
+ const json_t *json)
+{
+ struct TALER_RecoupConfirmationPS pc;
+ struct TALER_RecoupRefreshConfirmationPS pr;
+ struct TALER_ExchangePublicKeyP exchange_pub;
+ struct TALER_ExchangeSignatureP exchange_sig;
+ struct TALER_Amount amount;
+ struct GNUNET_TIME_Absolute timestamp;
+ const struct TALER_EXCHANGE_Keys *key_state;
+ struct GNUNET_JSON_Specification spec_withdraw[] = {
+ GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
+ GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
+ TALER_JSON_spec_amount ("amount", &amount),
+ GNUNET_JSON_spec_absolute_time ("timestamp", &timestamp),
+ GNUNET_JSON_spec_fixed_auto ("reserve_pub", &pc.reserve_pub),
+ GNUNET_JSON_spec_end ()
+ };
+ struct GNUNET_JSON_Specification spec_refresh[] = {
+ GNUNET_JSON_spec_fixed_auto ("exchange_sig", &exchange_sig),
+ GNUNET_JSON_spec_fixed_auto ("exchange_pub", &exchange_pub),
+ TALER_JSON_spec_amount ("amount", &amount),
+ GNUNET_JSON_spec_absolute_time ("timestamp", &timestamp),
+ GNUNET_JSON_spec_fixed_auto ("old_coin_pub", &pr.old_coin_pub),
+ GNUNET_JSON_spec_end ()
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_JSON_parse (json,
+ ph->was_refreshed ? spec_refresh : spec_withdraw,
+ NULL, NULL))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ key_state = TALER_EXCHANGE_get_keys (ph->exchange);
+ if (GNUNET_OK !=
+ TALER_EXCHANGE_test_signing_key (key_state,
+ &exchange_pub))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ if (ph->was_refreshed)
+ {
+ pr.purpose.purpose = htonl (
+ TALER_SIGNATURE_EXCHANGE_CONFIRM_RECOUP_REFRESH);
+ pr.purpose.size = htonl (sizeof (pr));
+ pr.timestamp = GNUNET_TIME_absolute_hton (timestamp);
+ TALER_amount_hton (&pr.recoup_amount,
+ &amount);
+ pr.coin_pub = ph->coin_pub;
+ if (GNUNET_OK !=
+ GNUNET_CRYPTO_eddsa_verify (
+ TALER_SIGNATURE_EXCHANGE_CONFIRM_RECOUP_REFRESH,
+ &pr.purpose,
+ &exchange_sig.eddsa_signature,
+ &exchange_pub.eddsa_pub))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ }
+ else
+ {
+ pc.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_RECOUP);
+ pc.purpose.size = htonl (sizeof (pc));
+ pc.timestamp = GNUNET_TIME_absolute_hton (timestamp);
+ TALER_amount_hton (&pc.recoup_amount,
+ &amount);
+ pc.coin_pub = ph->coin_pub;
+ if (GNUNET_OK !=
+ GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_RECOUP,
+ &pc.purpose,
+ &exchange_sig.eddsa_signature,
+ &exchange_pub.eddsa_pub))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ }
+ ph->cb (ph->cb_cls,
+ MHD_HTTP_OK,
+ TALER_EC_NONE,
+ &amount,
+ timestamp,
+ ph->was_refreshed ? NULL : &pc.reserve_pub,
+ ph->was_refreshed ? &pr.old_coin_pub : NULL,
+ json);
+ return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /recoup request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_RecoupHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_recoup_finished (void *cls,
+ long response_code,
+ const void *response)
+{
+ struct TALER_EXCHANGE_RecoupHandle *ph = cls;
+ const json_t *j = response;
+
+ ph->job = NULL;
+ switch (response_code)
+ {
+ case 0:
+ break;
+ case MHD_HTTP_OK:
+ if (GNUNET_OK !=
+ verify_recoup_signature_ok (ph,
+ j))
+ {
+ GNUNET_break_op (0);
+ response_code = 0;
+ break;
+ }
+ TALER_EXCHANGE_recoup_cancel (ph);
+ 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 */
+ break;
+ case MHD_HTTP_CONFLICT:
+ {
+ /* Insufficient funds, proof attached */
+ json_t *history;
+ struct TALER_Amount total;
+ const struct TALER_EXCHANGE_DenomPublicKey *dki;
+
+ dki = &ph->pk;
+ history = json_object_get (j,
+ "history");
+ if (GNUNET_OK !=
+ TALER_EXCHANGE_verify_coin_history (dki,
+ dki->fee_deposit.currency,
+ &ph->coin_pub,
+ history,
+ &total))
+ {
+ GNUNET_break_op (0);
+ response_code = 0;
+ }
+ ph->cb (ph->cb_cls,
+ response_code,
+ TALER_JSON_get_error_code (j),
+ &total,
+ GNUNET_TIME_UNIT_FOREVER_ABS,
+ NULL,
+ NULL,
+ j);
+ TALER_EXCHANGE_recoup_cancel (ph);
+ return;
+ }
+ case MHD_HTTP_FORBIDDEN:
+ /* 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 */
+ break;
+ case MHD_HTTP_NOT_FOUND:
+ /* Nothing really to verify, this should never
+ happen, we should pass the JSON reply to the application */
+ break;
+ case MHD_HTTP_GONE:
+ /* Kind of normal: the money was already sent to the merchant
+ (it was too late for the refund). */
+ break;
+ case MHD_HTTP_INTERNAL_SERVER_ERROR:
+ /* Server had an internal issue; we should retry, but this API
+ leaves this to the application */
+ break;
+ default:
+ /* unexpected response code */
+ GNUNET_log (GNUNET_ERROR_TYPE_ERROR,
+ "Unexpected response code %u\n",
+ (unsigned int) response_code);
+ GNUNET_break (0);
+ response_code = 0;
+ break;
+ }
+ ph->cb (ph->cb_cls,
+ response_code,
+ TALER_JSON_get_error_code (j),
+ NULL,
+ GNUNET_TIME_UNIT_FOREVER_ABS,
+ NULL,
+ NULL,
+ j);
+ TALER_EXCHANGE_recoup_cancel (ph);
+}
+
+
+/**
+ * Ask the exchange to pay back a coin due to the exchange triggering
+ * the emergency recoup protocol for a given denomination. The value
+ * of the coin will be refunded to the original customer (without fees).
+ *
+ * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param pk kind of coin to pay back
+ * @param denom_sig signature over the coin by the exchange using @a pk
+ * @param ps secret internals of the original planchet
+ * @param was_refreshed #GNUNET_YES if the coin in @a ps was refreshed
+ * @param recoup_cb the callback to call when the final result for this request is available
+ * @param recoup_cb_cls closure for @a recoup_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_RecoupHandle *
+TALER_EXCHANGE_recoup (struct TALER_EXCHANGE_Handle *exchange,
+ const struct TALER_EXCHANGE_DenomPublicKey *pk,
+ const struct TALER_DenominationSignature *denom_sig,
+ const struct TALER_PlanchetSecretsP *ps,
+ int was_refreshed,
+ TALER_EXCHANGE_RecoupResultCallback recoup_cb,
+ void *recoup_cb_cls)
+{
+ struct TALER_EXCHANGE_RecoupHandle *ph;
+ struct GNUNET_CURL_Context *ctx;
+ struct TALER_RecoupRequestPS pr;
+ struct TALER_CoinSpendSignatureP coin_sig;
+ struct GNUNET_HashCode h_denom_pub;
+ json_t *recoup_obj;
+ CURL *eh;
+
+ GNUNET_assert (GNUNET_YES ==
+ TEAH_handle_is_ready (exchange));
+ pr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_RECOUP);
+ pr.purpose.size = htonl (sizeof (struct TALER_RecoupRequestPS));
+ GNUNET_CRYPTO_eddsa_key_get_public (&ps->coin_priv.eddsa_priv,
+ &pr.coin_pub.eddsa_pub);
+ GNUNET_CRYPTO_rsa_public_key_hash (pk->key.rsa_public_key,
+ &h_denom_pub);
+ pr.h_denom_pub = pk->h_key;
+ pr.coin_blind = ps->blinding_key;
+ GNUNET_assert (GNUNET_OK ==
+ GNUNET_CRYPTO_eddsa_sign (&ps->coin_priv.eddsa_priv,
+ &pr.purpose,
+ &coin_sig.eddsa_signature));
+
+ recoup_obj = json_pack ("{s:o, s:o," /* denom pub/sig */
+ " s:o, s:o," /* coin pub/sig */
+ " s:o, s:o}", /* coin_bks */
+ "denom_pub_hash", GNUNET_JSON_from_data_auto (
+ &h_denom_pub),
+ "denom_sig", GNUNET_JSON_from_rsa_signature (
+ denom_sig->rsa_signature),
+ "coin_pub", GNUNET_JSON_from_data_auto (
+ &pr.coin_pub),
+ "coin_sig", GNUNET_JSON_from_data_auto (&coin_sig),
+ "coin_blind_key_secret", GNUNET_JSON_from_data_auto (
+ &ps->blinding_key),
+ "refreshed", json_boolean (was_refreshed)
+ );
+ if (NULL == recoup_obj)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+
+ ph = GNUNET_new (struct TALER_EXCHANGE_RecoupHandle);
+ ph->coin_pub = pr.coin_pub;
+ ph->exchange = exchange;
+ ph->pk = *pk;
+ ph->pk.key.rsa_public_key = NULL; /* zero out, as lifetime cannot be warranted */
+ ph->cb = recoup_cb;
+ ph->cb_cls = recoup_cb_cls;
+ ph->url = TEAH_path_to_url (exchange, "/recoup");
+ ph->was_refreshed = was_refreshed;
+ eh = TEL_curl_easy_get (ph->url);
+ if (GNUNET_OK !=
+ TALER_curl_easy_post (&ph->ctx,
+ eh,
+ recoup_obj))
+ {
+ GNUNET_break (0);
+ curl_easy_cleanup (eh);
+ json_decref (recoup_obj);
+ GNUNET_free (ph->url);
+ GNUNET_free (ph);
+ return NULL;
+ }
+ json_decref (recoup_obj);
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "URL for recoup: `%s'\n",
+ ph->url);
+ ctx = TEAH_handle_to_context (exchange);
+ ph->job = GNUNET_CURL_job_add2 (ctx,
+ eh,
+ ph->ctx.headers,
+ &handle_recoup_finished,
+ ph);
+ return ph;
+}
+
+
+/**
+ * Cancel a recoup request. This function cannot be used on a
+ * request handle if the callback was already invoked.
+ *
+ * @param ph the recoup handle
+ */
+void
+TALER_EXCHANGE_recoup_cancel (struct TALER_EXCHANGE_RecoupHandle *ph)
+{
+ if (NULL != ph->job)
+ {
+ GNUNET_CURL_job_cancel (ph->job);
+ ph->job = NULL;
+ }
+ GNUNET_free (ph->url);
+ TALER_curl_easy_post_finished (&ph->ctx);
+ GNUNET_free (ph);
+}
+
+
+/* end of exchange_api_recoup.c */