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-rw-r--r--src/lib/exchange_api_refund.c416
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diff --git a/src/lib/exchange_api_refund.c b/src/lib/exchange_api_refund.c
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+/*
+ This file is part of TALER
+ Copyright (C) 2014, 2015, 2016 GNUnet e.V.
+
+ 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 exchange-lib/exchange_api_refund.c
+ * @brief Implementation of the /refund 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 Refund Handle
+ */
+struct TALER_EXCHANGE_RefundHandle
+{
+
+ /**
+ * The connection to exchange this request handle will use
+ */
+ struct TALER_EXCHANGE_Handle *exchange;
+
+ /**
+ * The url for this request.
+ */
+ char *url;
+
+ /**
+ * JSON encoding of the request to POST.
+ */
+ char *json_enc;
+
+ /**
+ * Handle for the request.
+ */
+ struct GNUNET_CURL_Job *job;
+
+ /**
+ * Function to call with the result.
+ */
+ TALER_EXCHANGE_RefundResultCallback cb;
+
+ /**
+ * Closure for @a cb.
+ */
+ void *cb_cls;
+
+ /**
+ * Information the exchange should sign in response.
+ */
+ struct TALER_RefundConfirmationPS depconf;
+
+};
+
+
+/**
+ * Verify that the signature on the "200 OK" response
+ * from the exchange is valid.
+ *
+ * @param rh refund handle
+ * @param json json reply with the signature
+ * @param[out] exchange_pub set to the exchange's public key
+ * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not
+ */
+static int
+verify_refund_signature_ok (const struct TALER_EXCHANGE_RefundHandle *rh,
+ const json_t *json,
+ struct TALER_ExchangePublicKeyP *exchange_pub)
+{
+ struct TALER_ExchangeSignatureP exchange_sig;
+ const struct TALER_EXCHANGE_Keys *key_state;
+ struct GNUNET_JSON_Specification spec[] = {
+ GNUNET_JSON_spec_fixed_auto ("sig", &exchange_sig),
+ GNUNET_JSON_spec_fixed_auto ("pub", exchange_pub),
+ GNUNET_JSON_spec_end()
+ };
+
+ if (GNUNET_OK !=
+ GNUNET_JSON_parse (json,
+ spec,
+ NULL, NULL))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ key_state = TALER_EXCHANGE_get_keys (rh->exchange);
+ if (GNUNET_OK !=
+ TALER_EXCHANGE_test_signing_key (key_state,
+ exchange_pub))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ if (GNUNET_OK !=
+ GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND,
+ &rh->depconf.purpose,
+ &exchange_sig.eddsa_signature,
+ &exchange_pub->eddsa_pub))
+ {
+ GNUNET_break_op (0);
+ return GNUNET_SYSERR;
+ }
+ return GNUNET_OK;
+}
+
+
+/**
+ * Function called when we're done processing the
+ * HTTP /refund request.
+ *
+ * @param cls the `struct TALER_EXCHANGE_RefundHandle`
+ * @param response_code HTTP response code, 0 on error
+ * @param response parsed JSON result, NULL on error
+ */
+static void
+handle_refund_finished (void *cls,
+ long response_code,
+ const void *response)
+{
+ struct TALER_EXCHANGE_RefundHandle *rh = cls;
+ struct TALER_ExchangePublicKeyP exchange_pub;
+ struct TALER_ExchangePublicKeyP *ep = NULL;
+ const json_t *j = response;
+
+ rh->job = NULL;
+ switch (response_code)
+ {
+ case 0:
+ break;
+ case MHD_HTTP_OK:
+ if (GNUNET_OK !=
+ verify_refund_signature_ok (rh,
+ j,
+ &exchange_pub))
+ {
+ GNUNET_break_op (0);
+ response_code = 0;
+ }
+ else
+ {
+ ep = &exchange_pub;
+ }
+ break;
+ 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_UNAUTHORIZED:
+ /* 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_PRECONDITION_FAILED:
+ /* Client request was inconsistent; might be a currency missmatch
+ problem. */
+ break;
+ case MHD_HTTP_CONFLICT:
+ /* Two refund requests were made about the same deposit, but
+ carrying different refund transaction ids. */
+ 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;
+ }
+ rh->cb (rh->cb_cls,
+ response_code,
+ TALER_JSON_get_error_code (j),
+ ep,
+ j);
+ TALER_EXCHANGE_refund_cancel (rh);
+}
+
+
+/**
+ * Submit a refund request to the exchange and get the exchange's
+ * response. This API is used by a merchant. Note that
+ * while we return the response verbatim to the caller for further
+ * processing, we do already verify that the response is well-formed
+ * (i.e. that signatures included in the response are all valid). If
+ * the exchange's reply is not well-formed, we return an HTTP status code
+ * of zero to @a cb.
+ *
+ * The @a exchange must be ready to operate (i.e. have
+ * finished processing the /keys reply). If this check fails, we do
+ * NOT initiate the transaction with the exchange and instead return NULL.
+ *
+ * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param amount the amount to be refunded; must be larger than the refund fee
+ * (as that fee is still being subtracted), and smaller than the amount
+ * (with deposit fee) of the original deposit contribution of this coin
+ * @param refund_fee fee applicable to this coin for the refund
+ * @param h_contract_terms hash of the contact of the merchant with the customer that is being refunded
+ * @param coin_pub coin’s public key of the coin from the original deposit operation
+ * @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
+ * this is needed as we may first do a partial refund and later a full refund. If both
+ * refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
+ * refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
+ * @param merchant_priv the private key of the merchant, used to generate signature for refund request
+ * @param cb the callback to call when a reply for this request is available
+ * @param cb_cls closure for the above callback
+ * @return a handle for this request; NULL if the inputs are invalid (i.e.
+ * signatures fail to verify). In this case, the callback is not called.
+ */
+struct TALER_EXCHANGE_RefundHandle *
+TALER_EXCHANGE_refund (struct TALER_EXCHANGE_Handle *exchange,
+ const struct TALER_Amount *amount,
+ const struct TALER_Amount *refund_fee,
+ const struct GNUNET_HashCode *h_contract_terms,
+ const struct TALER_CoinSpendPublicKeyP *coin_pub,
+ uint64_t rtransaction_id,
+ const struct TALER_MerchantPrivateKeyP *merchant_priv,
+ TALER_EXCHANGE_RefundResultCallback cb,
+ void *cb_cls)
+{
+ struct TALER_RefundRequestPS rr;
+ struct TALER_MerchantSignatureP merchant_sig;
+
+ GNUNET_assert (GNUNET_YES ==
+ TEAH_handle_is_ready (exchange));
+ rr.purpose.purpose = htonl (TALER_SIGNATURE_MERCHANT_REFUND);
+ rr.purpose.size = htonl (sizeof (struct TALER_RefundRequestPS));
+ rr.h_contract_terms = *h_contract_terms;
+ rr.coin_pub = *coin_pub;
+ GNUNET_CRYPTO_eddsa_key_get_public (&merchant_priv->eddsa_priv,
+ &rr.merchant.eddsa_pub);
+ rr.rtransaction_id = GNUNET_htonll (rtransaction_id);
+ TALER_amount_hton (&rr.refund_amount,
+ amount);
+ TALER_amount_hton (&rr.refund_fee,
+ refund_fee);
+ GNUNET_assert (GNUNET_OK ==
+ GNUNET_CRYPTO_eddsa_sign (&merchant_priv->eddsa_priv,
+ &rr.purpose,
+ &merchant_sig.eddsa_sig));
+ return TALER_EXCHANGE_refund2 (exchange,
+ amount,
+ refund_fee,
+ h_contract_terms,
+ coin_pub,
+ rtransaction_id,
+ &rr.merchant,
+ &merchant_sig,
+ cb,
+ cb_cls);
+}
+
+
+/**
+ * Submit a refund request to the exchange and get the exchange's
+ * response. This API is used by a merchant. Note that
+ * while we return the response verbatim to the caller for further
+ * processing, we do already verify that the response is well-formed
+ * (i.e. that signatures included in the response are all valid). If
+ * the exchange's reply is not well-formed, we return an HTTP status code
+ * of zero to @a cb.
+ *
+ * The @a exchange must be ready to operate (i.e. have
+ * finished processing the /keys reply). If this check fails, we do
+ * NOT initiate the transaction with the exchange and instead return NULL.
+ *
+ * @param exchange the exchange handle; the exchange must be ready to operate
+ * @param amount the amount to be refunded; must be larger than the refund fee
+ * (as that fee is still being subtracted), and smaller than the amount
+ * (with deposit fee) of the original deposit contribution of this coin
+ * @param refund_fee fee applicable to this coin for the refund
+ * @param h_contract_terms hash of the contact of the merchant with the customer that is being refunded
+ * @param coin_pub coin’s public key of the coin from the original deposit operation
+ * @param rtransaction_id transaction id for the transaction between merchant and customer (of refunding operation);
+ * this is needed as we may first do a partial refund and later a full refund. If both
+ * refunds are also over the same amount, we need the @a rtransaction_id to make the disjoint
+ * refund requests different (as requests are idempotent and otherwise the 2nd refund might not work).
+ * @param merchant_pub public key of the merchant
+ * @param merchant_sig signature affirming the refund from the merchant
+ * @param cb the callback to call when a reply for this request is available
+ * @param cb_cls closure for the above callback
+ * @return a handle for this request; NULL if the inputs are invalid (i.e.
+ * signatures fail to verify). In this case, the callback is not called.
+ */
+struct TALER_EXCHANGE_RefundHandle *
+TALER_EXCHANGE_refund2 (struct TALER_EXCHANGE_Handle *exchange,
+ const struct TALER_Amount *amount,
+ const struct TALER_Amount *refund_fee,
+ const struct GNUNET_HashCode *h_contract_terms,
+ const struct TALER_CoinSpendPublicKeyP *coin_pub,
+ uint64_t rtransaction_id,
+ const struct TALER_MerchantPublicKeyP *merchant_pub,
+ const struct TALER_MerchantSignatureP *merchant_sig,
+ TALER_EXCHANGE_RefundResultCallback cb,
+ void *cb_cls)
+{
+ struct TALER_EXCHANGE_RefundHandle *rh;
+ struct GNUNET_CURL_Context *ctx;
+ json_t *refund_obj;
+ CURL *eh;
+
+refund_obj = json_pack ("{s:o, s:o," /* amount/fee */
+ " s:o, s:o," /* h_contract_terms, coin_pub */
+ " s:I," /* rtransaction id */
+ " s:o, s:o}", /* merchant_pub, merchant_sig */
+ "refund_amount", TALER_JSON_from_amount (amount),
+ "refund_fee", TALER_JSON_from_amount (refund_fee),
+ "h_contract_terms", GNUNET_JSON_from_data_auto (h_contract_terms),
+ "coin_pub", GNUNET_JSON_from_data_auto (coin_pub),
+ "rtransaction_id", (json_int_t) rtransaction_id,
+ "merchant_pub", GNUNET_JSON_from_data_auto (merchant_pub),
+ "merchant_sig", GNUNET_JSON_from_data_auto (merchant_sig)
+ );
+ if (NULL == refund_obj)
+ {
+ GNUNET_break (0);
+ return NULL;
+ }
+
+ rh = GNUNET_new (struct TALER_EXCHANGE_RefundHandle);
+ rh->exchange = exchange;
+ rh->cb = cb;
+ rh->cb_cls = cb_cls;
+ rh->url = TEAH_path_to_url (exchange, "/refund");
+ rh->depconf.purpose.size = htonl (sizeof (struct TALER_RefundConfirmationPS));
+ rh->depconf.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_REFUND);
+ rh->depconf.h_contract_terms = *h_contract_terms;
+ rh->depconf.coin_pub = *coin_pub;
+ rh->depconf.merchant = *merchant_pub;
+ rh->depconf.rtransaction_id = GNUNET_htonll (rtransaction_id);
+ TALER_amount_hton (&rh->depconf.refund_amount,
+ amount);
+ TALER_amount_hton (&rh->depconf.refund_fee,
+ refund_fee);
+
+ eh = TEL_curl_easy_get (rh->url);
+ GNUNET_assert (NULL != (rh->json_enc =
+ json_dumps (refund_obj,
+ JSON_COMPACT)));
+ json_decref (refund_obj);
+ GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
+ "URL for refund: `%s'\n",
+ rh->url);
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_setopt (eh,
+ CURLOPT_POSTFIELDS,
+ rh->json_enc));
+ GNUNET_assert (CURLE_OK ==
+ curl_easy_setopt (eh,
+ CURLOPT_POSTFIELDSIZE,
+ strlen (rh->json_enc)));
+ ctx = TEAH_handle_to_context (exchange);
+ rh->job = GNUNET_CURL_job_add (ctx,
+ eh,
+ GNUNET_YES,
+ &handle_refund_finished,
+ rh);
+ return rh;
+}
+
+
+/**
+ * Cancel a refund permission request. This function cannot be used
+ * on a request handle if a response is already served for it.
+ *
+ * @param refund the refund permission request handle
+ */
+void
+TALER_EXCHANGE_refund_cancel (struct TALER_EXCHANGE_RefundHandle *refund)
+{
+ if (NULL != refund->job)
+ {
+ GNUNET_CURL_job_cancel (refund->job);
+ refund->job = NULL;
+ }
+ GNUNET_free (refund->url);
+ GNUNET_free (refund->json_enc);
+ GNUNET_free (refund);
+}
+
+
+/* end of exchange_api_refund.c */