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Diffstat (limited to 'src/exchange-lib/exchange_api_wire.c')
| -rw-r--r-- | src/exchange-lib/exchange_api_wire.c | 318 |
1 files changed, 318 insertions, 0 deletions
diff --git a/src/exchange-lib/exchange_api_wire.c b/src/exchange-lib/exchange_api_wire.c new file mode 100644 index 00000000..0e93a9d2 --- /dev/null +++ b/src/exchange-lib/exchange_api_wire.c @@ -0,0 +1,318 @@ +/* + This file is part of TALER + Copyright (C) 2014, 2015, 2016 Inria and 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, If not, see + <http://www.gnu.org/licenses/> +*/ +/** + * @file exchange-lib/exchange_api_wire.c + * @brief Implementation of the /wire request of the exchange's HTTP API + * @author Christian Grothoff + */ +#include "platform.h" +#include <curl/curl.h> +#include <jansson.h> +#include <microhttpd.h> /* just for HTTP status codes */ +#include <gnunet/gnunet_util_lib.h> +#include "taler_exchange_service.h" +#include "taler_json_lib.h" +#include "taler_wire_plugin.h" +#include "exchange_api_common.h" +#include "exchange_api_context.h" +#include "exchange_api_handle.h" + + +/** + * @brief A Wire Handle + */ +struct TALER_EXCHANGE_WireHandle +{ + + /** + * 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 MAC_Job *job; + + /** + * Function to call with the result. + */ + TALER_EXCHANGE_WireResultCallback cb; + + /** + * Closure for @a cb. + */ + void *cb_cls; + + /** + * Download buffer + */ + struct MAC_DownloadBuffer db; + + /** + * Set to the "methods" JSON array returned by the + * /wire request. + */ + json_t *methods; + + /** + * Current iteration offset in the @e methods array. + */ + unsigned int methods_off; + +}; + + +/** + * Verify that the signature on the "200 OK" response + * for /wire/METHOD from the exchange is valid. + * + * @param wh wire handle with key material + * @param method method to verify the reply for + * @param json json reply with the signature + * @return #GNUNET_SYSERR if @a json is invalid, + * #GNUNET_NO if the method is unknown, + * #GNUNET_OK if the json is valid + */ +static int +verify_wire_method_signature_ok (const struct TALER_EXCHANGE_WireHandle *wh, + const char *method, + json_t *json) +{ + const struct TALER_EXCHANGE_Keys *key_state; + struct TALER_WIRE_Plugin *plugin; + char *lib_name; + int ret; + + key_state = TALER_EXCHANGE_get_keys (wh->exchange); + (void) GNUNET_asprintf (&lib_name, + "libtaler_plugin_wire_%s", + method); + plugin = GNUNET_PLUGIN_load (lib_name, + NULL); + if (NULL == plugin) + { + GNUNET_free (lib_name); + GNUNET_log (GNUNET_ERROR_TYPE_INFO, + "Wire transfer method `%s' not supported\n", + method); + return GNUNET_NO; + } + plugin->library_name = lib_name; + ret = plugin->wire_validate (plugin->cls, + json, + &key_state->master_pub); + GNUNET_PLUGIN_unload (lib_name, + plugin); + GNUNET_free (lib_name); + return (GNUNET_YES == ret) ? GNUNET_OK : GNUNET_SYSERR; +} + + +/** + * Function called when we're done processing the + * HTTP /wire request. + * + * @param cls the `struct TALER_EXCHANGE_WireHandle` + * @param eh the curl request handle + */ +static void +handle_wire_finished (void *cls, + CURL *eh) +{ + struct TALER_EXCHANGE_WireHandle *wh = cls; + long response_code; + json_t *json; + + wh->job = NULL; + json = MAC_download_get_result (&wh->db, + eh, + &response_code); + switch (response_code) + { + case 0: + break; + case MHD_HTTP_OK: + { + const char *key; + json_t *method; + json_t *keep; + int ret; + + /* We 'keep' methods that we support and that are well-formed; + we fail (by setting response_code=0) if any method that we do + support fails to verify. */ + keep = json_object (); + json_object_foreach (json, key, method) { + ret = verify_wire_method_signature_ok (wh, + key, + method); + if (GNUNET_SYSERR == ret) + { + /* bogus reply */ + GNUNET_break_op (0); + response_code = 0; + } + /* GNUNET_NO: not understood by us, simply skip! */ + if (GNUNET_OK == ret) + { + /* supported and valid, keep! */ + json_object_set (keep, + key, + method); + } + } + if (0 != response_code) + { + /* all supported methods were valid, use 'keep' for 'json' */ + json_decref (json); + json = keep; + break; + } + else + { + /* some supported methods were invalid, release 'keep', preserve + full 'json' for application-level error handling. */ + json_decref (keep); + } + } + 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_NOT_FOUND: + /* Nothing really to verify, this should never + happen, we should pass the JSON reply to the application */ + 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", + response_code); + GNUNET_break (0); + response_code = 0; + break; + } + wh->cb (wh->cb_cls, + response_code, + json); + if (NULL != json) + json_decref (json); + TALER_EXCHANGE_wire_cancel (wh); +} + + +/** + * Obtain information about a exchange's wire instructions. + * A exchange may provide wire instructions for creating + * a reserve. The wire instructions also indicate + * which wire formats merchants may use with the exchange. + * This API is typically used by a wallet for wiring + * funds, and possibly by a merchant to determine + * supported wire formats. + * + * Note that while we return the (main) 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. + * + * @param exchange the exchange handle; the exchange must be ready to operate + * @param wire_cb the callback to call when a reply for this request is available + * @param wire_cb_cls closure for the above callback + * @return a handle for this request + */ +struct TALER_EXCHANGE_WireHandle * +TALER_EXCHANGE_wire (struct TALER_EXCHANGE_Handle *exchange, + TALER_EXCHANGE_WireResultCallback wire_cb, + void *wire_cb_cls) +{ + struct TALER_EXCHANGE_WireHandle *wh; + struct TALER_EXCHANGE_Context *ctx; + CURL *eh; + + if (GNUNET_YES != + MAH_handle_is_ready (exchange)) + { + GNUNET_break (0); + return NULL; + } + wh = GNUNET_new (struct TALER_EXCHANGE_WireHandle); + wh->exchange = exchange; + wh->cb = wire_cb; + wh->cb_cls = wire_cb_cls; + wh->url = MAH_path_to_url (exchange, "/wire"); + + eh = curl_easy_init (); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_URL, + wh->url)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEFUNCTION, + &MAC_download_cb)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEDATA, + &wh->db)); + ctx = MAH_handle_to_context (exchange); + wh->job = MAC_job_add (ctx, + eh, + GNUNET_YES, + &handle_wire_finished, + wh); + return wh; +} + + +/** + * Cancel a wire information request. This function cannot be used + * on a request handle if a response is already served for it. + * + * @param wh the wire information request handle + */ +void +TALER_EXCHANGE_wire_cancel (struct TALER_EXCHANGE_WireHandle *wh) +{ + if (NULL != wh->job) + { + MAC_job_cancel (wh->job); + wh->job = NULL; + } + if (NULL != wh->methods) + { + json_decref (wh->methods); + wh->methods = NULL; + } + GNUNET_free_non_null (wh->db.buf); + GNUNET_free (wh->url); + GNUNET_free (wh); +} + + +/* end of exchange_api_wire.c */ |