diff options
Diffstat (limited to 'src/exchange-lib/exchange_api_refresh_link.c')
| -rw-r--r-- | src/exchange-lib/exchange_api_refresh_link.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/src/exchange-lib/exchange_api_refresh_link.c b/src/exchange-lib/exchange_api_refresh_link.c new file mode 100644 index 000000000..8bb40d7f4 --- /dev/null +++ b/src/exchange-lib/exchange_api_refresh_link.c @@ -0,0 +1,484 @@ +/* + This file is part of TALER + Copyright (C) 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, If not, see + <http://www.gnu.org/licenses/> +*/ +/** + * @file exchange-lib/exchange_api_refresh_link.c + * @brief Implementation of the /refresh/link request of the exchange's HTTP API + * @author Christian Grothoff + */ +#include "platform.h" +#include <curl/curl.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 "exchange_api_context.h" +#include "exchange_api_handle.h" +#include "taler_signatures.h" + + +/** + * @brief A /refresh/link Handle + */ +struct TALER_EXCHANGE_RefreshLinkHandle +{ + + /** + * 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_RefreshLinkCallback link_cb; + + /** + * Closure for @e cb. + */ + void *link_cb_cls; + + /** + * Download buffer + */ + struct MAC_DownloadBuffer db; + + /** + * Private key of the coin, required to decode link information. + */ + struct TALER_CoinSpendPrivateKeyP coin_priv; + +}; + + +/** + * Parse the provided linkage data from the "200 OK" response + * for one of the coins. + * + * @param rlh refresh link handle + * @param json json reply with the data for one coin + * @param trans_pub our transfer public key + * @param secret_enc encrypted key to decrypt link data + * @param[out] coin_priv where to return private coin key + * @param[out] sig where to return private coin signature + * @param[out] pub where to return the public key for the coin + * @return #GNUNET_OK on success, #GNUNET_SYSERR on error + */ +static int +parse_refresh_link_coin (const struct TALER_EXCHANGE_RefreshLinkHandle *rlh, + json_t *json, + const struct TALER_TransferPublicKeyP *trans_pub, + const struct TALER_EncryptedLinkSecretP *secret_enc, + struct TALER_CoinSpendPrivateKeyP *coin_priv, + struct TALER_DenominationSignature *sig, + struct TALER_DenominationPublicKey *pub) +{ + void *link_enc; + size_t link_enc_size; + struct GNUNET_CRYPTO_RsaSignature *bsig; + struct GNUNET_CRYPTO_RsaPublicKey *rpub; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_varsize ("link_enc", &link_enc, &link_enc_size), + GNUNET_JSON_spec_rsa_public_key ("denom_pub", &rpub), + GNUNET_JSON_spec_rsa_signature ("ev_sig", &bsig), + GNUNET_JSON_spec_end() + }; + struct TALER_RefreshLinkEncrypted *rle; + struct TALER_RefreshLinkDecrypted *rld; + struct TALER_LinkSecretP secret; + + /* parse reply */ + if (GNUNET_OK != + GNUNET_JSON_parse (json, + spec, + NULL, NULL)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + + /* decode and decrypt link data */ + rle = TALER_refresh_link_encrypted_decode (link_enc, + link_enc_size); + if (NULL == rle) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; + } + if (GNUNET_OK != + TALER_link_decrypt_secret2 (secret_enc, + trans_pub, + &rlh->coin_priv, + &secret)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; + } + rld = TALER_refresh_decrypt (rle, + &secret); + if (NULL == rld) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; + } + + /* extract coin and signature */ + *coin_priv = rld->coin_priv; + sig->rsa_signature + = GNUNET_CRYPTO_rsa_unblind (bsig, + rld->blinding_key.rsa_blinding_key, + rpub); + + /* clean up */ + GNUNET_free (rld); + pub->rsa_public_key = GNUNET_CRYPTO_rsa_public_key_dup (rpub); + GNUNET_JSON_parse_free (spec); + return GNUNET_OK; +} + + +/** + * Parse the provided linkage data from the "200 OK" response + * for one of the coins. + * + * @param[in,out] rlh refresh link handle (callback may be zero'ed out) + * @param json json reply with the data for one coin + * @return #GNUNET_OK on success, #GNUNET_SYSERR on error + */ +static int +parse_refresh_link_ok (struct TALER_EXCHANGE_RefreshLinkHandle *rlh, + json_t *json) +{ + unsigned int session; + unsigned int num_coins; + int ret; + + if (! json_is_array (json)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + num_coins = 0; + /* Theoretically, a coin may have been melted repeatedly + into different sessions; so the response is an array + which contains information by melting session. That + array contains another array. However, our API returns + a single 1d array, so we flatten the 2d array that is + returned into a single array. Note that usually a coin + is melted at most once, and so we'll only run this + loop once for 'session=0' in most cases. + + num_coins tracks the size of the 1d array we return, + whilst 'i' and 'session' track the 2d array. */ + for (session=0;session<json_array_size (json); session++) + { + json_t *jsona; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_json ("new_coins", &jsona), + GNUNET_JSON_spec_end() + }; + + if (GNUNET_OK != + GNUNET_JSON_parse (json_array_get (json, + session), + spec, + NULL, NULL)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + if (! json_is_array (jsona)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; + } + + /* count all coins over all sessions */ + num_coins += json_array_size (jsona); + GNUNET_JSON_parse_free (spec); + } + /* Now that we know how big the 1d array is, allocate + and fill it. */ + { + unsigned int off_coin; /* index into 1d array */ + unsigned int i; + struct TALER_CoinSpendPrivateKeyP coin_privs[num_coins]; + struct TALER_DenominationSignature sigs[num_coins]; + struct TALER_DenominationPublicKey pubs[num_coins]; + + memset (sigs, 0, sizeof (sigs)); + memset (pubs, 0, sizeof (pubs)); + off_coin = 0; + for (session=0;session<json_array_size (json); session++) + { + json_t *jsona; + struct TALER_TransferPublicKeyP trans_pub; + struct TALER_EncryptedLinkSecretP secret_enc; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_json ("new_coins", &jsona), + GNUNET_JSON_spec_fixed_auto ("transfer_pub", &trans_pub), + GNUNET_JSON_spec_fixed_auto ("secret_enc", &secret_enc), + GNUNET_JSON_spec_end() + }; + + if (GNUNET_OK != + GNUNET_JSON_parse (json_array_get (json, + session), + spec, + NULL, NULL)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + if (! json_is_array (jsona)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return GNUNET_SYSERR; + } + + /* decode all coins */ + for (i=0;i<json_array_size (jsona);i++) + { + if (GNUNET_OK != + parse_refresh_link_coin (rlh, + json_array_get (jsona, + i), + &trans_pub, + &secret_enc, + &coin_privs[i+off_coin], + &sigs[i+off_coin], + &pubs[i+off_coin])) + { + GNUNET_break_op (0); + break; + } + } + /* check if we really got all, then invoke callback */ + off_coin += i; + if (i != json_array_size (jsona)) + { + GNUNET_break_op (0); + ret = GNUNET_SYSERR; + GNUNET_JSON_parse_free (spec); + break; + } + GNUNET_JSON_parse_free (spec); + } /* end of for (session) */ + + if (off_coin == num_coins) + { + rlh->link_cb (rlh->link_cb_cls, + MHD_HTTP_OK, + num_coins, + coin_privs, + sigs, + pubs, + json); + rlh->link_cb = NULL; + ret = GNUNET_OK; + } + else + { + GNUNET_break_op (0); + ret = GNUNET_SYSERR; + } + + /* clean up */ + for (i=0;i<off_coin;i++) + { + if (NULL != sigs[i].rsa_signature) + GNUNET_CRYPTO_rsa_signature_free (sigs[i].rsa_signature); + if (NULL != pubs[i].rsa_public_key) + GNUNET_CRYPTO_rsa_public_key_free (pubs[i].rsa_public_key); + } + } + return ret; +} + + +/** + * Function called when we're done processing the + * HTTP /refresh/link request. + * + * @param cls the `struct TALER_EXCHANGE_RefreshLinkHandle` + * @param eh the curl request handle + */ +static void +handle_refresh_link_finished (void *cls, + CURL *eh) +{ + struct TALER_EXCHANGE_RefreshLinkHandle *rlh = cls; + long response_code; + json_t *json; + + rlh->job = NULL; + json = MAC_download_get_result (&rlh->db, + eh, + &response_code); + switch (response_code) + { + case 0: + break; + case MHD_HTTP_OK: + if (GNUNET_OK != + parse_refresh_link_ok (rlh, + json)) + { + GNUNET_break_op (0); + response_code = 0; + } + 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, exchange says this coin was not melted; 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; + } + if (NULL != rlh->link_cb) + rlh->link_cb (rlh->link_cb_cls, + response_code, + 0, NULL, NULL, NULL, + json); + json_decref (json); + TALER_EXCHANGE_refresh_link_cancel (rlh); +} + + +/** + * Submit a link request to the exchange and get the exchange's response. + * + * This API is typically not used by anyone, it is more a threat + * against those trying to receive a funds transfer by abusing the + * /refresh protocol. + * + * @param exchange the exchange handle; the exchange must be ready to operate + * @param coin_priv private key to request link data for + * @param link_cb the callback to call with the useful result of the + * refresh operation the @a coin_priv was involved in (if any) + * @param link_cb_cls closure for @a link_cb + * @return a handle for this request + */ +struct TALER_EXCHANGE_RefreshLinkHandle * +TALER_EXCHANGE_refresh_link (struct TALER_EXCHANGE_Handle *exchange, + const struct TALER_CoinSpendPrivateKeyP *coin_priv, + TALER_EXCHANGE_RefreshLinkCallback link_cb, + void *link_cb_cls) +{ + struct TALER_EXCHANGE_RefreshLinkHandle *rlh; + CURL *eh; + struct TALER_EXCHANGE_Context *ctx; + struct TALER_CoinSpendPublicKeyP coin_pub; + char *pub_str; + char *arg_str; + + if (GNUNET_YES != + MAH_handle_is_ready (exchange)) + { + GNUNET_break (0); + return NULL; + } + + GNUNET_CRYPTO_eddsa_key_get_public (&coin_priv->eddsa_priv, + &coin_pub.eddsa_pub); + pub_str = GNUNET_STRINGS_data_to_string_alloc (&coin_pub, + sizeof (struct TALER_CoinSpendPublicKeyP)); + GNUNET_asprintf (&arg_str, + "/refresh/link?coin_pub=%s", + pub_str); + GNUNET_free (pub_str); + + rlh = GNUNET_new (struct TALER_EXCHANGE_RefreshLinkHandle); + rlh->exchange = exchange; + rlh->link_cb = link_cb; + rlh->link_cb_cls = link_cb_cls; + rlh->coin_priv = *coin_priv; + rlh->url = MAH_path_to_url (exchange, arg_str); + GNUNET_free (arg_str); + + eh = curl_easy_init (); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_URL, + rlh->url)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEFUNCTION, + &MAC_download_cb)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEDATA, + &rlh->db)); + ctx = MAH_handle_to_context (exchange); + rlh->job = MAC_job_add (ctx, + eh, + GNUNET_YES, + &handle_refresh_link_finished, + rlh); + return rlh; +} + + +/** + * Cancel a refresh link request. This function cannot be used + * on a request handle if the callback was already invoked. + * + * @param rlh the refresh link handle + */ +void +TALER_EXCHANGE_refresh_link_cancel (struct TALER_EXCHANGE_RefreshLinkHandle *rlh) +{ + if (NULL != rlh->job) + { + MAC_job_cancel (rlh->job); + rlh->job = NULL; + } + GNUNET_free_non_null (rlh->db.buf); + GNUNET_free (rlh->url); + GNUNET_free (rlh); +} + + +/* end of exchange_api_refresh_link.c */ |