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Diffstat (limited to 'src/exchange-lib/exchange_api_deposit.c')
| -rw-r--r-- | src/exchange-lib/exchange_api_deposit.c | 569 |
1 files changed, 569 insertions, 0 deletions
diff --git a/src/exchange-lib/exchange_api_deposit.c b/src/exchange-lib/exchange_api_deposit.c new file mode 100644 index 000000000..deba4877d --- /dev/null +++ b/src/exchange-lib/exchange_api_deposit.c @@ -0,0 +1,569 @@ +/* + This file is part of TALER + Copyright (C) 2014, 2015 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_deposit.c + * @brief Implementation of the /deposit request of the exchange's HTTP API + * @author Sree Harsha Totakura <sreeharsha@totakura.in> + * @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 "exchange_api_common.h" +#include "exchange_api_json.h" +#include "exchange_api_context.h" +#include "exchange_api_handle.h" +#include "taler_signatures.h" + + +/** + * @brief A Deposit Handle + */ +struct TALER_EXCHANGE_DepositHandle +{ + + /** + * 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 MAC_Job *job; + + /** + * Function to call with the result. + */ + TALER_EXCHANGE_DepositResultCallback cb; + + /** + * Closure for @a cb. + */ + void *cb_cls; + + /** + * Download buffer + */ + struct MAC_DownloadBuffer db; + + /** + * Information the exchange should sign in response. + */ + struct TALER_DepositConfirmationPS depconf; + + /** + * Value of the /deposit transaction, including fee. + */ + struct TALER_Amount amount_with_fee; + + /** + * Total value of the coin being transacted with. + */ + struct TALER_Amount coin_value; + +}; + + +/** + * Verify that the signature on the "200 OK" response + * from the exchange is valid. + * + * @param dh deposit handle + * @param json json reply with the signature + * @return #GNUNET_OK if the signature is valid, #GNUNET_SYSERR if not + */ +static int +verify_deposit_signature_ok (const struct TALER_EXCHANGE_DepositHandle *dh, + json_t *json) +{ + struct TALER_ExchangeSignatureP exchange_sig; + struct TALER_ExchangePublicKeyP exchange_pub; + const struct TALER_EXCHANGE_Keys *key_state; + struct MAJ_Specification spec[] = { + MAJ_spec_fixed_auto ("sig", &exchange_sig), + MAJ_spec_fixed_auto ("pub", &exchange_pub), + MAJ_spec_end + }; + + if (GNUNET_OK != + MAJ_parse_json (json, + spec)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + key_state = TALER_EXCHANGE_get_keys (dh->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_DEPOSIT, + &dh->depconf.purpose, + &exchange_sig.eddsa_signature, + &exchange_pub.eddsa_pub)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + return GNUNET_OK; +} + + +/** + * Verify that the signatures on the "403 FORBIDDEN" response from the + * exchange demonstrating customer double-spending are valid. + * + * @param dh deposit handle + * @param json json reply with the signature(s) and transaction history + * @return #GNUNET_OK if the signature(s) is valid, #GNUNET_SYSERR if not + */ +static int +verify_deposit_signature_forbidden (const struct TALER_EXCHANGE_DepositHandle *dh, + json_t *json) +{ + json_t *history; + struct TALER_Amount total; + + history = json_object_get (json, + "history"); + if (GNUNET_OK != + TALER_EXCHANGE_verify_coin_history_ (dh->coin_value.currency, + &dh->depconf.coin_pub, + history, + &total)) + { + GNUNET_break_op (0); + return GNUNET_SYSERR; + } + if (GNUNET_OK != + TALER_amount_add (&total, + &total, + &dh->amount_with_fee)) + { + /* clearly not OK if our transaction would have caused + the overflow... */ + return GNUNET_OK; + } + + if (0 >= TALER_amount_cmp (&total, + &dh->coin_value)) + { + /* transaction should have still fit */ + GNUNET_break (0); + return GNUNET_SYSERR; + } + /* everything OK, proof of double-spending was provided */ + return GNUNET_OK; +} + + +/** + * Function called when we're done processing the + * HTTP /deposit request. + * + * @param cls the `struct TALER_EXCHANGE_DepositHandle` + * @param eh the curl request handle + */ +static void +handle_deposit_finished (void *cls, + CURL *eh) +{ + struct TALER_EXCHANGE_DepositHandle *dh = cls; + long response_code; + json_t *json; + + dh->job = NULL; + json = MAC_download_get_result (&dh->db, + eh, + &response_code); + switch (response_code) + { + case 0: + break; + case MHD_HTTP_OK: + if (GNUNET_OK != + verify_deposit_signature_ok (dh, + 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_FORBIDDEN: + /* Double spending; check signatures on transaction history */ + if (GNUNET_OK != + verify_deposit_signature_forbidden (dh, + json)) + { + GNUNET_break_op (0); + response_code = 0; + } + 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_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; + } + dh->cb (dh->cb_cls, + response_code, + json); + json_decref (json); + TALER_EXCHANGE_deposit_cancel (dh); +} + + +/** + * Verify signature information about the deposit. + * + * @param dki public key information + * @param amount the amount to be deposited + * @param h_wire hash of the merchant’s account details + * @param h_contract hash of the contact of the merchant with the customer (further details are never disclosed to the exchange) + * @param coin_pub coin’s public key + * @param denom_pub denomination key with which the coin is signed + * @param denom_sig exchange’s unblinded signature of the coin + * @param timestamp timestamp when the contract was finalized, must match approximately the current time of the exchange + * @param transaction_id transaction id for the transaction between merchant and customer + * @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests) + * @param refund_deadline date until which the merchant can issue a refund to the customer via the exchange (can be zero if refunds are not allowed) + * @param coin_sig the signature made with purpose #TALER_SIGNATURE_WALLET_COIN_DEPOSIT made by the customer with the coin’s private key. + * @return #GNUNET_OK if signatures are OK, #GNUNET_SYSERR if not + */ +static int +verify_signatures (const struct TALER_EXCHANGE_DenomPublicKey *dki, + const struct TALER_Amount *amount, + const struct GNUNET_HashCode *h_wire, + const struct GNUNET_HashCode *h_contract, + const struct TALER_CoinSpendPublicKeyP *coin_pub, + const struct TALER_DenominationSignature *denom_sig, + const struct TALER_DenominationPublicKey *denom_pub, + struct GNUNET_TIME_Absolute timestamp, + uint64_t transaction_id, + const struct TALER_MerchantPublicKeyP *merchant_pub, + struct GNUNET_TIME_Absolute refund_deadline, + const struct TALER_CoinSpendSignatureP *coin_sig) +{ + struct TALER_DepositRequestPS dr; + struct TALER_CoinPublicInfo coin_info; + + dr.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_DEPOSIT); + dr.purpose.size = htonl (sizeof (struct TALER_DepositRequestPS)); + dr.h_contract = *h_contract; + dr.h_wire = *h_wire; + dr.timestamp = GNUNET_TIME_absolute_hton (timestamp); + dr.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline); + dr.transaction_id = GNUNET_htonll (transaction_id); + TALER_amount_hton (&dr.amount_with_fee, + amount); + TALER_amount_hton (&dr.deposit_fee, + &dki->fee_deposit); + dr.merchant = *merchant_pub; + dr.coin_pub = *coin_pub; + if (GNUNET_OK != + GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_DEPOSIT, + &dr.purpose, + &coin_sig->eddsa_signature, + &coin_pub->eddsa_pub)) + { + TALER_LOG_WARNING ("Invalid coin signature on /deposit request\n"); + { + char *s; + s = TALER_amount_to_string (amount); + TALER_LOG_DEBUG ("... amount_with_fee was %s\n", s); + GNUNET_free (s); + s = TALER_amount_to_string (&dki->fee_deposit); + TALER_LOG_DEBUG ("... deposit_fee was %s\n", s); + GNUNET_free (s); + } + + return GNUNET_SYSERR; + } + + /* check coin signature */ + coin_info.coin_pub = *coin_pub; + coin_info.denom_pub = *denom_pub; + coin_info.denom_sig = *denom_sig; + if (GNUNET_YES != + TALER_test_coin_valid (&coin_info)) + { + TALER_LOG_WARNING ("Invalid coin passed for /deposit\n"); + return GNUNET_SYSERR; + } + if (0 < TALER_amount_cmp (&dki->fee_deposit, + amount)) + { + TALER_LOG_WARNING ("Deposit amount smaller than fee\n"); + return GNUNET_SYSERR; + } + return GNUNET_OK; +} + + +/** + * Submit a deposit permission to the exchange and get the exchange's response. + * 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. + * + * We also verify that the @a coin_sig is valid for this deposit + * request, and that the @a ub_sig is a valid signature for @a + * coin_pub. Also, the @a exchange must be ready to operate (i.e. have + * finished processing the /keys reply). If either 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 deposited + * @param wire_deadline date until which the merchant would like the exchange to settle the balance (advisory, the exchange cannot be + * forced to settle in the past or upon very short notice, but of course a well-behaved exchange will limit aggregation based on the advice received) + * @param wire_details the merchant’s account details, in a format supported by the exchange + * @param h_contract hash of the contact of the merchant with the customer (further details are never disclosed to the exchange) + * @param coin_pub coin’s public key + * @param denom_pub denomination key with which the coin is signed + * @param denom_sig exchange’s unblinded signature of the coin + * @param timestamp timestamp when the contract was finalized, must match approximately the current time of the exchange + * @param transaction_id transaction id for the transaction between merchant and customer + * @param merchant_pub the public key of the merchant (used to identify the merchant for refund requests) + * @param refund_deadline date until which the merchant can issue a refund to the customer via the exchange (can be zero if refunds are not allowed) + * @param coin_sig the signature made with purpose #TALER_SIGNATURE_WALLET_COIN_DEPOSIT made by the customer with the coin’s private key. + * @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_DepositHandle * +TALER_EXCHANGE_deposit (struct TALER_EXCHANGE_Handle *exchange, + const struct TALER_Amount *amount, + struct GNUNET_TIME_Absolute wire_deadline, + json_t *wire_details, + const struct GNUNET_HashCode *h_contract, + const struct TALER_CoinSpendPublicKeyP *coin_pub, + const struct TALER_DenominationSignature *denom_sig, + const struct TALER_DenominationPublicKey *denom_pub, + struct GNUNET_TIME_Absolute timestamp, + uint64_t transaction_id, + const struct TALER_MerchantPublicKeyP *merchant_pub, + struct GNUNET_TIME_Absolute refund_deadline, + const struct TALER_CoinSpendSignatureP *coin_sig, + TALER_EXCHANGE_DepositResultCallback cb, + void *cb_cls) +{ + const struct TALER_EXCHANGE_Keys *key_state; + const struct TALER_EXCHANGE_DenomPublicKey *dki; + struct TALER_EXCHANGE_DepositHandle *dh; + struct TALER_EXCHANGE_Context *ctx; + json_t *deposit_obj; + CURL *eh; + struct GNUNET_HashCode h_wire; + struct TALER_Amount amount_without_fee; + + (void) TALER_round_abs_time (&wire_deadline); + if (GNUNET_YES != + MAH_handle_is_ready (exchange)) + { + GNUNET_break (0); + return NULL; + } + /* initialize h_wire */ + if (GNUNET_OK != + TALER_hash_json (wire_details, + &h_wire)) + { + GNUNET_break (0); + return NULL; + } + key_state = TALER_EXCHANGE_get_keys (exchange); + dki = TALER_EXCHANGE_get_denomination_key (key_state, + denom_pub); + if (NULL == dki) + { + TALER_LOG_WARNING ("Denomination key unknown to exchange\n"); + return NULL; + } + if (GNUNET_SYSERR == + TALER_amount_subtract (&amount_without_fee, + amount, + &dki->fee_deposit)) + { + GNUNET_break (0); + return NULL; + } + + if (GNUNET_OK != + verify_signatures (dki, + amount, + &h_wire, + h_contract, + coin_pub, + denom_sig, + denom_pub, + timestamp, + transaction_id, + merchant_pub, + refund_deadline, + coin_sig)) + { + GNUNET_break_op (0); + return NULL; + } + + deposit_obj = json_pack ("{s:o, s:O," /* f/wire */ + " s:o, s:o," /* H_wire, H_contract */ + " s:o, s:o," /* coin_pub, denom_pub */ + " s:o, s:o," /* ub_sig, timestamp */ + " s:I, s:o," /* transaction id, merchant_pub */ + " s:o, s:o," /* refund_deadline, wire_deadline */ + " s:o}", /* coin_sig */ + "f", TALER_json_from_amount (amount), + "wire", wire_details, + "H_wire", TALER_json_from_data (&h_wire, + sizeof (h_wire)), + "H_contract", TALER_json_from_data (h_contract, + sizeof (struct GNUNET_HashCode)), + "coin_pub", TALER_json_from_data (coin_pub, + sizeof (*coin_pub)), + "denom_pub", TALER_json_from_rsa_public_key (denom_pub->rsa_public_key), + "ub_sig", TALER_json_from_rsa_signature (denom_sig->rsa_signature), + "timestamp", TALER_json_from_abs (timestamp), + "transaction_id", (json_int_t) transaction_id, + "merchant_pub", TALER_json_from_data (merchant_pub, + sizeof (*merchant_pub)), + "refund_deadline", TALER_json_from_abs (refund_deadline), + "edate", TALER_json_from_abs (wire_deadline), + "coin_sig", TALER_json_from_data (coin_sig, + sizeof (*coin_sig)) + ); + + dh = GNUNET_new (struct TALER_EXCHANGE_DepositHandle); + dh->exchange = exchange; + dh->cb = cb; + dh->cb_cls = cb_cls; + dh->url = MAH_path_to_url (exchange, "/deposit"); + dh->depconf.purpose.size = htonl (sizeof (struct TALER_DepositConfirmationPS)); + dh->depconf.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_DEPOSIT); + dh->depconf.h_contract = *h_contract; + dh->depconf.h_wire = h_wire; + dh->depconf.transaction_id = GNUNET_htonll (transaction_id); + dh->depconf.timestamp = GNUNET_TIME_absolute_hton (timestamp); + dh->depconf.refund_deadline = GNUNET_TIME_absolute_hton (refund_deadline); + TALER_amount_hton (&dh->depconf.amount_without_fee, + &amount_without_fee); + dh->depconf.coin_pub = *coin_pub; + dh->depconf.merchant = *merchant_pub; + dh->amount_with_fee = *amount; + dh->coin_value = dki->value; + + eh = curl_easy_init (); + GNUNET_assert (NULL != (dh->json_enc = + json_dumps (deposit_obj, + JSON_COMPACT))); + json_decref (deposit_obj); + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, + "URL for deposit: `%s'\n", + dh->url); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_URL, + dh->url)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_POSTFIELDS, + dh->json_enc)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_POSTFIELDSIZE, + strlen (dh->json_enc))); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEFUNCTION, + &MAC_download_cb)); + GNUNET_assert (CURLE_OK == + curl_easy_setopt (eh, + CURLOPT_WRITEDATA, + &dh->db)); + ctx = MAH_handle_to_context (exchange); + dh->job = MAC_job_add (ctx, + eh, + GNUNET_YES, + &handle_deposit_finished, + dh); + return dh; +} + + +/** + * Cancel a deposit permission request. This function cannot be used + * on a request handle if a response is already served for it. + * + * @param deposit the deposit permission request handle + */ +void +TALER_EXCHANGE_deposit_cancel (struct TALER_EXCHANGE_DepositHandle *deposit) +{ + if (NULL != deposit->job) + { + MAC_job_cancel (deposit->job); + deposit->job = NULL; + } + GNUNET_free_non_null (deposit->db.buf); + GNUNET_free (deposit->url); + GNUNET_free (deposit->json_enc); + GNUNET_free (deposit); +} + + +/* end of exchange_api_deposit.c */ |