/* This file is part of TALER Copyright (C) 2014-2021 Taler Systems SA 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 */ /** * @file lib/exchange_api_deposit.c * @brief Implementation of the /deposit request of the exchange's HTTP API * @author Sree Harsha Totakura * @author Christian Grothoff */ #include "platform.h" #include #include /* just for HTTP status codes */ #include #include #include #include "taler_json_lib.h" #include "taler_auditor_service.h" #include "taler_exchange_service.h" #include "exchange_api_handle.h" #include "taler_signatures.h" #include "exchange_api_curl_defaults.h" /** * 1:#AUDITOR_CHANCE is the probability that we report deposits * to the auditor. * * 20==5% of going to auditor. This is possibly still too high, but set * deliberately this high for testing */ #define AUDITOR_CHANCE 20 /** * @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; /** * Context for #TEH_curl_easy_post(). Keeps the data that must * persist for Curl to make the upload. */ struct TALER_CURL_PostContext ctx; /** * Handle for the request. */ struct GNUNET_CURL_Job *job; /** * Function to call with the result. */ TALER_EXCHANGE_DepositResultCallback cb; /** * Closure for @a cb. */ void *cb_cls; /** * Hash over the contract for which this deposit is made. */ struct TALER_PrivateContractHash h_contract_terms GNUNET_PACKED; /** * Hash over the wiring information of the merchant. */ struct TALER_MerchantWireHash h_wire GNUNET_PACKED; /** * Hash over the extension options of the deposit, 0 if there * were not extension options. */ struct TALER_ExtensionContractHash h_extensions GNUNET_PACKED; /** * Time when this confirmation was generated / when the exchange received * the deposit request. */ struct GNUNET_TIME_Timestamp exchange_timestamp; /** * By when does the exchange expect to pay the merchant * (as per the merchant's request). */ struct GNUNET_TIME_Timestamp wire_deadline; /** * How much time does the @e merchant have to issue a refund * request? Zero if refunds are not allowed. After this time, the * coin cannot be refunded. Note that the wire transfer will not be * performed by the exchange until the refund deadline. This value * is taken from the original deposit request. */ struct GNUNET_TIME_Timestamp refund_deadline; /** * Amount to be deposited, excluding fee. Calculated from the * amount with fee and the fee from the deposit request. */ struct TALER_Amount amount_without_fee; /** * The public key of the coin that was deposited. */ struct TALER_CoinSpendPublicKeyP coin_pub; /** * The Merchant's public key. Allows the merchant to later refund * the transaction or to inquire about the wire transfer identifier. */ struct TALER_MerchantPublicKeyP merchant_pub; /** * Exchange signature, set for #auditor_cb. */ struct TALER_ExchangeSignatureP exchange_sig; /** * Exchange signing public key, set for #auditor_cb. */ struct TALER_ExchangePublicKeyP exchange_pub; /** * Value of the /deposit transaction, including fee. */ struct TALER_Amount amount_with_fee; /** * @brief Public information about the coin's denomination key. * Note that the "key" field itself has been zero'ed out. */ struct TALER_EXCHANGE_DenomPublicKey dki; /** * Chance that we will inform the auditor about the deposit * is 1:n, where the value of this field is "n". */ unsigned int auditor_chance; }; /** * Function called for each auditor to give us a chance to possibly * launch a deposit confirmation interaction. * * @param cls closure * @param ah handle to the auditor * @param auditor_pub public key of the auditor * @return NULL if no deposit confirmation interaction was launched */ static struct TEAH_AuditorInteractionEntry * auditor_cb (void *cls, struct TALER_AUDITOR_Handle *ah, const struct TALER_AuditorPublicKeyP *auditor_pub) { struct TALER_EXCHANGE_DepositHandle *dh = cls; const struct TALER_EXCHANGE_Keys *key_state; const struct TALER_EXCHANGE_SigningPublicKey *spk; struct TEAH_AuditorInteractionEntry *aie; if (0 != GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_WEAK, dh->auditor_chance)) { GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Not providing deposit confirmation to auditor\n"); return NULL; } GNUNET_log (GNUNET_ERROR_TYPE_INFO, "Will provide deposit confirmation to auditor `%s'\n", TALER_B2S (auditor_pub)); key_state = TALER_EXCHANGE_get_keys (dh->exchange); spk = TALER_EXCHANGE_get_signing_key_info (key_state, &dh->exchange_pub); if (NULL == spk) { GNUNET_break_op (0); return NULL; } aie = GNUNET_new (struct TEAH_AuditorInteractionEntry); aie->dch = TALER_AUDITOR_deposit_confirmation ( ah, &dh->h_wire, &dh->h_extensions, &dh->h_contract_terms, dh->exchange_timestamp, dh->wire_deadline, dh->refund_deadline, &dh->amount_without_fee, &dh->coin_pub, &dh->merchant_pub, &dh->exchange_pub, &dh->exchange_sig, &key_state->master_pub, spk->valid_from, spk->valid_until, spk->valid_legal, &spk->master_sig, &TEAH_acc_confirmation_cb, aie); return aie; } /** * 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 enum GNUNET_GenericReturnValue verify_deposit_signature_conflict ( const struct TALER_EXCHANGE_DepositHandle *dh, const json_t *json) { json_t *history; struct TALER_Amount total; enum TALER_ErrorCode ec; struct TALER_DenominationHash h_denom_pub; memset (&h_denom_pub, 0, sizeof (h_denom_pub)); history = json_object_get (json, "history"); if (GNUNET_OK != TALER_EXCHANGE_verify_coin_history (&dh->dki, dh->dki.value.currency, &dh->coin_pub, history, &h_denom_pub, &total)) { GNUNET_break_op (0); return GNUNET_SYSERR; } ec = TALER_JSON_get_error_code (json); switch (ec) { case TALER_EC_EXCHANGE_GENERIC_INSUFFICIENT_FUNDS: if (0 > 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->dki.value)) { /* transaction should have still fit */ GNUNET_break (0); return GNUNET_SYSERR; } /* everything OK, proof of double-spending was provided */ return GNUNET_OK; case TALER_EC_EXCHANGE_GENERIC_COIN_CONFLICTING_DENOMINATION_KEY: if (0 != GNUNET_memcmp (&dh->dki.h_key, &h_denom_pub)) return GNUNET_OK; /* indeed, proof with different denomination key provided */ /* invalid proof provided */ return GNUNET_SYSERR; default: /* unexpected error code */ GNUNET_break_op (0); return GNUNET_SYSERR; } } /** * Function called when we're done processing the * HTTP /deposit request. * * @param cls the `struct TALER_EXCHANGE_DepositHandle` * @param response_code HTTP response code, 0 on error * @param response parsed JSON result, NULL on error */ static void handle_deposit_finished (void *cls, long response_code, const void *response) { struct TALER_EXCHANGE_DepositHandle *dh = cls; const json_t *j = response; struct TALER_EXCHANGE_DepositResult dr = { .hr.reply = j, .hr.http_status = (unsigned int) response_code }; dh->job = NULL; switch (response_code) { case 0: dr.hr.ec = TALER_EC_GENERIC_INVALID_RESPONSE; break; case MHD_HTTP_OK: { const struct TALER_EXCHANGE_Keys *key_state; struct GNUNET_JSON_Specification spec[] = { GNUNET_JSON_spec_fixed_auto ("exchange_sig", &dh->exchange_sig), GNUNET_JSON_spec_fixed_auto ("exchange_pub", &dh->exchange_pub), GNUNET_JSON_spec_mark_optional ( GNUNET_JSON_spec_string ("transaction_base_url", &dr.details.success.transaction_base_url)), GNUNET_JSON_spec_timestamp ("exchange_timestamp", &dh->exchange_timestamp), GNUNET_JSON_spec_end () }; if (GNUNET_OK != GNUNET_JSON_parse (j, spec, NULL, NULL)) { GNUNET_break_op (0); dr.hr.http_status = 0; dr.hr.ec = TALER_EC_GENERIC_REPLY_MALFORMED; break; } key_state = TALER_EXCHANGE_get_keys (dh->exchange); if (GNUNET_OK != TALER_EXCHANGE_test_signing_key (key_state, &dh->exchange_pub)) { GNUNET_break_op (0); dr.hr.http_status = 0; dr.hr.ec = TALER_EC_EXCHANGE_DEPOSIT_INVALID_SIGNATURE_BY_EXCHANGE; break; } if (GNUNET_OK != TALER_exchange_deposit_confirm_verify (&dh->h_contract_terms, &dh->h_wire, &dh->h_extensions, dh->exchange_timestamp, dh->wire_deadline, dh->refund_deadline, &dh->amount_without_fee, &dh->coin_pub, &dh->merchant_pub, &dh->exchange_pub, &dh->exchange_sig)) { GNUNET_break_op (0); dr.hr.http_status = 0; dr.hr.ec = TALER_EC_EXCHANGE_DEPOSIT_INVALID_SIGNATURE_BY_EXCHANGE; break; } TEAH_get_auditors_for_dc (dh->exchange, &auditor_cb, dh); } dr.details.success.exchange_sig = &dh->exchange_sig; dr.details.success.exchange_pub = &dh->exchange_pub; dr.details.success.deposit_timestamp = dh->exchange_timestamp; 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 */ dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); break; case MHD_HTTP_FORBIDDEN: dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); /* 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: dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); /* Nothing really to verify, this should never happen, we should pass the JSON reply to the application */ break; case MHD_HTTP_CONFLICT: /* Double spending; check signatures on transaction history */ if (GNUNET_OK != verify_deposit_signature_conflict (dh, j)) { GNUNET_break_op (0); dr.hr.http_status = 0; dr.hr.ec = TALER_EC_EXCHANGE_DEPOSIT_INVALID_SIGNATURE_BY_EXCHANGE; } else { dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); } break; case MHD_HTTP_GONE: /* could happen if denomination was revoked */ /* Note: one might want to check /keys for revocation signature here, alas tricky in case our /keys is outdated => left to clients */ dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); break; case MHD_HTTP_INTERNAL_SERVER_ERROR: dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); /* Server had an internal issue; we should retry, but this API leaves this to the application */ break; default: /* unexpected response code */ dr.hr.ec = TALER_JSON_get_error_code (j); dr.hr.hint = TALER_JSON_get_error_hint (j); GNUNET_log (GNUNET_ERROR_TYPE_ERROR, "Unexpected response code %u/%d for exchange deposit\n", (unsigned int) response_code, dr.hr.ec); GNUNET_break_op (0); break; } dh->cb (dh->cb_cls, &dr); 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_terms hash of the contact of the merchant with the customer (further details are never disclosed to the exchange) * @param ech hash over contract extensions * @param coin_pub coin’s public key * @param h_age_commitment coin’s hash of age commitment, might be NULL * @param denom_sig exchange’s unblinded signature of the coin * @param denom_pub denomination key with which the coin is signed * @param denom_pub_hash hash of @a denom_pub * @param timestamp timestamp when the deposit was finalized * @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 enum GNUNET_GenericReturnValue verify_signatures (const struct TALER_EXCHANGE_DenomPublicKey *dki, const struct TALER_Amount *amount, const struct TALER_MerchantWireHash *h_wire, const struct TALER_PrivateContractHash *h_contract_terms, const struct TALER_ExtensionContractHash *ech, const struct TALER_CoinSpendPublicKeyP *coin_pub, const struct TALER_AgeCommitmentHash *h_age_commitment, const struct TALER_DenominationSignature *denom_sig, const struct TALER_DenominationPublicKey *denom_pub, const struct TALER_DenominationHash *denom_pub_hash, struct GNUNET_TIME_Timestamp timestamp, const struct TALER_MerchantPublicKeyP *merchant_pub, struct GNUNET_TIME_Timestamp refund_deadline, const struct TALER_CoinSpendSignatureP *coin_sig) { if (GNUNET_OK != TALER_wallet_deposit_verify (amount, &dki->fees.deposit, h_wire, h_contract_terms, h_age_commitment, ech, denom_pub_hash, timestamp, merchant_pub, refund_deadline, coin_pub, coin_sig)) { GNUNET_break_op (0); TALER_LOG_WARNING ("Invalid coin signature on /deposit request!\n"); TALER_LOG_DEBUG ("... amount_with_fee was %s\n", TALER_amount2s (amount)); TALER_LOG_DEBUG ("... deposit_fee was %s\n", TALER_amount2s (&dki->fees.deposit)); return GNUNET_SYSERR; } /* check coin signature */ { struct TALER_CoinPublicInfo coin_info = { .coin_pub = *coin_pub, .denom_pub_hash = *denom_pub_hash, .denom_sig = *denom_sig, .age_commitment_hash = {{{0}}} }; if (NULL != h_age_commitment) { coin_info.age_commitment_hash = *h_age_commitment; } if (GNUNET_YES != TALER_test_coin_valid (&coin_info, denom_pub)) { GNUNET_break_op (0); TALER_LOG_WARNING ("Invalid coin passed for /deposit\n"); return GNUNET_SYSERR; } } /* Check coin does make a contribution */ if (0 < TALER_amount_cmp (&dki->fees.deposit, amount)) { GNUNET_break_op (0); TALER_LOG_WARNING ("Deposit amount smaller than fee\n"); return GNUNET_SYSERR; } return GNUNET_OK; } struct TALER_EXCHANGE_DepositHandle * TALER_EXCHANGE_deposit ( struct TALER_EXCHANGE_Handle *exchange, const struct TALER_Amount *amount, struct GNUNET_TIME_Timestamp wire_deadline, const char *merchant_payto_uri, const struct TALER_WireSaltP *wire_salt, const struct TALER_PrivateContractHash *h_contract_terms, const struct TALER_AgeCommitmentHash *h_age_commitment, const json_t *extension_details, const struct TALER_CoinSpendPublicKeyP *coin_pub, const struct TALER_DenominationSignature *denom_sig, const struct TALER_DenominationPublicKey *denom_pub, struct GNUNET_TIME_Timestamp timestamp, const struct TALER_MerchantPublicKeyP *merchant_pub, struct GNUNET_TIME_Timestamp refund_deadline, const struct TALER_CoinSpendSignatureP *coin_sig, TALER_EXCHANGE_DepositResultCallback cb, void *cb_cls, enum TALER_ErrorCode *ec) { const struct TALER_EXCHANGE_Keys *key_state; const struct TALER_EXCHANGE_DenomPublicKey *dki; struct TALER_EXCHANGE_DepositHandle *dh; struct GNUNET_CURL_Context *ctx; json_t *deposit_obj; CURL *eh; struct TALER_MerchantWireHash h_wire; struct TALER_DenominationHash denom_pub_hash; struct TALER_Amount amount_without_fee; struct TALER_ExtensionContractHash ech; char arg_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2 + 32]; if (NULL != extension_details) TALER_deposit_extension_hash (extension_details, &ech); { char pub_str[sizeof (struct TALER_CoinSpendPublicKeyP) * 2]; char *end; end = GNUNET_STRINGS_data_to_string ( coin_pub, sizeof (struct TALER_CoinSpendPublicKeyP), pub_str, sizeof (pub_str)); *end = '\0'; GNUNET_snprintf (arg_str, sizeof (arg_str), "/coins/%s/deposit", pub_str); } if (GNUNET_TIME_timestamp_cmp (refund_deadline, >, wire_deadline)) { GNUNET_break_op (0); *ec = TALER_EC_EXCHANGE_DEPOSIT_REFUND_DEADLINE_AFTER_WIRE_DEADLINE; return NULL; } GNUNET_assert (GNUNET_YES == TEAH_handle_is_ready (exchange)); /* initialize h_wire */ TALER_merchant_wire_signature_hash (merchant_payto_uri, wire_salt, &h_wire); key_state = TALER_EXCHANGE_get_keys (exchange); dki = TALER_EXCHANGE_get_denomination_key (key_state, denom_pub); if (NULL == dki) { *ec = TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN; GNUNET_break_op (0); return NULL; } if (0 > TALER_amount_subtract (&amount_without_fee, amount, &dki->fees.deposit)) { *ec = TALER_EC_EXCHANGE_DEPOSIT_FEE_ABOVE_AMOUNT; GNUNET_break_op (0); return NULL; } TALER_denom_pub_hash (denom_pub, &denom_pub_hash); if (GNUNET_OK != verify_signatures (dki, amount, &h_wire, h_contract_terms, (NULL != extension_details) ? &ech : NULL, coin_pub, h_age_commitment, denom_sig, denom_pub, &denom_pub_hash, timestamp, merchant_pub, refund_deadline, coin_sig)) { *ec = TALER_EC_EXCHANGE_DEPOSIT_COIN_SIGNATURE_INVALID; GNUNET_break_op (0); return NULL; } deposit_obj = GNUNET_JSON_PACK ( TALER_JSON_pack_amount ("contribution", amount), GNUNET_JSON_pack_string ("merchant_payto_uri", merchant_payto_uri), GNUNET_JSON_pack_data_auto ("wire_salt", wire_salt), GNUNET_JSON_pack_data_auto ("h_contract_terms", h_contract_terms), GNUNET_JSON_pack_allow_null ( GNUNET_JSON_pack_data_auto ("h_age_commitment", h_age_commitment)), GNUNET_JSON_pack_data_auto ("denom_pub_hash", &denom_pub_hash), TALER_JSON_pack_denom_sig ("ub_sig", denom_sig), GNUNET_JSON_pack_timestamp ("timestamp", timestamp), GNUNET_JSON_pack_data_auto ("merchant_pub", merchant_pub), GNUNET_JSON_pack_allow_null ( GNUNET_JSON_pack_timestamp ("refund_deadline", refund_deadline)), GNUNET_JSON_pack_timestamp ("wire_transfer_deadline", wire_deadline), GNUNET_JSON_pack_data_auto ("coin_sig", coin_sig)); dh = GNUNET_new (struct TALER_EXCHANGE_DepositHandle); dh->auditor_chance = AUDITOR_CHANCE; dh->exchange = exchange; dh->cb = cb; dh->cb_cls = cb_cls; dh->url = TEAH_path_to_url (exchange, arg_str); if (NULL == dh->url) { GNUNET_break (0); *ec = TALER_EC_GENERIC_ALLOCATION_FAILURE; GNUNET_free (dh); json_decref (deposit_obj); return NULL; } dh->h_contract_terms = *h_contract_terms; dh->h_wire = h_wire; /* dh->h_extensions = ... */ dh->refund_deadline = refund_deadline; dh->wire_deadline = wire_deadline; dh->amount_without_fee = amount_without_fee; dh->coin_pub = *coin_pub; dh->merchant_pub = *merchant_pub; dh->amount_with_fee = *amount; dh->dki = *dki; memset (&dh->dki.key, 0, sizeof (dh->dki.key)); /* lifetime not warranted, so better not copy the contents! */ eh = TALER_EXCHANGE_curl_easy_get_ (dh->url); if ( (NULL == eh) || (GNUNET_OK != TALER_curl_easy_post (&dh->ctx, eh, deposit_obj)) ) { *ec = TALER_EC_GENERIC_CURL_ALLOCATION_FAILURE; GNUNET_break (0); if (NULL != eh) curl_easy_cleanup (eh); json_decref (deposit_obj); GNUNET_free (dh->url); GNUNET_free (dh); return NULL; } json_decref (deposit_obj); GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, "URL for deposit: `%s'\n", dh->url); ctx = TEAH_handle_to_context (exchange); dh->job = GNUNET_CURL_job_add2 (ctx, eh, dh->ctx.headers, &handle_deposit_finished, dh); return dh; } void TALER_EXCHANGE_deposit_force_dc (struct TALER_EXCHANGE_DepositHandle *deposit) { deposit->auditor_chance = 1; } void TALER_EXCHANGE_deposit_cancel (struct TALER_EXCHANGE_DepositHandle *deposit) { if (NULL != deposit->job) { GNUNET_CURL_job_cancel (deposit->job); deposit->job = NULL; } GNUNET_free (deposit->url); TALER_curl_easy_post_finished (&deposit->ctx); GNUNET_free (deposit); } /* end of exchange_api_deposit.c */