diff options
Diffstat (limited to 'src/exchange/taler-exchange-httpd_refresh_melt.c')
| -rw-r--r-- | src/exchange/taler-exchange-httpd_refresh_melt.c | 1043 |
1 files changed, 1043 insertions, 0 deletions
diff --git a/src/exchange/taler-exchange-httpd_refresh_melt.c b/src/exchange/taler-exchange-httpd_refresh_melt.c new file mode 100644 index 000000000..1c4e5e864 --- /dev/null +++ b/src/exchange/taler-exchange-httpd_refresh_melt.c @@ -0,0 +1,1043 @@ +/* + This file is part of TALER + Copyright (C) 2014-2017 Inria & GNUnet e.V. + + TALER is free software; you can redistribute it and/or modify it under the + terms of the GNU Affero 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 Affero General Public License for more details. + + You should have received a copy of the GNU Affero General Public License along with + TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/> +*/ +/** + * @file taler-exchange-httpd_refresh_melt.c + * @brief Handle /refresh/melt requests + * @author Florian Dold + * @author Benedikt Mueller + * @author Christian Grothoff + */ +#include "platform.h" +#include <gnunet/gnunet_util_lib.h> +#include <jansson.h> +#include <microhttpd.h> +#include "taler-exchange-httpd_parsing.h" +#include "taler-exchange-httpd_mhd.h" +#include "taler-exchange-httpd_refresh_melt.h" +#include "taler-exchange-httpd_responses.h" +#include "taler-exchange-httpd_keystate.h" + + +/** + * How often should we retry a transaction before giving up + * (for transactions resulting in serialization/dead locks only). + */ +#define MAX_TRANSACTION_COMMIT_RETRIES 3 + +/** + * Code to begin a transaction, must be inline as we define a block + * that ends with #COMMIT_TRANSACTION() within which we perform a number + * of retries. Note that this code may call "return" internally, so + * it must be called within a function where any cleanup will be done + * by the caller. Furthermore, the function's return value must + * match that of a #TEH_RESPONSE_reply_internal_db_error() status code. + * + * @param session session handle + * @param connection connection handle + */ +#define START_TRANSACTION(session,connection) \ +{ /* start new scope, will be ended by COMMIT_TRANSACTION() */\ + unsigned int transaction_retries = 0; \ + enum GNUNET_DB_QueryStatus transaction_commit_result; \ +transaction_start_label: /* we will use goto for retries */ \ + if (GNUNET_OK != \ + TEH_plugin->start (TEH_plugin->cls, \ + session)) \ + { \ + GNUNET_break (0); \ + return TEH_RESPONSE_reply_internal_db_error (connection, \ + TALER_EC_DB_START_FAILED); \ + } + +/** + * Code to conclude a transaction, dual to #START_TRANSACTION(). Note + * that this code may call "return" internally, so it must be called + * within a function where any cleanup will be done by the caller. + * Furthermore, the function's return value must match that of a + * #TEH_RESPONSE_reply_internal_db_error() status code. + * + * @param session session handle + * @param connection connection handle + */ +#define COMMIT_TRANSACTION(session,connection) \ + transaction_commit_result = \ + TEH_plugin->commit (TEH_plugin->cls, \ + session); \ + if (GNUNET_DB_STATUS_HARD_ERROR == transaction_commit_result) \ + { \ + TALER_LOG_WARNING ("Transaction commit failed in %s\n", __FUNCTION__); \ + return TEH_RESPONSE_reply_commit_error (connection, \ + TALER_EC_DB_COMMIT_FAILED_HARD); \ + } \ + if (GNUNET_DB_STATUS_SOFT_ERROR == transaction_commit_result) \ + { \ + TALER_LOG_WARNING ("Transaction commit failed in %s\n", __FUNCTION__); \ + if (transaction_retries++ <= MAX_TRANSACTION_COMMIT_RETRIES) \ + goto transaction_start_label; \ + TALER_LOG_WARNING ("Transaction commit failed %u times in %s\n", \ + transaction_retries, \ + __FUNCTION__); \ + return TEH_RESPONSE_reply_commit_error (connection, \ + TALER_EC_DB_COMMIT_FAILED_ON_RETRY); \ + } \ +} /* end of scope opened by BEGIN_TRANSACTION */ + + +/** + * Code to include to retry a transaction, must only be used in between + * #START_TRANSACTION and #COMMIT_TRANSACTION. + * + * @param session session handle + * @param connection connection handle + */ +#define RETRY_TRANSACTION(session,connection) \ + do { \ + TEH_plugin->rollback (TEH_plugin->cls, \ + session); \ + if (transaction_retries++ <= MAX_TRANSACTION_COMMIT_RETRIES) \ + goto transaction_start_label; \ + TALER_LOG_WARNING ("Transaction commit failed %u times in %s\n", \ + transaction_retries, \ + __FUNCTION__); \ + return TEH_RESPONSE_reply_commit_error (connection, \ + TALER_EC_DB_COMMIT_FAILED_ON_RETRY); \ + } while (0) + + + + +/** + * @brief Details about a melt operation of an individual coin. + */ +struct TEH_DB_MeltDetails +{ + + /** + * Information about the coin being melted. + */ + struct TALER_CoinPublicInfo coin_info; + + /** + * Signature allowing the melt (using + * a `struct TALER_EXCHANGEDB_RefreshMeltConfirmSignRequestBody`) to sign over. + */ + struct TALER_CoinSpendSignatureP melt_sig; + + /** + * How much of the coin's value did the client allow to be melted? + * This amount includes the fees, so the final amount contributed + * to the melt is this value minus the fee for melting the coin. + */ + struct TALER_Amount melt_amount_with_fee; + + /** + * What fee is earned by the exchange? Set delayed during + * #verify_coin_public_info(). + */ + struct TALER_Amount melt_fee; +}; + + +/** + * Send a response for a failed "/refresh/melt" request. The + * transaction history of the given coin demonstrates that the + * @a residual value of the coin is below the @a requested + * contribution of the coin for the melt. Thus, the exchange + * refuses the melt operation. + * + * @param connection the connection to send the response to + * @param coin_pub public key of the coin + * @param coin_value original value of the coin + * @param tl transaction history for the coin + * @param requested how much this coin was supposed to contribute, including fee + * @param residual remaining value of the coin (after subtracting @a tl) + * @return a MHD result code + */ +static int +reply_refresh_melt_insufficient_funds (struct MHD_Connection *connection, + const struct TALER_CoinSpendPublicKeyP *coin_pub, + struct TALER_Amount coin_value, + struct TALER_EXCHANGEDB_TransactionList *tl, + struct TALER_Amount requested, + struct TALER_Amount residual) +{ + json_t *history; + + history = TEH_RESPONSE_compile_transaction_history (tl); + if (NULL == history) + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_HISTORY_DB_ERROR_INSUFFICIENT_FUNDS); + return TEH_RESPONSE_reply_json_pack (connection, + MHD_HTTP_FORBIDDEN, + "{s:s, s:I, s:o, s:o, s:o, s:o, s:o}", + "error", + "insufficient funds", + "code", + (json_int_t) TALER_EC_REFRESH_MELT_INSUFFICIENT_FUNDS, + "coin_pub", + GNUNET_JSON_from_data_auto (coin_pub), + "original_value", + TALER_JSON_from_amount (&coin_value), + "residual_value", + TALER_JSON_from_amount (&residual), + "requested_value", + TALER_JSON_from_amount (&requested), + "history", + history); +} + + +/** + * Send a response to a "/refresh/melt" request. + * + * @param connection the connection to send the response to + * @param session_hash hash of the refresh session + * @param noreveal_index which index will the client not have to reveal + * @return a MHD status code + */ +static int +reply_refresh_melt_success (struct MHD_Connection *connection, + const struct GNUNET_HashCode *session_hash, + uint16_t noreveal_index) +{ + struct TALER_RefreshMeltConfirmationPS body; + struct TALER_ExchangePublicKeyP pub; + struct TALER_ExchangeSignatureP sig; + json_t *sig_json; + + body.purpose.size = htonl (sizeof (struct TALER_RefreshMeltConfirmationPS)); + body.purpose.purpose = htonl (TALER_SIGNATURE_EXCHANGE_CONFIRM_MELT); + body.session_hash = *session_hash; + body.noreveal_index = htons (noreveal_index); + body.reserved = htons (0); + TEH_KS_sign (&body.purpose, + &pub, + &sig); + sig_json = GNUNET_JSON_from_data_auto (&sig); + GNUNET_assert (NULL != sig_json); + return TEH_RESPONSE_reply_json_pack (connection, + MHD_HTTP_OK, + "{s:i, s:o, s:o}", + "noreveal_index", (int) noreveal_index, + "exchange_sig", sig_json, + "exchange_pub", GNUNET_JSON_from_data_auto (&pub)); +} + + +/** + * Parse coin melt requests from a JSON object and write them to + * the database. + * + * @param connection the connection to send errors to + * @param session the database connection + * @param key_state the exchange's key state + * @param session_hash hash identifying the refresh session + * @param coin_details details about the coin being melted + * @param[out] meltp on success, set to melt details + * @return #GNUNET_OK on success, + * #GNUNET_NO if an error message was generated, + * #GNUNET_SYSERR on internal errors (no response generated) + */ +static int +refresh_check_melt (struct MHD_Connection *connection, + struct TALER_EXCHANGEDB_Session *session, + const struct TEH_KS_StateHandle *key_state, + const struct GNUNET_HashCode *session_hash, + const struct TEH_DB_MeltDetails *coin_details, + struct TALER_EXCHANGEDB_RefreshMelt *meltp) +{ + struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dk; + struct TALER_EXCHANGEDB_DenominationKeyInformationP *dki; + struct TALER_EXCHANGEDB_TransactionList *tl; + struct TALER_Amount coin_value; + struct TALER_Amount coin_residual; + struct TALER_Amount spent; + int res; + enum GNUNET_DB_QueryStatus qs; + + dk = TEH_KS_denomination_key_lookup (key_state, + &coin_details->coin_info.denom_pub, + TEH_KS_DKU_DEPOSIT); + if (NULL == dk) + return (MHD_YES == + TEH_RESPONSE_reply_internal_error (connection, + TALER_EC_REFRESH_MELT_DB_DENOMINATION_KEY_NOT_FOUND, + "denomination key no longer available while executing transaction")) + ? GNUNET_NO : GNUNET_SYSERR; + dki = &dk->issue; + TALER_amount_ntoh (&coin_value, + &dki->properties.value); + /* fee for THIS transaction; the melt amount includes the fee! */ + spent = coin_details->melt_amount_with_fee; + /* add historic transaction costs of this coin */ + qs = TEH_plugin->get_coin_transactions (TEH_plugin->cls, + session, + &coin_details->coin_info.coin_pub, + &tl); + (void) qs; /* FIXME #5010 */ + if (GNUNET_OK != + TEH_DB_calculate_transaction_list_totals (tl, + &spent, + &spent)) + { + GNUNET_break (0); + TEH_plugin->free_coin_transaction_list (TEH_plugin->cls, + tl); + return (MHD_YES == + TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_COIN_HISTORY_COMPUTATION_FAILED)) + ? GNUNET_NO : GNUNET_SYSERR; + } + /* Refuse to refresh when the coin's value is insufficient + for the cost of all transactions. */ + if (TALER_amount_cmp (&coin_value, + &spent) < 0) + { + GNUNET_assert (GNUNET_SYSERR != + TALER_amount_subtract (&coin_residual, + &spent, + &coin_details->melt_amount_with_fee)); + res = (MHD_YES == + reply_refresh_melt_insufficient_funds (connection, + &coin_details->coin_info.coin_pub, + coin_value, + tl, + coin_details->melt_amount_with_fee, + coin_residual)) + ? GNUNET_NO : GNUNET_SYSERR; + TEH_plugin->free_coin_transaction_list (TEH_plugin->cls, + tl); + return res; + } + TEH_plugin->free_coin_transaction_list (TEH_plugin->cls, + tl); + + meltp->coin = coin_details->coin_info; + meltp->coin_sig = coin_details->melt_sig; + meltp->session_hash = *session_hash; + meltp->amount_with_fee = coin_details->melt_amount_with_fee; + meltp->melt_fee = coin_details->melt_fee; + return GNUNET_OK; +} + + +/** + * Execute a "/refresh/melt". We have been given a list of valid + * coins and a request to melt them into the given + * @a refresh_session_pub. Check that the coins all have the + * required value left and if so, store that they have been + * melted and confirm the melting operation to the client. + * + * @param connection the MHD connection to handle + * @param session_hash hash code of the session the coins are melted into + * @param num_new_denoms number of entries in @a denom_pubs, size of y-dimension of @a commit_coin array + * @param denom_pubs public keys of the coins we want to withdraw in the end + * @param coin_melt_detail signature and (residual) value of the respective coin should be melted + * @param commit_coin 2d array of coin commitments (what the exchange is to sign + * once the "/refres/reveal" of cut and choose is done), + * x-dimension must be #TALER_CNC_KAPPA + * @param transfer_pubs array of transfer public keys (what the exchange is + * to return via "/refresh/link" to enable linkage in the + * future) of length #TALER_CNC_KAPPA + * @return MHD result code + */ +static int +execute_refresh_melt (struct MHD_Connection *connection, + const struct GNUNET_HashCode *session_hash, + unsigned int num_new_denoms, + const struct TALER_DenominationPublicKey *denom_pubs, + const struct TEH_DB_MeltDetails *coin_melt_detail, + struct TALER_EXCHANGEDB_RefreshCommitCoin *const* commit_coin, + const struct TALER_TransferPublicKeyP *transfer_pubs) +{ + struct TEH_KS_StateHandle *key_state; + struct TALER_EXCHANGEDB_RefreshSession refresh_session; + struct TALER_EXCHANGEDB_Session *session; + int res; + + if (NULL == (session = TEH_plugin->get_session (TEH_plugin->cls))) + { + GNUNET_break (0); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_DB_SETUP_FAILED); + } + START_TRANSACTION (session, connection); + res = TEH_plugin->get_refresh_session (TEH_plugin->cls, + session, + session_hash, + &refresh_session); + if (GNUNET_YES == res) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + res = reply_refresh_melt_success (connection, + session_hash, + refresh_session.noreveal_index); + return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES; + } + if (GNUNET_SYSERR == res) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_DB_FETCH_ERROR); + } + + /* store 'global' session data */ + refresh_session.num_newcoins = num_new_denoms; + refresh_session.noreveal_index + = GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_STRONG, + TALER_CNC_KAPPA); + key_state = TEH_KS_acquire (); + if (GNUNET_OK != + (res = refresh_check_melt (connection, + session, + key_state, + session_hash, + coin_melt_detail, + &refresh_session.melt))) + { + TEH_KS_release (key_state); + TEH_plugin->rollback (TEH_plugin->cls, + session); + return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES; + } + TEH_KS_release (key_state); + + if (GNUNET_OK != + (res = TEH_plugin->create_refresh_session (TEH_plugin->cls, + session, + session_hash, + &refresh_session))) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_DB_STORE_SESSION_ERROR); + } + + /* store requested new denominations */ + if (GNUNET_OK != + TEH_plugin->insert_refresh_order (TEH_plugin->cls, + session, + session_hash, + num_new_denoms, + denom_pubs)) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_DB_STORE_ORDER_ERROR); + } + + if (GNUNET_OK != + TEH_plugin->insert_refresh_commit_coins (TEH_plugin->cls, + session, + session_hash, + num_new_denoms, + commit_coin[refresh_session.noreveal_index])) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_DB_STORE_ORDER_ERROR); + } + if (GNUNET_OK != + TEH_plugin->insert_refresh_transfer_public_key (TEH_plugin->cls, + session, + session_hash, + &transfer_pubs[refresh_session.noreveal_index])) + { + TEH_plugin->rollback (TEH_plugin->cls, + session); + return TEH_RESPONSE_reply_internal_db_error (connection, + TALER_EC_REFRESH_MELT_DB_STORE_TRANSFER_ERROR); + } + + COMMIT_TRANSACTION (session, connection); + return reply_refresh_melt_success (connection, + session_hash, + refresh_session.noreveal_index); +} + + +/** + * Handle a "/refresh/melt" request after the main JSON parsing has happened. + * We now need to validate the coins being melted and the session signature + * and then hand things of to execute the melt operation. + * + * @param connection the MHD connection to handle + * @param num_new_denoms number of coins to be created, size of y-dimension of @a commit_link array + * @param denom_pubs array of @a num_new_denoms keys + * @param coin_melt_details melting details + * @param session_hash hash over the data that the client commits to + * @param commit_coin 2d array of coin commitments (what the exchange is to sign + * once the "/refres/reveal" of cut and choose is done) + * @param transfer_pubs array of transfer public keys (which the exchange is + * to return via "/refresh/link" to enable linkage in the + * future) of length #TALER_CNC_KAPPA + * @return MHD result code + */ +static int +handle_refresh_melt_binary (struct MHD_Connection *connection, + unsigned int num_new_denoms, + const struct TALER_DenominationPublicKey *denom_pubs, + const struct TEH_DB_MeltDetails *coin_melt_details, + const struct GNUNET_HashCode *session_hash, + struct TALER_EXCHANGEDB_RefreshCommitCoin *const* commit_coin, + const struct TALER_TransferPublicKeyP *transfer_pubs) +{ + unsigned int i; + struct TEH_KS_StateHandle *key_state; + struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dk; + struct TALER_EXCHANGEDB_DenominationKeyInformationP *dki; + struct TALER_Amount cost; + struct TALER_Amount total_cost; + struct TALER_Amount value; + struct TALER_Amount fee_withdraw; + struct TALER_Amount fee_melt; + struct TALER_Amount total_melt; + + GNUNET_log (GNUNET_ERROR_TYPE_DEBUG, + "/refresh/melt request for session %s\n", + GNUNET_h2s (session_hash)); + + GNUNET_assert (GNUNET_OK == + TALER_amount_get_zero (TEH_exchange_currency_string, + &total_cost)); + key_state = TEH_KS_acquire (); + for (i=0;i<num_new_denoms;i++) + { + dk = TEH_KS_denomination_key_lookup (key_state, + &denom_pubs[i], + TEH_KS_DKU_WITHDRAW); + if (NULL == dk) + { + GNUNET_break_op (0); + TEH_KS_release (key_state); + return TEH_RESPONSE_reply_arg_invalid (connection, + TALER_EC_REFRESH_MELT_FRESH_DENOMINATION_KEY_NOT_FOUND, + "new_denoms"); + } + dki = &dk->issue; + TALER_amount_ntoh (&value, + &dki->properties.value); + TALER_amount_ntoh (&fee_withdraw, + &dki->properties.fee_withdraw); + if ( (GNUNET_OK != + TALER_amount_add (&cost, + &value, + &fee_withdraw)) || + (GNUNET_OK != + TALER_amount_add (&total_cost, + &cost, + &total_cost)) ) + { + GNUNET_break_op (0); + TEH_KS_release (key_state); + return TEH_RESPONSE_reply_internal_error (connection, + TALER_EC_REFRESH_MELT_COST_CALCULATION_OVERFLOW, + "cost calculation failure"); + } + } + + dk = TEH_KS_denomination_key_lookup (key_state, + &coin_melt_details->coin_info.denom_pub, + TEH_KS_DKU_DEPOSIT); + if (NULL == dk) + { + GNUNET_break (0); + return TEH_RESPONSE_reply_arg_unknown (connection, + TALER_EC_REFRESH_MELT_DENOMINATION_KEY_NOT_FOUND, + "denom_pub"); + } + dki = &dk->issue; + TALER_amount_ntoh (&fee_melt, + &dki->properties.fee_refresh); + if (GNUNET_OK != + TALER_amount_subtract (&total_melt, + &coin_melt_details->melt_amount_with_fee, + &fee_melt)) + { + GNUNET_break_op (0); + TEH_KS_release (key_state); + return TEH_RESPONSE_reply_external_error (connection, + TALER_EC_REFRESH_MELT_FEES_EXCEED_CONTRIBUTION, + "Melt contribution below melting fee"); + } + TEH_KS_release (key_state); + if (0 != + TALER_amount_cmp (&total_cost, + &total_melt)) + { + GNUNET_break_op (0); + /* We require total value of coins being melted and + total value of coins being generated to match! */ + return TEH_RESPONSE_reply_json_pack (connection, + MHD_HTTP_BAD_REQUEST, + "{s:s, s:I}", + "error", "value mismatch", + "code", (json_int_t) TALER_EC_REFRESH_MELT_FEES_MISSMATCH); + } + return execute_refresh_melt (connection, + session_hash, + num_new_denoms, + denom_pubs, + coin_melt_details, + commit_coin, + transfer_pubs); +} + + +/** + * Extract public coin information from a JSON object. + * + * @param connection the connection to send error responses to + * @param coin_info the JSON object to extract the coin info from + * @param[out] r_melt_detail set to details about the coin's melting permission (if valid) + * @return #GNUNET_YES if coin public info in JSON was valid + * #GNUNET_NO JSON was invalid, response was generated + * #GNUNET_SYSERR on internal error + */ +static int +get_coin_public_info (struct MHD_Connection *connection, + const json_t *coin_info, + struct TEH_DB_MeltDetails *r_melt_detail) +{ + int ret; + struct TALER_CoinSpendSignatureP melt_sig; + struct TALER_DenominationSignature sig; + struct TALER_DenominationPublicKey pk; + struct TALER_Amount amount; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_fixed_auto ("coin_pub", &r_melt_detail->coin_info.coin_pub), + TALER_JSON_spec_denomination_signature ("denom_sig", &sig), + TALER_JSON_spec_denomination_public_key ("denom_pub", &pk), + GNUNET_JSON_spec_fixed_auto ("confirm_sig", &melt_sig), + TALER_JSON_spec_amount ("value_with_fee", &amount), + GNUNET_JSON_spec_end () + }; + + ret = TEH_PARSE_json_data (connection, + coin_info, + spec); + if (GNUNET_OK != ret) + { + GNUNET_break_op (0); + return ret; + } + /* check exchange signature on the coin */ + r_melt_detail->coin_info.denom_sig = sig; + r_melt_detail->coin_info.denom_pub = pk; + if (GNUNET_OK != + TALER_test_coin_valid (&r_melt_detail->coin_info)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + r_melt_detail->coin_info.denom_sig.rsa_signature = NULL; + r_melt_detail->coin_info.denom_pub.rsa_public_key = NULL; + return (MHD_YES == + TEH_RESPONSE_reply_signature_invalid (connection, + TALER_EC_REFRESH_MELT_DENOMINATION_SIGNATURE_INVALID, + "denom_sig")) + ? GNUNET_NO : GNUNET_SYSERR; + } + r_melt_detail->melt_sig = melt_sig; + r_melt_detail->melt_amount_with_fee = amount; + return GNUNET_OK; +} + + +/** + * Verify that the signature shows that this coin is to be melted into + * the given @a session_hash melting session, and that this is a valid + * coin (we know the denomination key and the signature on it is + * valid). Essentially, this does all of the per-coin checks that can + * be done before the transaction starts. + * + * @param connection the connection to send error responses to + * @param session_hash hash over refresh session the coin is melted into + * @param[in,out] melt_detail details about the coin's melting permission, + * the `melt_fee` is updated + * @return #GNUNET_YES if coin public info in JSON was valid + * #GNUNET_NO JSON was invalid, response was generated + * #GNUNET_SYSERR on internal error + */ +static int +verify_coin_public_info (struct MHD_Connection *connection, + const struct GNUNET_HashCode *session_hash, + struct TEH_DB_MeltDetails *melt_detail) +{ + struct TALER_RefreshMeltCoinAffirmationPS body; + struct TEH_KS_StateHandle *key_state; + struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dki; + struct TALER_Amount fee_refresh; + + /* FIXME: we lookup the dki twice during /refresh/melt. + This should be avoided. */ + key_state = TEH_KS_acquire (); + dki = TEH_KS_denomination_key_lookup (key_state, + &melt_detail->coin_info.denom_pub, + TEH_KS_DKU_DEPOSIT); + if (NULL == dki) + { + TEH_KS_release (key_state); + TALER_LOG_WARNING ("Unknown denomination key in /refresh/melt request\n"); + return TEH_RESPONSE_reply_arg_unknown (connection, + TALER_EC_REFRESH_MELT_DENOMINATION_KEY_NOT_FOUND, + "denom_pub"); + } + TALER_amount_ntoh (&fee_refresh, + &dki->issue.properties.fee_refresh); + melt_detail->melt_fee = fee_refresh; + body.purpose.size = htonl (sizeof (struct TALER_RefreshMeltCoinAffirmationPS)); + body.purpose.purpose = htonl (TALER_SIGNATURE_WALLET_COIN_MELT); + body.session_hash = *session_hash; + TALER_amount_hton (&body.amount_with_fee, + &melt_detail->melt_amount_with_fee); + TALER_amount_hton (&body.melt_fee, + &fee_refresh); + body.coin_pub = melt_detail->coin_info.coin_pub; + if (TALER_amount_cmp (&fee_refresh, + &melt_detail->melt_amount_with_fee) > 0) + { + GNUNET_break_op (0); + TEH_KS_release (key_state); + return (MHD_YES == + TEH_RESPONSE_reply_external_error (connection, + TALER_EC_REFRESH_MELT_AMOUNT_INSUFFICIENT, + "melt amount smaller than melting fee")) + ? GNUNET_NO : GNUNET_SYSERR; + } + + TEH_KS_release (key_state); + if (GNUNET_OK != + GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_COIN_MELT, + &body.purpose, + &melt_detail->melt_sig.eddsa_signature, + &melt_detail->coin_info.coin_pub.eddsa_pub)) + { + GNUNET_break_op (0); + if (MHD_YES != + TEH_RESPONSE_reply_signature_invalid (connection, + TALER_EC_REFRESH_MELT_COIN_SIGNATURE_INVALID, + "confirm_sig")) + return GNUNET_SYSERR; + return GNUNET_NO; + } + return GNUNET_OK; +} + + +/** + * Release memory from the @a commit_coin array. + * + * @param commit_coin array to release + * @param kappa size of 1st dimension + * @param num_new_coins size of 2nd dimension + */ +static void +free_commit_coins (struct TALER_EXCHANGEDB_RefreshCommitCoin **commit_coin, + unsigned int kappa, + unsigned int num_new_coins) +{ + unsigned int i; + unsigned int j; + + for (i=0;i<kappa;i++) + { + if (NULL == commit_coin[i]) + break; + for (j=0;j<num_new_coins;j++) + GNUNET_free_non_null (commit_coin[i][j].coin_ev); + GNUNET_free (commit_coin[i]); + } +} + + +/** + * Handle a "/refresh/melt" request after the first parsing has happened. + * We now need to validate the coins being melted and the session signature + * and then hand things of to execute the melt operation. This function + * parses the JSON arrays and then passes processing on to + * #handle_refresh_melt_binary(). + * + * @param connection the MHD connection to handle + * @param new_denoms array of denomination keys + * @param melt_coin coin to melt + * @param transfer_pubs #TALER_CNC_KAPPA-dimensional array of transfer keys + * @param coin_evs #TALER_CNC_KAPPA-dimensional array of envelopes to sign + * @return MHD result code + */ +static int +handle_refresh_melt_json (struct MHD_Connection *connection, + const json_t *new_denoms, + const json_t *melt_coin, + const json_t *transfer_pubs, + const json_t *coin_evs) +{ + int res; + unsigned int i; + unsigned int j; + struct TALER_DenominationPublicKey *denom_pubs; + unsigned int num_newcoins; + struct TEH_DB_MeltDetails coin_melt_details; + struct GNUNET_HashCode session_hash; + struct GNUNET_HashContext *hash_context; + struct TALER_EXCHANGEDB_RefreshCommitCoin *commit_coin[TALER_CNC_KAPPA]; + struct TALER_TransferPublicKeyP transfer_pub[TALER_CNC_KAPPA]; + + /* For the signature check, we hash most of the inputs together + (except for the signatures on the coins). */ + hash_context = GNUNET_CRYPTO_hash_context_start (); + + for (i = 0; i < TALER_CNC_KAPPA; i++) + { + struct GNUNET_JSON_Specification trans_spec[] = { + GNUNET_JSON_spec_fixed_auto (NULL, &transfer_pub[i]), + GNUNET_JSON_spec_end () + }; + + res = TEH_PARSE_json_array (connection, + transfer_pubs, + trans_spec, + i, -1); + if (GNUNET_OK != res) + { + GNUNET_break_op (0); + res = (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES; + goto cleanup_hc; + } + GNUNET_CRYPTO_hash_context_read (hash_context, + &transfer_pub[i], + sizeof (struct TALER_TransferPublicKeyP)); + } + + + num_newcoins = json_array_size (new_denoms); + denom_pubs = GNUNET_new_array (num_newcoins, + struct TALER_DenominationPublicKey); + for (i=0;i<num_newcoins;i++) + { + char *buf; + size_t buf_size; + struct GNUNET_JSON_Specification spec[] = { + TALER_JSON_spec_denomination_public_key (NULL, + &denom_pubs[i]), + GNUNET_JSON_spec_end () + }; + + res = TEH_PARSE_json_array (connection, + new_denoms, + spec, + i, -1); + if (GNUNET_OK != res) + { + res = (GNUNET_NO == res) ? MHD_YES : MHD_NO; + goto cleanup_denoms; + } + buf_size = GNUNET_CRYPTO_rsa_public_key_encode (denom_pubs[i].rsa_public_key, + &buf); + GNUNET_CRYPTO_hash_context_read (hash_context, + buf, + buf_size); + GNUNET_free (buf); + } + + { + /* decode JSON data on coin to melt */ + struct TALER_AmountNBO melt_amount; + + res = get_coin_public_info (connection, + melt_coin, + &coin_melt_details); + if (GNUNET_OK != res) + { + GNUNET_break_op (0); + res = (GNUNET_NO == res) ? MHD_YES : MHD_NO; + goto cleanup_melt_details; + } + TALER_amount_hton (&melt_amount, + &coin_melt_details.melt_amount_with_fee); + GNUNET_CRYPTO_hash_context_read (hash_context, + &coin_melt_details.coin_info.coin_pub, + sizeof (struct TALER_CoinSpendPublicKeyP)); + GNUNET_CRYPTO_hash_context_read (hash_context, + &melt_amount, + sizeof (struct TALER_AmountNBO)); + } + + /* parse JSON arrays into binary arrays and hash everything + together for the signature check */ + memset (commit_coin, + 0, + sizeof (commit_coin)); + for (i = 0; i < TALER_CNC_KAPPA; i++) + { + commit_coin[i] = GNUNET_new_array (num_newcoins, + struct TALER_EXCHANGEDB_RefreshCommitCoin); + for (j = 0; j < num_newcoins; j++) + { + struct TALER_EXCHANGEDB_RefreshCommitCoin *rcc = &commit_coin[i][j]; + struct GNUNET_JSON_Specification coin_spec[] = { + GNUNET_JSON_spec_varsize (NULL, + (void **) &rcc->coin_ev, + &rcc->coin_ev_size), + GNUNET_JSON_spec_end () + }; + + res = TEH_PARSE_json_array (connection, + coin_evs, + coin_spec, + i, j, -1); + if (GNUNET_OK != res) + { + GNUNET_break_op (0); + res = (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES; + goto cleanup; + } + + GNUNET_CRYPTO_hash_context_read (hash_context, + rcc->coin_ev, + rcc->coin_ev_size); + } + } + + GNUNET_CRYPTO_hash_context_finish (hash_context, + &session_hash); + hash_context = NULL; + /* verify signature on coins to melt */ + res = verify_coin_public_info (connection, + &session_hash, + &coin_melt_details); + if (GNUNET_OK != res) + { + GNUNET_break_op (0); + res = (GNUNET_NO == res) ? MHD_YES : MHD_NO; + goto cleanup; + } + + /* execute commit */ + res = handle_refresh_melt_binary (connection, + num_newcoins, + denom_pubs, + &coin_melt_details, + &session_hash, + commit_coin, + transfer_pub); + cleanup: + free_commit_coins (commit_coin, + TALER_CNC_KAPPA, + num_newcoins); + cleanup_melt_details: + if (NULL != coin_melt_details.coin_info.denom_pub.rsa_public_key) + GNUNET_CRYPTO_rsa_public_key_free (coin_melt_details.coin_info.denom_pub.rsa_public_key); + if (NULL != coin_melt_details.coin_info.denom_sig.rsa_signature) + GNUNET_CRYPTO_rsa_signature_free (coin_melt_details.coin_info.denom_sig.rsa_signature); + cleanup_denoms: + if (NULL != denom_pubs) + { + for (j=0;j<num_newcoins;j++) + if (NULL != denom_pubs[j].rsa_public_key) + GNUNET_CRYPTO_rsa_public_key_free (denom_pubs[j].rsa_public_key); + GNUNET_free (denom_pubs); + } + cleanup_hc: + if (NULL != hash_context) + GNUNET_CRYPTO_hash_context_abort (hash_context); + return res; +} + + +/** + * Handle a "/refresh/melt" request. Parses the request into the JSON + * components and then hands things of to #handle_refresh_melt_json() + * to validate the melted coins, the signature and execute the melt + * using TEH_DB_execute_refresh_melt(). + * + * @param rh context of the handler + * @param connection the MHD connection to handle + * @param[in,out] connection_cls the connection's closure (can be updated) + * @param upload_data upload data + * @param[in,out] upload_data_size number of bytes (left) in @a upload_data + * @return MHD result code + */ +int +TEH_REFRESH_handler_refresh_melt (struct TEH_RequestHandler *rh, + struct MHD_Connection *connection, + void **connection_cls, + const char *upload_data, + size_t *upload_data_size) +{ + json_t *root; + json_t *new_denoms; + json_t *melt_coin; + json_t *coin_evs; + json_t *transfer_pubs; + int res; + struct GNUNET_JSON_Specification spec[] = { + GNUNET_JSON_spec_json ("new_denoms", &new_denoms), + GNUNET_JSON_spec_json ("melt_coin", &melt_coin), + GNUNET_JSON_spec_json ("coin_evs", &coin_evs), + GNUNET_JSON_spec_json ("transfer_pubs", &transfer_pubs), + GNUNET_JSON_spec_end () + }; + + res = TEH_PARSE_post_json (connection, + connection_cls, + upload_data, + upload_data_size, + &root); + if (GNUNET_SYSERR == res) + return MHD_NO; + if ( (GNUNET_NO == res) || (NULL == root) ) + return MHD_YES; + + res = TEH_PARSE_json_data (connection, + root, + spec); + json_decref (root); + if (GNUNET_OK != res) + return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES; + + /* Determine dimensionality of the request (kappa, #old and #new coins) */ + if (TALER_CNC_KAPPA != json_array_size (coin_evs)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return TEH_RESPONSE_reply_arg_invalid (connection, + TALER_EC_REFRESH_MELT_CNC_COIN_ARRAY_SIZE_INVALID, + "coin_evs"); + } + if (TALER_CNC_KAPPA != json_array_size (transfer_pubs)) + { + GNUNET_break_op (0); + GNUNET_JSON_parse_free (spec); + return TEH_RESPONSE_reply_arg_invalid (connection, + TALER_EC_REFRESH_MELT_CNC_TRANSFER_ARRAY_SIZE_INVALID, + "transfer_pubs"); + } + res = handle_refresh_melt_json (connection, + new_denoms, + melt_coin, + transfer_pubs, + coin_evs); + GNUNET_JSON_parse_free (spec); + return res; +} + + +/* end of taler-exchange-httpd_refresh_melt.c */ |