/*
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 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
*/
/**
* @file taler-exchange-httpd_withdraw.c
* @brief Handle /reserves/$RESERVE_PUB/withdraw requests
* @author Florian Dold
* @author Benedikt Mueller
* @author Christian Grothoff
*/
#include "platform.h"
#include
#include
#include "taler_json_lib.h"
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_withdraw.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keys.h"
/**
* Send reserve history information to client with the
* message that we have insufficient funds for the
* requested withdraw operation.
*
* @param connection connection to the client
* @param ebalance expected balance based on our database
* @param withdraw_amount amount that the client requested to withdraw
* @param rh reserve history to return
* @return MHD result code
*/
static MHD_RESULT
reply_withdraw_insufficient_funds (
struct MHD_Connection *connection,
const struct TALER_Amount *ebalance,
const struct TALER_Amount *withdraw_amount,
const struct TALER_EXCHANGEDB_ReserveHistory *rh)
{
json_t *json_history;
json_history = TEH_RESPONSE_compile_reserve_history (rh);
if (NULL == json_history)
return TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_EXCHANGE_WITHDRAW_HISTORY_ERROR_INSUFFICIENT_FUNDS,
NULL);
return TALER_MHD_REPLY_JSON_PACK (
connection,
MHD_HTTP_CONFLICT,
TALER_JSON_pack_ec (TALER_EC_EXCHANGE_WITHDRAW_INSUFFICIENT_FUNDS),
TALER_JSON_pack_amount ("balance",
ebalance),
TALER_JSON_pack_amount ("requested_amount",
withdraw_amount),
GNUNET_JSON_pack_array_steal ("history",
json_history));
}
/**
* Context for #withdraw_transaction.
*/
struct WithdrawContext
{
/**
* Hash of the (blinded) message to be signed by the Exchange.
*/
struct TALER_BlindedCoinHashP h_coin_envelope;
/**
* Value of the coin being exchanged (matching the denomination key)
* plus the transaction fee. We include this in what is being
* signed so that we can verify a reserve's remaining total balance
* without needing to access the respective denomination key
* information each time.
*/
struct TALER_Amount amount_with_fee;
/**
* Blinded planchet.
*/
struct TALER_BlindedPlanchet blinded_planchet;
/**
* Set to the resulting signed coin data to be returned to the client.
*/
struct TALER_EXCHANGEDB_CollectableBlindcoin collectable;
/**
* KYC status for the operation.
*/
struct TALER_EXCHANGEDB_KycStatus kyc;
};
/**
* Function implementing withdraw transaction. Runs the
* transaction logic; IF it returns a non-error code, the transaction
* logic MUST NOT queue a MHD response. IF it returns an hard error,
* the transaction logic MUST queue a MHD response and set @a mhd_ret.
* IF it returns the soft error code, the function MAY be called again
* to retry and MUST not queue a MHD response.
*
* Note that "wc->collectable.sig" is set before entering this function as we
* signed before entering the transaction.
*
* @param cls a `struct WithdrawContext *`
* @param connection MHD request which triggered the transaction
* @param[out] mhd_ret set to MHD response status for @a connection,
* if transaction failed (!)
* @return transaction status
*/
static enum GNUNET_DB_QueryStatus
withdraw_transaction (void *cls,
struct MHD_Connection *connection,
MHD_RESULT *mhd_ret)
{
struct WithdrawContext *wc = cls;
enum GNUNET_DB_QueryStatus qs;
bool found = false;
bool balance_ok = false;
struct GNUNET_TIME_Timestamp now;
uint64_t ruuid;
const struct TALER_CsNonce *nonce;
const struct TALER_BlindedPlanchet *bp;
now = GNUNET_TIME_timestamp_get ();
bp = &wc->blinded_planchet;
nonce =
(TALER_DENOMINATION_CS == bp->cipher)
? &bp->details.cs_blinded_planchet.nonce
: NULL;
qs = TEH_plugin->do_withdraw (TEH_plugin->cls,
nonce,
&wc->collectable,
now,
&found,
&balance_ok,
&wc->kyc,
&ruuid);
if (0 > qs)
{
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"do_withdraw");
return qs;
}
if (! found)
{
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_NOT_FOUND,
TALER_EC_EXCHANGE_WITHDRAW_RESERVE_UNKNOWN,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
}
if (! balance_ok)
{
struct TALER_EXCHANGEDB_ReserveHistory *rh;
struct TALER_Amount balance;
TEH_plugin->rollback (TEH_plugin->cls);
// FIXME: maybe start read-committed here?
if (GNUNET_OK !=
TEH_plugin->start (TEH_plugin->cls,
"get_reserve_history on insufficient balance"))
{
GNUNET_break (0);
if (NULL != mhd_ret)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_START_FAILED,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
}
/* The reserve does not have the required amount (actual
* amount + withdraw fee) */
qs = TEH_plugin->get_reserve_history (TEH_plugin->cls,
&wc->collectable.reserve_pub,
&balance,
&rh);
if (NULL == rh)
{
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"reserve history");
return GNUNET_DB_STATUS_HARD_ERROR;
}
*mhd_ret = reply_withdraw_insufficient_funds (
connection,
&balance,
&wc->collectable.amount_with_fee,
rh);
TEH_plugin->free_reserve_history (TEH_plugin->cls,
rh);
return GNUNET_DB_STATUS_HARD_ERROR;
}
if ( (TEH_KYC_NONE != TEH_kyc_config.mode) &&
(! wc->kyc.ok) &&
(TALER_EXCHANGEDB_KYC_W2W == wc->kyc.type) )
{
/* Wallet-to-wallet payments _always_ require KYC */
*mhd_ret = TALER_MHD_REPLY_JSON_PACK (
connection,
MHD_HTTP_ACCEPTED,
GNUNET_JSON_pack_uint64 ("payment_target_uuid",
wc->kyc.payment_target_uuid));
return GNUNET_DB_STATUS_HARD_ERROR;
}
if ( (TEH_KYC_NONE != TEH_kyc_config.mode) &&
(! wc->kyc.ok) &&
(TALER_EXCHANGEDB_KYC_WITHDRAW == wc->kyc.type) &&
(! GNUNET_TIME_relative_is_zero (TEH_kyc_config.withdraw_period)) )
{
/* Withdraws require KYC if above threshold */
enum GNUNET_DB_QueryStatus qs2;
bool below_limit;
qs2 = TEH_plugin->do_withdraw_limit_check (
TEH_plugin->cls,
ruuid,
GNUNET_TIME_absolute_subtract (now.abs_time,
TEH_kyc_config.withdraw_period),
&TEH_kyc_config.withdraw_limit,
&below_limit);
if (0 > qs2)
{
GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs2);
if (GNUNET_DB_STATUS_HARD_ERROR == qs2)
*mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"do_withdraw_limit_check");
return qs2;
}
if (! below_limit)
{
*mhd_ret = TALER_MHD_REPLY_JSON_PACK (
connection,
MHD_HTTP_ACCEPTED,
GNUNET_JSON_pack_uint64 ("payment_target_uuid",
wc->kyc.payment_target_uuid));
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
return qs;
}
/**
* Check if the @a rc is replayed and we already have an
* answer. If so, replay the existing answer and return the
* HTTP response.
*
* @param rc request context
* @param[in,out] wc parsed request data
* @param[out] mret HTTP status, set if we return true
* @return true if the request is idempotent with an existing request
* false if we did not find the request in the DB and did not set @a mret
*/
static bool
check_request_idempotent (struct TEH_RequestContext *rc,
struct WithdrawContext *wc,
MHD_RESULT *mret)
{
enum GNUNET_DB_QueryStatus qs;
qs = TEH_plugin->get_withdraw_info (TEH_plugin->cls,
&wc->h_coin_envelope,
&wc->collectable);
if (0 > qs)
{
GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mret = TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"get_withdraw_info");
return true; /* well, kind-of */
}
if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
return false;
/* generate idempotent reply */
*mret = TALER_MHD_REPLY_JSON_PACK (
rc->connection,
MHD_HTTP_OK,
TALER_JSON_pack_blinded_denom_sig ("ev_sig",
&wc->collectable.sig));
TALER_blinded_denom_sig_free (&wc->collectable.sig);
return true;
}
MHD_RESULT
TEH_handler_withdraw (struct TEH_RequestContext *rc,
const struct TALER_ReservePublicKeyP *reserve_pub,
const json_t *root)
{
struct WithdrawContext wc;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto ("reserve_sig",
&wc.collectable.reserve_sig),
GNUNET_JSON_spec_fixed_auto ("denom_pub_hash",
&wc.collectable.denom_pub_hash),
TALER_JSON_spec_blinded_planchet ("coin_ev",
&wc.blinded_planchet),
GNUNET_JSON_spec_end ()
};
enum TALER_ErrorCode ec;
struct TEH_DenominationKey *dk;
memset (&wc,
0,
sizeof (wc));
wc.collectable.reserve_pub = *reserve_pub;
{
enum GNUNET_GenericReturnValue res;
res = TALER_MHD_parse_json_data (rc->connection,
root,
spec);
if (GNUNET_OK != res)
return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
}
{
MHD_RESULT mret;
struct TEH_KeyStateHandle *ksh;
ksh = TEH_keys_get_state ();
if (NULL == ksh)
{
if (! check_request_idempotent (rc,
&wc,
&mret))
{
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING,
NULL);
}
GNUNET_JSON_parse_free (spec);
return mret;
}
dk = TEH_keys_denomination_by_hash2 (ksh,
&wc.collectable.denom_pub_hash,
NULL,
NULL);
if (NULL == dk)
{
if (! check_request_idempotent (rc,
&wc,
&mret))
{
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_unknown_denom_pub_hash (
rc->connection,
&wc.collectable.denom_pub_hash);
}
GNUNET_JSON_parse_free (spec);
return mret;
}
if (GNUNET_TIME_absolute_is_past (dk->meta.expire_withdraw.abs_time))
{
/* This denomination is past the expiration time for withdraws */
if (! check_request_idempotent (rc,
&wc,
&mret))
{
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.collectable.denom_pub_hash,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_EXPIRED,
"WITHDRAW");
}
GNUNET_JSON_parse_free (spec);
return mret;
}
if (GNUNET_TIME_absolute_is_future (dk->meta.start.abs_time))
{
/* This denomination is not yet valid, no need to check
for idempotency! */
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.collectable.denom_pub_hash,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_VALIDITY_IN_FUTURE,
"WITHDRAW");
}
if (dk->recoup_possible)
{
/* This denomination has been revoked */
if (! check_request_idempotent (rc,
&wc,
&mret))
{
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.collectable.denom_pub_hash,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_REVOKED,
"WITHDRAW");
}
GNUNET_JSON_parse_free (spec);
return mret;
}
if (dk->denom_pub.cipher != wc.blinded_planchet.cipher)
{
/* denomination cipher and blinded planchet cipher not the same */
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_EXCHANGE_GENERIC_CIPHER_MISMATCH,
NULL);
}
}
if (0 >
TALER_amount_add (&wc.collectable.amount_with_fee,
&dk->meta.value,
&dk->meta.fees.withdraw))
{
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_EXCHANGE_WITHDRAW_AMOUNT_FEE_OVERFLOW,
NULL);
}
if (GNUNET_OK !=
TALER_coin_ev_hash (&wc.blinded_planchet,
&wc.collectable.denom_pub_hash,
&wc.collectable.h_coin_envelope))
{
GNUNET_break (0);
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
NULL);
}
TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
if (GNUNET_OK !=
TALER_wallet_withdraw_verify (&wc.collectable.denom_pub_hash,
&wc.collectable.amount_with_fee,
&wc.collectable.h_coin_envelope,
&wc.collectable.reserve_pub,
&wc.collectable.reserve_sig))
{
GNUNET_break_op (0);
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_FORBIDDEN,
TALER_EC_EXCHANGE_WITHDRAW_RESERVE_SIGNATURE_INVALID,
NULL);
}
/* Sign before transaction! */
ec = TEH_keys_denomination_sign_withdraw (
&wc.collectable.denom_pub_hash,
&wc.blinded_planchet,
&wc.collectable.sig);
if (TALER_EC_NONE != ec)
{
GNUNET_break (0);
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_ec (rc->connection,
ec,
NULL);
}
/* run transaction */
{
MHD_RESULT mhd_ret;
if (GNUNET_OK !=
TEH_DB_run_transaction (rc->connection,
"run withdraw",
TEH_MT_REQUEST_WITHDRAW,
&mhd_ret,
&withdraw_transaction,
&wc))
{
/* Even if #withdraw_transaction() failed, it may have created a signature
(or we might have done it optimistically above). */
TALER_blinded_denom_sig_free (&wc.collectable.sig);
GNUNET_JSON_parse_free (spec);
return mhd_ret;
}
}
/* Clean up and send back final response */
GNUNET_JSON_parse_free (spec);
{
MHD_RESULT ret;
ret = TALER_MHD_REPLY_JSON_PACK (
rc->connection,
MHD_HTTP_OK,
TALER_JSON_pack_blinded_denom_sig ("ev_sig",
&wc.collectable.sig));
TALER_blinded_denom_sig_free (&wc.collectable.sig);
return ret;
}
}
/* end of taler-exchange-httpd_withdraw.c */