/*
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"
/**
* Perform RSA signature before checking with the database?
* Reduces time spent in transaction, but may cause us to
* waste CPU time if DB check fails.
*/
#define OPTIMISTIC_SIGN 1
/**
* 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 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_EXCHANGEDB_ReserveHistory *rh)
{
json_t *json_history;
struct TALER_Amount balance;
json_history = TEH_RESPONSE_compile_reserve_history (rh,
&balance);
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);
if (0 !=
TALER_amount_cmp (&balance,
ebalance))
{
GNUNET_break (0);
json_decref (json_history);
return TALER_MHD_reply_with_error (connection,
MHD_HTTP_INTERNAL_SERVER_ERROR,
TALER_EC_GENERIC_DB_INVARIANT_FAILURE,
"reserve balance corrupt");
}
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",
&balance),
GNUNET_JSON_pack_array_steal ("history",
json_history));
}
/**
* Context for #withdraw_transaction.
*/
struct WithdrawContext
{
/**
* Details about the withdrawal request.
*/
struct TALER_WithdrawRequestPS wsrd;
/**
* Value of the coin plus withdraw fee.
*/
struct TALER_Amount amount_required;
/**
* Hash of the denomination public key.
*/
struct TALER_DenominationHash denom_pub_hash;
/**
* Signature over the request.
*/
struct TALER_ReserveSignatureP signature;
/**
* Blinded planchet.
*/
char *blinded_msg;
/**
* Number of bytes in @e blinded_msg.
*/
size_t blinded_msg_len;
/**
* 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;
/**
* Set to true if the operation was denied due to
* failing @e kyc checks.
*/
bool kyc_denied;
};
/**
* Function called with another amount that was
* already withdrawn. Accumulates all amounts in
* @a cls.
*
* @param[in,out] cls a `struct TALER_Amount`
* @param val value to add to @a cls
*/
static void
accumulate_withdraws (void *cls,
const struct TALER_Amount *val)
{
struct TALER_Amount *acc = cls;
if (GNUNET_OK !=
TALER_amount_is_valid (acc))
return; /* ignore */
GNUNET_break (0 <=
TALER_amount_add (acc,
acc,
val));
}
/**
* 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" may already be set before entering
* this function, either because OPTIMISTIC_SIGN was used and we signed
* before entering the transaction, or because this function is run
* twice (!) by #TEH_DB_run_transaction() and the first time created
* the signature and then failed to commit. Furthermore, we may get
* a 2nd correct signature briefly if "get_withdraw_info" succeeds and
* finds one in the DB. To avoid signing twice, the function may
* return a valid signature in "wc->collectable.sig" **even if it failed**.
* The caller must thus free the signature in either case.
*
* @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;
struct TALER_EXCHANGEDB_Reserve r;
enum GNUNET_DB_QueryStatus qs;
struct TALER_BlindedDenominationSignature denom_sig;
#if OPTIMISTIC_SIGN
/* store away optimistic signature to protect
it from being overwritten by get_withdraw_info */
denom_sig = wc->collectable.sig;
memset (&wc->collectable.sig,
0,
sizeof (wc->collectable.sig));
#endif
qs = TEH_plugin->get_withdraw_info (TEH_plugin->cls,
&wc->wsrd.h_coin_envelope,
&wc->collectable);
if (0 > qs)
{
GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == 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,
"withdraw details");
wc->collectable.sig = denom_sig;
return qs;
}
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Asked to withdraw from %s amount of %s\n",
TALER_B2S (&wc->wsrd.reserve_pub),
TALER_amount2s (&wc->amount_required));
/* Don't sign again if we have already signed the coin */
if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
{
/* Toss out the optimistic signature, we got another one from the DB;
optimization trade-off loses in this case: we unnecessarily computed
a signature :-( */
#if OPTIMISTIC_SIGN
TALER_blinded_denom_sig_free (&denom_sig);
#endif
return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
}
/* We should never get more than one result, and we handled
the errors (negative case) above, so that leaves no results. */
GNUNET_assert (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs);
wc->collectable.sig = denom_sig; /* Note: might still be NULL if we didn't do OPTIMISTIC_SIGN */
/* Check if balance is sufficient */
r.pub = wc->wsrd.reserve_pub; /* other fields of 'r' initialized in reserves_get (if successful) */
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Trying to withdraw from reserve: %s\n",
TALER_B2S (&r.pub));
qs = TEH_plugin->reserves_get (TEH_plugin->cls,
&r,
&wc->kyc);
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,
"reserves");
return qs;
}
if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
{
*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 (0 < TALER_amount_cmp (&wc->amount_required,
&r.balance))
{
struct TALER_EXCHANGEDB_ReserveHistory *rh;
/* The reserve does not have the required amount (actual
* amount + withdraw fee) */
#if GNUNET_EXTRA_LOGGING
{
char *amount_required;
char *r_balance;
amount_required = TALER_amount_to_string (&wc->amount_required);
r_balance = TALER_amount_to_string (&r.balance);
TALER_LOG_DEBUG ("Asked %s over a reserve worth %s\n",
amount_required,
r_balance);
GNUNET_free (amount_required);
GNUNET_free (r_balance);
}
#endif
qs = TEH_plugin->get_reserve_history (TEH_plugin->cls,
&wc->wsrd.reserve_pub,
&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,
&r.balance,
rh);
TEH_plugin->free_reserve_history (TEH_plugin->cls,
rh);
return GNUNET_DB_STATUS_HARD_ERROR;
}
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"KYC status is %s for %s\n",
wc->kyc.ok ? "ok" : "missing",
TALER_B2S (&r.pub));
if ( (! wc->kyc.ok) &&
(TEH_KYC_NONE != TEH_kyc_config.mode) &&
(TALER_EXCHANGEDB_KYC_W2W == wc->kyc.type) )
{
/* Wallet-to-wallet payments _always_ require KYC */
wc->kyc_denied = true;
return qs;
}
if ( (! wc->kyc.ok) &&
(TEH_KYC_NONE != TEH_kyc_config.mode) &&
(TALER_EXCHANGEDB_KYC_WITHDRAW == wc->kyc.type) &&
(! GNUNET_TIME_relative_is_zero (TEH_kyc_config.withdraw_period)) )
{
/* Withdraws require KYC if above threshold */
struct TALER_Amount acc;
enum GNUNET_DB_QueryStatus qs2;
acc = wc->amount_required;
qs2 = TEH_plugin->select_withdraw_amounts_by_account (
TEH_plugin->cls,
&wc->wsrd.reserve_pub,
TEH_kyc_config.withdraw_period,
&accumulate_withdraws,
&acc);
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,
"withdraw details");
return qs2;
}
if (GNUNET_OK !=
TALER_amount_is_valid (&acc))
{
GNUNET_break (0);
*mhd_ret = TALER_MHD_reply_with_ec (connection,
TALER_EC_GENERIC_INTERNAL_INVARIANT_FAILURE,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
}
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Amount withdrawn so far is %s\n",
TALER_amount2s (&acc));
if (1 == /* 1: acc > withdraw_limit */
TALER_amount_cmp (&acc,
&TEH_kyc_config.withdraw_limit))
{
wc->kyc_denied = true;
return qs;
}
}
/* Balance is good, sign the coin! */
#if ! OPTIMISTIC_SIGN
if (NULL == wc->collectable.sig.rsa_signature)
{
enum TALER_ErrorCode ec = TALER_EC_NONE;
wc->collectable.sig
= TEH_keys_denomination_sign (&wc->denom_pub_hash,
wc->blinded_msg,
wc->blinded_msg_len,
&ec);
if (TALER_EC_NONE != ec)
{
GNUNET_break (0);
*mhd_ret = TALER_MHD_reply_with_ec (connection,
ec,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
#endif
wc->collectable.denom_pub_hash = wc->denom_pub_hash;
wc->collectable.amount_with_fee = wc->amount_required;
wc->collectable.reserve_pub = wc->wsrd.reserve_pub;
wc->collectable.h_coin_envelope = wc->wsrd.h_coin_envelope;
wc->collectable.reserve_sig = wc->signature;
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Persisting withdraw from %s over %s\n",
TALER_B2S (&r.pub),
TALER_amount2s (&wc->amount_required));
qs = TEH_plugin->insert_withdraw_info (TEH_plugin->cls,
&wc->collectable);
if (0 > qs)
{
GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == 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_STORE_FAILED,
"withdraw details");
return qs;
}
return qs;
}
MHD_RESULT
TEH_handler_withdraw (struct TEH_RequestContext *rc,
const json_t *root,
const char *const args[2])
{
struct WithdrawContext wc;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_varsize ("coin_ev",
(void **) &wc.blinded_msg,
&wc.blinded_msg_len),
GNUNET_JSON_spec_fixed_auto ("reserve_sig",
&wc.signature),
GNUNET_JSON_spec_fixed_auto ("denom_pub_hash",
&wc.denom_pub_hash),
GNUNET_JSON_spec_end ()
};
enum TALER_ErrorCode ec;
struct TEH_DenominationKey *dk;
memset (&wc,
0,
sizeof (wc));
if (GNUNET_OK !=
GNUNET_STRINGS_string_to_data (args[0],
strlen (args[0]),
&wc.wsrd.reserve_pub,
sizeof (wc.wsrd.reserve_pub)))
{
GNUNET_break_op (0);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_MERCHANT_GENERIC_RESERVE_PUB_MALFORMED,
args[0]);
}
{
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 GNUNET_TIME_Absolute now;
dk = TEH_keys_denomination_by_hash (&wc.denom_pub_hash,
rc->connection,
&mret);
if (NULL == dk)
{
GNUNET_JSON_parse_free (spec);
return mret;
}
now = GNUNET_TIME_absolute_get ();
(void) GNUNET_TIME_round_abs (&now);
if (GNUNET_TIME_absolute_is_past (dk->meta.expire_withdraw))
{
struct GNUNET_TIME_Absolute now;
now = GNUNET_TIME_absolute_get ();
(void) GNUNET_TIME_round_abs (&now);
/* This denomination is past the expiration time for withdraws */
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.denom_pub_hash,
now,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_EXPIRED,
"WITHDRAW");
}
if (GNUNET_TIME_absolute_is_future (dk->meta.start))
{
struct GNUNET_TIME_Absolute now;
now = GNUNET_TIME_absolute_get ();
(void) GNUNET_TIME_round_abs (&now);
/* This denomination is not yet valid */
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.denom_pub_hash,
now,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_VALIDITY_IN_FUTURE,
"WITHDRAW");
}
if (dk->recoup_possible)
{
struct GNUNET_TIME_Absolute now;
now = GNUNET_TIME_absolute_get ();
(void) GNUNET_TIME_round_abs (&now);
/* This denomination has been revoked */
GNUNET_JSON_parse_free (spec);
return TEH_RESPONSE_reply_expired_denom_pub_hash (
rc->connection,
&wc.denom_pub_hash,
now,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_REVOKED,
"WITHDRAW");
}
}
{
if (0 >
TALER_amount_add (&wc.amount_required,
&dk->meta.value,
&dk->meta.fee_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);
}
TALER_amount_hton (&wc.wsrd.amount_with_fee,
&wc.amount_required);
}
/* verify signature! */
wc.wsrd.purpose.size
= htonl (sizeof (wc.wsrd));
wc.wsrd.purpose.purpose
= htonl (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW);
wc.wsrd.h_denomination_pub
= wc.denom_pub_hash;
TALER_coin_ev_hash (wc.blinded_msg,
wc.blinded_msg_len,
&wc.wsrd.h_coin_envelope);
if (GNUNET_OK !=
GNUNET_CRYPTO_eddsa_verify (TALER_SIGNATURE_WALLET_RESERVE_WITHDRAW,
&wc.wsrd,
&wc.signature.eddsa_signature,
&wc.wsrd.reserve_pub.eddsa_pub))
{
TALER_LOG_WARNING (
"Client supplied invalid signature for withdraw request\n");
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_error (rc->connection,
MHD_HTTP_FORBIDDEN,
TALER_EC_EXCHANGE_WITHDRAW_RESERVE_SIGNATURE_INVALID,
NULL);
}
#if OPTIMISTIC_SIGN
/* Sign before transaction! */
ec = TALER_EC_NONE;
wc.collectable.sig
= TEH_keys_denomination_sign (&wc.denom_pub_hash,
wc.blinded_msg,
wc.blinded_msg_len,
&ec);
if (TALER_EC_NONE != ec)
{
GNUNET_break (0);
GNUNET_JSON_parse_free (spec);
return TALER_MHD_reply_with_ec (rc->connection,
ec,
NULL);
}
#endif
/* run transaction and sign (if not optimistically signed before) */
wc.kyc_denied = false;
{
MHD_RESULT mhd_ret;
if (GNUNET_OK !=
TEH_DB_run_transaction (rc->connection,
"run 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);
if (wc.kyc_denied)
{
TALER_blinded_denom_sig_free (&wc.collectable.sig);
return TALER_MHD_REPLY_JSON_PACK (
rc->connection,
MHD_HTTP_ACCEPTED,
GNUNET_JSON_pack_uint64 ("payment_target_uuid",
wc.kyc.payment_target_uuid));
}
{
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 */