/*
This file is part of TALER
Copyright (C) 2023 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_age-withdraw.c
* @brief Handle /reserves/$RESERVE_PUB/age-withdraw requests
* @author Özgür Kesim
*/
#include "platform.h"
#include
#include
#include
#include
#include
#include "taler-exchange-httpd.h"
#include "taler_error_codes.h"
#include "taler_json_lib.h"
#include "taler_kyclogic_lib.h"
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_age-withdraw.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keys.h"
#include "taler_util.h"
/**
* Context for #age_withdraw_transaction.
*/
struct AgeWithdrawContext
{
/**
* KYC status for the operation.
*/
struct TALER_EXCHANGEDB_KycStatus kyc;
/**
* Timestamp
*/
struct GNUNET_TIME_Timestamp now;
/**
* Hash of the wire source URL, needed when kyc is needed.
*/
struct TALER_PaytoHashP h_payto;
/**
* The data from the age-withdraw request, as we persist it
*/
struct TALER_EXCHANGEDB_AgeWithdraw commitment;
/**
* Number of coins/denonations in the reveal
*/
uint32_t num_coins;
/**
* kappa * #num_coins hashes of blinded coin planchets.
* FIXME[oec]: Make the [][] structure more explicit.
*/
struct TALER_BlindedPlanchet *coin_evs;
/**
* #num_coins hashes of the denominations from which the coins are withdrawn.
* Those must support age restriction.
*/
struct TALER_DenominationHashP *denom_hs;
};
/*
* @brief Free the resources within a AgeWithdrawContext
*
* @param awc the context to free
*/
static void
free_age_withdraw_context_resources (struct AgeWithdrawContext *awc)
{
GNUNET_free (awc->denom_hs);
GNUNET_free (awc->coin_evs);
GNUNET_free (awc->commitment.denom_serials);
/*
* Note:
* awc->commitment.denom_sigs and .h_coin_evs were stack allocated and
* .denom_pub_hashes is NULL for this context.
*/
}
/**
* Parse the denominations and blinded coin data of an '/age-withdraw' request.
*
* @param connection The MHD connection to handle
* @param j_denom_hs Array of n hashes of the denominations for the withdrawal, in JSON format
* @param j_blinded_coin_evs Array of n arrays of kappa blinded envelopes of in JSON format for the coins.
* @param[out] awc The context of the operation, only partially built at call time
* @param[out] mhd_ret The result if a reply is queued for MHD
* @return true on success, false on failure, with a reply already queued for MHD
*/
static enum GNUNET_GenericReturnValue
parse_age_withdraw_json (
struct MHD_Connection *connection,
const json_t *j_denom_hs,
const json_t *j_blinded_coin_evs,
struct AgeWithdrawContext *awc,
MHD_RESULT *mhd_ret)
{
char buf[256] = {0};
const char *error = NULL;
unsigned int idx = 0;
json_t *value = NULL;
struct GNUNET_HashContext *hash_context;
/* The age value MUST be on the beginning of an age group */
if (awc->commitment.max_age !=
TALER_get_lowest_age (&TEH_age_restriction_config.mask,
awc->commitment.max_age))
{
error = "max_age must be the lower edge of an age group";
goto EXIT;
}
/* Verify JSON-structure consistency */
{
uint32_t num_coins = json_array_size (j_denom_hs);
if (! json_is_array (j_denom_hs))
error = "denoms_h must be an array";
else if (! json_is_array (j_blinded_coin_evs))
error = "coin_evs must be an array";
else if (num_coins == 0)
error = "denoms_h must not be empty";
else if (num_coins != json_array_size (j_blinded_coin_evs))
error = "denoms_h and coins_evs must be arrays of the same size";
else if (num_coins > TALER_MAX_FRESH_COINS)
/**
* The wallet had committed to more than the maximum coins allowed, the
* reserve has been charged, but now the user can not withdraw any money
* from it. Note that the user can't get their money back in this case!
**/
error = "maximum number of coins that can be withdrawn has been exceeded";
_Static_assert ((TALER_MAX_FRESH_COINS < INT_MAX / TALER_CNC_KAPPA),
"TALER_MAX_FRESH_COINS too large");
if (NULL != error)
goto EXIT;
awc->num_coins = num_coins;
awc->commitment.num_coins = num_coins;
}
/* Continue parsing the parts */
/* Parse denomination keys */
awc->denom_hs = GNUNET_new_array (awc->num_coins,
struct TALER_DenominationHashP);
json_array_foreach (j_denom_hs, idx, value) {
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto (NULL, &awc->denom_hs[idx]),
GNUNET_JSON_spec_end ()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (value, spec, NULL, NULL))
{
GNUNET_snprintf (buf,
sizeof(buf),
"couldn't parse entry no. %d in array denoms_h",
idx + 1);
error = buf;
goto EXIT;
}
};
/* no overflow because
* num_coins <= TALER_MAX_FRESH_COINS
* and
* TALER_MAX_FRESH_COINS * TALER_CNC_KAPPA < INT_MAX
*/
awc->coin_evs = GNUNET_new_array (awc->num_coins * TALER_CNC_KAPPA,
struct TALER_BlindedPlanchet);
hash_context = GNUNET_CRYPTO_hash_context_start ();
GNUNET_assert (NULL != hash_context);
/* Parse blinded envelopes. */
json_array_foreach (j_blinded_coin_evs, idx, value) {
const json_t *j_kappa_coin_evs = value;
if (! json_is_array (j_kappa_coin_evs))
{
GNUNET_snprintf (buf,
sizeof(buf),
"enxtry %d in array blinded_coin_evs is not an array",
idx + 1);
error = buf;
goto EXIT;
}
else if (TALER_CNC_KAPPA != json_array_size (j_kappa_coin_evs))
{
GNUNET_snprintf (buf,
sizeof(buf),
"array no. %d in coin_evs not of correct size",
idx + 1);
error = buf;
goto EXIT;
}
/* Now parse the individual kappa envelopes and calculate the hash of
* the commitment along the way. */
{
size_t off = idx * TALER_CNC_KAPPA;
unsigned int kappa = 0;
enum GNUNET_GenericReturnValue ret;
json_array_foreach (j_kappa_coin_evs, kappa, value) {
struct GNUNET_JSON_Specification spec[] = {
TALER_JSON_spec_blinded_planchet (NULL, &awc->coin_evs[off + kappa]),
GNUNET_JSON_spec_end ()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (value, spec, NULL, NULL))
{
GNUNET_snprintf (buf,
sizeof(buf),
"couldn't parse array no. %d in blinded_coin_evs[%d]",
kappa + 1,
idx + 1);
error = buf;
goto EXIT;
}
/* Continue to hash of the coin candidates */
{
struct TALER_BlindedCoinHashP bch;
ret = TALER_coin_ev_hash (&awc->coin_evs[off + kappa],
&awc->denom_hs[idx],
&bch);
GNUNET_assert (GNUNET_OK == ret);
GNUNET_CRYPTO_hash_context_read (hash_context,
&bch,
sizeof(bch));
}
/* Check for duplicate planchets
* FIXME: is this needed?
*/
for (unsigned int i = 0; i < off + kappa; i++)
{
if (0 == TALER_blinded_planchet_cmp (&awc->coin_evs[off + kappa],
&awc->coin_evs[i]))
{
error = "duplicate planchet";
goto EXIT;
}
}
}
}
}; /* json_array_foreach over j_blinded_coin_evs */
/* Finally, calculate the h_commitment from all blinded envelopes */
GNUNET_CRYPTO_hash_context_finish (hash_context,
&awc->commitment.h_commitment.hash);
GNUNET_assert (NULL == error);
EXIT:
if (NULL != error)
{
/* Note: resources are freed in caller */
*mhd_ret = TALER_MHD_reply_with_ec (
connection,
TALER_EC_GENERIC_PARAMETER_MALFORMED,
error);
return GNUNET_SYSERR;
}
return GNUNET_OK;
}
/**
* Check if the given denomination is still or already valid, has not been
* revoked and supports age restriction.
*
* @param connection HTTP-connection to the client
* @param ksh The handle to the current state of (denomination) keys in the exchange
* @param denom_h Hash of the denomination key to check
* @param[out] pdk On success, will contain the denomination key details
* @param[out] result On failure, an MHD-response will be qeued and result will be set to accordingly
* @return true on success (denomination valid), false otherwise
*/
static bool
denomination_is_valid (
struct MHD_Connection *connection,
struct TEH_KeyStateHandle *ksh,
const struct TALER_DenominationHashP *denom_h,
struct TEH_DenominationKey **pdk,
MHD_RESULT *result)
{
struct TEH_DenominationKey *dk;
dk = TEH_keys_denomination_by_hash_from_state (ksh,
denom_h,
connection,
result);
if (NULL == dk)
{
/* The denomination doesn't exist */
/* Note: a HTTP-response has been queued and result has been set by
* TEH_keys_denominations_by_hash_from_state */
return false;
}
if (GNUNET_TIME_absolute_is_past (dk->meta.expire_withdraw.abs_time))
{
/* This denomination is past the expiration time for withdraws */
/* FIXME[oec]: add idempotency check */
*result = TEH_RESPONSE_reply_expired_denom_pub_hash (
connection,
denom_h,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_EXPIRED,
"age-withdraw_reveal");
return false;
}
if (GNUNET_TIME_absolute_is_future (dk->meta.start.abs_time))
{
/* This denomination is not yet valid */
*result = TEH_RESPONSE_reply_expired_denom_pub_hash (
connection,
denom_h,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_VALIDITY_IN_FUTURE,
"age-withdraw_reveal");
return false;
}
if (dk->recoup_possible)
{
/* This denomination has been revoked */
*result = TALER_MHD_reply_with_ec (
connection,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_REVOKED,
NULL);
return false;
}
if (0 == dk->denom_pub.age_mask.bits)
{
/* This denomation does not support age restriction */
char msg[256] = {0};
GNUNET_snprintf (msg,
sizeof(msg),
"denomination %s does not support age restriction",
GNUNET_h2s (&denom_h->hash));
*result = TALER_MHD_reply_with_ec (
connection,
TALER_EC_EXCHANGE_GENERIC_DENOMINATION_KEY_UNKNOWN,
msg);
return false;
}
*pdk = dk;
return true;
}
/**
* Check if the given array of hashes of denomination_keys a) belong
* to valid denominations and b) those are marked as age restricted.
* Also, calculate the total amount of the denominations including fees
* for withdraw.
*
* @param connection The HTTP connection to the client
* @param len The lengths of the array @a denoms_h
* @param denom_hs array of hashes of denomination public keys
* @param coin_evs array of blinded coin planchets
* @param[out] denom_serials On success, will be filled with the serial-id's of the denomination keys. Caller must deallocate.
* @param[out] amount_with_fee On success, will contain the committed amount including fees
* @param[out] result In the error cases, a response will be queued with MHD and this will be the result.
* @return GNUNET_OK if the denominations are valid and support age-restriction
* GNUNET_SYSERR otherwise
*/
static enum GNUNET_GenericReturnValue
are_denominations_valid (
struct MHD_Connection *connection,
uint32_t len,
const struct TALER_DenominationHashP *denom_hs,
const struct TALER_BlindedPlanchet *coin_evs,
uint64_t **denom_serials,
struct TALER_Amount *amount_with_fee,
MHD_RESULT *result)
{
struct TALER_Amount total_amount;
struct TALER_Amount total_fee;
struct TEH_KeyStateHandle *ksh;
uint64_t *serials;
ksh = TEH_keys_get_state ();
if (NULL == ksh)
{
*result = TALER_MHD_reply_with_ec (connection,
TALER_EC_EXCHANGE_GENERIC_KEYS_MISSING,
NULL);
return GNUNET_SYSERR;
}
*denom_serials =
serials = GNUNET_new_array (len, uint64_t);
TALER_amount_set_zero (TEH_currency, &total_amount);
TALER_amount_set_zero (TEH_currency, &total_fee);
for (uint32_t i = 0; i < len; i++)
{
struct TEH_DenominationKey *dk;
if (! denomination_is_valid (connection,
ksh,
&denom_hs[i],
&dk,
result))
/* FIXME[oec]: add idempotency check */
return GNUNET_SYSERR;
/* Ensure the ciphers from the planchets match the denominations' */
if (dk->denom_pub.cipher != coin_evs[i].cipher)
{
GNUNET_break_op (0);
*result = TALER_MHD_reply_with_ec (connection,
TALER_EC_EXCHANGE_GENERIC_CIPHER_MISMATCH,
NULL);
return GNUNET_SYSERR;
}
/* Accumulate the values */
if (0 > TALER_amount_add (&total_amount,
&total_amount,
&dk->meta.value))
{
GNUNET_break_op (0);
*result = TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_EXCHANGE_AGE_WITHDRAW_AMOUNT_OVERFLOW,
"amount");
return GNUNET_SYSERR;
}
/* Accumulate the withdraw fees */
if (0 > TALER_amount_add (&total_fee,
&total_fee,
&dk->meta.fees.withdraw))
{
GNUNET_break_op (0);
*result = TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_EXCHANGE_AGE_WITHDRAW_AMOUNT_OVERFLOW,
"fee");
return GNUNET_SYSERR;
}
serials[i] = dk->meta.serial;
}
/* Save the total amount including fees */
GNUNET_assert (0 < TALER_amount_add (amount_with_fee,
&total_amount,
&total_fee));
return GNUNET_OK;
}
/**
* @brief Verify the signature of the request body with the reserve key
*
* @param connection the connection to the client
* @param commitment the age withdraw commitment
* @param mhd_ret the response to fill in the error case
* @return GNUNET_OK on success
*/
static enum GNUNET_GenericReturnValue
verify_reserve_signature (
struct MHD_Connection *connection,
const struct TALER_EXCHANGEDB_AgeWithdraw *commitment,
enum MHD_Result *mhd_ret)
{
TEH_METRICS_num_verifications[TEH_MT_SIGNATURE_EDDSA]++;
if (GNUNET_OK !=
TALER_wallet_age_withdraw_verify (&commitment->h_commitment,
&commitment->amount_with_fee,
&TEH_age_restriction_config.mask,
commitment->max_age,
&commitment->reserve_pub,
&commitment->reserve_sig))
{
GNUNET_break_op (0);
*mhd_ret = TALER_MHD_reply_with_ec (connection,
TALER_EC_EXCHANGE_WITHDRAW_RESERVE_SIGNATURE_INVALID,
NULL);
return GNUNET_SYSERR;
}
return GNUNET_OK;
}
/**
* Send a response to a "age-withdraw" request.
*
* @param connection the connection to send the response to
* @param ach value the client committed to
* @param noreveal_index which index will the client not have to reveal
* @return a MHD status code
*/
static MHD_RESULT
reply_age_withdraw_success (
struct MHD_Connection *connection,
const struct TALER_AgeWithdrawCommitmentHashP *ach,
uint32_t noreveal_index)
{
struct TALER_ExchangePublicKeyP pub;
struct TALER_ExchangeSignatureP sig;
enum TALER_ErrorCode ec =
TALER_exchange_online_age_withdraw_confirmation_sign (
&TEH_keys_exchange_sign_,
ach,
noreveal_index,
&pub,
&sig);
if (TALER_EC_NONE != ec)
return TALER_MHD_reply_with_ec (connection,
ec,
NULL);
return TALER_MHD_REPLY_JSON_PACK (connection,
MHD_HTTP_OK,
GNUNET_JSON_pack_uint64 ("noreveal_index",
noreveal_index),
GNUNET_JSON_pack_data_auto ("exchange_sig",
&sig),
GNUNET_JSON_pack_data_auto ("exchange_pub",
&pub));
}
/**
* Check if the request is replayed and we already have an
* answer. If so, replay the existing answer and return the
* HTTP response.
*
* @param con connection to the client
* @param[in,out] awc 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
request_is_idempotent (struct MHD_Connection *con,
struct AgeWithdrawContext *awc,
MHD_RESULT *mret)
{
enum GNUNET_DB_QueryStatus qs;
struct TALER_EXCHANGEDB_AgeWithdraw commitment;
qs = TEH_plugin->get_age_withdraw (TEH_plugin->cls,
&awc->commitment.reserve_pub,
&awc->commitment.h_commitment,
&commitment);
if (0 > qs)
{
GNUNET_break (GNUNET_DB_STATUS_SOFT_ERROR == qs);
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mret = TALER_MHD_reply_with_ec (con,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"get_age_withdraw");
return true; /* Well, kind-of. At least we have set mret. */
}
if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
return false;
/* Generate idempotent reply */
TEH_METRICS_num_requests[TEH_MT_REQUEST_IDEMPOTENT_AGE_WITHDRAW]++;
*mret = reply_age_withdraw_success (con,
&commitment.h_commitment,
commitment.noreveal_index);
return true;
}
/**
* Function called to iterate over KYC-relevant transaction amounts for a
* particular time range. Called within a database transaction, so must
* not start a new one.
*
* @param cls closure, identifies the event type and account to iterate
* over events for
* @param limit maximum time-range for which events should be fetched
* (timestamp in the past)
* @param cb function to call on each event found, events must be returned
* in reverse chronological order
* @param cb_cls closure for @a cb, of type struct AgeWithdrawContext
*/
static void
age_withdraw_amount_cb (void *cls,
struct GNUNET_TIME_Absolute limit,
TALER_EXCHANGEDB_KycAmountCallback cb,
void *cb_cls)
{
struct AgeWithdrawContext *awc = cls;
enum GNUNET_DB_QueryStatus qs;
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Signaling amount %s for KYC check during age-withdrawal\n",
TALER_amount2s (&awc->commitment.amount_with_fee));
if (GNUNET_OK !=
cb (cb_cls,
&awc->commitment.amount_with_fee,
awc->now.abs_time))
return;
qs = TEH_plugin->select_withdraw_amounts_for_kyc_check (TEH_plugin->cls,
&awc->h_payto,
limit,
cb,
cb_cls);
GNUNET_log (GNUNET_ERROR_TYPE_INFO,
"Got %d additional transactions for this age-withdrawal and limit %llu\n",
qs,
(unsigned long long) limit.abs_value_us);
GNUNET_break (qs >= 0);
}
/**
* Function implementing age 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.
*
* @param cls a `struct AgeWithdrawContext *`
* @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
age_withdraw_transaction (void *cls,
struct MHD_Connection *connection,
MHD_RESULT *mhd_ret)
{
struct AgeWithdrawContext *awc = cls;
enum GNUNET_DB_QueryStatus qs;
qs = TEH_plugin->reserves_get_origin (TEH_plugin->cls,
&awc->commitment.reserve_pub,
&awc->h_payto);
if (qs < 0)
return qs;
/* If _no_ results, reserve was created by merge,
in which case no KYC check is required as the
merge already did that. */
if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
{
char *kyc_required;
qs = TALER_KYCLOGIC_kyc_test_required (
TALER_KYCLOGIC_KYC_TRIGGER_AGE_WITHDRAW,
&awc->h_payto,
TEH_plugin->select_satisfied_kyc_processes,
TEH_plugin->cls,
&age_withdraw_amount_cb,
awc,
&kyc_required);
if (qs < 0)
{
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
{
GNUNET_break (0);
*mhd_ret = TALER_MHD_reply_with_ec (connection,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"kyc_test_required");
}
return qs;
}
if (NULL != kyc_required)
{
/* Mark result and return by inserting KYC requirement into DB! */
awc->kyc.ok = false;
return TEH_plugin->insert_kyc_requirement_for_account (
TEH_plugin->cls,
kyc_required,
&awc->h_payto,
&awc->commitment.reserve_pub,
&awc->kyc.requirement_row);
}
}
awc->kyc.ok = true;
/* KYC requirement fulfilled, do the age-withdraw transaction */
{
bool found = false;
bool balance_ok = false;
bool age_ok = false;
bool conflict = false;
uint16_t allowed_maximum_age = 0;
uint32_t reserve_birthday = 0;
qs = TEH_plugin->do_age_withdraw (TEH_plugin->cls,
&awc->commitment,
awc->now,
&found,
&balance_ok,
&age_ok,
&allowed_maximum_age,
&reserve_birthday,
&conflict);
if (0 > qs)
{
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
*mhd_ret = TALER_MHD_reply_with_ec (connection,
TALER_EC_GENERIC_DB_FETCH_FAILED,
"do_age_withdraw");
return qs;
}
else if (! found)
{
*mhd_ret = TALER_MHD_reply_with_ec (connection,
TALER_EC_EXCHANGE_GENERIC_RESERVE_UNKNOWN,
NULL);
return GNUNET_DB_STATUS_HARD_ERROR;
}
else if (! age_ok)
{
enum TALER_ErrorCode ec =
TALER_EC_EXCHANGE_AGE_WITHDRAW_MAXIMUM_AGE_TOO_LARGE;
*mhd_ret =
TALER_MHD_REPLY_JSON_PACK (
connection,
MHD_HTTP_CONFLICT,
TALER_MHD_PACK_EC (ec),
GNUNET_JSON_pack_uint64 ("allowed_maximum_age",
allowed_maximum_age),
GNUNET_JSON_pack_uint64 ("reserve_birthday",
reserve_birthday));
return GNUNET_DB_STATUS_HARD_ERROR;
}
else if (! balance_ok)
{
TEH_plugin->rollback (TEH_plugin->cls);
*mhd_ret = TEH_RESPONSE_reply_reserve_insufficient_balance (
connection,
TALER_EC_EXCHANGE_AGE_WITHDRAW_INSUFFICIENT_FUNDS,
&awc->commitment.amount_with_fee,
&awc->commitment.reserve_pub);
return GNUNET_DB_STATUS_HARD_ERROR;
}
else if (conflict)
{
/* do_age_withdraw signaled a conflict, so there MUST be an entry
* in the DB. Put that into the response */
bool ok = request_is_idempotent (connection,
awc,
mhd_ret);
GNUNET_assert (ok);
return GNUNET_DB_STATUS_SUCCESS_ONE_RESULT;
}
*mhd_ret = -1;
}
if (GNUNET_DB_STATUS_SUCCESS_ONE_RESULT == qs)
TEH_METRICS_num_success[TEH_MT_SUCCESS_AGE_WITHDRAW]++;
return qs;
}
/**
* @brief Sign the chosen blinded coins, debit the reserve and persist
* the commitment.
*
* On conflict, the noreveal_index from the previous, existing
* commitment is returned to the client, returning success.
*
* On error (like, insufficient funds), the client is notified.
*
* Note that on success, there are two possible states:
* 1.) KYC is required (awc.kyc.ok == false) or
* 2.) age withdraw was successful.
*
* @param connection HTTP-connection to the client
* @param awc The context for the current age withdraw request
* @param[out] result On error, a HTTP-response will be queued and result set accordingly
* @return GNUNET_OK on success, GNUNET_SYSERR otherwise
*/
static enum GNUNET_GenericReturnValue
sign_and_do_age_withdraw (
struct MHD_Connection *connection,
struct AgeWithdrawContext *awc,
MHD_RESULT *result)
{
enum GNUNET_GenericReturnValue ret = GNUNET_SYSERR;
struct TALER_BlindedCoinHashP h_coin_evs[awc->num_coins];
struct TALER_BlindedDenominationSignature denom_sigs[awc->num_coins];
uint8_t noreveal_index;
awc->now = GNUNET_TIME_timestamp_get ();
/* Pick the challenge */
noreveal_index =
GNUNET_CRYPTO_random_u32 (GNUNET_CRYPTO_QUALITY_STRONG,
TALER_CNC_KAPPA);
awc->commitment.noreveal_index = noreveal_index;
/* Choose and sign the coins */
{
struct TEH_CoinSignData csds[awc->num_coins];
enum TALER_ErrorCode ec;
/* Pick the chosen blinded coins */
for (uint32_t i = 0; inum_coins; i++)
{
csds[i].bp = &awc->coin_evs[TALER_CNC_KAPPA * i + noreveal_index];
csds[i].h_denom_pub = &awc->denom_hs[i];
}
ec = TEH_keys_denomination_batch_sign (csds,
awc->num_coins,
false,
denom_sigs);
if (TALER_EC_NONE != ec)
{
GNUNET_break (0);
*result = TALER_MHD_reply_with_ec (connection,
ec,
NULL);
return GNUNET_SYSERR;
}
}
GNUNET_log (GNUNET_ERROR_TYPE_DEBUG,
"Signatures ready, starting DB interaction\n");
/* Prepare the hashes of the coins for insertion */
for (uint32_t i = 0; inum_coins; i++)
{
TALER_coin_ev_hash (&awc->coin_evs[TALER_CNC_KAPPA * i + noreveal_index],
&awc->denom_hs[i],
&h_coin_evs[i]);
}
/* Run the transaction */
awc->commitment.h_coin_evs = h_coin_evs;
awc->commitment.denom_sigs = denom_sigs;
ret = TEH_DB_run_transaction (connection,
"run age withdraw",
TEH_MT_REQUEST_AGE_WITHDRAW,
result,
&age_withdraw_transaction,
awc);
/* Free resources */
for (unsigned int i = 0; inum_coins; i++)
TALER_blinded_denom_sig_free (&denom_sigs[i]);
awc->commitment.h_coin_evs = NULL;
awc->commitment.denom_sigs = NULL;
return ret;
}
MHD_RESULT
TEH_handler_age_withdraw (struct TEH_RequestContext *rc,
const struct TALER_ReservePublicKeyP *reserve_pub,
const json_t *root)
{
MHD_RESULT mhd_ret;
const json_t *j_denom_hs;
const json_t *j_blinded_coin_evs;
struct AgeWithdrawContext awc = {0};
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_array_const ("denom_hs",
&j_denom_hs),
GNUNET_JSON_spec_array_const ("blinded_coin_evs",
&j_blinded_coin_evs),
GNUNET_JSON_spec_uint16 ("max_age",
&awc.commitment.max_age),
GNUNET_JSON_spec_fixed_auto ("reserve_sig",
&awc.commitment.reserve_sig),
GNUNET_JSON_spec_end ()
};
awc.commitment.reserve_pub = *reserve_pub;
/* Parse the JSON body */
{
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;
}
do {
/* Note: If we break the statement here at any point,
* a response to the client MUST have been populated
* with an appropriate answer and mhd_ret MUST have
* been set accordingly.
*/
/* Parse denoms_h and blinded_coins_evs, partially fill awc */
if (GNUNET_OK !=
parse_age_withdraw_json (rc->connection,
j_denom_hs,
j_blinded_coin_evs,
&awc,
&mhd_ret))
break;
/* Ensure validity of denoms and calculate amounts and fees */
if (GNUNET_OK !=
are_denominations_valid (rc->connection,
awc.num_coins,
awc.denom_hs,
awc.coin_evs,
&awc.commitment.denom_serials,
&awc.commitment.amount_with_fee,
&mhd_ret))
break;
/* Now that amount_with_fee is calculated, verify the signature of
* the request body with the reserve key.
*/
if (GNUNET_OK !=
verify_reserve_signature (rc->connection,
&awc.commitment,
&mhd_ret))
break;
/* Sign the chosen blinded coins, persist the commitment and
* charge the reserve.
* On error (like, insufficient funds), the client is notified.
* On conflict, the noreveal_index from the previous, existing
* commitment is returned to the client, returning success.
* Note that on success, there are two possible states:
* KYC is required (awc.kyc.ok == false) or
* age withdraw was successful.
*/
if (GNUNET_OK !=
sign_and_do_age_withdraw (rc->connection,
&awc,
&mhd_ret))
break;
/* Send back final response, depending on the outcome of
* the DB-transaction */
if (! awc.kyc.ok)
mhd_ret = TEH_RESPONSE_reply_kyc_required (rc->connection,
&awc.h_payto,
&awc.kyc);
else
mhd_ret = reply_age_withdraw_success (rc->connection,
&awc.commitment.h_commitment,
awc.commitment.noreveal_index);
} while(0);
GNUNET_JSON_parse_free (spec);
free_age_withdraw_context_resources (&awc);
return mhd_ret;
}
/* end of taler-exchange-httpd_age-withdraw.c */