WiP:age-withdraw: started handler for age-withdraw reveal

This commit is contained in:
Özgür Kesim 2023-01-24 11:04:44 +01:00
parent ae94c954a5
commit e36c6748bd
Signed by: oec
GPG Key ID: 3D76A56D79EDD9D7
2 changed files with 304 additions and 1 deletions

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@ -0,0 +1,303 @@
/*
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 <http://www.gnu.org/licenses/>
*/
/**
* @file taler-exchange-httpd_age-withdraw_reveal.c
* @brief Handle /age-withdraw/$ACH/reveal requests
* @author Özgür Kesim
*/
#include "platform.h"
#include <gnunet/gnunet_util_lib.h>
#include <jansson.h>
#include <microhttpd.h>
#include "taler_mhd_lib.h"
#include "taler-exchange-httpd_mhd.h"
#include "taler-exchange-httpd_age-withdraw_reveal.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keys.h"
/**
* State for an /age-withdraw/$ACH/reveal operation.
*/
struct AgeRevealContext
{
/**
* Commitment for the age-withdraw operation.
*/
struct TALER_AgeWithdrawCommitmentHashP ach;
/**
* Public key of the reserve for with the age-withdraw commitment was
* originally made. This parameter is provided by the client again
* during the call to reveal in order to save a database-lookup .
*/
struct TALER_ReservePublicKeyP reserve_pub;
/**
* Number of coins/denonations in the reveal
*/
uint32_t num_coins;
/**
* TODO:oec num_coins denoms
*/
struct TALER_DenominationHashP *denoms_h;
/**
* TODO:oec num_coins blinded coins
*/
struct TALER_BlindedCoinHashP *coin_evs;
/**
* TODO:oec num_coins*(kappa - 1) disclosed coins
*/
struct GNUNET_CRYPTO_EddsaPrivateKey *disclosed_coins;
};
/**
* Helper function to free resources in the context
*/
void
age_reveal_context_free (struct AgeRevealContext *actx)
{
GNUNET_free (actx->denoms_h);
GNUNET_free (actx->coin_evs);
GNUNET_free (actx->disclosed_coins);
}
/**
* Handle a "/age-withdraw/$ACH/reveal request. Parses the given JSON
* ... TODO:oec:description
*
* @param connection The MHD connection to handle
* @param actx The context of the operation, only partially built at call time
* @param j_denoms_h Array of hashes of the denominations for the withdrawal, in JSON format
* @param j_coin_evs The blinded envelopes in JSON format for the coins that are not revealed and will be signed on success
* @param j_disclosed_coins The n*(kappa-1) disclosed coins' private keys in JSON format, from which all other attributes (age restriction, blinding, nonce) will be derived from
*/
MHD_RESULT
handle_age_withdraw_reveal_json (
struct MHD_Connection *connection,
struct AgeRevealContext *actx,
const json_t *j_denoms_h,
const json_t *j_coin_evs,
const json_t *j_disclosed_coins)
{
MHD_RESULT mhd_ret = MHD_NO;
/* Verify JSON-structure consistency */
{
const char *error = NULL;
actx->num_coins = json_array_size (j_denoms_h); /* 0, if j_denoms_h is not an array */
if (! json_is_array (j_denoms_h))
error = "denoms_h must be an array";
else if (! json_is_array (j_coin_evs))
error = "coin_evs must be an array";
else if (! json_is_array (j_disclosed_coins))
error = "disclosed_coins must be an array";
else if (actx->num_coins == 0)
error = "denoms_h must not be empty";
else if (actx->num_coins != json_array_size (j_coin_evs))
error = "denoms_h and coins_evs must be arrays of the same size";
else if (actx->num_coins * (TALER_CNC_KAPPA - 1)
!= json_array_size (j_disclosed_coins))
error = "the size of array disclosed_coins must be "
TALER_CNC_KAPPA_MINUS_ONE_STR " times of the size of denoms_h";
else if (actx->num_coins > TALER_MAX_FRESH_COINS)
/**
* FIXME?: If the user had commited to more than the maximum coins allowed,
* the reserve has been charged, but now the user can not withdraw any money
* from it. How can the user get their money back?
**/
error = "maximum number of coins that can be withdrawn has been exceeded";
if (NULL != error)
return TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_GENERIC_PARAMETER_MALFORMED,
error);
}
/* Parse denomination keys */
{
unsigned int idx;
json_t *jh;
actx->denoms_h = GNUNET_new_array (actx->num_coins,
struct TALER_DenominationHashP);
json_array_foreach (j_denoms_h, idx, jh) {
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto (NULL, &actx->denoms_h[idx]),
GNUNET_JSON_spec_end ()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (jh, spec, NULL, NULL))
{
char msg[256] = {0};
GNUNET_snprintf (msg,
sizeof(msg),
"couldn't parse entry no. %d in array denoms_h",
idx + 1);
mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_GENERIC_PARAMETER_MALFORMED,
msg);
goto EXIT;
}
};
}
/* Parse blinded envelopes */
{
unsigned int idx;
json_t *ce;
actx->coin_evs = GNUNET_new_array (actx->num_coins,
struct TALER_BlindedCoinHashP);
json_array_foreach (j_coin_evs, idx, ce) {
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto (NULL, &actx->coin_evs[idx]),
GNUNET_JSON_spec_end ()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (ce, spec, NULL, NULL))
{
char msg[256] = {0};
GNUNET_snprintf (msg,
sizeof(msg),
"couldn't parse entry no. %d in array coin_evs",
idx + 1);
mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_GENERIC_PARAMETER_MALFORMED,
msg);
goto EXIT;
}
};
}
/* Parse diclosed keys */
{
unsigned int idx;
json_t *dc;
actx->disclosed_coins = GNUNET_new_array (
actx->num_coins * (TALER_CNC_KAPPA),
struct GNUNET_CRYPTO_EddsaPrivateKey);
json_array_foreach (j_coin_evs, idx, dc) {
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto (NULL, &actx->disclosed_coins[idx]),
GNUNET_JSON_spec_end ()
};
if (GNUNET_OK !=
GNUNET_JSON_parse (dc, spec, NULL, NULL))
{
char msg[256] = {0};
GNUNET_snprintf (msg,
sizeof(msg),
"couldn't parse entry no. %d in array disclosed_coins",
idx + 1);
mhd_ret = TALER_MHD_reply_with_error (connection,
MHD_HTTP_BAD_REQUEST,
TALER_EC_GENERIC_PARAMETER_MALFORMED,
msg);
goto EXIT;
}
};
}
/* TODO:oec: find commitment */
/* TODO:oec: check validity of denoms */
/* TODO:oec: check amount total against denoms */
/* TODO:oec: compute the disclosed blinded coins */
/* TODO:oec: generate h_commitment_comp */
/* TODO:oec: compare h_commitment_comp against h_commitment */
/* TODO:oec: sign the coins */
/* TODO:oec: send response */
/* TODO */
EXIT:
age_reveal_context_free (actx);
return mhd_ret;
}
MHD_RESULT
TEH_handler_age_withdraw_reveal (
struct TEH_RequestContext *rc,
const struct TALER_AgeWithdrawCommitmentHashP *ach,
const json_t *root)
{
struct AgeRevealContext actx = {0};
json_t *j_denoms_h;
json_t *j_coin_evs;
json_t *j_disclosed_coins;
struct GNUNET_JSON_Specification spec[] = {
GNUNET_JSON_spec_fixed_auto ("reserve_pub", &actx.reserve_pub),
GNUNET_JSON_spec_json ("denoms_h", &j_denoms_h),
GNUNET_JSON_spec_json ("coin_evs", &j_coin_evs),
GNUNET_JSON_spec_json ("disclosed_coins", &j_disclosed_coins),
GNUNET_JSON_spec_end ()
};
actx.ach = *ach;
/* Parse JSON body*/
{
enum GNUNET_GenericReturnValue res;
res = TALER_MHD_parse_json_data (rc->connection,
root,
spec);
if (GNUNET_OK != res)
{
GNUNET_break_op (0);
return (GNUNET_SYSERR == res) ? MHD_NO : MHD_YES;
}
}
/* handle reveal request */
{
MHD_RESULT res;
res = handle_age_withdraw_reveal_json (rc->connection,
&actx,
j_denoms_h,
j_coin_evs,
j_disclosed_coins);
GNUNET_JSON_parse_free (spec);
return res;
}
}
/* end of taler-exchange-httpd_age-withdraw_reveal.c */

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@ -50,7 +50,7 @@
MHD_RESULT
TEH_handler_age_withdraw_reveal (
struct TEH_RequestContext *rc,
const struct TALER_AgeRestrictedCoinsCommitmentP *ach,
const struct TALER_AgeWithdrawCommitmentHashP *ach,
const json_t *root);
#endif