/*
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
*/
/**
* @file taler-exchange-httpd_refresh_reveal.c
* @brief Handle /refresh/reveal requests
* @author Florian Dold
* @author Benedikt Mueller
* @author Christian Grothoff
*/
#include "platform.h"
#include
#include
#include
#include "taler-exchange-httpd_parsing.h"
#include "taler-exchange-httpd_mhd.h"
#include "taler-exchange-httpd_refresh_reveal.h"
#include "taler-exchange-httpd_responses.h"
#include "taler-exchange-httpd_keystate.h"
/**
* Maximum number of fresh coins we allow per refresh operation.
*/
#define MAX_FRESH_COINS 256
/**
* Send a response for "/refresh/reveal".
*
* @param connection the connection to send the response to
* @param num_newcoins number of new coins for which we reveal data
* @param sigs array of @a num_newcoins signatures revealed
* @return a MHD result code
*/
static int
reply_refresh_reveal_success (struct MHD_Connection *connection,
unsigned int num_newcoins,
const struct TALER_DenominationSignature *sigs)
{
json_t *root;
json_t *obj;
json_t *list;
int ret;
list = json_array ();
for (unsigned int newcoin_index = 0;
newcoin_index < num_newcoins;
newcoin_index++)
{
obj = json_object ();
json_object_set_new (obj,
"ev_sig",
GNUNET_JSON_from_rsa_signature (sigs[newcoin_index].rsa_signature));
GNUNET_assert (0 ==
json_array_append_new (list,
obj));
}
root = json_object ();
json_object_set_new (root,
"ev_sigs",
list);
ret = TEH_RESPONSE_reply_json (connection,
root,
MHD_HTTP_OK);
json_decref (root);
return ret;
}
/**
* Send a response for a failed "/refresh/reveal", where the
* revealed value(s) do not match the original commitment.
*
* @param connection the connection to send the response to
* @param rc commitment computed by the exchange
* @return a MHD result code
*/
static int
reply_refresh_reveal_missmatch (struct MHD_Connection *connection,
const struct TALER_RefreshCommitmentP *rc)
{
return TEH_RESPONSE_reply_json_pack (connection,
MHD_HTTP_CONFLICT,
"{s:s, s:I, s:o}",
"error", "commitment violation",
"code", (json_int_t) TALER_EC_REFRESH_REVEAL_COMMITMENT_VIOLATION,
"rc_expected", GNUNET_JSON_from_data_auto (rc));
}
/**
* State for a /refresh/reveal operation.
*/
struct RevealContext
{
/**
* Commitment of the refresh operaton.
*/
struct TALER_RefreshCommitmentP rc;
/**
* Transfer public key at gamma.
*/
struct TALER_TransferPublicKeyP gamma_tp;
/**
* Transfer private keys revealed to us.
*/
struct TALER_TransferPrivateKeyP transfer_privs[TALER_CNC_KAPPA - 1];
/**
* Denominations being requested.
*/
const struct TALER_EXCHANGEDB_DenominationKeyIssueInformation **dkis;
/**
* Envelopes to be signed.
*/
const struct TALER_RefreshCoinData *rcds;
/**
* Envelopes with the signatures to be returned. Initially NULL.
*/
struct TALER_DenominationSignature *ev_sigs;
/**
* Size of the @e dkis, @e rcds and @e ev_sigs arrays (if non-NULL).
*/
unsigned int num_fresh_coins;
};
/**
* Function called with information about a refresh order we already
* persisted. Stores the result in @a cls so we don't do the calculation
* again.
*
* @param cls closure with a `struct RevealContext`
* @param rowid unique serial ID for the row in our database
* @param num_newcoins size of the @a rrcs array
* @param rrcs array of @a num_newcoins information about coins to be created
* @param num_tprivs number of entries in @a tprivs, should be #TALER_CNC_KAPPA - 1
* @param tprivs array of @e num_tprivs transfer private keys
* @param tp transfer public key information
*/
static void
check_exists_cb (void *cls,
uint32_t num_newcoins,
const struct TALER_EXCHANGEDB_RefreshRevealedCoin *rrcs,
unsigned int num_tprivs,
const struct TALER_TransferPrivateKeyP *tprivs,
const struct TALER_TransferPublicKeyP *tp)
{
struct RevealContext *rctx = cls;
if (0 == num_newcoins)
{
GNUNET_break (0);
return;
}
GNUNET_break (TALER_CNC_KAPPA - 1 == num_tprivs);
GNUNET_break_op (0 == memcmp (tp,
&rctx->gamma_tp,
sizeof (struct TALER_TransferPublicKeyP)));
GNUNET_break_op (0 == memcmp (tprivs,
&rctx->transfer_privs,
sizeof (struct TALER_TransferPrivateKeyP) * num_tprivs));
rctx->ev_sigs = GNUNET_new_array (num_newcoins,
struct TALER_DenominationSignature);
for (unsigned int i=0;iev_sigs[i].rsa_signature
= GNUNET_CRYPTO_rsa_signature_dup (rrcs[i].coin_sig.rsa_signature);
}
/**
* Execute a "/refresh/reveal". The client is revealing to us the
* transfer keys for @a #TALER_CNC_KAPPA-1 sets of coins. Verify that the
* revealed transfer keys would allow linkage to the blinded coins,
* and if so, return the signed coins for corresponding to the set of
* coins that was not chosen.
*
* 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 closure of type `struct RevealContext`
* @param connection MHD request which triggered the transaction
* @param session database session to use
* @param[out] mhd_ret set to MHD response status for @a connection,
* if transaction failed (!)
* @return transaction status
*/
static enum GNUNET_DB_QueryStatus
refresh_reveal_transaction (void *cls,
struct MHD_Connection *connection,
struct TALER_EXCHANGEDB_Session *session,
int *mhd_ret)
{
struct RevealContext *rctx = cls;
struct TALER_EXCHANGEDB_RefreshMelt refresh_melt;
enum GNUNET_DB_QueryStatus qs;
/* Try to see if we already have given an answer before. */
qs = TEH_plugin->get_refresh_reveal (TEH_plugin->cls,
session,
&rctx->rc,
&check_exists_cb,
rctx);
switch (qs) {
case GNUNET_DB_STATUS_SUCCESS_NO_RESULTS:
/* continue normal execution */
break;
case GNUNET_DB_STATUS_SOFT_ERROR:
return qs;
case GNUNET_DB_STATUS_HARD_ERROR:
GNUNET_break (qs);
*mhd_ret = TEH_RESPONSE_reply_internal_db_error (connection,
TALER_EC_REFRESH_REVEAL_DB_FETCH_REVEAL_ERROR);
return GNUNET_DB_STATUS_HARD_ERROR;
case GNUNET_DB_STATUS_SUCCESS_ONE_RESULT:
default:
/* Hossa, already found our reply! */
GNUNET_assert (NULL != rctx->ev_sigs);
return qs;
}
/* Obtain basic information about the refresh operation and what
gamma we committed to. */
qs = TEH_plugin->get_melt (TEH_plugin->cls,
session,
&rctx->rc,
&refresh_melt);
if (GNUNET_DB_STATUS_SUCCESS_NO_RESULTS == qs)
{
*mhd_ret = TEH_RESPONSE_reply_arg_invalid (connection,
TALER_EC_REFRESH_REVEAL_SESSION_UNKNOWN,
"rc");
return GNUNET_DB_STATUS_HARD_ERROR;
}
if (GNUNET_DB_STATUS_SOFT_ERROR == qs)
return qs;
if ( (GNUNET_DB_STATUS_HARD_ERROR == qs) ||
(refresh_melt.session.noreveal_index >= TALER_CNC_KAPPA) )
{
GNUNET_break (0);
*mhd_ret = TEH_RESPONSE_reply_internal_db_error (connection,
TALER_EC_REFRESH_REVEAL_DB_FETCH_SESSION_ERROR);
return GNUNET_DB_STATUS_HARD_ERROR;
}
/* Verify commitment */
{
/* Note that the contents of rcs[refresh_melt.session.noreveal_index]
will be aliased and are *not* allocated (or deallocated) in
this function -- in contrast to the other offsets! */
struct TALER_RefreshCommitmentEntry rcs[TALER_CNC_KAPPA];
struct TALER_RefreshCommitmentP rc_expected;
unsigned int off;
off = 0; /* did we pass session.noreveal_index yet? */
for (unsigned int i=0;itransfer_pub = rctx->gamma_tp;
rce->new_coins = (struct TALER_RefreshCoinData *) rctx->rcds;
off = 1;
}
else
{
/* Reconstruct coin envelopes from transfer private key */
struct TALER_TransferPrivateKeyP *tpriv = &rctx->transfer_privs[i - off];
struct TALER_TransferSecretP ts;
GNUNET_CRYPTO_ecdhe_key_get_public (&tpriv->ecdhe_priv,
&rce->transfer_pub.ecdhe_pub);
TALER_link_reveal_transfer_secret (tpriv,
&refresh_melt.session.coin.coin_pub,
&ts);
rce->new_coins = GNUNET_new_array (rctx->num_fresh_coins,
struct TALER_RefreshCoinData);
for (unsigned int j=0;jnum_fresh_coins;j++)
{
struct TALER_RefreshCoinData *rcd = &rce->new_coins[j];
struct TALER_PlanchetSecretsP ps;
struct TALER_PlanchetDetail pd;
rcd->dk = &rctx->dkis[j]->denom_pub;
TALER_planchet_setup_refresh (&ts,
j,
&ps);
TALER_planchet_prepare (rcd->dk,
&ps,
&pd);
rcd->coin_ev = pd.coin_ev;
rcd->coin_ev_size = pd.coin_ev_size;
}
}
}
TALER_refresh_get_commitment (&rc_expected,
TALER_CNC_KAPPA,
rctx->num_fresh_coins,
rcs,
&refresh_melt.session.coin.coin_pub,
&refresh_melt.session.amount_with_fee);
/* Free resources allocated above */
for (unsigned int i=0;inum_fresh_coins;j++)
{
struct TALER_RefreshCoinData *rcd = &rce->new_coins[j];
GNUNET_free (rcd->coin_ev);
}
GNUNET_free (rce->new_coins);
}
/* Verify rc_expected matches rc */
if (0 != memcmp (&rctx->rc,
&rc_expected,
sizeof (struct TALER_RefreshCommitmentP)))
{
GNUNET_break_op (0);
*mhd_ret = reply_refresh_reveal_missmatch (connection,
&rc_expected);
return GNUNET_DB_STATUS_HARD_ERROR;
}
} /* end of checking "rc_expected" */
/* check amounts add up! */
{
struct TALER_Amount refresh_cost;
refresh_cost = refresh_melt.melt_fee;
for (unsigned int i=0;inum_fresh_coins;i++)
{
struct TALER_Amount fee_withdraw;
struct TALER_Amount value;
struct TALER_Amount total;
TALER_amount_ntoh (&fee_withdraw,
&rctx->dkis[i]->issue.properties.fee_withdraw);
TALER_amount_ntoh (&value,
&rctx->dkis[i]->issue.properties.value);
if ( (GNUNET_OK !=
TALER_amount_add (&total,
&fee_withdraw,
&value)) ||
(GNUNET_OK !=
TALER_amount_add (&refresh_cost,
&refresh_cost,
&total)) )
{
GNUNET_break_op (0);
*mhd_ret = TEH_RESPONSE_reply_internal_error (connection,
TALER_EC_REFRESH_REVEAL_COST_CALCULATION_OVERFLOW,
"failed to add up refresh costs");
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
if (0 < TALER_amount_cmp (&refresh_cost,
&refresh_melt.session.amount_with_fee))
{
GNUNET_break_op (0);
*mhd_ret = TEH_RESPONSE_reply_external_error (connection,
TALER_EC_REFRESH_REVEAL_AMOUNT_INSUFFICIENT,
"melted coin value is insufficient to cover cost of operation");
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
/* Client request OK, sign coins */
rctx->ev_sigs = GNUNET_new_array (rctx->num_fresh_coins,
struct TALER_DenominationSignature);
for (unsigned int i=0;inum_fresh_coins;i++)
{
rctx->ev_sigs[i].rsa_signature
= GNUNET_CRYPTO_rsa_sign_blinded (rctx->dkis[i]->denom_priv.rsa_private_key,
rctx->rcds[i].coin_ev,
rctx->rcds[i].coin_ev_size);
if (NULL == rctx->ev_sigs[i].rsa_signature)
{
*mhd_ret = TEH_RESPONSE_reply_internal_db_error (connection,
TALER_EC_REFRESH_REVEAL_SIGNING_ERROR);
return GNUNET_DB_STATUS_HARD_ERROR;
}
}
/* Persist operation result in DB */
{
struct TALER_EXCHANGEDB_RefreshRevealedCoin rrcs[rctx->num_fresh_coins];
for (unsigned int i=0;inum_fresh_coins;i++)
{
struct TALER_EXCHANGEDB_RefreshRevealedCoin *rrc = &rrcs[i];
rrc->denom_pub = rctx->dkis[i]->denom_pub;
rrc->coin_ev = rctx->rcds[i].coin_ev;
rrc->coin_ev_size = rctx->rcds[i].coin_ev_size;
rrc->coin_sig = rctx->ev_sigs[i];
}
qs = TEH_plugin->insert_refresh_reveal (TEH_plugin->cls,
session,
&rctx->rc,
rctx->num_fresh_coins,
rrcs,
TALER_CNC_KAPPA - 1,
rctx->transfer_privs,
&rctx->gamma_tp);
}
if (GNUNET_DB_STATUS_HARD_ERROR == qs)
{
*mhd_ret = TEH_RESPONSE_reply_internal_db_error (connection,
TALER_EC_REFRESH_REVEAL_DB_COMMIT_ERROR);
}
return qs;
}
/**
* Handle a "/refresh/reveal" request. Parses the given JSON
* transfer private keys and if successful, passes everything to
* #TEH_DB_execute_refresh_reveal() which will verify that the
* revealed information is valid then returns the signed refreshed
* coins.
*
* @param connection the MHD connection to handle
* @param rctx context for the operation, partially built at this time
* @param transfer_pub transfer public key
* @param tp_json private transfer keys in JSON format
* @param new_denoms_h_json requests for fresh coins to be created
* @param coin_evs envelopes of gamma-selected coins to be signed
* @return MHD result code
*/
static int
handle_refresh_reveal_json (struct MHD_Connection *connection,
struct RevealContext *rctx,
const json_t *tp_json,
const json_t *new_denoms_h_json,
const json_t *coin_evs)
{
unsigned int num_fresh_coins = json_array_size (new_denoms_h_json);
unsigned int num_tprivs = json_array_size (tp_json);
struct TEH_KS_StateHandle *key_state;
GNUNET_assert (num_tprivs == TALER_CNC_KAPPA - 1);
if ( (num_fresh_coins >= MAX_FRESH_COINS) ||
(0 == num_fresh_coins) )
{
GNUNET_break_op (0);
return TEH_RESPONSE_reply_arg_invalid (connection,
TALER_EC_REFRESH_REVEAL_NEW_DENOMS_ARRAY_SIZE_EXCESSIVE,
"new_denoms");
}
if (json_array_size (new_denoms_h_json) !=
json_array_size (coin_evs))
{
GNUNET_break_op (0);
return TEH_RESPONSE_reply_arg_invalid (connection,
TALER_EC_REFRESH_REVEAL_NEW_DENOMS_ARRAY_SIZE_MISSMATCH,
"new_denoms/coin_evs");
}
/* Parse transfer private keys array */
for (unsigned int i=0;itransfer_privs[i]),
GNUNET_JSON_spec_end ()
};
int res;
res = TEH_PARSE_json_array (connection,
tp_json,
trans_spec,
i,
-1);
if (GNUNET_OK != res)
return (GNUNET_NO == res) ? MHD_YES : MHD_NO;
}
/* Resolve denomination hashes */
{
const struct TALER_EXCHANGEDB_DenominationKeyIssueInformation *dkis[num_fresh_coins];
struct TALER_RefreshCoinData rcds[num_fresh_coins];
int res;
/* Resolve denomination hashes */
key_state = TEH_KS_acquire ();
if (NULL == key_state)
{
TALER_LOG_ERROR ("Lacking keys to operate\n");
/* FIXME: use correct EC code! */
return TEH_RESPONSE_reply_internal_error (connection,
TALER_EC_REFRESH_REVEAL_SIGNING_ERROR,
"exchange lacks keys");
}
/* Parse denomination key hashes */
for (unsigned int i=0;icoin_ev,
&rcd->coin_ev_size),
GNUNET_JSON_spec_end ()
};
res = TEH_PARSE_json_array (connection,
coin_evs,
spec,
i,
-1);
if (GNUNET_OK != res)
{
for (unsigned int j=0;jdk = &dkis[i]->denom_pub;
}
rctx->num_fresh_coins = num_fresh_coins;
rctx->rcds = rcds;
rctx->dkis = dkis;
/* do transactional work */
if (GNUNET_OK ==
TEH_DB_run_transaction (connection,
"run reveal",
&res,
&refresh_reveal_transaction,
rctx))
{
/* Generate final (positive) response */
GNUNET_assert (NULL != rctx->ev_sigs);
res = reply_refresh_reveal_success (connection,
num_fresh_coins,
rctx->ev_sigs);
}
/* free resources */
if (NULL != rctx->ev_sigs)
{
for (unsigned int i=0;iev_sigs[i].rsa_signature)
GNUNET_CRYPTO_rsa_signature_free (rctx->ev_sigs[i].rsa_signature);
GNUNET_free (rctx->ev_sigs);
}
for (unsigned int i=0;i