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--
-- This file is part of TALER
-- Copyright (C) 2014--2022 Taler Systems SA
--
-- TALER is free software; you can redistribute it and/or modify it under the
-- terms of the GNU 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 General Public License for more details.
--
-- You should have received a copy of the GNU General Public License along with
-- TALER; see the file COPYING. If not, see <http://www.gnu.org/licenses/>
--
CREATE OR REPLACE FUNCTION exchange_do_melt(
IN in_cs_rms BYTEA,
IN in_amount_with_fee taler_amount,
IN in_rc BYTEA,
IN in_old_coin_pub BYTEA,
IN in_old_coin_sig BYTEA,
IN in_known_coin_id INT8, -- not used, but that's OK
IN in_noreveal_index INT4,
IN in_zombie_required BOOLEAN,
OUT out_balance_ok BOOLEAN,
OUT out_zombie_bad BOOLEAN,
OUT out_noreveal_index INT4)
LANGUAGE plpgsql
AS $$
DECLARE
denom_max INT8;
BEGIN
-- Shards: INSERT refresh_commitments (by rc)
-- (rare:) SELECT refresh_commitments (by old_coin_pub) -- crosses shards!
-- (rare:) SEELCT refresh_revealed_coins (by melt_serial_id)
-- (rare:) PERFORM recoup_refresh (by rrc_serial) -- crosses shards!
-- UPDATE known_coins (by coin_pub)
INSERT INTO exchange.refresh_commitments
(rc
,old_coin_pub
,old_coin_sig
,amount_with_fee
,noreveal_index
)
VALUES
(in_rc
,in_old_coin_pub
,in_old_coin_sig
,in_amount_with_fee
,in_noreveal_index)
ON CONFLICT DO NOTHING;
IF NOT FOUND
THEN
-- Idempotency check: see if an identical record exists.
out_noreveal_index=-1;
SELECT
noreveal_index
INTO
out_noreveal_index
FROM exchange.refresh_commitments
WHERE rc=in_rc;
out_balance_ok=FOUND;
out_zombie_bad=FALSE; -- zombie is OK
RETURN;
END IF;
IF in_zombie_required
THEN
-- Check if this coin was part of a refresh
-- operation that was subsequently involved
-- in a recoup operation. We begin by all
-- refresh operations our coin was involved
-- with, then find all associated reveal
-- operations, and then see if any of these
-- reveal operations was involved in a recoup.
PERFORM
FROM recoup_refresh
WHERE rrc_serial IN
(SELECT rrc_serial
FROM refresh_revealed_coins
WHERE melt_serial_id IN
(SELECT melt_serial_id
FROM refresh_commitments
WHERE old_coin_pub=in_old_coin_pub));
IF NOT FOUND
THEN
out_zombie_bad=TRUE;
out_balance_ok=FALSE;
RETURN;
END IF;
END IF;
out_zombie_bad=FALSE; -- zombie is OK
-- Check and update balance of the coin.
UPDATE known_coins kc
SET
remaining.frac=(kc.remaining).frac-in_amount_with_fee.frac
+ CASE
WHEN (kc.remaining).frac < in_amount_with_fee.frac
THEN 100000000
ELSE 0
END,
remaining.val=(kc.remaining).val-in_amount_with_fee.val
- CASE
WHEN (kc.remaining).frac < in_amount_with_fee.frac
THEN 1
ELSE 0
END
WHERE coin_pub=in_old_coin_pub
AND ( ((kc.remaining).val > in_amount_with_fee.val) OR
( ((kc.remaining).frac >= in_amount_with_fee.frac) AND
((kc.remaining).val >= in_amount_with_fee.val) ) );
IF NOT FOUND
THEN
-- Insufficient balance.
out_noreveal_index=-1;
out_balance_ok=FALSE;
RETURN;
END IF;
-- Special actions needed for a CS melt?
IF NOT NULL in_cs_rms
THEN
-- Get maximum denominations serial value in
-- existence, this will determine how long the
-- nonce will be locked.
SELECT
denominations_serial
INTO
denom_max
FROM exchange.denominations
ORDER BY denominations_serial DESC
LIMIT 1;
-- Cache CS signature to prevent replays in the future
-- (and check if cached signature exists at the same time).
INSERT INTO exchange.cs_nonce_locks
(nonce
,max_denomination_serial
,op_hash)
VALUES
(cs_rms
,denom_serial
,in_rc)
ON CONFLICT DO NOTHING;
IF NOT FOUND
THEN
-- Record exists, make sure it is the same
SELECT 1
FROM exchange.cs_nonce_locks
WHERE nonce=cs_rms
AND op_hash=in_rc;
IF NOT FOUND
THEN
-- Nonce reuse detected
out_balance_ok=FALSE;
out_zombie_bad=FALSE;
out_noreveal_index=42; -- FIXME: return error message more nicely!
ASSERT false, 'nonce reuse attempted by client';
END IF;
END IF;
END IF;
-- Everything fine, return success!
out_balance_ok=TRUE;
out_noreveal_index=in_noreveal_index;
END $$;
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