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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_withdraw(
IN cs_nonce BYTEA,
IN amount_val INT8,
IN amount_frac INT4,
IN h_denom_pub BYTEA,
IN rpub BYTEA,
IN reserve_sig BYTEA,
IN h_coin_envelope BYTEA,
IN denom_sig BYTEA,
IN now INT8,
IN min_reserve_gc INT8,
OUT reserve_found BOOLEAN,
OUT balance_ok BOOLEAN,
OUT nonce_ok BOOLEAN,
OUT ruuid INT8)
LANGUAGE plpgsql
AS $$
DECLARE
reserve_gc INT8;
DECLARE
denom_serial INT8;
DECLARE
reserve_val INT8;
DECLARE
reserve_frac INT4;
BEGIN
-- Shards: reserves by reserve_pub (SELECT)
-- reserves_out (INSERT, with CONFLICT detection) by wih
-- reserves by reserve_pub (UPDATE)
-- reserves_in by reserve_pub (SELECT)
-- wire_targets by wire_target_h_payto
SELECT denominations_serial
INTO denom_serial
FROM exchange.denominations
WHERE denom_pub_hash=h_denom_pub;
IF NOT FOUND
THEN
-- denomination unknown, should be impossible!
reserve_found=FALSE;
balance_ok=FALSE;
ruuid=0;
ASSERT false, 'denomination unknown';
RETURN;
END IF;
SELECT
current_balance_val
,current_balance_frac
,gc_date
,reserve_uuid
INTO
reserve_val
,reserve_frac
,reserve_gc
,ruuid
FROM exchange.reserves
WHERE reserves.reserve_pub=rpub;
IF NOT FOUND
THEN
-- reserve unknown
reserve_found=FALSE;
balance_ok=FALSE;
nonce_ok=TRUE;
ruuid=2;
RETURN;
END IF;
-- We optimistically insert, and then on conflict declare
-- the query successful due to idempotency.
INSERT INTO exchange.reserves_out
(h_blind_ev
,denominations_serial
,denom_sig
,reserve_uuid
,reserve_sig
,execution_date
,amount_with_fee_val
,amount_with_fee_frac)
VALUES
(h_coin_envelope
,denom_serial
,denom_sig
,ruuid
,reserve_sig
,now
,amount_val
,amount_frac)
ON CONFLICT DO NOTHING;
IF NOT FOUND
THEN
-- idempotent query, all constraints must be satisfied
reserve_found=TRUE;
balance_ok=TRUE;
nonce_ok=TRUE;
RETURN;
END IF;
-- Check reserve balance is sufficient.
IF (reserve_val > amount_val)
THEN
IF (reserve_frac >= amount_frac)
THEN
reserve_val=reserve_val - amount_val;
reserve_frac=reserve_frac - amount_frac;
ELSE
reserve_val=reserve_val - amount_val - 1;
reserve_frac=reserve_frac + 100000000 - amount_frac;
END IF;
ELSE
IF (reserve_val = amount_val) AND (reserve_frac >= amount_frac)
THEN
reserve_val=0;
reserve_frac=reserve_frac - amount_frac;
ELSE
reserve_found=TRUE;
nonce_ok=TRUE; -- we do not really know
balance_ok=FALSE;
RETURN;
END IF;
END IF;
-- Calculate new expiration dates.
min_reserve_gc=GREATEST(min_reserve_gc,reserve_gc);
-- Update reserve balance.
UPDATE reserves SET
gc_date=min_reserve_gc
,current_balance_val=reserve_val
,current_balance_frac=reserve_frac
WHERE
reserves.reserve_pub=rpub;
reserve_found=TRUE;
balance_ok=TRUE;
-- Special actions needed for a CS withdraw?
IF NOT NULL cs_nonce
THEN
-- 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_nonce
,denom_serial
,h_coin_envelope)
ON CONFLICT DO NOTHING;
IF NOT FOUND
THEN
-- See if the existing entry is identical.
SELECT 1
FROM exchange.cs_nonce_locks
WHERE nonce=cs_nonce
AND op_hash=h_coin_envelope;
IF NOT FOUND
THEN
reserve_found=FALSE;
balance_ok=FALSE;
nonce_ok=FALSE;
RETURN;
END IF;
END IF;
ELSE
nonce_ok=TRUE; -- no nonce, hence OK!
END IF;
END $$;
COMMENT ON FUNCTION exchange_do_withdraw(BYTEA, INT8, INT4, BYTEA, BYTEA, BYTEA, BYTEA, BYTEA, INT8, INT8)
IS 'Checks whether the reserve has sufficient balance for a withdraw operation (or the request is repeated and was previously approved) and if so updates the database with the result';
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