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Diffstat (limited to 'src/exchangedb/exchange_do_refund.sql')
| -rw-r--r-- | src/exchangedb/exchange_do_refund.sql | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/src/exchangedb/exchange_do_refund.sql b/src/exchangedb/exchange_do_refund.sql new file mode 100644 index 000000000..a95746127 --- /dev/null +++ b/src/exchangedb/exchange_do_refund.sql @@ -0,0 +1,205 @@ +-- +-- This file is part of TALER +-- Copyright (C) 2014--2023 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_refund( + IN in_amount_with_fee taler_amount, + IN in_amount taler_amount, + IN in_deposit_fee taler_amount, + IN in_h_contract_terms BYTEA, + IN in_rtransaction_id INT8, + IN in_deposit_shard INT8, + IN in_known_coin_id INT8, + IN in_coin_pub BYTEA, + IN in_merchant_pub BYTEA, + IN in_merchant_sig BYTEA, + OUT out_not_found BOOLEAN, + OUT out_refund_ok BOOLEAN, + OUT out_gone BOOLEAN, + OUT out_conflict BOOLEAN) +LANGUAGE plpgsql +AS $$ +DECLARE + bdsi INT8; -- ID of deposit being refunded +DECLARE + tmp_val INT8; -- total amount refunded +DECLARE + tmp_frac INT8; -- total amount refunded, large fraction to deal with overflows! +DECLARE + tmp taler_amount; -- total amount refunded, normalized +DECLARE + deposit taler_amount; -- amount that was originally deposited +BEGIN +-- Shards: SELECT deposits (coin_pub, shard, h_contract_terms, merchant_pub) +-- INSERT refunds (by coin_pub, rtransaction_id) ON CONFLICT DO NOTHING +-- SELECT refunds (by coin_pub) +-- UPDATE known_coins (by coin_pub) + +SELECT + bdep.batch_deposit_serial_id + ,(cdep.amount_with_fee).val + ,(cdep.amount_with_fee).frac + ,bdep.done + INTO + bdsi + ,deposit.val + ,deposit.frac + ,out_gone + FROM batch_deposits bdep + JOIN coin_deposits cdep + USING (batch_deposit_serial_id) + WHERE cdep.coin_pub=in_coin_pub + AND shard=in_deposit_shard + AND merchant_pub=in_merchant_pub + AND h_contract_terms=in_h_contract_terms; + +IF NOT FOUND +THEN + -- No matching deposit found! + out_refund_ok=FALSE; + out_conflict=FALSE; + out_not_found=TRUE; + out_gone=FALSE; + RETURN; +END IF; + +INSERT INTO refunds + (batch_deposit_serial_id + ,coin_pub + ,merchant_sig + ,rtransaction_id + ,amount_with_fee + ) + VALUES + (bdsi + ,in_coin_pub + ,in_merchant_sig + ,in_rtransaction_id + ,in_amount_with_fee + ) + ON CONFLICT DO NOTHING; + +IF NOT FOUND +THEN + -- Idempotency check: see if an identical record exists. + -- Note that by checking 'coin_sig', we implicitly check + -- identity over everything that the signature covers. + -- We do select over merchant_pub and h_contract_terms + -- primarily here to maximally use the existing index. + PERFORM + FROM exchange.refunds + WHERE coin_pub=in_coin_pub + AND batch_deposit_serial_id=bdsi + AND rtransaction_id=in_rtransaction_id + AND amount_with_fee=in_amount_with_fee; + + IF NOT FOUND + THEN + -- Deposit exists, but have conflicting refund. + out_refund_ok=FALSE; + out_conflict=TRUE; + out_not_found=FALSE; + RETURN; + END IF; + + -- Idempotent request known, return success. + out_refund_ok=TRUE; + out_conflict=FALSE; + out_not_found=FALSE; + out_gone=FALSE; + RETURN; +END IF; + +IF out_gone +THEN + -- money already sent to the merchant. Tough luck. + out_refund_ok=FALSE; + out_conflict=FALSE; + out_not_found=FALSE; + RETURN; +END IF; + +-- Check refund balance invariant. +SELECT + SUM((refs.amount_with_fee).val) -- overflow here is not plausible + ,SUM(CAST((refs.amount_with_fee).frac AS INT8)) -- compute using 64 bits + INTO + tmp_val + ,tmp_frac + FROM refunds refs + WHERE coin_pub=in_coin_pub + AND batch_deposit_serial_id=bdsi; +IF tmp_val IS NULL +THEN + RAISE NOTICE 'failed to sum up existing refunds'; + out_refund_ok=FALSE; + out_conflict=FALSE; + out_not_found=FALSE; + RETURN; +END IF; + +-- Normalize result before continuing +tmp.val = tmp_val + tmp_frac / 100000000; +tmp.frac = tmp_frac % 100000000; + +-- Actually check if the deposits are sufficient for the refund. Verbosely. ;-) +IF (tmp.val < deposit.val) +THEN + out_refund_ok=TRUE; +ELSE + IF (tmp.val = deposit.val) AND (tmp.frac <= deposit.frac) + THEN + out_refund_ok=TRUE; + ELSE + out_refund_ok=FALSE; + END IF; +END IF; + +IF (tmp.val = deposit.val) AND (tmp.frac = deposit.frac) +THEN + -- Refunds have reached the full value of the original + -- deposit. Also refund the deposit fee. + in_amount.frac = in_amount.frac + in_deposit_fee.frac; + in_amount.val = in_amount.val + in_deposit_fee.val; + + -- Normalize result before continuing + in_amount.val = in_amount.val + in_amount.frac / 100000000; + in_amount.frac = in_amount.frac % 100000000; +END IF; + +-- Update balance of the coin. +UPDATE known_coins kc + SET + remaining.frac=(kc.remaining).frac+in_amount.frac + - CASE + WHEN (kc.remaining).frac+in_amount.frac >= 100000000 + THEN 100000000 + ELSE 0 + END, + remaining.val=(kc.remaining).val+in_amount.val + + CASE + WHEN (kc.remaining).frac+in_amount.frac >= 100000000 + THEN 1 + ELSE 0 + END + WHERE coin_pub=in_coin_pub; + +out_conflict=FALSE; +out_not_found=FALSE; + +END $$; + +COMMENT ON FUNCTION exchange_do_refund(taler_amount, taler_amount, taler_amount, BYTEA, INT8, INT8, INT8, BYTEA, BYTEA, BYTEA) + IS 'Executes a refund operation, checking that the corresponding deposit was sufficient to cover the refunded amount'; |