Re: How to ensure that a stored function always returns TRUE or FALSE?

Hi

2016-03-02 19:31 GMT+01:00 Alexander Farber <alexander(dot)farber(at)gmail(dot)com>:

> Thank you all for the valuable replies.
>
> I've also got suggestions to use IS NOT DISTINCT FROM or STRICT at
> http://stackoverflow.com/questions/35742865/how-to-ensure-that-a-stored-function-always-returns-true-or-false
>
>
> but the former has the edge case of NULL=NULL returning TRUE
> and with the latter I would have to be careful with the way I call my
> function -
> and I am worried I might forget it later and this is a security related...
>
> So I will probably use this function:
>
> CREATE OR REPLACE FUNCTION check_user(in_social integer,
> in_sid varchar(255),
> in_auth varchar(32))
> RETURNS boolean AS
> $func$
> SELECT CASE
> WHEN in_social IS NULL THEN FALSE
> WHEN in_sid IS NULL THEN FALSE
> WHEN in_auth IS NULL THEN FALSE
> ELSE (MD5('secret word' || in_social || in_sid) = in_auth)
> END;
>
> $func$ LANGUAGE sql IMMUTABLE;
>

this solution is ilustrative, but probably slower

I hope so function

REATE OR REPLACE FUNCTION check_user(in_social integer,
in_sid varchar(255),
in_auth varchar(32))
RETURNS boolean AS
$func$
SELECT COALESCE(MD5('secret word' || in_social || in_sid) =
in_auth, FALSE)
$func$ LANGUAGE sql IMMUTABLE;

should to return same result quckly.

Regards

Pavel

>
> Regards
> Alex
>
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