Re: Sanitize schema name

On 05/09/2015 01:03 PM, Ludovic Gasc wrote:
> 2015-05-08 0:12 GMT+02:00 Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com
> <mailto:adrian(dot)klaver(at)aklaver(dot)com>>:
>
> On 05/07/2015 01:06 PM, Ludovic Gasc wrote:
>
> Thanks all for your answers, you understand well my need.
>
> About PQescapeIdentifier:
> 1. An idea of release date for the next version of psycopg2 ?
> 2. Are you sure it's enough to protect against SQL injections,
> because
> you can read in the documentation: *Tip:* As with string
> literals, to
> prevent SQL injection attacks, SQL identifiers must be escaped
> when they
> are received from an untrustworthy source.
>
> About format() it doesn't work for schema, example:
> SELECT format('SELECT * FROM %I WHERE id=1', 'lg.devices')
> => SELECT * FROM "lg.devices" WHERE id=1
> SELECT * FROM "lg.devices" WHERE id=1
> => ERROR: relation "lg.devices" does not exist
> LIGNE 1 : SELECT * FROM "lg.devices" WHERE id=1
> ^
>
> ********** Error **********
>
> ERROR: relation "lg.devices" does not exist
>
>
> Try:
>
> SELECT format('SELECT * FROM %I.%I WHERE id=1', 'lg', 'devices')
>
>
> Ok, now, it works, but, I need to launch the query two times: First time
> with SELECT format(, a second time with the result of the first query.
> It should be possible to execute that only in one pass ?

As far as I know, only in plpgsql:

http://www.postgresql.org/docs/9.4/static/plpgsql-statements.html#PLPGSQL-QUOTE-LITERAL-EXAMPLE

Hence the previous suggestion about creating a psycopg2 function that
you could use directly.

>
>
>
> Still not sure why you cannot use search_path and avoid the schema
> qualification altogether?
>
>
> Because I use a pool of pgsql sockets where no connexions are dedicated
> to one particular client.

So all the clients are connecting to a single database with many
schemas, each schema unique to a client?

> I could change that each time just before to execute each query, but it
> shouldn't be very efficient.

So is the login role for each client unique, where you could use ALTER
ROLE SET search_path to have it preset:

http://www.postgresql.org/docs/9.4/interactive/sql-alterrole.html

>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com <mailto:adrian(dot)klaver(at)aklaver(dot)com>
>
>

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com