Re: POLA violation with \c service=

From: David Fetter <david(at)fetter(dot)org>
To: Andrew Dunstan <andrew(at)dunslane(dot)net>
Cc: Heikki Linnakangas <hlinnakangas(at)vmware(dot)com>, Albe Laurenz <laurenz(dot)albe(at)wien(dot)gv(dot)at>, PG Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: POLA violation with \c service=
Date: 2014-12-31 00:48:11
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On Wed, Dec 17, 2014 at 08:14:04AM -0500, Andrew Dunstan wrote:
> On 12/17/2014 04:11 AM, Heikki Linnakangas wrote:
> >On 12/17/2014 10:03 AM, Albe Laurenz wrote:
> >>David Fetter wrote:
> >>>I've noticed that psql's \c function handles service= requests in a
> >>>way that I can only characterize as broken.
> >>>
> >>>This came up in the context of connecting to a cloud hosting service
> >>>named after warriors or a river or something, whose default hostnames
> >>>are long, confusing, and easy to typo, so I suspect that service= may
> >>>come up more often going forward than it has until now.
> >>>
> >>>For example, when I try to use
> >>>
> >>>\c "service=foo"
> >>>
> >>>It will correctly figure out which database I'm trying to connect to,
> >>>but fail to notice that it's on a different host, port, etc., and
> >>>hence fail to connect with a somewhat unhelpful error message.
> >>>
> >>>I can think of a few approaches for fixing this:
> >>>
> >>>0. Leave it broken.
> >>>1. Disable "service=" requests entirely in \c context, and error out
> >>>if attempted.
> >>>2. Ensure that \c actually uses all of the available information.
> >>>
> >>>Is there another one I missed?
> >>>
> >>>If not, which of the approaches seems reasonable?
> >>
> >>#2 is the correct solution, #1 a band aid.
> >
> >It would be handy, if \c "service=foo" actually worked. We should do #3.
> >If the database name is actually a connection string, or a service
> >specification, it should not re-use the hostname and port from previous
> >connection, but use the values from the connection string or service file.
> Yeah, that's the correct solution. It should not be terribly difficult to
> create a test for a conninfo string in the dbname parameter. That's what
> libpq does after all. We certainly don't want psql to have to try to
> interpret the service file. psql just needs to let libpq do its work in this
> situation.

This took a little longer to get time to polish than I'd hoped, but
please find attached a patch which:

- Correctly connects to service= and postgres(ql)?:// with \c
- Disallows tab completion in the above cases

I'd like to see about having tab completion actually work correctly in
at least the service= case, but that's a matter for a follow-on patch.

Thanks to Andrew Dunstan for the original patch, and to Andrew Gierth
for his help getting it into shape.

David Fetter <david(at)fetter(dot)org>
Phone: +1 415 235 3778 AIM: dfetter666 Yahoo!: dfetter
Skype: davidfetter XMPP: david(dot)fetter(at)gmail(dot)com

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Attachment Content-Type Size
psql_fix_uri_service_001.patch text/plain 5.7 KB

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