Re: libpq and sslmode=require

Bruce Momjian wrote:
> In testing an SSL patch, I found that if I use 'sslmode=require' in the
> libpq connection string, it does not use SSL over a unix-domain socket.
>
> libpq should either use SSL (which I don't think it can), or error out,
> or we should at least document this behavior.

We discussed this before 8.3 already. It might be time to address this
now that the SSL support is being redesigned.

SSL over Unix-domain sockets with libpq works perfectly fine if you
remove the code in libpq and/or the postmaster (forgot which exactly)
that thinks that it doesn't work.

The issue previously was the libpq defaults to sslmode=prefer and that
would impose a noticeable connection initiation overhead on everyone's
Unix-domain socket uses. You could make it use SSL in require mode, but
it seems weird that prefer mode would end up doing something different
than require mode.

Maybe Magnus has an opinion on how we could make this fit into the new
scheme of things. I assume since we require certificates to be set up
now, SSL will by default be off and so using it over Unix-domain sockets
when enabled would not be in the common path, which was the objection
previously.