Re: FE/BE protocol oddity

Tom Lane writes:

> Good point. Probably, PQfinish should only send the X message if the
> connection has gotten past the authentication stage. A separate but
> also useful change would be to do immediate socket close on detecting
> auth failure, before returning to the client application.

Further investigation shows that all of this used to work correctly until
the infamous async connection patch. The comment now reads:
(fe-connect.c)

/*
* We used to close the socket at this point, but that makes it
* awkward for those above us if they wish to remove this socket from
* their own records (an fd_set for example). We'll just have this
* socket closed when PQfinish is called (which is compulsory even
* after an error, since the connection structure must be freed).
*/

I guess there is sort of a point there. So I'm leaning towards adding a
"startup complete" flag somewhere in PGconn and simply fix up
closePGconn().

> > Btw., is recv(sock, x, 1, MSG_PEEK) == 0 an appropriate way to check for a
> > closed connection without reading anything?
>
> Seems a little risky as far as portability goes; is MSG_PEEK supported
> on BeOS, Darwin, Cygwin, etc?

Darwin is FreeBSD, so yes. Cygwin says it supports recv() and MSG_PEEK is
trivial from there. BeOS is going backrupt before the next release
anyway. ;-) Seriously, in the worst case we'll get EINVAL.

> Might be better to fix the backend libpq routines to understand
> whether a connection-close event is expected or not, and only emit a
> complaint to the log when it's not. Not sure how far such a change
> would need to propagate though...

Deep...

--
Peter Eisentraut peter_e(at)gmx(dot)net http://funkturm.homeip.net/~peter