[Twisted-Python] Re: [Twisted-commits] InMemoryUsernamePasswordDatabaseDontUse didn't raise the error properly when the password was wrong

Jp Calderone exarkun at intarweb.us
Sun Sep 28 20:31:16 EDT 2003

On Sun, Sep 28, 2003 at 08:04:45PM -0400, Glyph Lefkowitz wrote:
> Itamar Shtull-Trauring wrote:
> >On Sun, 28 Sep 2003 17:44:47 -0600
> >teratorn CVS <teratorn at wolfwood.twistedmatrix.com> wrote:
> >
> >
> >>-            return failure.Failure(error.UnauthorizedLogin())
> >>+            raise error.UnauthorizedLogin()
> >>
> >
> >
> >Uh. Why does one work and not the other? That looks like a bug in
> >Deferred to me. Aren't returned Failures supposed to be the same as
> >raised exceptions in callbacks?
> >
> Considering that the two are equivalent, the former style is preferred 
> in situations like this, since it does not create Python traceback info 
> (which is _noticeably_ slower than not doing it).

  ... and then gets send to the PB client, producing a full traceback on the
client side, instead of just a one-line exception string.

  In this case, that means the client is able to discern between invalid
usernames and invalid passwords, which would be a serious problem, if we
were talking about anything other than InMemoryUsernamePassword-
DatabaseDontUse.  As it is, I think InMemoryUsernamePasswordDatabaseDontUse
should intentionally reveal even more information about why the login failed
(making it more useful for debugging and less useful for production), and
the difference between returning a Failure constructed from an exception and
raising an exception in a callback be spelled out explicitly somewhere.  Who
knows when the difference will be forgotten and something unintentionally
revealed, as it was in InMemoryUsernamePasswordDatabaseDontUse?


( LIST=(~/.sigs/*.sig)
  cat ${LIST[$(($RANDOM % ${#LIST[*]}))]}
  echo -- $'\n' `uptime | sed -e 's/.*m//'` ) > ~/.signature
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