[Tutor] Trapping HTTP Authentication Failure

[Michael Powe]

On Sat, Sep 11, 2010 at 02:25:24PM +0200, Evert Rol wrote:
> <snip />
 
> >> I'm not sure what you're exactly doing here, or what you're getting,
> >> but I did get curious and dug around urllib2.py. Apparently, there is
> >> a hardcoded 5 retries before the authentication really fails. So any
> >> stack trace would be the normal stack trace times 5. Not the 30 you
> >> mentioned, but annoying enough anyway (I don't see how it would fail
> >> for every element in the loop though. Once it raises an exception,
> >> the program basically ends).

> > It never throws an exception.  Or, if it does, something about the way
> > I'm calling suppresses it.  IOW, I can put in a bogus credential and
> > start the script and sit here for 5 minutes and see nothing.  Then ^C
> > and I get a huge stacktrace that shows the repeated calls.  After the
> > timeout on one element in the list, it goes to the next element, times
> > out, goes to the next.
 
> Ok, now I had to try and recreate something myself. So my processData is:
 
> def processData(f):
>    global overview_url
>    overview_url = baseurl + f
>    getData(authHeaders)
> 
> (f being a filename, out of a list of many). Other code same as yours.
 
> It definitely throws a 401 exception after 5 retries. No time-outs,
> no long waits. In fact, a time-out would to me indicate another
> problem (it still should throw an exception, though). So, unless
> you're catching the exception in processData somehow, I don't see
> where things could go wrong.

> I assume you have no problem with correct credentials or simply
> using a webbrowser?

Hello,

Yes, I can retrieve data without any problem.  I can break the URL and
generate a 404 exception that is trapped and I can break it in other
ways that generate other types of exceptions.  And trap them.

I went back and looked at the code in urllib2.py and I see the
timeout counter and that it raises an HTTPError after 5 tries.  But I
don't get anything back.  If I just let the code run to completion, I
get sent back to the prompt.  I put a try/catch in the method and I
already have one on the call in main.

 
 
> >> I don't know why it's hard-coded that way, and not just an option
> >> with a default of 5, but that's currently how it is (maybe someone
> >> else on this list knows?).
> > 
> > I don't know, but even if I could set it to 1, I'm not helped unless
> > there's a way for me to make it throw an exception and exit the loop. 

Actually, there's a comment in the code about why it is set to 5 --
it's arbitrary, and allows for the Password Manager to prompt for
credentials while not letting the request be reissued until 'recursion
depth is exceeded.'

I guess I'll have to go back to ground zero and write a stub to
generate the error and then build back up to where it disappears.

Thanks.

mp

-- 
Michael Powe		michael at trollope.org		Naugatuck CT USA
It turns out that it will be easier to simply block the top offenders
manually; the rules for pattern matching are too arcane, obscure, and
difficult to program. -- t. pascal, comp.mail.misc, "procmail to
filter spam"
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