XML-RPC "filter"

Diez B. Roggisch deets at nospam.web.de
Tue Sep 9 17:55:43 CEST 2008

Luigi wrote:

> Dear all,
> I'm writing an XML-RPC server which should be able to modify the
> incoming request before dispatching it. In particular I wand to added
> two fixed parameters to the method called: one is the client host
> address, and the other is the user name provided as for Basic
> Authentication (http://user@www.bla-bla.com).
> To do this, at the present I've overwritten the do_POST method of
> SimpleXMLRPCRequestHandler, including at a certain point this code:
> ....
> data = ''.join(L)
> params, method = xmlrpclib.loads(data)
> user = "unknown"
> if self.headers.has_key('Authorization'):
>   # handle Basic authentication
>   (enctype, encstr) =  self.headers.get('Authorization').split()
>   user, password = base64.standard_b64decode(encstr).split(':')
> params = list(params)
> params.append(self.address_string())
> params.append(user)
> params = tuple(params)
> data = xmlrpclib.dumps(params, methodname=method)
> (I slightly modified it to make it more readable at mail level)
> It works, but I don't really like it because it completely overwrites
> the do_POST method that in the future Python releases is going to
> change (I verified it). Do you know a better way to do this?

I would go for a slightly different approach: make your server have a
dispatch-method that delegates the calls to the underlying actual
implementation. But *before* that happens, extract the information as
above, and either

 - prepend it to the argument list

 - stuff it into threadlocal variables, and only access these if needed in
your implementation.


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