New submission from Samwyse:
When a URL is opened, the opener-director is responsible for locating the
proper handler for the specified protocol. Frequently, an existing protocol
handler will be subclassed and then added to the collection maintained by the
director. When urlopen is called, the specified request is immediately handed
off to the director's "open" method which finds the correct handler and invokes
the protocol-specific XXX_open method. At least in the case of the HTTP
protocols, if an error occurs then the director is called again to find and
invoke a handler for the error; these handlers generally open a new connection
after adding headers to avoid the error going forward. Finally, it is important
to note that at the present time, the HTTP handlers in urllib2 are built using
a class (infourl) that isn't prepared to deal with a persistent connection, so
they always add a "Connection: close" header to the request.
Unfortunately, NTLM only certifies the current connection, meaning that a
"Connection: keep-alive" header must be used to keep it open throughout the
authentication process. Furthermore, because the opener director only provides
a do_open method, there is no way to discover the type of connection without
also opening it. This means that the HTTPNtlmAuthHandler cannot use the normal
HTTPHandler and must therefore must hardcode the HTTPConnection class. If a
custom class is required for whatever reason, the only way to cause it to be
used is to monkey-patch the code. For an example, see
http://code.google.com/p/python-ntlm/source/browse/trunk/python26/ntlm_examples/test_ntlmauth.py
This can be avoided if, instead of putting the instantiation of the desired
HTTP connection class inline, the HTTPHandler classes used a class instance
variable. Something like the following should work without breaking any
existing code:
class HTTPHandler(AbstractHTTPHandler):
_connection = httplib.HTTPConnection
@property
def connection(self):
"""Returns the class of connection being handled."""
return self._connection
def http_open(self, req):
return self.do_open(_connection, req)
http_request = AbstractHTTPHandler.do_request_
----------
components: Library (Lib)
messages: 182343
nosy: samwyse
priority: normal
severity: normal
status: open
title: unable to discover preferred HTTPConnection class
versions: 3rd party, Python 2.6, Python 2.7, Python 3.1, Python 3.2, Python
3.3, Python 3.4, Python 3.5
_______________________________________
Python tracker <[email protected]>
<http://bugs.python.org/issue17229>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
