#!/usr/bin/python
# urllib2 with kerberos proof of concept
# Copyright 2008 Lime Nest LLC
# Copyright 2008 Lime Spot LLC
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
# http://www.apache.org/licenses/LICENSE-2.0
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import re
import logging
import sys
import urllib2 as u2
import kerberos as k
def getLogger():
log = logging.getLogger("http_kerberos_auth_handler")
handler = logging.StreamHandler()
formatter = logging.Formatter('%(asctime)s %(levelname)s %(message)s')
handler.setFormatter(formatter)
log.addHandler(handler)
return log
log = getLogger()
class HTTPKerberosAuthHandler(u2.BaseHandler):
"""auth handler for urllib2 that does Kerberos HTTP Negotiate Authentication
"""
rx = re.compile('(?:.*,)*\s*Negotiate\s*([^,]*),?', re.I)
handler_order = 480 # before Digest auth
def negotiate_value(self, headers):
authreq = headers.get('www-authenticate', None)
if authreq:
mo = HTTPKerberosAuthHandler.rx.search(authreq)
if mo:
return mo.group(1)
else:
log.debug("regex failed on: %s" % authreq)
else:
log.debug("www-authenticate header not found")
return None
def __init__(self):
self.retried = 0
self.context = None
def generate_request_header(self, req, headers):
neg_value = self.negotiate_value(headers)
if neg_value is None:
self.retried = 0
return None
if self.retried > 0:
raise u2.HTTPError(req.get_full_url(), 401, "kerberos negotiate auth failed",
headers, None)
self.retried += 1
log.debug("retry count: %d" % self.retried)
log.debug("req.get_host() returned %s" % req.get_host())
result, self.context = k.authGSSClientInit("HTTP@%s" % req.get_host())
if result < 1:
log.warning("authGSSClientInit returned result %d" % result)
return None
log.debug("authGSSClientInit() succeeded")
result = k.authGSSClientStep(self.context, neg_value)
if result < 0:
log.warning("authGSSClientStep returned result %d" % result)
return None
log.debug("authGSSClientStep() succeeded")
response = k.authGSSClientResponse(self.context)
log.debug("authGSSClientResponse() succeeded")
return "Negotiate %s" % response
def authenticate_server(self, headers):
neg_value = self.negotiate_value(headers)
if neg_value is None:
log.critical("mutual auth failed. No negotiate header")
return None
if k.authGSSClientStep(self.context, neg_value) < 1:
log.critical("mutual auth failed: authGSSClientStep returned result %d" % result)
def clean_context(self):
if self.context is not None:
log.debug("cleaning context")
k.authGSSClientClean(self.context)
self.context = None
def http_error_401(self, req, fp, code, msg, headers):
log.debug("inside http_error_401")
try:
neg_hdr = self.generate_request_header(req, headers)
if neg_hdr is None:
log.debug("neg_hdr was None")
return None
req.add_unredirected_header('Authorization', neg_hdr)
resp = self.parent.open(req)
self.authenticate_server(resp.info())
return resp
except k.GSSError, e:
log.critical("GSSAPI Error: %s/%s" % (e[0][0], e[1][0]))
return None
finally:
self.clean_context()
self.retried = 0
def test():
log.setLevel(logging.DEBUG)
log.info("starting test")
opener = u2.build_opener()
opener.add_handler(HTTPKerberosAuthHandler())
resp = opener.open(sys.argv[1])
print dir(resp), resp.info(), resp.code
if __name__ == '__main__':
test()
