From 50c2720bee4ee8d08172438325f915699931203d Mon Sep 17 00:00:00 2001
From: Unknown <tolsen@limebits.com>
Date: Tue, 24 Jun 2008 16:26:51 -0400
Subject: initial revision.  it works!

---
 http_negotiate_auth_handler.py | 139 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 http_negotiate_auth_handler.py

diff --git a/http_negotiate_auth_handler.py b/http_negotiate_auth_handler.py
new file mode 100644
index 0000000..76a8821
--- /dev/null
+++ b/http_negotiate_auth_handler.py
@@ -0,0 +1,139 @@
+#!/usr/bin/python
+
+# urllib2 with kerberos proof of concept
+# Copyright 2008 Lime Spot LLC
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# A copy of the GNU General Public License can be found at
+# <http://www.gnu.org/licenses/>.
+
+import re
+import logging
+import sys
+import urllib2 as u2
+
+import kerberos as k
+
+def getLogger():
+    log = logging.getLogger("http_negotiate_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 HTTPNegotiateAuthHandler(u2.BaseHandler):
+    """auth handler for urllib2 that does 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 = HTTPNegotiateAuthHandler.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 > 5:
+            raise HTTPError(req.get_full_url(), 401, "negotiate auth failed",
+                            headers, None)
+
+        self.retried += 1
+
+        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:
+            k.authGSSClientClean(self.context)
+
+    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
+        
+        finally:
+            self.clean_context()
+
+def test():
+    log.setLevel(logging.DEBUG)
+    log.info("starting test")
+    opener = u2.build_opener()
+    opener.add_handler(HTTPNegotiateAuthHandler())
+    resp = opener.open(sys.argv[1])
+    print dir(resp), resp.info(), resp.code
+    
+
+if __name__ == '__main__':
+    test()
+
-- 
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