# HG changeset patch

# User Senthil Kumaran <senthil@uthcode.com>

# Date 1469947146 25200

# Node ID a0ac52ed8f7918222603b584ec8fc93d9b7bc0a5

# Parent  4cb94e561e2db9865fb4d752f2bceefca4c6819a# Parent  3c19023c9fec5a615c25598468b44fade89049ce

[merge from 3.4] - Prevent HTTPoxy attack (CVE-2016-1000110)

Ignore the HTTP_PROXY variable when REQUEST_METHOD environment is set, which

indicates that the script is in CGI mode.

Issue #27568 Reported and patch contributed by Rémi Rampin.

diff --git a/Doc/howto/urllib2.rst b/Doc/howto/urllib2.rst

--- a/Doc/howto/urllib2.rst

+++ b/Doc/howto/urllib2.rst

@@ -538,6 +538,11 @@ setting up a `Basic Authentication`_ han

     through a proxy.  However, this can be enabled by extending urllib.request as

     shown in the recipe [#]_.

+.. note::

+

+    ``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set; see

+    the documentation on :func:`~urllib.request.getproxies`.

+

 Sockets and Layers

 ==================

diff --git a/Doc/library/urllib.request.rst b/Doc/library/urllib.request.rst

--- a/Doc/library/urllib.request.rst

+++ b/Doc/library/urllib.request.rst

@@ -166,6 +166,16 @@ The :mod:`urllib.request` module defines the following functions:

    cannot find it, looks for proxy information from Mac OSX System

    Configuration for Mac OS X and Windows Systems Registry for Windows.

+    .. note::

+

+       If the environment variable ``REQUEST_METHOD`` is set, which usually

+       indicates your script is running in a CGI environment, the environment

+       variable ``HTTP_PROXY`` (uppercase ``_PROXY``) will be ignored. This is

+       because that variable can be injected by a client using the "Proxy:" HTTP

+       header. If you need to use an HTTP proxy in a CGI environment, either use

+       ``ProxyHandler`` explicitly, or make sure the variable name is in

+       lowercase (or at least the ``_proxy`` suffix).

+

 The following classes are provided:

@@ -275,6 +285,11 @@ The following classes are provided:

    To disable autodetected proxy pass an empty dictionary.

+    .. note::

+

+       ``HTTP_PROXY`` will be ignored if a variable ``REQUEST_METHOD`` is set;

+       see the documentation on :func:`~urllib.request.getproxies`.

+

 .. class:: HTTPPasswordMgr()

diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py

--- a/Lib/test/test_urllib.py

+++ b/Lib/test/test_urllib.py

@@ -225,6 +225,18 @@ class ProxyTests(unittest.TestCase):

         self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com')

         self.assertTrue(urllib.request.proxy_bypass_environment('anotherdomain.com'))

+    def test_proxy_cgi_ignore(self):

+        try:

+            self.env.set('HTTP_PROXY', 'http://somewhere:3128')

+            proxies = urllib.request.getproxies_environment()

+            self.assertEqual('http://somewhere:3128', proxies['http'])

+            self.env.set('REQUEST_METHOD', 'GET')

+            proxies = urllib.request.getproxies_environment()

+            self.assertNotIn('http', proxies)

+        finally:

+            self.env.unset('REQUEST_METHOD')

+            self.env.unset('HTTP_PROXY')

+

 class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin, FakeFTPMixin):

     """Test urlopen() opening a fake http connection."""

diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py

--- a/Lib/urllib/request.py

+++ b/Lib/urllib/request.py

@@ -2394,6 +2394,11 @@ def getproxies_environment():

         name = name.lower()

         if value and name[-6:] == '_proxy':

             proxies[name[:-6]] = value

+    # CVE-2016-1000110 - If we are running as CGI script, forget HTTP_PROXY

+    # (non-all-lowercase) as it may be set from the web server by a "Proxy:"

+    # header from the client

+    if 'REQUEST_METHOD' in os.environ:

+        proxies.pop('http', None)

     return proxies

 def proxy_bypass_environment(host):