# HG changeset patch

# User Senthil Kumaran <senthil@uthcode.com>

# Date 1469882993 25200

# Node ID ba915d561667fa0584ad89f8d5a844fd43803c0d

# Parent  c8c1ea94379a7706638f1571988576d504d7fc98

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 reported and patch contributed by RĂ©mi Rampin.

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

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

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

@@ -525,6 +525,11 @@ setting up a `Basic Authentication`_ han

     through a proxy.  However, this can be enabled by extending urllib2 as

     shown in the recipe [#]_.

+.. note::

+

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

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

+

 Sockets and Layers

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

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

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

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

@@ -295,6 +295,16 @@ Utility functions

    If both lowercase and uppercase environment variables exist (and disagree),

    lowercase is preferred.

+    .. 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).

+

 .. note::

     urllib also exposes certain utility functions like splittype, splithost and

     others parsing URL into various components. But it is recommended to use

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

--- a/Doc/library/urllib2.rst

+++ b/Doc/library/urllib2.rst

@@ -229,6 +229,11 @@ 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.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

@@ -170,6 +170,18 @@ class ProxyTests(unittest.TestCase):

         self.assertTrue(urllib.proxy_bypass_environment('anotherdomain.com:8888'))

         self.assertTrue(urllib.proxy_bypass_environment('newdomain.com:1234'))

+    def test_proxy_cgi_ignore(self):

+        try:

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

+            proxies = urllib.getproxies_environment()

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

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

+            proxies = urllib.getproxies_environment()

+            self.assertNotIn('http', proxies)

+        finally:

+            self.env.unset('REQUEST_METHOD')

+            self.env.unset('HTTP_PROXY')

+

     def test_proxy_bypass_environment_host_match(self):

         bypass = urllib.proxy_bypass_environment

         self.env.set('NO_PROXY',

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

--- a/Lib/urllib.py

+++ b/Lib/urllib.py

@@ -1380,12 +1380,21 @@ def getproxies_environment():

     If you need a different way, you can pass a proxies dictionary to the

     [Fancy]URLopener constructor.

     """

+    # Get all variables

     proxies = {}

     for name, value in os.environ.items():

         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 "proxy" is lowercase, it will still be used thanks to the next block

+    if 'REQUEST_METHOD' in os.environ:

+        proxies.pop('http', None)

+

+    # Get lowercase variables

     for name, value in os.environ.items():

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

             name = name.lower()