backport fix for Issue #26804.

urllib.request will prefer lower_case proxy environment variables over
UPPER_CASE or Mixed_Case ones.

2 files changed, 79 insertions, 15 deletions

diff --git a/Lib/test/test_urllib.py b/Lib/test/test_urllib.py
index e14cccc..e8c14c2 100644
--- a/Lib/test/test_urllib.py
+++ b/Lib/test/test_urllib.py
@@ -1,5 +1,6 @@
 """Regresssion tests for urllib"""
 
+import collections
 import urllib
 import httplib
 import unittest
@@ -158,8 +159,46 @@ class ProxyTests(unittest.TestCase):
         # getproxies_environment use lowered case truncated (no '_proxy') keys
         self.assertEqual('localhost', proxies['no'])
         # List of no_proxies with space.
-        self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com')
+        self.env.set('NO_PROXY', 'localhost, anotherdomain.com, newdomain.com:1234')
         self.assertTrue(urllib.proxy_bypass_environment('anotherdomain.com'))
+        self.assertTrue(urllib.proxy_bypass_environment('anotherdomain.com:8888'))
+        self.assertTrue(urllib.proxy_bypass_environment('newdomain.com:1234'))
+
+
+class ProxyTests_withOrderedEnv(unittest.TestCase):
+
+    def setUp(self):
+        # We need to test conditions, where variable order _is_ significant
+        self._saved_env = os.environ
+        # Monkey patch os.environ, start with empty fake environment
+        os.environ = collections.OrderedDict()
+
+    def tearDown(self):
+        os.environ = self._saved_env
+
+    def test_getproxies_environment_prefer_lowercase(self):
+        # Test lowercase preference with removal
+        os.environ['no_proxy'] = ''
+        os.environ['No_Proxy'] = 'localhost'
+        self.assertFalse(urllib.proxy_bypass_environment('localhost'))
+        self.assertFalse(urllib.proxy_bypass_environment('arbitrary'))
+        os.environ['http_proxy'] = ''
+        os.environ['HTTP_PROXY'] = 'http://somewhere:3128'
+        proxies = urllib.getproxies_environment()
+        self.assertEqual({}, proxies)
+        # Test lowercase preference of proxy bypass and correct matching including ports
+        os.environ['no_proxy'] = 'localhost, noproxy.com, my.proxy:1234'
+        os.environ['No_Proxy'] = 'xyz.com'
+        self.assertTrue(urllib.proxy_bypass_environment('localhost'))
+        self.assertTrue(urllib.proxy_bypass_environment('noproxy.com:5678'))
+        self.assertTrue(urllib.proxy_bypass_environment('my.proxy:1234'))
+        self.assertFalse(urllib.proxy_bypass_environment('my.proxy'))
+        self.assertFalse(urllib.proxy_bypass_environment('arbitrary'))
+        # Test lowercase preference with replacement
+        os.environ['http_proxy'] = 'http://somewhere:3128'
+        os.environ['Http_Proxy'] = 'http://somewhereelse:3128'
+        proxies = urllib.getproxies_environment()
+        self.assertEqual('http://somewhere:3128', proxies['http'])
 
 
 class urlopen_HttpTests(unittest.TestCase, FakeHTTPMixin):
@@ -1030,6 +1069,8 @@ def test_main():
             Pathname_Tests,
             Utility_Tests,
             URLopener_Tests,
+            ProxyTests,
+            ProxyTests_withOrderedEnv,
             #FTPWrapperTests,
         )
 
diff --git a/Lib/urllib.py b/Lib/urllib.py
index 0cb3df9..6d17e6f 100644
--- a/Lib/urllib.py
+++ b/Lib/urllib.py
@@ -1379,25 +1379,42 @@ def getproxies_environment():
     """Return a dictionary of scheme -> proxy server URL mappings.
 
     Scan the environment for variables named <scheme>_proxy;
-    this seems to be the standard convention.  If you need a
-    different way, you can pass a proxies dictionary to the
-    [Fancy]URLopener constructor.
+    this seems to be the standard convention.  In order to prefer lowercase
+    variables, we process the environment in two passes, first matches any
+    and second matches only lower case proxies.
 
+    If you need a different way, you can pass a proxies dictionary to the
+    [Fancy]URLopener constructor.
     """
     proxies = {}
     for name, value in os.environ.items():
         name = name.lower()
         if value and name[-6:] == '_proxy':
             proxies[name[:-6]] = value
+
+    for name, value in os.environ.items():
+        if name[-6:] == '_proxy':
+            name = name.lower()
+            if value:
+                proxies[name[:-6]] = value
+            else:
+                proxies.pop(name[:-6], None)
+
     return proxies
 
-def proxy_bypass_environment(host):
+def proxy_bypass_environment(host, proxies=None):
     """Test if proxies should not be used for a particular host.
 
-    Checks the environment for a variable named no_proxy, which should
-    be a list of DNS suffixes separated by commas, or '*' for all hosts.
+    Checks the proxies dict for the value of no_proxy, which should be a
+    list of comma separated DNS suffixes, or '*' for all hosts.
     """
-    no_proxy = os.environ.get('no_proxy', '') or os.environ.get('NO_PROXY', '')
+    if proxies is None:
+        proxies = getproxies_environment()
+    # don't bypass, if no_proxy isn't specified
+    try:
+        no_proxy = proxies['no']
+    except KeyError:
+        return 0
     # '*' is special case for always bypass
     if no_proxy == '*':
         return 1
@@ -1483,8 +1500,14 @@ if sys.platform == 'darwin':
         return _get_proxies()
 
     def proxy_bypass(host):
-        if getproxies_environment():
-            return proxy_bypass_environment(host)
+        """Return True, if a host should be bypassed.
+
+        Checks proxy settings gathered from the environment, if specified, or
+        from the MacOSX framework SystemConfiguration.
+        """
+        proxies = getproxies_environment()
+        if proxies:
+            return proxy_bypass_environment(host, proxies)
         else:
             return proxy_bypass_macosx_sysconf(host)
 
@@ -1600,14 +1623,14 @@ elif os.name == 'nt':
         return 0
 
     def proxy_bypass(host):
-        """Return a dictionary of scheme -> proxy server URL mappings.
+        """Return True, if the host should be bypassed.
 
-        Returns settings gathered from the environment, if specified,
+        Checks proxy settings gathered from the environment, if specified,
         or the registry.
-
         """
-        if getproxies_environment():
-            return proxy_bypass_environment(host)
+        proxies = getproxies_environment()
+        if proxies:
+            return proxy_bypass_environment(host, proxies)
         else:
             return proxy_bypass_registry(host)