#9824: encode , and ; in cookie values so that browsers don't split on them

There is a small chance of backward incompatibility here, but only for
non-SimpleCookie applications reading SimpleCookie generated cookies.  Even
then, any such ap is likely to be handling escaped values already, and it would
take a fairly perverse implementation of unescaping to fail to unescape these
newly escaped chars, so the risk seems minimal.

Lib/http/cookies.py

@@ -173,6 +173,11 @@ _Translator       = {
     '\033' : '\\033',  '\034' : '\\034',  '\035' : '\\035',
     '\036' : '\\036',  '\037' : '\\037',
 
+    # Because of the way browsers really handle cookies (as opposed
+    # to what the RFC says) we also encode , and ;
+
+    ',' : '\\054', ';' : '\\073',
+
     '"' : '\\"',       '\\' : '\\\\',
 
     '\177' : '\\177',  '\200' : '\\200',  '\201' : '\\201',

Lib/test/test_http_cookies.py

@@ -69,6 +69,14 @@ class CookieTests(unittest.TestCase):
         </script>
         """)
 
+    def test_extended_encode(self):
+        # Issue 9824: some browsers don't follow the standard; we now
+        # encode , and ; to keep them from tripping up.
+        C = cookies.SimpleCookie()
+        C['val'] = "some,funky;stuff"
+        self.assertEqual(C.output(['val']),
+            'Set-Cookie: val="some\\054funky\\073stuff"')
+
     def test_special_attrs(self):
         # 'expires'
         C = cookies.SimpleCookie('Customer="WILE_E_COYOTE"')

Misc/NEWS

@@ -20,6 +20,9 @@ Core and Builtins
 Library
 -------
 
+- Issue 9824: SimpleCookie now encodes , and ; in values to cater to how
+  browsers actually parse cookies.
+
 - Issue 9333: os.symlink now available regardless of user privileges.
   The function now raises OSError on Windows >=6.0 when the user is unable
   to create symbolic links. XP and 2003 still raise NotImplementedError.