bpo-39603: Prevent header injection in http methods (GH-18485) (GH-21539)

reject control chars in http method in http.client.putrequest to prevent http header injection
(cherry picked from commit 8ca8a2e8fb068863c1138f07e3098478ef8be12e)

Co-authored-by: AMIR <31338382+amiremohamadi@users.noreply.github.com>

[rebased for py2.7]

2 files changed, 37 insertions, 0 deletions

diff --git a/Lib/httplib.py b/Lib/httplib.py
index fcc4152aaf2..81a08d5d714 100644
--- a/Lib/httplib.py
+++ b/Lib/httplib.py
@@ -257,6 +257,10 @@ _contains_disallowed_url_pchar_re = re.compile('[\x00-\x20\x7f-\xff]')
 #  _is_allowed_url_pchars_re = re.compile(r"^[/!$&'()*+,;=:@%a-zA-Z0-9._~-]+$")
 # We are more lenient for assumed real world compatibility purposes.
 
+# These characters are not allowed within HTTP method names
+# to prevent http header injection.
+_contains_disallowed_method_pchar_re = re.compile('[\x00-\x1f]')
+
 # We always set the Content-Length header for these methods because some
 # servers will otherwise respond with a 411
 _METHODS_EXPECTING_BODY = {'PATCH', 'POST', 'PUT'}
@@ -935,6 +939,8 @@ class HTTPConnection:
         else:
             raise CannotSendRequest()
 
+        self._validate_method(method)
+
         # Save the method for use later in the response phase
         self._method = method
 
@@ -1020,6 +1026,17 @@ class HTTPConnection:
         # On Python 2, request is already encoded (default)
         return request
 
+    def _validate_method(self, method):
+        """Validate a method name for putrequest."""
+        # prevent http header injection
+        match = _contains_disallowed_method_pchar_re.search(method)
+        if match:
+            msg = (
+                "method can't contain control characters. {method!r} "
+                "(found at least {matched!r})"
+            ).format(matched=match.group(), method=method)
+            raise ValueError(msg)
+
     def _validate_path(self, url):
         """Validate a url for putrequest."""
         # Prevent CVE-2019-9740.
diff --git a/Lib/test/test_httplib.py b/Lib/test/test_httplib.py
index d8a57f73530..e20a0986dce 100644
--- a/Lib/test/test_httplib.py
+++ b/Lib/test/test_httplib.py
@@ -384,6 +384,26 @@ class HeaderTests(TestCase):
             with self.assertRaisesRegexp(ValueError, 'Invalid header'):
                 conn.putheader(name, value)
 
+    def test_invalid_method_names(self):
+        methods = (
+            'GET\r',
+            'POST\n',
+            'PUT\n\r',
+            'POST\nValue',
+            'POST\nHOST:abc',
+            'GET\nrHost:abc\n',
+            'POST\rRemainder:\r',
+            'GET\rHOST:\n',
+            '\nPUT'
+        )
+
+        for method in methods:
+            with self.assertRaisesRegexp(
+                    ValueError, "method can't contain control characters"):
+                conn = httplib.HTTPConnection('example.com')
+                conn.sock = FakeSocket(None)
+                conn.request(method=method, url="/")
+
 
 class BasicTest(TestCase):
     def test_status_lines(self):