Sending "Bearer" and "Bearer " resulted in a 500.

rest_framework/authentication.py

@@ -310,6 +310,13 @@ class OAuth2Authentication(BaseAuthentication):
 
         auth = get_authorization_header(request).split()
 
+        if len(auth) == 1:
+            msg = 'Invalid bearer header. No credentials provided.'
+            raise exceptions.AuthenticationFailed(msg)
+        elif len(auth) > 2:
+            msg = 'Invalid bearer header. Token string should not contain spaces.'
+            raise exceptions.AuthenticationFailed(msg)
+
         if auth and auth[0].lower() == b'bearer':
             access_token = auth[1]
         elif 'access_token' in request.POST:
@@ -319,13 +326,6 @@ class OAuth2Authentication(BaseAuthentication):
         else:
             return None
 
-        if len(auth) == 1:
-            msg = 'Invalid bearer header. No credentials provided.'
-            raise exceptions.AuthenticationFailed(msg)
-        elif len(auth) > 2:
-            msg = 'Invalid bearer header. Token string should not contain spaces.'
-            raise exceptions.AuthenticationFailed(msg)
-
         return self.authenticate_credentials(request, access_token)
 
     def authenticate_credentials(self, request, access_token):

rest_framework/tests/test_authentication.py

@@ -550,6 +550,15 @@ class OAuth2Tests(TestCase):
         self.assertEqual(response.status_code, 401)
 
     @unittest.skipUnless(oauth2_provider, 'django-oauth2-provider not installed')
+    def test_get_form_with_wrong_authorization_header_token_missing(self):
+        """Ensure that a wrong token lead to the correct HTTP error status code"""
+        auth = "Bearer"
+        response = self.csrf_client.get('/oauth2-test/', {}, HTTP_AUTHORIZATION=auth)
+        self.assertEqual(response.status_code, 401)
+        response = self.csrf_client.get('/oauth2-test/', HTTP_AUTHORIZATION=auth)
+        self.assertEqual(response.status_code, 401)
+
+    @unittest.skipUnless(oauth2_provider, 'django-oauth2-provider not installed')
     def test_get_form_passing_auth(self):
         """Ensure GETing form over OAuth with correct client credentials succeed"""
         auth = self._create_authorization_header()