Issue #2202: Fix UnboundLocalError in AbstractDigestAuthHandler.get_algorithm_impls

Raise ValueError if algorithm is not MD5 or SHA.

Initial patch by Mathieu Dupuy.

Lib/test/test_urllib2.py

@@ -13,7 +13,8 @@ import urllib.request
 # proxy config data structure but is testable on all platforms.
 from urllib.request import (Request, OpenerDirector, HTTPBasicAuthHandler,
                             HTTPPasswordMgrWithPriorAuth, _parse_proxy,
-                            _proxy_bypass_macosx_sysconf)
+                            _proxy_bypass_macosx_sysconf,
+                            AbstractDigestAuthHandler)
 from urllib.parse import urlparse
 import urllib.error
 import http.client
@@ -1680,6 +1681,15 @@ class MiscTests(unittest.TestCase):
 
         self.assertRaises(ValueError, _parse_proxy, 'file:/ftp.example.com'),
 
+    def test_unsupported_algorithm(self):
+        handler = AbstractDigestAuthHandler()
+        with self.assertRaises(ValueError) as exc:
+            handler.get_algorithm_impls('invalid')
+        self.assertEqual(
+            str(exc.exception),
+            "Unsupported digest authentication algorithm 'invalid'"
+        )
+
 
 class RequestTests(unittest.TestCase):
     class PutRequest(Request):

Lib/urllib/request.py

@@ -1171,6 +1171,9 @@ class AbstractDigestAuthHandler:
         elif algorithm == 'SHA':
             H = lambda x: hashlib.sha1(x.encode("ascii")).hexdigest()
         # XXX MD5-sess
+        else:
+            raise ValueError("Unsupported digest authentication "
+                             "algorithm %r" % algorithm)
         KD = lambda s, d: H("%s:%s" % (s, d))
         return H, KD
 

Misc/NEWS

@@ -201,6 +201,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #2202: Fix UnboundLocalError in
+  AbstractDigestAuthHandler.get_algorithm_impls.  Initial patch by Mathieu Dupuy.
+
 - Issue #26167: Minimized overhead in copy.copy() and copy.deepcopy().
   Optimized copying and deepcopying bytearrays, NotImplemented, slices,
   short lists, tuples, dicts, sets.