Improve backwards compatibility of encoding rules.

If a LDAP connection is initialized without explicitly setting
``bytes_mode`` to either True or False, show warnings instead of raising
a TypeError.

Lib/ldap/ldapobject.py

@@ -88,6 +88,9 @@ class SimpleLDAPObject:
 
     # Bytes mode
     # ----------
+
+    # By default, raise a TypeError when receiving invalid args
+    self.bytes_mode_hardfail = True
     if bytes_mode is None and PY2:
       warnings.warn(
         "Under Python 2, python-ldap uses bytes by default. "
@@ -97,6 +100,8 @@ class SimpleLDAPObject:
         stacklevel=2,
       )
       bytes_mode = True
+      # Disable hard failure when running in backwards compatibility mode.
+      self.bytes_mode_hardfail = False
     elif bytes_mode and not PY2:
       raise ValueError("bytes_mode is *not* supported under Python 3.")
     # On by default on Py2, off on Py3.
@@ -115,7 +120,15 @@ class SimpleLDAPObject:
       return value
     elif self.bytes_mode:
       if not isinstance(value, bytes):
-        raise TypeError("All provided fields *must* be bytes when bytes mode is on; got %r" % (value,))
+        if self.bytes_mode_hardfail:
+          raise TypeError("All provided fields *must* be bytes when bytes mode is on; got %r" % (value,))
+        else:
+          warnings.warn(
+            "Received non-bytes value %r with default (disabled) bytes mode; please choose an explicit "
+            "option for bytes_mode on your LDAP connection" % (value,),
+            BytesWarning,
+            stacklevel=6,
+          )
       return value.decode('utf-8')
     else:
       if not isinstance(value, text_type):

README

@@ -43,7 +43,8 @@ through the ``bytes_mode`` flag to ``ldap.initialize()``.
 When porting from ``python-ldap``, users are advised to update their code to set ``bytes_mode=False``
 on calls to these methods.
 Under Python 2, ``pyldap`` checks aggressively the type of provided arguments, and will raise a ``TypeError``
-for any invalid parameter.
+for any invalid parameter; however, if the ``bytes_mode`` kwarg isn't provided, ``pyldap`` will only
+raise warnings.
 
 The typical usage is as follow; note that only the result's *values* are of the bytes type:
 

Tests/t_search.py

@@ -81,8 +81,12 @@ class TestSearch(unittest.TestCase):
             for value in values:
                 self.assertEqual(type(value), bytes)
 
-    def _get_bytes_ldapobject(self):
-        l = LDAPObject(server.get_url(), bytes_mode=True)
+    def _get_bytes_ldapobject(self, explicit=True):
+        if explicit:
+            kwargs = {'bytes_mode': True}
+        else:
+            kwargs = {}
+        l = LDAPObject(server.get_url(), **kwargs)
         l.protocol_version = 3
         l.set_option(ldap.OPT_REFERRALS,0)
         l.simple_bind_s(self.server.get_root_dn().encode('utf-8'),
@@ -115,6 +119,15 @@ class TestSearch(unittest.TestCase):
             for value in values:
                 self.assertEqual(type(value), bytes)
 
+    @unittest.skipUnless(PY2, "no bytes_mode under Py3")
+    def test_unset_bytesmode_search_warns_bytes(self):
+        l = self._get_bytes_ldapobject(explicit=False)
+        base = self.server.get_dn_suffix()
+
+        l.search_s(base.encode('utf-8'), ldap.SCOPE_SUBTREE, '(cn=Foo*)', [b'*'])
+        l.search_s(base.encode('utf-8'), ldap.SCOPE_SUBTREE, b'(cn=Foo*)', ['*'])
+        l.search_s(base, ldap.SCOPE_SUBTREE, b'(cn=Foo*)', [b'*'])
+
     def test_search_subtree(self):
         base = self.server.get_dn_suffix()
         l = self.ldap