Ticket #3008: DN objects hash differently depending on case

Because the attrs & values in DN's, RDN's and AVA's are comparison case-
insensitive the hash value between two objects which compare as equal but
differ in case must also yield the same hash value. This is critical when
these objects are used as a dict key or in a set because dicts and sets
use the object's __hash__ value in conjunction with the objects __eq__
method to lookup the object.

The defect is the DN, RDN & AVA objects computed their hash from the case-
preserving string representation thus two otherwise equal objects
incorrectly yielded different hash values.

The problem manifests itself when one of these objects is used as a key in
a dict, for example a dn.

dn1 = DN(('cn', 'Bob'))
dn2 = DN(('cn', 'bob'))

dn1 == dn2 --> True

hash(dn1) == hash(dn2) --> False

d = {}

d[dn1] = x
d[dn2] = y

len(d) --> 2

The patch fixes the above by lower casing the string representation of
the object prior to computing it's hash.

The patch also corrects a spelling mistake and a bogus return value in
ldapupdate.py which happened to be discovered while researching this
bug.

1 files changed, 1 insertions, 1 deletions

diff --git a/ipaserver/install/ldapupdate.py b/ipaserver/install/ldapupdate.py
index a51edff9..d673ad57 100644
--- a/ipaserver/install/ldapupdate.py
+++ b/ipaserver/install/ldapupdate.py
@@ -265,7 +265,7 @@ class LDAPUpdate:
 
         if not all_updates.get(dn):
             all_updates[dn] = update
-            return all_updates
+            return
 
         existing_update = all_updates[dn]
         if 'default' in update: