python-ldap: Retrieve only a few entries from LDAP search

Question

I wish to mimic the ldapsearch -z flag behavior of retrieving only a specific amount of entries from LDAP using python-ldap.

However, it keeps failing with the exception SIZELIMIT_EXCEEDED.

There are multiple links where the problem is reported, but the suggested solution doesn't seem to work

Python-ldap search: Size Limit Exceeded

LDAP: ldap.SIZELIMIT_EXCEEDED

I am using search_ext_s() with sizelimit parameter set to 1, which I am sure is not more than the server limit

On Wireshark, I see that 1 entry is returned and the server raises SIZELIMIT_EXCEEDED. This is the same as ldapsearch -z behavior

But the following line raises an exception and I don't know how to retrieve the returned entry

conn.search_ext_s(<base>,ldap.SCOPE_SUBTREE,'(cn=demo_user*)',['dn'],sizelimit=1)

Answer 1

Based upon the discussion in the comments, this is how I achieved it:

import ldap

# These are not mandatory, I just have a habit
# of setting against Microsoft Active Directory

ldap.set_option(ldap.OPT_REFERRALS, 0)
ldap.set_option(ldap.OPT_PROTOCOL_VERSION, 3)

conn = ldap.initialize('ldap://<SERVER-IP>')
conn.simple_bind(<username>, <password>)

# Using async search version
ldap_result_id = conn.search_ext(<base-dn>, ldap.SCOPE_SUBTREE,
                                 <filter>, [desired-attrs],
                                 sizelimit=<your-desired-sizelimit>)
result_set = []
try:
  while 1:
    result_type, result_data = conn.result(ldap_result_id, 0)
    if (result_data == []):
      break
    else:
      # Handle the singular entry anyway you wish.
      # I am appending here
      if result_type == ldap.RES_SEARCH_ENTRY:
        result_set.append(result_data)
except ldap.SIZELIMIT_EXCEEDED:
  print 'Hitting sizelimit'

print result_set

Sample Output:

# My server has about 500 entries for 'demo_user' - 1,2,3 etc.
# My filter is '(cn=demo_user*)', attrs = ['cn'] with sizelimit of 5

$ python ldap_sizelimit.py

Hitting sizelimit
[[('CN=demo_user0,OU=DemoUsers,DC=ad,DC=local', {'cn': ['demo_user0']})], 
[('CN=demo_user1,OU=DemoUsers,DC=ad,DC=local', {'cn': ['demo_user1']})], 
[('CN=demo_user10,OU=DemoUsers,DC=ad,DC=local', {'cn': ['demo_user10']})], 
[('CN=demo_user100,OU=DemoUsers,DC=ad,DC=local', {'cn': ['demo_user100']})], 
[('CN=demo_user101,OU=DemoUsers,DC=ad,DC=local', {'cn': ['demo_user101']})]]

You may use play around with more srv controls to sort these etc. but I think the basic idea is conveyed ;)