Northwestern netid lookup script using LDAP

netid_lookup.py

# reads netids from stdin and prints email addresses to stdout                                            
# see http://ldap3.readthedocs.io/tutorial_searches.html                                                  
# and https://www.it.northwestern.edu/bin/docs/CentralAuthenticationServicesThroughLDAP.pdf    
# 
# prereq: pip install ldap3
# usage: echo abc2020@u.northwestern.edu | python netid_lookup.py

from ldap3 import Server, Connection, ALL, ALL_ATTRIBUTES
import sys


def connect():
    server = Server(host='directory.northwestern.edu', get_info=ALL)
    return Connection(server, auto_bind=True)
    

def lookup_netid(conn, email):
    conn.search(search_base='dc=northwestern,dc=edu', search_filter='(mail=%s)' % email,
                attributes=ALL_ATTRIBUTES)
    return conn.entries[0].uid if len(conn.entries) else None


def main():
    conn = connect()
    for netid in sys.stdin:
        netid = lookup_netid(conn, netid)
        print(netid if netid else "")


if __name__ == "__main__":
    main()