Allow users to update their own ssh key

chgLDAPsshkey.py

#!/usr/bin/python
# rick@drawbrid.ge
import sys
import ldap
import getpass
import struct
from base64 import decodestring as decode
import argparse
parser = argparse.ArgumentParser(description="Update SSH Keys")
parser.add_argument('--file','-f', action='store', type=str, nargs=1, default='~/.ssh/id_rsa.pub', help='Supply ssh public key file')
parser.add_argument('--user','-u', action='store', type=str, nargs=1, required=True, help ='Supply your ldap username')
args = parser.parse_args()

def getsshkey(keyfile):
    # Checks keystring is actually ssh-rsa type
    openssh_pubkey = open(keyfile).readline().rstrip('\n')
    type, key_string, comment = openssh_pubkey.split()
    data = decode(key_string)
    int_len = 4
    str_len = struct.unpack('>I', data[:int_len])[0]
    if data[int_len:int_len+str_len] == type:
        return openssh_pubkey
    else:
        print("Improper key type, or encoding error. We only allow RSA type ssh-keys.\nGenerate a proper key like this."
              "\nssh-keygen -t rsa -b 2048 -C youremailaddress")
        sys.exit(1)

def changeSshKey(user, ldap_pass, openssh_pubkey):
    user_dn = 'uid=' + user + ',ou=users,dc=domain,dc=net'
    try:
        ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, ldap.OPT_X_TLS_NEVER)
        l = ldap.initialize("ldaps:/yoursecureserver:636/")
        l.set_option(ldap.OPT_REFERRALS,0)
        l.set_option(ldap.OPT_PROTOCOL_VERSION,3)
        l.set_option(ldap.OPT_X_TLS,ldap.OPT_X_TLS_DEMAND)
        l.set_option(ldap.OPT_X_TLS_DEMAND,True)
        l.set_option(ldap.OPT_DEBUG_LEVEL,255)
        l.simple_bind_s(user_dn, ldap_pass)
        mod_attrs = [ (ldap.MOD_REPLACE, 'sshPublicKey', openssh_pubkey) ]
        l.modify_s(user_dn, mod_attrs)
        print("Public SSH key for %s updated") % user_dn
        l.unbind_s()
    except ldap.LDAPError, e:
        print e

if __name__ == "__main__":
    ldap_pass = getpass.getpass('Enter your LDAP password: ')
    user = str(args.user[0]).lower()
    file = args.file[0]
    key = getsshkey(file)
    changeSshKey(user, ldap_pass, key)