#!/usr/bin/env fail2ban-python
# Inspired by https://isc.sans.edu/forums/diary/When+Google+isnt+Google/15968/
#
# Written in Python to reuse built-in Python batteries and not depend on
# presence of host and cut commands
#
import sys
from fail2ban.server.ipdns import DNSUtils, IPAddr

def process_args(argv):
    if len(argv) != 2:
       raise ValueError("Please provide a single IP as an argument. Got: %s\n"
                        % (argv[1:]))
    ip = argv[1]

    if not IPAddr(ip).isValid:
       raise ValueError("Argument must be a single valid IP. Got: %s\n"
                        % ip)
    return ip

google_ips = None

def is_googlebot(ip):
    import re

    host = DNSUtils.ipToName(ip)
    if not host or not re.match(r'.*\.google(bot)?\.com$', host):
       return False
    host_ips = DNSUtils.dnsToIp(host)
    return (ip in host_ips)

if __name__ == '__main__': # pragma: no cover
    try:
      ret = is_googlebot(process_args(sys.argv))
    except ValueError as e:
      sys.stderr.write(str(e))
      sys.exit(2)
    sys.exit(0 if ret else 1)