hoststobind.py

#!/usr/bin/env python

# hoststobind - read a hosts file and write BIND zone files to the current directory
#
# Copyright (C) 2011 James McDonald <james@jamesmcdonald.com>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# This is not very clever - junk in the hosts file will generate junk output
# I wrote it on a plane to solve a specific issue
# It explicitly ignores IPv6 entries (anything with a :)

from __future__ import print_function

import os
import socket
import argparse

# A generic SOA with 5 minute TTL. This will need to be edited for real Internet use.
ZONEHEADER = """; generated zone file - please check manually before Internet DNS use
$TTL 300
$ORIGIN %s.
@\t\tIN\tSOA\t @ root (
\t\t\t\t42\t; serial
\t\t\t\t3H\t; refresh
\t\t\t\t15M\t; retry
\t\t\t\t1W\t; expiry
\t\t\t\t1D\t; minumum ttl
)

"""

def hoststobind(hostsfile, outputdir='bindconf', verbose = False):
    forward = {}
    reverse = {}

    hosts = open(hostsfile, "r")
    for line in hosts:
        # Skip local, IPv6 and comments
        if 'localhost' in line or ':' in line or line.startswith('#'): continue
        cooked = line.strip().split()
        if len(cooked) == 0:
            continue
        
        # Set reverse to first name on line
        ip = [int(x) for x in cooked[0].split('.')]
        network = "%d.%d.%d.in-addr.arpa" % (ip[2],ip[1],ip[0])
        if network not in reverse:
            reverse[network] = {}
            if verbose:
                print("Added reverse {0}".format(network))
        reverse[network][ip[3]] = cooked[1]

        # Add a forward to the IP for each host
        for host in cooked[1:]:
            # Skip bare names
            if '.' not in host: continue
            (hostname, domainname) = host.split('.',1)
            if domainname not in forward:
                forward[domainname] = {}
                if verbose:
                    print("Added forward {0}".format(domainname))
            forward[domainname][hostname] = cooked[0]

    if not os.path.isdir(outputdir):
        os.makedirs(outputdir, mode=0755)
    os.chdir(outputdir)
    if verbose:
        print("Creating output in {}".format(os.getcwd()))

    z = open("named.zones", "w")

    for network in reverse:
        if verbose:
            print("Writing file {}...".format(network), end='')
        w = open(network, "w")
        w.write(ZONEHEADER % (network))
        for host in sorted(reverse[network]):
            w.write("%d\t\tIN\tPTR\t%s.\n" % (host, reverse[network][host]))
        w.close()
        z.write("zone \"%s\" { type master; file \"%s\"; };\n" % (network, network));
        if verbose:
            print("done")

    for domain in forward:
        if verbose:
            print("Writing file {}...".format(domain), end='')
        w = open(domain, "w")
        w.write(ZONEHEADER % (domain))
        for entry in sorted(forward[domain].items(),
            lambda x,y: -1 if socket.inet_aton(x[1])<socket.inet_aton(y[1]) else 1):
            # Use a 32 character hostname field. If your have silly hostnames, your output may suck.
            w.write("%-31s IN\tA\t%s\n" % (entry[0], entry[1]))
        w.close()
        z.write("zone \"%s\" { type master; file \"%s\"; };\n" % (domain, domain));
        if verbose:
            print("done")

    z.close()

if __name__=='__main__':
    parser = argparse.ArgumentParser(description="Convert hosts file to bind zone files.")
    parser.add_argument('hosts_file', help='the hosts file to convert')
    parser.add_argument('-v', '--verbose', action='store_true', help='show some verbose output')
    parser.add_argument('-o', '--output', default='bindconf', help='directory for output (default: %(default)s)')
    args = parser.parse_args()
    print(args)
    hoststobind(args.hosts_file, outputdir=args.output, verbose=args.verbose)