| 1 | #!/usr/bin/env python3 |
| 2 | # |
| 3 | |
| 4 | import argparse |
| 5 | import ipaddress |
| 6 | import subprocess |
| 7 | |
| 8 | import dns.message |
| 9 | import dns.query |
| 10 | import dns.resolver |
| 11 | |
| 12 | def get_argument_parser(): |
| 13 | parser = argparse.ArgumentParser( |
| 14 | prog='update_dns_entry.py', |
| 15 | description='Generate fixed-address DHCP configuration based for hosts based on DNS entries' |
| 16 | ) |
| 17 | parser.add_argument( |
| 18 | '-s', '--server', default=None, required=True, |
| 19 | help='Server for DNS updates' |
| 20 | ) |
| 21 | parser.add_argument( |
| 22 | '-u', '--user', default=None, |
| 23 | help='The user to use with samba-tool' |
| 24 | ) |
| 25 | parser.add_argument( |
| 26 | '-z', '--zone', required=True, |
| 27 | help='The zone in which to update the entry' |
| 28 | ) |
| 29 | parser.add_argument( |
| 30 | '-n', '--name', required=True, |
| 31 | help='DNS entry name' |
| 32 | ) |
| 33 | parser.add_argument( |
| 34 | '-v', '--value', required=True, |
| 35 | help='DNS entry value' |
| 36 | ) |
| 37 | parser.add_argument( |
| 38 | '-t', '--type', default='A', |
| 39 | help='Entry type' |
| 40 | ) |
| 41 | return parser |
| 42 | |
| 43 | |
| 44 | def update_dns_entry(server, zone, name, entry_type, value, user=None, with_reverse = True): |
| 45 | if entry_type == "A": |
| 46 | assert(ipaddress.ip_address(value)) |
| 47 | try: |
| 48 | server_ip = str(ipaddress.ip_address(server)) |
| 49 | except ValueError: |
| 50 | server_ip = dns.resolver.resolve(server)[0].to_text() |
| 51 | |
| 52 | commands = [] |
| 53 | # Verify existing entry |
| 54 | query = dns.message.make_query('.'.join([name, zone]), entry_type) |
| 55 | record = dns.query.udp(query, server_ip); |
| 56 | if len(record.answer) == 0: |
| 57 | # Create |
| 58 | argv = ['samba-tool', 'dns', 'add', server, zone, name, entry_type, value] |
| 59 | if user is not None: |
| 60 | argv += ['-U', user] |
| 61 | commands.append(argv) |
| 62 | else: |
| 63 | assert(len(record.answer) == 1) |
| 64 | # Check validity |
| 65 | existing = (record.answer)[0][0].to_text() |
| 66 | if existing != value: |
| 67 | # Update |
| 68 | argv = ['samba-tool', 'dns', 'update', server, zone, name, entry_type, existing, value] |
| 69 | if user is not None: |
| 70 | argv += ['-U', user] |
| 71 | commands.append(argv) |
| 72 | |
| 73 | # Check reverse |
| 74 | if with_reverse and entry_type == 'A': |
| 75 | rname, rzone = ipaddress.ip_address(value).reverse_pointer.split('.', 1) |
| 76 | rvalue = '.'.join([name, zone]) + '.' |
| 77 | rtype = 'PTR' |
| 78 | query = dns.message.make_query(ipaddress.ip_address(value).reverse_pointer, rtype) |
| 79 | record = dns.query.udp(query, server_ip) |
| 80 | if len(record.answer) == 0: |
| 81 | argv = ['samba-tool', 'dns', 'add', server, rzone, rname, rtype, rvalue] |
| 82 | if user is not None: |
| 83 | argv += ['-U', user] |
| 84 | commands.append(argv) |
| 85 | else: |
| 86 | assert(len(record.answer) == 1) |
| 87 | existing = (record.answer)[0][0].to_text() |
| 88 | if existing != value: |
| 89 | argv = ['samba-tool', 'dns', 'update', server, rzone, rname, rtype, existing, rvalue] |
| 90 | if user is not None: |
| 91 | argv += ['-U', user] |
| 92 | commands.append(argv) |
| 93 | |
| 94 | # Run commands |
| 95 | for command in commands: |
| 96 | subprocess.run(command, check=True) |
| 97 | |
| 98 | |
| 99 | if __name__ == '__main__': |
| 100 | parser = get_argument_parser() |
| 101 | args = parser.parse_args() |
| 102 | update_dns_entry(args.server, args.zone, args.name, args.type, args.value, user=args.user) |