#!/usr/bin/env python3 # # Copyright (C) 2018 VyOS maintainers and contributors # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License version 2 or later as # published by the Free Software Foundation. # # 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 . # # import sys import os import argparse import jinja2 import netifaces import vyos.util from vyos.config import Config from vyos import ConfigError parser = argparse.ArgumentParser() parser.add_argument("--dhclient", action="store_true", help="Started from dhclient-script") config_file = r'/etc/powerdns/recursor.conf' # XXX: pdns recursor doesn't like whitespace near entry separators, # especially in the semicolon-separated lists of name servers. # Please be careful if you edit the template. config_tmpl = """ ### Autogenerated by dns_forwarding.py ### # Non-configurable defaults daemon=yes threads=1 allow-from=0.0.0.0/0, ::/0 log-common-errors=yes non-local-bind=yes query-local-address=0.0.0.0 query-local-address6=:: # cache-size max-cache-entries={{ cache_size }} # negative TTL for NXDOMAIN max-negative-ttl={{ negative_ttl }} # ignore-hosts-file export-etc-hosts={{ export_hosts_file }} # listen-on local-address={{ listen_on | join(',') }} # domain ... server ... {% if domains -%} forward-zones-recurse={% for d in domains %} {{ d.name }}={{ d.servers | join(";") }} {{- "," if not loop.last -}} {% endfor %} {% endif %} # dnssec dnssec={{ dnssec }} {% if name_servers -%} # name-server forward-zones-recurse=.={{ name_servers | join(';') }} {% else %} # no name-servers specified - start full recursor {% endif %} """ default_config_data = { 'cache_size': 10000, 'export_hosts_file': 'yes', 'listen_on': [], 'interfaces': [], 'name_servers': [], 'negative_ttl': 3600, 'domains': [], 'dnssec': 'process-no-validate' } # borrowed from: https://github.com/donjajo/py-world/blob/master/resolvconfReader.py, THX! def get_resolvers(file): try: with open(file, 'r') as resolvconf: lines = [line.split('#', 1)[0].rstrip() for line in resolvconf.readlines()] resolvers = [line.split()[1] for line in lines if 'nameserver' in line] return resolvers except IOError: return [] def get_config(arguments): dns = default_config_data conf = Config() if arguments.dhclient: conf.exists = conf.exists_effective conf.return_value = conf.return_effective_value conf.return_values = conf.return_effective_values if not conf.exists('service dns forwarding'): return None conf.set_level('service dns forwarding') if conf.exists('cache-size'): cache_size = conf.return_value('cache-size') dns['cache_size'] = cache_size if conf.exists('negative-ttl'): negative_ttl = conf.return_value('negative-ttl') dns['negative_ttl'] = negative_ttl if conf.exists('domain'): for node in conf.list_nodes('domain'): servers = conf.return_values("domain {0} server".format(node)) domain = { "name": node, "servers": bracketize_ipv6_addrs(servers) } dns['domains'].append(domain) if conf.exists('ignore-hosts-file'): dns['export_hosts_file'] = "no" if conf.exists('name-server'): name_servers = conf.return_values('name-server') dns['name_servers'] = dns['name_servers'] + name_servers if conf.exists('system'): conf.set_level('system') system_name_servers = [] system_name_servers = conf.return_values('name-server') if not system_name_servers: print( "DNS forwarding warning: No name-servers set under 'system name-server'\n") else: dns['name_servers'] = dns['name_servers'] + system_name_servers conf.set_level('service dns forwarding') dns['name_servers'] = bracketize_ipv6_addrs(dns['name_servers']) if conf.exists('listen-address'): dns['listen_on'] = conf.return_values('listen-address') if conf.exists('dnssec'): dns['dnssec'] = conf.return_value('dnssec') ## Hacks and tricks # The old VyOS syntax that comes from dnsmasq was "listen-on $interface". # pdns wants addresses instead, so we emulate it by looking up all addresses # of a given interface and writing them to the config if conf.exists('listen-on'): print("WARNING: since VyOS 1.2.0, \"service dns forwarding listen-on\" is a limited compatibility option.") print("It will only make DNS forwarder listen on addresses assigned to the interface at the time of commit") print("which means it will NOT work properly with VRRP/clustering or addresses received from DHCP.") print("Please reconfigure your system with \"service dns forwarding listen-address\" instead.") interfaces = conf.return_values('listen-on') listen4 = [] listen6 = [] for interface in interfaces: try: addrs = netifaces.ifaddresses(interface) except ValueError: print( "WARNING: interface {0} does not exist".format(interface)) continue if netifaces.AF_INET in addrs.keys(): for ip4 in addrs[netifaces.AF_INET]: listen4.append(ip4['addr']) if netifaces.AF_INET6 in addrs.keys(): for ip6 in addrs[netifaces.AF_INET6]: listen6.append(ip6['addr']) if (not listen4) and (not (listen6)): print( "WARNING: interface {0} has no configured addresses".format(interface)) dns['listen_on'] = dns['listen_on'] + listen4 + listen6 # Save interfaces in the dict for the reference dns['interfaces'] = interfaces # Add name servers received from DHCP if conf.exists('dhcp'): interfaces = [] interfaces = conf.return_values('dhcp') for interface in interfaces: dhcp_resolvers = get_resolvers( "/etc/resolv.conf.dhclient-new-{0}".format(interface)) if dhcp_resolvers: dns['name_servers'] = dns['name_servers'] + dhcp_resolvers return dns def bracketize_ipv6_addrs(addrs): """Wraps each IPv6 addr in addrs in [], leaving IPv4 addrs untouched.""" return ['[{0}]'.format(a) if a.count(':') > 1 else a for a in addrs] def verify(dns): # bail out early - looks like removal from running config if dns is None: return None if not dns['listen_on']: raise ConfigError( "Error: DNS forwarding requires either a listen-address (preferred) or a listen-on option") if dns['domains']: for domain in dns['domains']: if not domain['servers']: raise ConfigError( 'Error: No server configured for domain {0}'.format(domain['name'])) return None def generate(dns): # bail out early - looks like removal from running config if dns is None: return None tmpl = jinja2.Template(config_tmpl, trim_blocks=True) config_text = tmpl.render(dns) with open(config_file, 'w') as f: f.write(config_text) return None def apply(dns): if dns is not None: os.system("systemctl restart pdns-recursor") else: # DNS forwarding is removed in the commit os.system("systemctl stop pdns-recursor") if os.path.isfile(config_file): os.unlink(config_file) if __name__ == '__main__': args = parser.parse_args() if args.dhclient: # There's a big chance it was triggered by a commit still in progress # so we need to wait until the new values are in the running config vyos.util.wait_for_commit_lock() try: c = get_config(args) verify(c) generate(c) apply(c) except ConfigError as e: print(e) sys.exit(1)