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#!/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 <http://www.gnu.org/licenses/>.
#
#
import sys
import os
import time
import netifaces
from vyos.config import Config
from vyos.util import ConfigError
config_file = r'/etc/powerdns/recursor.conf'
# borrowed from: https://github.com/donjajo/py-world/blob/master/resolvconfReader.py, THX!
def get_resolvers(file):
resolvers = []
try:
with open(file, 'r') as resolvconf:
for line in resolvconf.readlines():
line = line.split('#',1)[0];
line = line.rstrip();
if 'nameserver' in line:
resolvers.append(line.split()[1])
return resolvers
except IOError as error:
return error.strerror
def get_config():
dns = {}
conf = Config()
conf.set_level('service dns forwarding')
if not conf.exists(''):
return dns
if conf.exists('cache-size'):
cache = conf.return_value('cache-size')
dns.setdefault('cache-size', cache)
if conf.exists('dhcp'):
dns.setdefault('dhcp', [])
interfaces = []
interfaces = conf.return_values('dhcp')
for interface in interfaces:
resolvers = get_resolvers("/etc/resolv.conf.dhclient-new-{0}".format(interface))
dhcp = {
"interface": interface,
"resolvers": resolvers
}
dns['dhcp'].append(dhcp)
if conf.exists('domain'):
dns.setdefault('domain', [])
for node in conf.list_nodes('domain'):
server = conf.return_values("domain {0} server".format(node))
domain = {
"name": node,
"server": server
}
dns['domain'].append(domain)
if conf.exists('ignore-hosts-file'):
dns.setdefault('ignore-hosts-file', True)
if conf.exists('listen-on'):
interfaces = []
interfaces = conf.return_values('listen-on')
dns.setdefault('listen-on', interfaces)
if conf.exists('name-server'):
nameservers = []
nameservers = conf.return_values('name-server')
dns.setdefault('name-server', nameservers)
if conf.exists('system'):
conf.set_level('system')
nameservers = []
nameservers = conf.return_values('name-server')
if len(nameservers) == 0:
print("DNS forwarding warning: No name-servers set under 'system name-server'\n")
else:
dns.setdefault('system-name-server', nameservers)
return dns
def verify(dns):
if len(dns) > 0:
if 'listen-on' not in dns.keys():
raise ConfigError('Error: DNS forwarding requires a configured listen interface!')
for interface in dns['listen-on']:
try:
netifaces.ifaddresses(interface)[netifaces.AF_INET]
except KeyError as e:
raise ConfigError('Error: Interface {0} has no IP address assigned'.format(interface))
if 'domain' in dns.keys():
for domain in dns['domain']:
if len(domain['server']) == 0:
raise ConfigError('Error: No server configured for domain {0}'.format(domain['name']))
return None
def generate(dns):
config_header = '### Autogenerated by vyos-config-dns-forwarding.py on {tm} ###\n'.format(tm=time.strftime("%a, %d %b %Y %H:%M:%S", time.localtime()))
fwds = []
fwds_src = []
# write new configuration file
f = open(config_file, 'w')
f.write(config_header)
f.write('daemon=yes\n')
f.write('threads=1\n')
f.write('allow-from=0.0.0.0/0\n')
f.write('log-common-errors=yes\n')
if 'listen-on' in dns.keys():
listen4 = []
listen6 = []
for interface in dns['listen-on']:
addrs = netifaces.ifaddresses(interface)
for ip4 in addrs[netifaces.AF_INET]:
listen4.append(ip4['addr'])
for ip6 in addrs[netifaces.AF_INET6]:
listen6.append(ip6['addr'])
# build local-address string, example:
# local-address=172.16.37.240, 127.0.0.1, 172.16.254.35, 172.16.77.1, 2001:DB8::1:25, ::1
f.write('local-address=' + ', '.join(listen4) + ', ' + ', '.join(listen6) + '\n')
if 'cache-size' in dns.keys():
f.write("max-cache-entries={0}\n".format(dns['cache-size']))
if 'dhcp' in dns.keys():
for dhcp in dns['dhcp']:
fwds_src.append('DHCP: {0} ({1})'.format(dhcp['interface'], ', '.join(str(ns) for ns in dhcp['resolvers'])))
fwds.append(', '.join(str(ns) for ns in dhcp['resolvers']))
if 'domain' in dns.keys():
zones = []
for domain in dns['domain']:
zones.append('{0}={1}'.format(domain['name'], ';'.join(str(ns) for ns in domain['server'])))
f.write('forward-zones=' + ', '.join(zones) + '\n')
if 'ignore-hosts-file' in dns.keys():
f.write("export-etc-hosts=no\n")
if 'name-server' in dns.keys():
fwds_src.append('statically configured: {0}'.format(', '.join(str(ns) for ns in dns['name-server'])))
fwds.append(', '.join(str(ns) for ns in dns['name-server']))
if 'system-name-server' in dns.keys():
fwds_src.append('system: {0}'.format(', '.join(str(ns) for ns in dns['system-name-server'])))
fwds.append(', '.join(str(ns) for ns in dns['system-name-server']))
if len(fwds) > 0:
f.write('\n')
f.write('# ' + '\n# '.join(fwds_src) + '\n')
f.write('forward-zones-recurse=.=' + '; '.join(fwds) + '\n')
f.close()
return None
def apply(dns):
if len(dns) == 0:
cmd = "sudo systemctl stop pdns-recursor"
else:
cmd = "sudo systemctl restart pdns-recursor"
os.system(cmd)
return None
if __name__ == '__main__':
try:
c = get_config()
verify(c)
generate(c)
apply(c)
except ConfigError as e:
print(e)
sys.exit(1)
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