host_name.py
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host_name.py
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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/>.
	#
	#

	"""
	conf-mode script for 'system host-name' and 'system domain-name'.
	"""

	import os
	import re
	import sys
	import copy
	import glob
	import subprocess
	import argparse
	import jinja2

	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_hosts = '/etc/hosts'
	config_file_resolv = '/etc/resolv.conf'

	config_tmpl_hosts = """
	### Autogenerated by host_name.py ###
	127.0.0.1 localhost
	127.0.1.1 {{ hostname }}{% if domain_name %}.{{ domain_name }}{% endif %}

	# The following lines are desirable for IPv6 capable hosts
	::1 localhost ip6-localhost ip6-loopback
	fe00::0 ip6-localnet
	ff00::0 ip6-mcastprefix
	ff02::1 ip6-allnodes
	ff02::2 ip6-allrouters

	# static hostname mappings
	{%- if static_host_mapping['hostnames'] %}
	{% for hn in static_host_mapping['hostnames'] -%}
	{{static_host_mapping['hostnames'][hn]['ipaddr']}}\t{{static_host_mapping['hostnames'][hn]['alias']}}\t{{hn}}
	{% endfor -%}
	{%- endif %}

	### modifications from other scripts should be added below

	"""

	config_tmpl_resolv = """
	### Autogenerated by host_name.py ###
	{% for ns in nameserver -%}
	nameserver {{ ns }}
	{% endfor -%}

	{%- if domain_name %}
	domain {{ domain_name }}
	{%- endif %}

	{%- if domain_search %}
	search {{ domain_search \| join(" ") }}
	{%- endif %}

	"""

	default_config_data = {
	'hostname': 'vyos',
	'domain_name': '',
	'domain_search': [],
	'nameserver': [],
	'no_dhcp_ns': False
	}

	# borrowed from: https://github.com/donjajo/py-world/blob/master/resolvconfReader.py, THX!
	def get_resolvers(file):
	resolv = {}
	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]
	domains = [line.split()[1] for line in lines if 'search' in line]
	resolv['resolvers'] = resolvers
	resolv['domains'] = domains
	return resolv
	except IOError:
	return []


	def get_config(arguments):
	conf = Config()
	hosts = copy.deepcopy(default_config_data)

	if arguments.dhclient:
	conf.exists = conf.exists_effective
	conf.return_value = conf.return_effective_value
	conf.return_values = conf.return_effective_values

	if conf.exists("system host-name"):
	hosts['hostname'] = conf.return_value("system host-name")

	if conf.exists("system domain-name"):
	hosts['domain_name'] = conf.return_value("system domain-name")
	hosts['domain_search'].append(hosts['domain_name'])

	for search in conf.return_values("system domain-search domain"):
	hosts['domain_search'].append(search)

	if conf.exists("system name-server"):
	if not isinstance(conf.return_values("system name-server"), list):
	hosts['nameserver'] = conf.return_values("system name-server").replace("'", "").split()
	else:
	hosts['nameserver'] = conf.return_values("system name-server")

	if conf.exists("system disable-dhcp-nameservers"):
	hosts['no_dhcp_ns'] = conf.exists('system disable-dhcp-nameservers')

	# system static-host-mapping
	hosts['static_host_mapping'] = {'hostnames': {}}

	if conf.exists('system static-host-mapping host-name'):
	for hn in conf.list_nodes('system static-host-mapping host-name'):
	hosts['static_host_mapping']['hostnames'][hn] = {
	'ipaddr': conf.return_value('system static-host-mapping host-name ' + hn + ' inet'),
	'alias': ''
	}

	if conf.exists('system static-host-mapping host-name ' + hn + ' alias'):
	a = conf.return_values(
	'system static-host-mapping host-name ' + hn + ' alias')
	hosts['static_host_mapping']['hostnames'][hn]['alias'] = " ".join(a)

	return hosts


	def verify(config):
	if config is None:
	return None

	# pattern $VAR(@) "^[[:alnum:]][-.[:alnum:]]*[[:alnum:]]$" ; "invalid host name $VAR(@)"
	hostname_regex = re.compile("^[A-Za-z0-9][-.A-Za-z0-9]*[A-Za-z0-9]$")
	if not hostname_regex.match(config['hostname']):
	raise ConfigError('Invalid host name ' + config["hostname"])

	# pattern $VAR(@) "^.{1,63}$" ; "invalid host-name length"
	length = len(config['hostname'])
	if length < 1 or length > 63:
	raise ConfigError(
	'Invalid host-name length, must be less than 63 characters')

	# The search list is currently limited to six domains with a total of 256 characters.
	# https://linux.die.net/man/5/resolv.conf
	if len(config['domain_search']) > 6:
	raise ConfigError(
	'The search list is currently limited to six domains')

	tmp = ' '.join(config['domain_search'])
	if len(tmp) > 256:
	raise ConfigError(
	'The search list is currently limited to 256 characters')

	# static mappings alias hostname
	if config['static_host_mapping']['hostnames']:
	for hn in config['static_host_mapping']['hostnames']:
	if not config['static_host_mapping']['hostnames'][hn]['ipaddr']:
	raise ConfigError('IP address required for ' + hn)
	for hn_alias in config['static_host_mapping']['hostnames'][hn]['alias'].split(' '):
	if not hostname_regex.match(hn_alias) and len(hn_alias) != 0:
	raise ConfigError('Invalid hostname alias ' + hn_alias)

	return None


	def generate(config):
	if config is None:
	return None

	# If "system disable-dhcp-nameservers" is __configured__ all DNS resolvers
	# received via dhclient should not be added into the final 'resolv.conf'.
	#
	# We iterate over every resolver file and retrieve the received nameservers
	# for later adjustment of the system nameservers
	dhcp_ns = []
	dhcp_sd = []
	for file in glob.glob('/etc/resolv.conf.dhclient-new*'):
	for key, value in get_resolvers(file).items():
	ns = [r for r in value if key == 'resolvers']
	dhcp_ns.extend(ns)
	sd = [d for d in value if key == 'domains']
	dhcp_sd.extend(sd)

	if not config['no_dhcp_ns']:
	config['nameserver'] += dhcp_ns
	config['domain_search'] += dhcp_sd

	# We have third party scripts altering /etc/hosts, too.
	# One example are the DHCP hostname update scripts thus we need to cache in
	# every modification first - so changing domain-name, domain-search or hostname
	# during runtime works
	old_hosts = ""
	with open(config_file_hosts, 'r') as f:
	# Skips text before the beginning of our marker.
	# NOTE: Marker __MUST__ match the one specified in config_tmpl_hosts
	for line in f:
	if line.strip() == '### modifications from other scripts should be added below':
	break

	for line in f:
	# This additional line.strip() filters empty lines
	if line.strip():
	old_hosts += line

	# Add an additional newline
	old_hosts += '\n'

	tmpl = jinja2.Template(config_tmpl_hosts)
	config_text = tmpl.render(config)

	with open(config_file_hosts, 'w') as f:
	f.write(config_text)
	f.write(old_hosts)

	tmpl = jinja2.Template(config_tmpl_resolv)
	config_text = tmpl.render(config)
	with open(config_file_resolv, 'w') as f:
	f.write(config_text)

	return None


	def apply(config):
	if config is None:
	return None

	fqdn = config['hostname']
	if config['domain_name']:
	fqdn += '.' + config['domain_name']

	# rsyslog runs into a race condition at boot time with systemd
	# restart rsyslog only if the hostname changed.
	hn = subprocess.check_output(['hostnamectl', '--static']).decode().strip()

	os.system("hostnamectl set-hostname --static {0}".format(fqdn.rstrip('.')))

	# Restart services that use the hostname
	if hn != fqdn:
	os.system("systemctl restart rsyslog.service")

	# If SNMP is running, restart it too
	if os.system("pgrep snmpd > /dev/null") == 0:
	os.system("systemctl restart snmpd.service")

	# restart pdns if it is used
	if os.system("/usr/bin/rec_control ping >/dev/null 2>&1") == 0:
	os.system("/etc/init.d/pdns-recursor restart >/dev/null")

	return None


	if __name__ == '__main__':
	args = parser.parse_args()
	try:
	c = get_config(args)
	verify(c)
	generate(c)
	apply(c)
	except ConfigError as e:
	print(e)
	sys.exit(1)

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