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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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