diff options
Diffstat (limited to 'src/conf_mode/service_dhcp-server.py')
| -rwxr-xr-x | src/conf_mode/service_dhcp-server.py | 328 |
1 files changed, 328 insertions, 0 deletions
diff --git a/src/conf_mode/service_dhcp-server.py b/src/conf_mode/service_dhcp-server.py new file mode 100755 index 000000000..ac7d95632 --- /dev/null +++ b/src/conf_mode/service_dhcp-server.py @@ -0,0 +1,328 @@ +#!/usr/bin/env python3 +# +# Copyright (C) 2018-2023 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 os + +from ipaddress import ip_address +from ipaddress import ip_network +from netaddr import IPAddress +from netaddr import IPRange +from sys import exit + +from vyos.config import Config +from vyos.template import render +from vyos.utils.dict import dict_search +from vyos.utils.process import call +from vyos.utils.process import run +from vyos.utils.network import is_subnet_connected +from vyos.utils.network import is_addr_assigned +from vyos import ConfigError +from vyos import airbag +airbag.enable() + +config_file = '/run/dhcp-server/dhcpd.conf' +systemd_override = r'/run/systemd/system/isc-dhcp-server.service.d/10-override.conf' + +def dhcp_slice_range(exclude_list, range_dict): + """ + This function is intended to slice a DHCP range. What does it mean? + + Lets assume we have a DHCP range from '192.0.2.1' to '192.0.2.100' + but want to exclude address '192.0.2.74' and '192.0.2.75'. We will + pass an input 'range_dict' in the format: + {'start' : '192.0.2.1', 'stop' : '192.0.2.100' } + and we will receive an output list of: + [{'start' : '192.0.2.1' , 'stop' : '192.0.2.73' }, + {'start' : '192.0.2.76', 'stop' : '192.0.2.100' }] + The resulting list can then be used in turn to build the proper dhcpd + configuration file. + """ + output = [] + # exclude list must be sorted for this to work + exclude_list = sorted(exclude_list) + range_start = range_dict['start'] + range_stop = range_dict['stop'] + range_last_exclude = '' + + for e in exclude_list: + if (ip_address(e) >= ip_address(range_start)) and \ + (ip_address(e) <= ip_address(range_stop)): + range_last_exclude = e + + for e in exclude_list: + if (ip_address(e) >= ip_address(range_start)) and \ + (ip_address(e) <= ip_address(range_stop)): + + # Build new address range ending one address before exclude address + r = { + 'start' : range_start, + 'stop' : str(ip_address(e) -1) + } + # On the next run our address range will start one address after + # the exclude address + range_start = str(ip_address(e) + 1) + + # on subsequent exclude addresses we can not + # append them to our output + if not (ip_address(r['start']) > ip_address(r['stop'])): + # Everything is fine, add range to result + output.append(r) + + # Take care of last IP address range spanning from the last exclude + # address (+1) to the end of the initial configured range + if ip_address(e) == ip_address(range_last_exclude): + r = { + 'start': str(ip_address(e) + 1), + 'stop': str(range_stop) + } + if not (ip_address(r['start']) > ip_address(r['stop'])): + output.append(r) + else: + # if the excluded address was not part of the range, we simply return + # the entire ranga again + if not range_last_exclude: + if range_dict not in output: + output.append(range_dict) + + return output + +def get_config(config=None): + if config: + conf = config + else: + conf = Config() + base = ['service', 'dhcp-server'] + if not conf.exists(base): + return None + + dhcp = conf.get_config_dict(base, key_mangling=('-', '_'), + no_tag_node_value_mangle=True, + get_first_key=True, + with_recursive_defaults=True) + + if 'shared_network_name' in dhcp: + for network, network_config in dhcp['shared_network_name'].items(): + if 'subnet' in network_config: + for subnet, subnet_config in network_config['subnet'].items(): + # If exclude IP addresses are defined we need to slice them out of + # the defined ranges + if {'exclude', 'range'} <= set(subnet_config): + new_range_id = 0 + new_range_dict = {} + for r, r_config in subnet_config['range'].items(): + for slice in dhcp_slice_range(subnet_config['exclude'], r_config): + new_range_dict.update({new_range_id : slice}) + new_range_id +=1 + + dhcp['shared_network_name'][network]['subnet'][subnet].update( + {'range' : new_range_dict}) + + return dhcp + +def verify(dhcp): + # bail out early - looks like removal from running config + if not dhcp or 'disable' in dhcp: + return None + + # If DHCP is enabled we need one share-network + if 'shared_network_name' not in dhcp: + raise ConfigError('No DHCP shared networks configured.\n' \ + 'At least one DHCP shared network must be configured.') + + # Inspect shared-network/subnet + listen_ok = False + subnets = [] + failover_ok = False + shared_networks = len(dhcp['shared_network_name']) + disabled_shared_networks = 0 + + + # A shared-network requires a subnet definition + for network, network_config in dhcp['shared_network_name'].items(): + if 'disable' in network_config: + disabled_shared_networks += 1 + + if 'subnet' not in network_config: + raise ConfigError(f'No subnets defined for {network}. At least one\n' \ + 'lease subnet must be configured.') + + for subnet, subnet_config in network_config['subnet'].items(): + # All delivered static routes require a next-hop to be set + if 'static_route' in subnet_config: + for route, route_option in subnet_config['static_route'].items(): + if 'next_hop' not in route_option: + raise ConfigError(f'DHCP static-route "{route}" requires router to be defined!') + + # DHCP failover needs at least one subnet that uses it + if 'enable_failover' in subnet_config: + if 'failover' not in dhcp: + raise ConfigError(f'Can not enable failover for "{subnet}" in "{network}".\n' \ + 'Failover is not configured globally!') + failover_ok = True + + # Check if DHCP address range is inside configured subnet declaration + if 'range' in subnet_config: + networks = [] + for range, range_config in subnet_config['range'].items(): + if not {'start', 'stop'} <= set(range_config): + raise ConfigError(f'DHCP range "{range}" start and stop address must be defined!') + + # Start/Stop address must be inside network + for key in ['start', 'stop']: + if ip_address(range_config[key]) not in ip_network(subnet): + raise ConfigError(f'DHCP range "{range}" {key} address not within shared-network "{network}, {subnet}"!') + + # Stop address must be greater or equal to start address + if ip_address(range_config['stop']) < ip_address(range_config['start']): + raise ConfigError(f'DHCP range "{range}" stop address must be greater or equal\n' \ + 'to the ranges start address!') + + for network in networks: + start = range_config['start'] + stop = range_config['stop'] + if start in network: + raise ConfigError(f'Range "{range}" start address "{start}" already part of another range!') + if stop in network: + raise ConfigError(f'Range "{range}" stop address "{stop}" already part of another range!') + + tmp = IPRange(range_config['start'], range_config['stop']) + networks.append(tmp) + + # Exclude addresses must be in bound + if 'exclude' in subnet_config: + for exclude in subnet_config['exclude']: + if ip_address(exclude) not in ip_network(subnet): + raise ConfigError(f'Excluded IP address "{exclude}" not within shared-network "{network}, {subnet}"!') + + # At least one DHCP address range or static-mapping required + if 'range' not in subnet_config and 'static_mapping' not in subnet_config: + raise ConfigError(f'No DHCP address range or active static-mapping configured\n' \ + f'within shared-network "{network}, {subnet}"!') + + if 'static_mapping' in subnet_config: + # Static mappings require just a MAC address (will use an IP from the dynamic pool if IP is not set) + for mapping, mapping_config in subnet_config['static_mapping'].items(): + if 'ip_address' in mapping_config: + if ip_address(mapping_config['ip_address']) not in ip_network(subnet): + raise ConfigError(f'Configured static lease address for mapping "{mapping}" is\n' \ + f'not within shared-network "{network}, {subnet}"!') + + if 'mac_address' not in mapping_config: + raise ConfigError(f'MAC address required for static mapping "{mapping}"\n' \ + f'within shared-network "{network}, {subnet}"!') + + # There must be one subnet connected to a listen interface. + # This only counts if the network itself is not disabled! + if 'disable' not in network_config: + if is_subnet_connected(subnet, primary=False): + listen_ok = True + + # Subnets must be non overlapping + if subnet in subnets: + raise ConfigError(f'Configured subnets must be unique! Subnet "{subnet}"\n' + 'defined multiple times!') + subnets.append(subnet) + + # Check for overlapping subnets + net = ip_network(subnet) + for n in subnets: + net2 = ip_network(n) + if (net != net2): + if net.overlaps(net2): + raise ConfigError(f'Conflicting subnet ranges: "{net}" overlaps "{net2}"!') + + # Prevent 'disable' for shared-network if only one network is configured + if (shared_networks - disabled_shared_networks) < 1: + raise ConfigError(f'At least one shared network must be active!') + + if 'failover' in dhcp: + if not failover_ok: + raise ConfigError('DHCP failover must be enabled for at least one subnet!') + + for key in ['name', 'remote', 'source_address', 'status']: + if key not in dhcp['failover']: + tmp = key.replace('_', '-') + raise ConfigError(f'DHCP failover requires "{tmp}" to be specified!') + + for address in (dict_search('listen_address', dhcp) or []): + if is_addr_assigned(address): + listen_ok = True + # no need to probe further networks, we have one that is valid + continue + else: + raise ConfigError(f'listen-address "{address}" not configured on any interface') + + + if not listen_ok: + raise ConfigError('None of the configured subnets have an appropriate primary IP address on any\n' + 'broadcast interface configured, nor was there an explicit listen-address\n' + 'configured for serving DHCP relay packets!') + + return None + +def generate(dhcp): + # bail out early - looks like removal from running config + if not dhcp or 'disable' in dhcp: + return None + + # Please see: https://vyos.dev/T1129 for quoting of the raw + # parameters we can pass to ISC DHCPd + tmp_file = '/tmp/dhcpd.conf' + render(tmp_file, 'dhcp-server/dhcpd.conf.j2', dhcp, + formater=lambda _: _.replace(""", '"')) + # XXX: as we have the ability for a user to pass in "raw" options via VyOS + # CLI (see T3544) we now ask ISC dhcpd to test the newly rendered + # configuration + tmp = run(f'/usr/sbin/dhcpd -4 -q -t -cf {tmp_file}') + if tmp > 0: + if os.path.exists(tmp_file): + os.unlink(tmp_file) + raise ConfigError('Configuration file errors encountered - check your options!') + + # Now that we know that the newly rendered configuration is "good" we can + # render the "real" configuration + render(config_file, 'dhcp-server/dhcpd.conf.j2', dhcp, + formater=lambda _: _.replace(""", '"')) + render(systemd_override, 'dhcp-server/10-override.conf.j2', dhcp) + + # Clean up configuration test file + if os.path.exists(tmp_file): + os.unlink(tmp_file) + + return None + +def apply(dhcp): + call('systemctl daemon-reload') + # bail out early - looks like removal from running config + if not dhcp or 'disable' in dhcp: + call('systemctl stop isc-dhcp-server.service') + if os.path.exists(config_file): + os.unlink(config_file) + + return None + + call('systemctl restart isc-dhcp-server.service') + return None + +if __name__ == '__main__': + try: + c = get_config() + verify(c) + generate(c) + apply(c) + except ConfigError as e: + print(e) + exit(1) |