#!/usr/bin/env python3 # # Copyright (C) 2018-2022 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 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' 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(""", '"')) return None def apply(dhcp): # 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)