#!/usr/bin/env python3 # # Copyright (C) 2018-2020 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, ip_network from jinja2 import FileSystemLoader, Environment from socket import inet_ntoa from struct import pack from sys import exit from vyos.config import Config from vyos.defaults import directories as vyos_data_dir from vyos.validate import is_subnet_connected from vyos import ConfigError from vyos.util import run config_file = r'/etc/dhcp/dhcpd.conf' lease_file = r'/config/dhcpd.leases' pid_file = r'/var/run/dhcpd.pid' daemon_config_file = r'/etc/default/isc-dhcpv4-server' default_config_data = { 'lease_file': lease_file, 'disabled': False, 'ddns_enable': False, 'global_parameters': [], 'hostfile_update': False, 'host_decl_name': False, 'static_route': False, 'wpad': False, 'shared_network': [], } def dhcp_slice_range(exclude_list, range_list): """ 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_list' 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) for ra in range_list: range_start = ra['start'] range_stop = ra['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 IP address range ending one IP address before exclude address r = { 'start' : range_start, 'stop' : str(ip_address(e) -1) } # On the next run our IP 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 we have no exclude in the whole range - we just take the range # as it is if not range_last_exclude: if ra not in output: output.append(ra) return output def dhcp_static_route(static_subnet, static_router): # https://ercpe.de/blog/pushing-static-routes-with-isc-dhcp-server # Option format is: # <netmask>, <network-byte1>, <network-byte2>, <network-byte3>, <router-byte1>, <router-byte2>, <router-byte3> # where bytes with the value 0 are omitted. net = ip_network(static_subnet) # add netmask string = str(net.prefixlen) + ',' # add network bytes if net.prefixlen: width = net.prefixlen // 8 if net.prefixlen % 8: width += 1 string += ','.join(map(str,tuple(net.network_address.packed)[:width])) + ',' # add router bytes string += ','.join(static_router.split('.')) return string def get_config(): dhcp = default_config_data conf = Config() if not conf.exists('service dhcp-server'): return None else: conf.set_level('service dhcp-server') # check for global disable of DHCP service if conf.exists('disable'): dhcp['disabled'] = True # check for global dynamic DNS upste if conf.exists('dynamic-dns-update'): dhcp['ddns_enable'] = True # HACKS AND TRICKS # # check for global 'raw' ISC DHCP parameters configured by users # actually this is a bad idea in general to pass raw parameters from any user if conf.exists('global-parameters'): dhcp['global_parameters'] = conf.return_values('global-parameters') # check for global DHCP server updating /etc/host per lease if conf.exists('hostfile-update'): dhcp['hostfile_update'] = True # If enabled every host declaration within that scope, the name provided # for the host declaration will be supplied to the client as its hostname. if conf.exists('host-decl-name'): dhcp['host_decl_name'] = True # check for multiple, shared networks served with DHCP addresses if conf.exists('shared-network-name'): for network in conf.list_nodes('shared-network-name'): conf.set_level('service dhcp-server shared-network-name {0}'.format(network)) config = { 'name': network, 'authoritative': False, 'description': '', 'disabled': False, 'network_parameters': [], 'subnet': [] } # check if DHCP server should be authoritative on this network if conf.exists('authoritative'): config['authoritative'] = True # A description for this given network if conf.exists('description'): config['description'] = conf.return_value('description') # If disabled, the shared-network configuration becomes inactive in # the running DHCP server instance if conf.exists('disable'): config['disabled'] = True # HACKS AND TRICKS # # check for 'raw' ISC DHCP parameters configured by users # actually this is a bad idea in general to pass raw parameters # from any user # # deprecate this and issue a warning like we do for DNS forwarding? if conf.exists('shared-network-parameters'): config['network_parameters'] = conf.return_values('shared-network-parameters') # check for multiple subnet configurations in a shared network # config segment if conf.exists('subnet'): for net in conf.list_nodes('subnet'): conf.set_level('service dhcp-server shared-network-name {0} subnet {1}'.format(network, net)) subnet = { 'network': net, 'address': str(ip_network(net).network_address), 'netmask': str(ip_network(net).netmask), 'bootfile_name': '', 'bootfile_server': '', 'client_prefix_length': '', 'default_router': '', 'rfc3442_default_router': '', 'dns_server': [], 'domain_name': '', 'domain_search': [], 'exclude': [], 'failover_local_addr': '', 'failover_name': '', 'failover_peer_addr': '', 'failover_status': '', 'ip_forwarding': False, 'lease': '86400', 'ntp_server': [], 'pop_server': [], 'server_identifier': '', 'smtp_server': [], 'range': [], 'static_mapping': [], 'static_subnet': '', 'static_router': '', 'static_route': '', 'subnet_parameters': [], 'tftp_server': '', 'time_offset': '', 'time_server': [], 'wins_server': [], 'wpad_url': '' } # Used to identify a bootstrap file if conf.exists('bootfile-name'): subnet['bootfile_name'] = conf.return_value('bootfile-name') # Specify host address of the server from which the initial boot file # (specified above) is to be loaded. Should be a numeric IP address or # domain name. if conf.exists('bootfile-server'): subnet['bootfile_server'] = conf.return_value('bootfile-server') # The subnet mask option specifies the client's subnet mask as per RFC 950. If no subnet # mask option is provided anywhere in scope, as a last resort dhcpd will use the subnet # mask from the subnet declaration for the network on which an address is being assigned. if conf.exists('client-prefix-length'): # snippet borrowed from https://stackoverflow.com/questions/33750233/convert-cidr-to-subnet-mask-in-python host_bits = 32 - int(conf.return_value('client-prefix-length')) subnet['client_prefix_length'] = inet_ntoa(pack('!I', (1 << 32) - (1 << host_bits))) # Default router IP address on the client's subnet if conf.exists('default-router'): subnet['default_router'] = conf.return_value('default-router') subnet['rfc3442_default_router'] = dhcp_static_route("0.0.0.0/0", subnet['default_router']) # Specifies a list of Domain Name System (STD 13, RFC 1035) name servers available to # the client. Servers should be listed in order of preference. if conf.exists('dns-server'): subnet['dns_server'] = conf.return_values('dns-server') # Option specifies the domain name that client should use when resolving hostnames # via the Domain Name System. if conf.exists('domain-name'): subnet['domain_name'] = conf.return_value('domain-name') # The domain-search option specifies a 'search list' of Domain Names to be used # by the client to locate not-fully-qualified domain names. if conf.exists('domain-search'): for domain in conf.return_values('domain-search'): subnet['domain_search'].append('"' + domain + '"') # IP address (local) for failover peer to connect if conf.exists('failover local-address'): subnet['failover_local_addr'] = conf.return_value('failover local-address') # DHCP failover peer name if conf.exists('failover name'): subnet['failover_name'] = conf.return_value('failover name') # IP address (remote) of failover peer if conf.exists('failover peer-address'): subnet['failover_peer_addr'] = conf.return_value('failover peer-address') # DHCP failover peer status (primary|secondary) if conf.exists('failover status'): subnet['failover_status'] = conf.return_value('failover status') # Option specifies whether the client should configure its IP layer for packet # forwarding if conf.exists('ip-forwarding'): subnet['ip_forwarding'] = True # Time should be the length in seconds that will be assigned to a lease if the # client requesting the lease does not ask for a specific expiration time if conf.exists('lease'): subnet['lease'] = conf.return_value('lease') # Specifies a list of IP addresses indicating NTP (RFC 5905) servers available # to the client. if conf.exists('ntp-server'): subnet['ntp_server'] = conf.return_values('ntp-server') # POP3 server option specifies a list of POP3 servers available to the client. # Servers should be listed in order of preference. if conf.exists('pop-server'): subnet['pop_server'] = conf.return_values('pop-server') # DHCP servers include this option in the DHCPOFFER in order to allow the client # to distinguish between lease offers. DHCP clients use the contents of the # 'server identifier' field as the destination address for any DHCP messages # unicast to the DHCP server if conf.exists('server-identifier'): subnet['server_identifier'] = conf.return_value('server-identifier') # SMTP server option specifies a list of SMTP servers available to the client. # Servers should be listed in order of preference. if conf.exists('smtp-server'): subnet['smtp_server'] = conf.return_values('smtp-server') # For any subnet on which addresses will be assigned dynamically, there must be at # least one range statement. The range statement gives the lowest and highest IP # addresses in a range. All IP addresses in the range should be in the subnet in # which the range statement is declared. if conf.exists('range'): for range in conf.list_nodes('range'): range = { 'start': conf.return_value('range {0} start'.format(range)), 'stop': conf.return_value('range {0} stop'.format(range)) } subnet['range'].append(range) # IP address that needs to be excluded from DHCP lease range if conf.exists('exclude'): subnet['exclude'] = conf.return_values('exclude') subnet['range'] = dhcp_slice_range(subnet['exclude'], subnet['range']) # Static DHCP leases if conf.exists('static-mapping'): addresses_for_exclude = [] for mapping in conf.list_nodes('static-mapping'): conf.set_level('service dhcp-server shared-network-name {0} subnet {1} static-mapping {2}'.format(network, net, mapping)) mapping = { 'name': mapping, 'disabled': False, 'ip_address': '', 'mac_address': '', 'static_parameters': [] } # This static lease is disabled if conf.exists('disable'): mapping['disabled'] = True # IP address used for this DHCP client if conf.exists('ip-address'): mapping['ip_address'] = conf.return_value('ip-address') addresses_for_exclude.append(mapping['ip_address']) # MAC address of requesting DHCP client if conf.exists('mac-address'): mapping['mac_address'] = conf.return_value('mac-address') # HACKS AND TRICKS # # check for 'raw' ISC DHCP parameters configured by users # actually this is a bad idea in general to pass raw parameters # from any user # # deprecate this and issue a warning like we do for DNS forwarding? if conf.exists('static-mapping-parameters'): mapping['static_parameters'] = conf.return_values('static-mapping-parameters') # append static-mapping configuration to subnet list subnet['static_mapping'].append(mapping) # Now we have all static DHCP leases - we also need to slice them # out of our DHCP ranges to avoid ISC DHCPd warnings as: # dhcpd: Dynamic and static leases present for 192.0.2.51. # dhcpd: Remove host declaration DMZ_PC1 or remove 192.0.2.51 # dhcpd: from the dynamic address pool for DMZ subnet['range'] = dhcp_slice_range(addresses_for_exclude, subnet['range']) # Reset config level to matching hirachy conf.set_level('service dhcp-server shared-network-name {0} subnet {1}'.format(network, net)) # This option specifies a list of static routes that the client should install in its routing # cache. If multiple routes to the same destination are specified, they are listed in descending # order of priority. if conf.exists('static-route destination-subnet'): subnet['static_subnet'] = conf.return_value('static-route destination-subnet') # Required for global config section dhcp['static_route'] = True if conf.exists('static-route router'): subnet['static_router'] = conf.return_value('static-route router') if subnet['static_router'] and subnet['static_subnet']: subnet['static_route'] = dhcp_static_route(subnet['static_subnet'], subnet['static_router']) # HACKS AND TRICKS # # check for 'raw' ISC DHCP parameters configured by users # actually this is a bad idea in general to pass raw parameters # from any user # # deprecate this and issue a warning like we do for DNS forwarding? if conf.exists('subnet-parameters'): subnet['subnet_parameters'] = conf.return_values('subnet-parameters') # This option is used to identify a TFTP server and, if supported by the client, should have # the same effect as the server-name declaration. BOOTP clients are unlikely to support this # option. Some DHCP clients will support it, and others actually require it. if conf.exists('tftp-server-name'): subnet['tftp_server'] = conf.return_value('tftp-server-name') # The time-offset option specifies the offset of the client’s subnet in seconds from # Coordinated Universal Time (UTC). if conf.exists('time-offset'): subnet['time_offset'] = conf.return_value('time-offset') # The time-server option specifies a list of RFC 868 time servers available to the client. # Servers should be listed in order of preference. if conf.exists('time-server'): subnet['time_server'] = conf.return_values('time-server') # The NetBIOS name server (NBNS) option specifies a list of RFC 1001/1002 NBNS name servers # listed in order of preference. NetBIOS Name Service is currently more commonly referred to # as WINS. WINS servers can be specified using the netbios-name-servers option. if conf.exists('wins-server'): subnet['wins_server'] = conf.return_values('wins-server') # URL for Web Proxy Autodiscovery Protocol if conf.exists('wpad-url'): subnet['wpad_url'] = conf.return_value('wpad-url') # Required for global config section dhcp['wpad'] = True # append subnet configuration to shared network subnet list config['subnet'].append(subnet) # append shared network configuration to config dictionary dhcp['shared_network'].append(config) return dhcp def verify(dhcp): if (dhcp is None) or (dhcp['disabled'] is True): return None # If DHCP is enabled we need one share-network if len(dhcp['shared_network']) == 0: raise ConfigError('No DHCP shared networks configured.\n' \ 'At least one DHCP shared network must be configured.') # Inspect shared-network/subnet failover_names = [] listen_ok = False subnets = [] # A shared-network requires a subnet definition for network in dhcp['shared_network']: if len(network['subnet']) == 0: raise ConfigError('No DHCP lease subnets configured for {0}. At least one\n' \ 'lease subnet must be configured for each shared network.'.format(network['name'])) for subnet in network['subnet']: # Subnet static route declaration requires destination and router if subnet['static_subnet'] or subnet['static_router']: if not (subnet['static_subnet'] and subnet['static_router']): raise ConfigError('Please specify missing DHCP static-route parameter(s):\n' \ 'destination-subnet | router') # Failover requires all 4 parameters set if subnet['failover_local_addr'] or subnet['failover_peer_addr'] or subnet['failover_name'] or subnet['failover_status']: if not (subnet['failover_local_addr'] and subnet['failover_peer_addr'] and subnet['failover_name'] and subnet['failover_status']): raise ConfigError('Please specify missing DHCP failover parameter(s):\n' \ 'local-address | peer-address | name | status') # Failover names must be uniquie if subnet['failover_name'] in failover_names: raise ConfigError('Failover names must be unique:\n' \ '{0} has already been configured!'.format(subnet['failover_name'])) else: failover_names.append(subnet['failover_name']) # Failover requires start/stop ranges for pool if (len(subnet['range']) == 0): raise ConfigError('At least one start-stop range must be configured for {0}\n' \ 'to set up DHCP failover!'.format(subnet['network'])) # Check if DHCP address range is inside configured subnet declaration range_start = [] range_stop = [] for range in subnet['range']: start = range['start'] stop = range['stop'] # DHCP stop IP required after start IP if start and not stop: raise ConfigError('DHCP range stop address for start {0} is not defined!'.format(start)) # Start address must be inside network if not ip_address(start) in ip_network(subnet['network']): raise ConfigError('DHCP range start address {0} is not in subnet {1}\n' \ 'specified for shared network {2}!'.format(start, subnet['network'], network['name'])) # Stop address must be inside network if not ip_address(stop) in ip_network(subnet['network']): raise ConfigError('DHCP range stop address {0} is not in subnet {1}\n' \ 'specified for shared network {2}!'.format(stop, subnet['network'], network['name'])) # Stop address must be greater or equal to start address if not ip_address(stop) >= ip_address(start): raise ConfigError('DHCP range stop address {0} must be greater or equal\n' \ 'to the range start address {1}!'.format(stop, start)) # Range start address must be unique if start in range_start: raise ConfigError('Conflicting DHCP lease range:\n' \ 'Pool start address {0} defined multipe times!'.format(start)) else: range_start.append(start) # Range stop address must be unique if stop in range_stop: raise ConfigError('Conflicting DHCP lease range:\n' \ 'Pool stop address {0} defined multipe times!'.format(stop)) else: range_stop.append(stop) # Exclude addresses must be in bound for exclude in subnet['exclude']: if not ip_address(exclude) in ip_network(subnet['network']): raise ConfigError('Exclude IP address {0} is outside of the DHCP lease network {1}\n' \ 'under shared network {2}!'.format(exclude, subnet['network'], network['name'])) # At least one DHCP address range or static-mapping required active_mapping = False if (len(subnet['range']) == 0): for mapping in subnet['static_mapping']: # we need at least one active mapping if (not active_mapping) and (not mapping['disabled']): active_mapping = True else: active_mapping = True if not active_mapping: raise ConfigError('No DHCP address range or active static-mapping set\n' \ 'for subnet {0}!'.format(subnet['network'])) # Static mappings require just a MAC address (will use an IP from the dynamic pool if IP is not set) for mapping in subnet['static_mapping']: if mapping['ip_address']: # Static IP address must be in bound if not ip_address(mapping['ip_address']) in ip_network(subnet['network']): raise ConfigError('DHCP static lease IP address {0} for static mapping {1}\n' \ 'in shared network {2} is outside DHCP lease subnet {3}!' \ .format(mapping['ip_address'], mapping['name'], network['name'], subnet['network'])) # Static mapping requires MAC address if not mapping['mac_address']: raise ConfigError('DHCP static lease MAC address not specified for static mapping\n' \ '{0} under shared network name {1}!'.format(mapping['name'], network['name'])) # There must be one subnet connected to a listen interface. # This only counts if the network itself is not disabled! if not network['disabled']: if is_subnet_connected(subnet['network'], primary=True): listen_ok = True # Subnets must be non overlapping if subnet['network'] in subnets: raise ConfigError('DHCP subnets must be unique! Subnet {0} defined multiple times!'.format(subnet['network'])) else: subnets.append(subnet['network']) # Check for overlapping subnets net = ip_network(subnet['network']) for n in subnets: net2 = ip_network(n) if (net != net2): if net.overlaps(net2): raise ConfigError('DHCP conflicting subnet ranges: {0} overlaps {1}'.format(net, net2)) if not listen_ok: raise ConfigError('DHCP server configuration error!\n' \ 'None of configured DHCP subnets does not have appropriate\n' \ 'primary IP address on any broadcast interface.') return None def generate(dhcp): if dhcp is None: return None if dhcp['disabled'] is True: print('Warning: DHCP server will be deactivated because it is disabled') return None # Prepare Jinja2 template loader from files tmpl_path = os.path.join(vyos_data_dir['data'], 'templates', 'dhcp-server') fs_loader = FileSystemLoader(tmpl_path) env = Environment(loader=fs_loader) tmpl = env.get_template('dhcpd.conf.tmpl') config_text = tmpl.render(dhcp) # Please see: https://phabricator.vyos.net/T1129 for quoting of the raw parameters # we can pass to ISC DHCPd config_text = config_text.replace(""",'"') with open(config_file, 'w') as f: f.write(config_text) tmpl = env.get_template('daemon.tmpl') config_text = tmpl.render(dhcp) with open(daemon_config_file, 'w') as f: f.write(config_text) return None def apply(dhcp): if (dhcp is None) or dhcp['disabled']: # DHCP server is removed in the commit run('sudo systemctl stop isc-dhcpv4-server.service') if os.path.exists(config_file): os.unlink(config_file) if os.path.exists(daemon_config_file): os.unlink(daemon_config_file) else: # If our file holding DHCP leases does yet not exist - create it if not os.path.exists(lease_file): os.mknod(lease_file) run('sudo systemctl restart isc-dhcpv4-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)