| # Copyright 2016 - The Android Open Source Project |
| # |
| # Licensed under the Apache License, Version 2.0 (the "License"); |
| # you may not use this file except in compliance with the License. |
| # You may obtain a copy of the License at |
| # |
| # http://www.apache.org/licenses/LICENSE-2.0 |
| # |
| # Unless required by applicable law or agreed to in writing, software |
| # distributed under the License is distributed on an "AS IS" BASIS, |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| # See the License for the specific language governing permissions and |
| # limitations under the License. |
| |
| import copy |
| |
| _ROUTER_DNS = '8.8.8.8, 4.4.4.4' |
| |
| |
| class Subnet(object): |
| """Configs for a subnet on the dhcp server. |
| |
| Attributes: |
| network: ipaddress.IPv4Network, the network that this subnet is in. |
| start: ipaddress.IPv4Address, the start ip address. |
| end: ipaddress.IPv4Address, the end ip address. |
| router: The router to give to all hosts in this subnet. |
| lease_time: The lease time of all hosts in this subnet. |
| additional_parameters: A dictionary corresponding to DHCP parameters. |
| additional_options: A dictionary corresponding to DHCP options. |
| """ |
| |
| def __init__(self, |
| subnet, |
| start=None, |
| end=None, |
| router=None, |
| lease_time=None, |
| additional_parameters={}, |
| additional_options={}): |
| """ |
| Args: |
| subnet: ipaddress.IPv4Network, The address space of the subnetwork |
| served by the DHCP server. |
| start: ipaddress.IPv4Address, The start of the address range to |
| give hosts in this subnet. If not given, the second ip in |
| the network is used, under the assumption that the first |
| address is the router. |
| end: ipaddress.IPv4Address, The end of the address range to give |
| hosts. If not given then the address prior to the broadcast |
| address (i.e. the second to last ip in the network) is used. |
| router: ipaddress.IPv4Address, The router hosts should use in this |
| subnet. If not given the first ip in the network is used. |
| lease_time: int, The amount of lease time in seconds |
| hosts in this subnet have. |
| additional_parameters: A dictionary corresponding to DHCP parameters. |
| additional_options: A dictionary corresponding to DHCP options. |
| """ |
| self.network = subnet |
| |
| if start: |
| self.start = start |
| else: |
| self.start = self.network[2] |
| |
| if not self.start in self.network: |
| raise ValueError('The start range is not in the subnet.') |
| if self.start.is_reserved: |
| raise ValueError('The start of the range cannot be reserved.') |
| |
| if end: |
| self.end = end |
| else: |
| self.end = self.network[-2] |
| |
| if not self.end in self.network: |
| raise ValueError('The end range is not in the subnet.') |
| if self.end.is_reserved: |
| raise ValueError('The end of the range cannot be reserved.') |
| if self.end < self.start: |
| raise ValueError( |
| 'The end must be an address larger than the start.') |
| |
| if router: |
| if router >= self.start and router <= self.end: |
| raise ValueError('Router must not be in pool range.') |
| if not router in self.network: |
| raise ValueError('Router must be in the given subnet.') |
| |
| self.router = router |
| else: |
| # TODO: Use some more clever logic so that we don't have to search |
| # every host potentially. |
| # This is especially important if we support IPv6 networks in this |
| # configuration. The improved logic that we can use is: |
| # a) erroring out if start and end encompass the whole network, and |
| # b) picking any address before self.start or after self.end. |
| self.router = None |
| for host in self.network.hosts(): |
| if host < self.start or host > self.end: |
| self.router = host |
| break |
| |
| if not self.router: |
| raise ValueError('No useable host found.') |
| |
| self.lease_time = lease_time |
| self.additional_parameters = additional_parameters |
| self.additional_options = additional_options |
| if 'domain-name-servers' not in self.additional_options: |
| self.additional_options['domain-name-servers'] = _ROUTER_DNS |
| |
| |
| class StaticMapping(object): |
| """Represents a static dhcp host. |
| |
| Attributes: |
| identifier: How id of the host (usually the mac addres |
| e.g. 00:11:22:33:44:55). |
| address: ipaddress.IPv4Address, The ipv4 address to give the host. |
| lease_time: How long to give a lease to this host. |
| """ |
| |
| def __init__(self, identifier, address, lease_time=None): |
| self.identifier = identifier |
| self.ipv4_address = address |
| self.lease_time = lease_time |
| |
| |
| class DhcpConfig(object): |
| """The configs for a dhcp server. |
| |
| Attributes: |
| subnets: A list of all subnets for the dhcp server to create. |
| static_mappings: A list of static host addresses. |
| default_lease_time: The default time for a lease. |
| max_lease_time: The max time to allow a lease. |
| """ |
| |
| def __init__(self, |
| subnets=None, |
| static_mappings=None, |
| default_lease_time=600, |
| max_lease_time=7200): |
| self.subnets = copy.deepcopy(subnets) if subnets else [] |
| self.static_mappings = (copy.deepcopy(static_mappings) |
| if static_mappings else []) |
| self.default_lease_time = default_lease_time |
| self.max_lease_time = max_lease_time |
| |
| def render_config_file(self): |
| """Renders the config parameters into a format compatible with |
| the ISC DHCP server (dhcpd). |
| """ |
| lines = [] |
| |
| if self.default_lease_time: |
| lines.append('default-lease-time %d;' % self.default_lease_time) |
| if self.max_lease_time: |
| lines.append('max-lease-time %s;' % self.max_lease_time) |
| |
| for subnet in self.subnets: |
| address = subnet.network.network_address |
| mask = subnet.network.netmask |
| router = subnet.router |
| start = subnet.start |
| end = subnet.end |
| lease_time = subnet.lease_time |
| additional_parameters = subnet.additional_parameters |
| additional_options = subnet.additional_options |
| |
| lines.append('subnet %s netmask %s {' % (address, mask)) |
| lines.append('\tpool {') |
| lines.append('\t\toption subnet-mask %s;' % mask) |
| lines.append('\t\toption routers %s;' % router) |
| lines.append('\t\trange %s %s;' % (start, end)) |
| if lease_time: |
| lines.append('\t\tdefault-lease-time %d;' % lease_time) |
| lines.append('\t\tmax-lease-time %d;' % lease_time) |
| for param, value in additional_parameters.items(): |
| lines.append('\t\t%s %s;' % (param, value)) |
| for option, value in additional_options.items(): |
| lines.append('\t\toption %s %s;' % (option, value)) |
| lines.append('\t}') |
| lines.append('}') |
| |
| for mapping in self.static_mappings: |
| identifier = mapping.identifier |
| fixed_address = mapping.ipv4_address |
| host_fake_name = 'host%s' % identifier.replace(':', '') |
| lease_time = mapping.lease_time |
| |
| lines.append('host %s {' % host_fake_name) |
| lines.append('\thardware ethernet %s;' % identifier) |
| lines.append('\tfixed-address %s;' % fixed_address) |
| if lease_time: |
| lines.append('\tdefault-lease-time %d;' % lease_time) |
| lines.append('\tmax-lease-time %d;' % lease_time) |
| lines.append('}') |
| |
| config_str = '\n'.join(lines) |
| |
| return config_str |
