summaryrefslogtreecommitdiff
path: root/src/conf_mode/service_dhcp-server.py
blob: 341b31dd7ed998df595f91e8786f2265b1a6f352 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
#!/usr/bin/env python3
#
# Copyright (C) 2018-2024 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.base import DeprecationWarning
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

    common_deprecation_msg = 'are subject of removal in VyOS 1.5! Please raise a feature request for proper CLI nodes!'
    if 'global_parameters' in dhcp:
        DeprecationWarning(f'Additional global parameters {common_deprecation_msg}')

    # A shared-network requires a subnet definition
    for network, network_config in dhcp['shared_network_name'].items():
        if 'shared_network_parameters' in network_config:
            DeprecationWarning(f'Additional shared network parameters in "{network}" {common_deprecation_msg}')

        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():
            if 'subnet_parameters' in subnet_config:
                DeprecationWarning(f'Additional subnet parameters in "{subnet}" {common_deprecation_msg}')

            # 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)
                used_ips = []
                used_mac = []
                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}"!')

                        if mapping_config['ip_address'] in used_ips:
                            raise ConfigError(f'Configured IP address for static mapping "{mapping}" already exists on another static mapping')
                        used_ips.append(mapping_config['ip_address'])

                    if 'mac_address' in mapping_config:
                        if mapping_config['mac_address'] in used_mac:
                            raise ConfigError(f'Configured MAC address for static mapping "{mapping}" already exists on another static mapping')
                        used_mac.append(mapping_config['mac_address'])

            # 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("&quot;", '"'))
    # 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("&quot;", '"'))
    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)