T5474: establish common file name pattern for XML conf mode commands

We will use _ as CLI level divider. The XML definition filename and also
the Python helper should match the CLI node.

Example:
set interfaces ethernet -> interfaces_ethernet.xml.in
set interfaces bond -> interfaces_bond.xml.in
set service dhcp-server -> service_dhcp-server-xml.in

(cherry picked from commit 4ef110fd2c501b718344c72d495ad7e16d2bd465)

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("&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)