504 lines
17 KiB
Python
504 lines
17 KiB
Python
"""Shared library for the vpn-router package.
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Everything derivable from the configuration file alone, with no running
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network required. Used by both 'configure' and 'setup'.
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"""
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import base64
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import binascii
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import configparser
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import ipaddress
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import os
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import pathlib
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import shutil
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import subprocess
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import sys
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import jinja2
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LIB_DIR = pathlib.Path(__file__).resolve().parent
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if str(LIB_DIR) not in sys.path:
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sys.path.insert(0, str(LIB_DIR))
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import vpnrouter_platforms
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CONFIG_FILE = pathlib.Path('/etc/vpn-router/vpn-router.conf')
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TEMPLATE_DIR = pathlib.Path('/usr/share/vpn-router/templates')
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PKI_DIR = pathlib.Path('/etc/vpn-router/pki')
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SIMPLE_CA = LIB_DIR / 'simple-ca'
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SWANCTL_CONF_D = pathlib.Path('/etc/swanctl/conf.d')
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REMOTE_SITE = SWANCTL_CONF_D / 'remote-site.conf'
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ROAD_WARRIOR = SWANCTL_CONF_D / 'road-warrior.conf'
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P2S_FORWARDER = pathlib.Path('/etc/systemd/resolved.conf.d/p2s-forwarder.conf')
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WG_CONF = pathlib.Path('/etc/wireguard/wg0.conf')
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CA_CERT_DEST = pathlib.Path('/etc/swanctl/x509ca/ca.pem')
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SERVER_CERT = pathlib.Path('/etc/swanctl/x509/server.pem')
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SERVER_KEY = pathlib.Path('/etc/swanctl/private/server.key')
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CRL_DEST = pathlib.Path('/etc/swanctl/x509crl/crl.pem')
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TRUST_ANCHOR = pathlib.Path('/usr/local/share/ca-certificates/vpn-router-ca.crt')
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# section -> option -> default
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SCHEMA = {
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'general': {'platform': 'generic'},
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'interfaces': {'external': '', 'internal': ''},
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'wan': {'local_fqdn': '', 'local_id_mode': 'fqdn'},
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'local': {'cidrs': '', 'int_gateway_ip': ''},
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'remote': {'addrs': '', 'id': '', 'cidrs': '', 'psk_b64': '', 'psk_file': ''},
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'p2s': {'enabled': 'false', 'address_pool': '', 'ca_name': 'VPN Router CA'},
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'wireguard': {'enabled': 'false', 'address': '', 'listen_port': '51820'},
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}
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ID_MODES = ('fqdn', 'public_ip', 'internal_ip')
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class ConfigError(Exception):
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"""A setting is present but malformed."""
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def warn(message):
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print(f'vpn-router: warning: {message}', file=sys.stderr)
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def fail(message):
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print(f'vpn-router: error: {message}', file=sys.stderr)
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sys.exit(1)
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def new_parser():
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"""A parser that tolerates operator comments and never interpolates.
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interpolation=None matters: the default BasicInterpolation treats '%' as
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syntax, which would break any value containing it.
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Inline comments are enabled, which configparser leaves off by default
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because it makes '#' and ';' unusable inside values. That is an acceptable
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trade here precisely because the one setting that can hold arbitrary
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characters, the pre-shared key, is base64-encoded, and base64 uses none of
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those characters.
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"""
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return configparser.ConfigParser(
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interpolation=None,
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comment_prefixes=('#', ';'),
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inline_comment_prefixes=('#', ';'),
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)
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def default_parser():
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parser = new_parser()
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for section, options in SCHEMA.items():
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parser[section] = dict(options)
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return parser
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def load_config(path=CONFIG_FILE):
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"""Read the configuration, filling in defaults for anything absent."""
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parser = default_parser()
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if path.exists():
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try:
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parser.read(path, encoding='utf-8')
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except configparser.Error as exc:
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fail(f'cannot parse {path}: {exc}')
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return parser
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def _split_list(value):
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return [item.strip() for item in value.split(',') if item.strip()]
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def _get(cfg, section, option):
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return cfg.get(section, option, fallback=SCHEMA[section][option]).strip()
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def _get_bool(cfg, section, option):
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try:
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return cfg.getboolean(section, option,
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fallback=SCHEMA[section][option] == 'true')
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except ValueError:
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raise ConfigError(f'{section}.{option} is not a boolean')
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def _check_networks(value, name):
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for item in _split_list(value):
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try:
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ipaddress.ip_network(item, strict=False)
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except ValueError:
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raise ConfigError(f'{name}: {item!r} is not a valid CIDR')
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def _check_address(value, name):
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if not value:
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return
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try:
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ipaddress.ip_address(value)
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except ValueError:
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raise ConfigError(f'{name}: {value!r} is not a valid IP address')
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def validate(cfg):
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"""Reject values that are present but malformed. Absent is not an error."""
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platform = _get(cfg, 'general', 'platform')
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installed = vpnrouter_platforms.available()
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if platform and platform not in installed:
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raise ConfigError(
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f'general.platform: {platform!r} is not installed, expected one of '
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f'{", ".join(installed)}')
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id_mode = _get(cfg, 'wan', 'local_id_mode')
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if id_mode and id_mode not in ID_MODES:
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raise ConfigError(
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f'wan.local_id_mode: {id_mode!r} is not one of {", ".join(ID_MODES)}')
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_check_networks(_get(cfg, 'local', 'cidrs'), 'local.cidrs')
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_check_networks(_get(cfg, 'remote', 'cidrs'), 'remote.cidrs')
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_check_networks(_get(cfg, 'p2s', 'address_pool'), 'p2s.address_pool')
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_check_address(_get(cfg, 'local', 'int_gateway_ip'), 'local.int_gateway_ip')
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for option in ('external', 'internal'):
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name = _get(cfg, 'interfaces', option)
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if name and not (pathlib.Path('/sys/class/net') / name).exists():
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raise ConfigError(
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f'interfaces.{option}: interface {name!r} does not exist')
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wg_address = _get(cfg, 'wireguard', 'address')
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if wg_address:
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try:
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ipaddress.ip_interface(wg_address)
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except ValueError:
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raise ConfigError(
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f'wireguard.address: {wg_address!r} is not an address with prefix')
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port = _get(cfg, 'wireguard', 'listen_port')
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if port:
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if not port.isdigit() or not 1 <= int(port) <= 65535:
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raise ConfigError(f'wireguard.listen_port: {port!r} is not a valid port')
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for section in ('p2s', 'wireguard'):
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_get_bool(cfg, section, 'enabled')
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def resolve_psk(cfg):
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"""Return the pre-shared key, or '' when none is configured."""
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psk_file = _get(cfg, 'remote', 'psk_file')
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if psk_file:
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path = pathlib.Path(psk_file)
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if not path.is_file():
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raise ConfigError(f'remote.psk_file: {psk_file} does not exist')
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return path.read_text(encoding='utf-8').strip()
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psk_b64 = _get(cfg, 'remote', 'psk_b64')
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if not psk_b64:
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return ''
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try:
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return base64.b64decode(psk_b64, validate=True).decode('utf-8')
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except (binascii.Error, UnicodeDecodeError) as exc:
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raise ConfigError(f'remote.psk_b64 is not valid base64 text: {exc}')
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def platform_module(cfg):
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"""Import the configured platform module, falling back to the default."""
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name = _get(cfg, 'general', 'platform') or vpnrouter_platforms.DEFAULT
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try:
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return vpnrouter_platforms.load(name)
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except ModuleNotFoundError:
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warn(f'platform {name!r} is not installed, using '
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f'{vpnrouter_platforms.DEFAULT}')
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return vpnrouter_platforms.load(vpnrouter_platforms.DEFAULT)
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def _join(*groups):
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items = []
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for group in groups:
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for item in _split_list(group):
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if item not in items:
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items.append(item)
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return ', '.join(items)
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def interface_addresses(name, setting):
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"""IPv4 addresses configured on an interface.
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The interface name is configuration; its addresses are read from the
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system. Looking up the addresses of a named interface is deterministic -
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unlike working out which interface to use, which is a guess the package
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deliberately does not make.
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"""
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if not name:
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return []
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if not (pathlib.Path('/sys/class/net') / name).exists():
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raise ConfigError(f'{setting}: interface {name!r} does not exist')
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result = subprocess.run(
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['ip', '-o', '-4', 'addr', 'show', 'dev', name],
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capture_output=True, text=True,
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)
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if result.returncode != 0:
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raise ConfigError(f'{setting}: cannot read addresses of {name!r}')
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addresses = []
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for line in result.stdout.splitlines():
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fields = line.split()
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if len(fields) >= 4:
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addresses.append(fields[3].split('/')[0])
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return addresses
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def build_context(cfg, local_id_override=None):
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"""Assemble the template context from the configuration."""
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extras = vpnrouter_platforms.context(platform_module(cfg))
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ext_iface = _get(cfg, 'interfaces', 'external')
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int_iface = _get(cfg, 'interfaces', 'internal')
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ext_addrs = interface_addresses(ext_iface, 'interfaces.external')
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int_addrs = interface_addresses(int_iface, 'interfaces.internal')
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if ext_iface and not ext_addrs:
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warn(f'{ext_iface} has no IPv4 address yet')
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local_addrs = ', '.join(ext_addrs)
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int_addr = int_addrs[0] if int_addrs else ''
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local_fqdn = _get(cfg, 'wan', 'local_fqdn')
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id_mode = _get(cfg, 'wan', 'local_id_mode') or 'fqdn'
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local_cidrs = _get(cfg, 'local', 'cidrs')
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if local_id_override:
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local_id = local_id_override
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elif id_mode == 'fqdn':
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local_id = f'@{local_fqdn}' if local_fqdn else ''
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elif id_mode == 'internal_ip':
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local_id = int_addr
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else:
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# public_ip is resolved once the network is up, and the caller then
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# re-renders with local_id_override set.
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local_id = ''
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cidr_list = _split_list(local_cidrs)
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return {
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'platform': _get(cfg, 'general', 'platform') or 'generic',
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'wan_iface': ext_iface,
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'int_iface': int_iface,
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'local_addrs': local_addrs,
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'local_addr_list': _split_list(local_addrs),
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'local_fqdn': local_fqdn,
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'local_id_mode': id_mode,
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'local_id': local_id,
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'local_cidrs': local_cidrs,
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'local_cidr_list': cidr_list,
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'local_subnet': cidr_list[0] if cidr_list else '',
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'local_ts': _join(local_cidrs, extras['EXTRA_LOCAL_TS']),
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'int_addr': int_addr,
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'int_gateway_ip': _get(cfg, 'local', 'int_gateway_ip'),
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'remote_addrs': _get(cfg, 'remote', 'addrs'),
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'remote_id': _get(cfg, 'remote', 'id'),
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'remote_cidrs': _get(cfg, 'remote', 'cidrs'),
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'psk': resolve_psk(cfg),
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'p2s_enabled': _get_bool(cfg, 'p2s', 'enabled'),
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'p2s_address_pool': _get(cfg, 'p2s', 'address_pool'),
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'p2s_ca_name': _get(cfg, 'p2s', 'ca_name'),
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'p2s_dns': _join(local_addrs, extras['EXTRA_P2S_DNS']),
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'wg_enabled': _get_bool(cfg, 'wireguard', 'enabled'),
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'wg_address': _get(cfg, 'wireguard', 'address'),
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'wg_listen_port': _get(cfg, 'wireguard', 'listen_port'),
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}
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def s2s_ready(ctx):
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return all([
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ctx['local_addrs'], ctx['local_fqdn'], ctx['local_cidrs'],
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ctx['remote_addrs'], ctx['remote_id'], ctx['remote_cidrs'],
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ctx['psk'], ctx['local_id'],
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])
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def routing_ready(ctx):
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"""Routing and NAT need both interfaces named, plus the subnets involved."""
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return all([ctx['local_cidrs'], ctx['int_gateway_ip'],
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ctx['int_iface'], ctx['wan_iface']])
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def p2s_ready(ctx):
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return bool(ctx['p2s_enabled'] and ctx['p2s_address_pool'] and ctx['local_fqdn'])
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def wg_ready(ctx):
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return bool(ctx['wg_enabled'] and ctx['wg_address'])
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def _jinja_env():
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return jinja2.Environment(
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loader=jinja2.FileSystemLoader(str(TEMPLATE_DIR)),
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keep_trailing_newline=True,
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undefined=jinja2.StrictUndefined,
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autoescape=False,
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)
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def render(env, ctx, template_name, dest, mode):
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"""Render a template, writing only when the content changes."""
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content = env.get_template(template_name).render(ctx)
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dest = pathlib.Path(dest)
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if dest.exists() and dest.read_text(encoding='utf-8') == content:
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os.chmod(dest, mode)
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return False
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dest.parent.mkdir(parents=True, exist_ok=True)
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dest.write_text(content, encoding='utf-8')
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os.chmod(dest, mode)
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return True
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def existing_peers(path):
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"""Return the [Peer] sections of an existing WireGuard config.
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Peers are added by the operator by hand, so re-rendering the [Interface]
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section must not discard them.
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"""
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path = pathlib.Path(path)
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if not path.is_file():
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return ''
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lines = path.read_text(encoding='utf-8').splitlines(keepends=True)
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for index, line in enumerate(lines):
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if line.strip().lower() == '[peer]':
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return ''.join(lines[index:])
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return ''
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def render_wg_conf(env, ctx, dest=WG_CONF, mode=0o600):
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"""Render wg0.conf, carrying any operator-defined peers across."""
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content = env.get_template('wg0.conf.j2').render(ctx)
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peers = existing_peers(dest)
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if peers:
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content = content.rstrip('\n') + '\n\n' + peers
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dest = pathlib.Path(dest)
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if dest.exists() and dest.read_text(encoding='utf-8') == content:
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os.chmod(dest, mode)
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return False
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dest.parent.mkdir(parents=True, exist_ok=True)
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dest.write_text(content, encoding='utf-8')
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os.chmod(dest, mode)
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return True
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def remove(path):
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"""Remove a generated file. Returns True when something was removed."""
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path = pathlib.Path(path)
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if path.exists():
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path.unlink()
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return True
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return False
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def install_file(src, dest, mode):
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"""Copy src to dest when the content differs. Returns True on change."""
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src, dest = pathlib.Path(src), pathlib.Path(dest)
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if not src.is_file():
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return False
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if dest.exists() and dest.read_bytes() == src.read_bytes():
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os.chmod(dest, mode)
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return False
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dest.parent.mkdir(parents=True, exist_ok=True)
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shutil.copyfile(src, dest)
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os.chmod(dest, mode)
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return True
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def _simple_ca(*args):
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result = subprocess.run(
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[sys.executable, str(SIMPLE_CA), *args],
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capture_output=True, text=True,
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)
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if result.returncode != 0:
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fail(f'simple-ca {" ".join(args)} failed: {result.stderr.strip()}')
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return result.stdout
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def provision_pki(ctx):
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"""Create the CA and server certificate when the PKI directory is empty."""
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PKI_DIR.mkdir(parents=True, exist_ok=True)
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os.chmod(PKI_DIR, 0o700)
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if any(PKI_DIR.iterdir()):
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return
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if not ctx['p2s_ca_name']:
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warn('p2s.ca_name is empty, not creating a local CA')
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return
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if not SIMPLE_CA.is_file():
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fail(f'{SIMPLE_CA} is missing')
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_simple_ca('make-ca', '--ca-dir', str(PKI_DIR), ctx['p2s_ca_name'])
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_simple_ca('make-cert', '--ca-dir', str(PKI_DIR),
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ctx['local_fqdn'], ctx['local_fqdn'])
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def distribute_pki(ctx):
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"""Copy PKI material to each consumer. Returns True when anything changed."""
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label = ctx['local_fqdn'].split('.', 1)[0] if ctx['local_fqdn'] else ''
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bundle = PKI_DIR / 'ca_bundle.pem'
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ca_src = bundle if bundle.is_file() else PKI_DIR / 'ca_cert.pem'
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changed = False
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changed |= install_file(ca_src, CA_CERT_DEST, 0o644)
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if label:
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changed |= install_file(PKI_DIR / f'{label}_cert.pem', SERVER_CERT, 0o644)
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changed |= install_file(PKI_DIR / f'{label}_key.pem', SERVER_KEY, 0o600)
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changed |= install_file(PKI_DIR / 'crl.pem', CRL_DEST, 0o644)
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if install_file(PKI_DIR / 'ca_cert.pem', TRUST_ANCHOR, 0o644):
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changed = True
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if shutil.which('update-ca-certificates'):
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subprocess.run(['update-ca-certificates'],
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capture_output=True, text=True)
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return changed
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def configure(cfg=None, local_id_override=None):
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"""Render configuration files and provision PKI.
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Returns (ctx, changed) where changed is a set naming what needs reloading:
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'swanctl', 'resolved', 'wireguard'.
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"""
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if cfg is None:
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cfg = load_config()
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try:
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validate(cfg)
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ctx = build_context(cfg, local_id_override=local_id_override)
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except ConfigError as exc:
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fail(str(exc))
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changed = set()
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if p2s_ready(ctx):
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provision_pki(ctx)
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if distribute_pki(ctx):
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changed.add('swanctl')
|
|
|
|
env = _jinja_env()
|
|
|
|
if s2s_ready(ctx):
|
|
if render(env, ctx, 'remote-site.conf.j2', REMOTE_SITE, 0o600):
|
|
changed.add('swanctl')
|
|
elif remove(REMOTE_SITE):
|
|
changed.add('swanctl')
|
|
|
|
if p2s_ready(ctx):
|
|
if render(env, ctx, 'road-warrior.conf.j2', ROAD_WARRIOR, 0o600):
|
|
changed.add('swanctl')
|
|
if render(env, ctx, 'p2s-forwarder.conf.j2', P2S_FORWARDER, 0o644):
|
|
changed.add('resolved')
|
|
else:
|
|
if remove(ROAD_WARRIOR):
|
|
changed.add('swanctl')
|
|
if remove(P2S_FORWARDER):
|
|
changed.add('resolved')
|
|
|
|
if wg_ready(ctx):
|
|
if render_wg_conf(env, ctx):
|
|
changed.add('wireguard')
|
|
elif remove(WG_CONF):
|
|
changed.add('wireguard')
|
|
|
|
return ctx, changed
|