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"""DNS Authenticator for deSEC."""
import json
import logging
import time
import dns.resolver
import requests
from certbot import interfaces
try:
# needed for compatibility with older certbots, see #13
import zope.interface
zope_interface_implementer = zope.interface.implementer
zope_interface_provider = zope.interface.provider
i_authenticator = interfaces.IAuthenticator
i_plugin_factory = interfaces.IPluginFactory
except ImportError:
def get_noop_dec(*args):
def noop_dec(obj):
return obj
return noop_dec
zope_interface_implementer = zope_interface_provider = get_noop_dec
i_authenticator = i_plugin_factory = None
from certbot import errors
from certbot.plugins import dns_common
logger = logging.getLogger(__name__)
logger.setLevel(logging.DEBUG)
@zope_interface_implementer(i_authenticator) # needed for compatibility with older certbots, see #13
@zope_interface_provider(i_plugin_factory) # needed for compatibility with older certbots, see #13
class Authenticator(dns_common.DNSAuthenticator):
"""DNS Authenticator for deSEC
This Authenticator uses the deSEC REST API to fulfill a dns-01 challenge.
"""
description = "Obtain certificates using a DNS TXT record (if you are using deSEC.io for DNS)."
DEFAULT_ENDPOINT = "https://desec.io/api/v1"
def __init__(self, *args, **kwargs):
super(Authenticator, self).__init__(*args, **kwargs)
self.credentials = None
@classmethod
def add_parser_arguments(cls, add): # pylint: disable=arguments-differ
super(Authenticator, cls).add_parser_arguments(
add, default_propagation_seconds=80 # TODO decrease after deSEC fixed their NOTIFY problem
)
add("credentials", help="deSEC credentials INI file.")
def more_info(self): # pylint: disable=missing-docstring,no-self-use
return (
"This plugin configures a DNS TXT record to respond to a dns-01 challenge using "
"the deSEC Remote REST API."
)
def _setup_credentials(self):
self.credentials = self._configure_credentials(
key="credentials",
label="deSEC credentials INI file",
required_variables={
"token": "Access token for deSEC API.",
},
)
def _desec_work(self, domain, validation_name, validation, set_operator):
client = self._get_desec_client()
try:
for _ in range(7):
validation_name = dns.resolver.resolve(validation_name, 'CNAME')[0].target
logger.debug(f"CNAME lookup result: {validation_name}")
except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer, dns.resolver.NoResolverConfiguration):
pass
if isinstance(validation_name, dns.name.Name):
validation_name = validation_name.to_text().rstrip('.')
zone = client.get_authoritative_zone(validation_name)
subname = validation_name.rsplit(zone['name'], 1)[0].rstrip('.')
records = client.get_txt_rrset(zone, subname)
logger.debug(f"Current TXT records: {records}")
records = set_operator(records, {f'"{validation}"'})
logger.debug(f"Setting TXT records: {records}")
client.set_txt_rrset(zone, subname, records)
def _perform(self, domain, validation_name, validation):
logger.debug(f"Authenticator._perform: {domain}, {validation_name}, {validation}")
self._desec_work(domain, validation_name, validation, set.union)
def _cleanup(self, domain, validation_name, validation):
logger.debug(f"Authenticator._cleanup: {domain}, {validation_name}, {validation}")
self._desec_work(domain, validation_name, validation, set.difference)
def _get_desec_client(self):
return _DesecConfigClient(
self.credentials.conf("endpoint") or self.DEFAULT_ENDPOINT,
self.credentials.conf("token"),
)
class _DesecConfigClient(object):
"""
Encapsulates all communication with the deSEC REST API.
"""
def __init__(self, endpoint, token):
logger.debug("creating _DesecConfigClient")
self.endpoint = endpoint.rstrip('/')
self.token = token
self.session = requests.Session()
self.session.headers["Authorization"] = f"Token {token}"
self.session.headers["Content-Type"] = "application/json"
@staticmethod
def desec_request(method, **kwargs):
for _ in range(3):
response: requests.Response = method(**kwargs)
if response.status_code == 429 and 'Retry-After' in response.headers:
try:
cooldown = int(response.headers['Retry-After'])
except ValueError:
return response
logger.debug(f"deSEC API limit reached. Retrying request after {cooldown}s.")
time.sleep(cooldown)
else:
return response
return response
def desec_get(self, **kwargs):
return self.desec_request(self.session.get, **kwargs)
def desec_put(self, **kwargs):
return self.desec_request(self.session.put, **kwargs)
def get_authoritative_zone(self, qname):
response = self.desec_get(url=f"{self.endpoint}/domains/?owns_qname={qname}")
self._check_response_status(response)
data = self._response_json(response)
try:
return data[0]
except IndexError:
raise errors.PluginError(f"Could not find suitable domain in your account (did you create it?): {qname}")
def get_txt_rrset(self, zone, subname):
domain = zone['name']
response = self.desec_get(
url=f"{self.endpoint}/domains/{domain}/rrsets/{subname}.../TXT/",
)
if response.status_code == 404:
return set()
self._check_response_status(response, domain=domain)
return set(self._response_json(response).get('records', set()))
def set_txt_rrset(self, zone, subname, records: set):
domain = zone['name']
response = self.desec_put(
url=f"{self.endpoint}/domains/{domain}/rrsets/",
data=json.dumps([
{"subname": subname, "type": "TXT", "ttl": zone['minimum_ttl'], "records": list(records)},
]),
)
return self._check_response_status(response, domain=domain)
def _check_response_status(self, response, **kwargs):
if 200 <= response.status_code <= 299:
return
elif response.status_code in [401, 403]:
raise errors.PluginError(f"Could not authenticate against deSEC API: {response.content}")
elif response.status_code == 404:
raise errors.PluginError(f"Not found ({kwargs}): {response.content}")
elif response.status_code == 429:
raise errors.PluginError(f"deSEC throttled your request even after we waited the prescribed cool-down "
f"time. Did you use the API in parallel? {response.content}")
elif response.status_code >= 500:
raise errors.PluginError(f"deSEC API server error (status {response.status_code}): {response.content}")
else:
raise errors.PluginError(f"Unknown error when talking to deSEC (status {response.status_code}: "
f"Request was on '{response.request.url}' with payload {response.request.body}. "
f"Response was '{response.content}'.")
def _response_json(self, response):
try:
return response.json()
except json.JSONDecodeError:
raise errors.PluginError(f"deSEC API sent non-JSON response (status {response.status_code}): "
f"{response.content}")
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