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532 lines
18 KiB
Python
532 lines
18 KiB
Python
"""ACME protocol client class and helper functions."""
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import csv
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import logging
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import os
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import shutil
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import sys
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import Crypto.PublicKey.RSA
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import M2Crypto
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import zope.component
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from letsencrypt import acme
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from letsencrypt.client import auth_handler
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from letsencrypt.client import client_authenticator
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from letsencrypt.client import crypto_util
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from letsencrypt.client import errors
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from letsencrypt.client import interfaces
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from letsencrypt.client import le_util
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from letsencrypt.client import network
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from letsencrypt.client import reverter
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from letsencrypt.client import revoker
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from letsencrypt.client.apache import configurator
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class Client(object):
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"""ACME protocol client.
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:ivar network: Network object for sending and receiving messages
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:type network: :class:`letsencrypt.client.network.Network`
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:ivar authkey: Authorization Key
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:type authkey: :class:`letsencrypt.client.le_util.Key`
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:ivar auth_handler: Object that supports the IAuthenticator interface.
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auth_handler contains both a dv_authenticator and a client_authenticator
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:type auth_handler: :class:`letsencrypt.client.auth_handler.AuthHandler`
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:ivar installer: Object supporting the IInstaller interface.
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:type installer: :class:`letsencrypt.client.interfaces.IInstaller`
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:ivar config: Configuration.
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:type config: :class:`~letsencrypt.client.interfaces.IConfig`
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"""
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def __init__(self, config, authkey, dv_auth, installer):
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"""Initialize a client.
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:param dv_auth: IAuthenticator that can solve the
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:const:`letsencrypt.client.constants.DV_CHALLENGES`
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:type dv_auth: :class:`letsencrypt.client.interfaces.IAuthenticator`
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"""
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self.network = network.Network(config.server)
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self.authkey = authkey
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self.installer = installer
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self.config = config
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if dv_auth is not None:
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client_auth = client_authenticator.ClientAuthenticator(config)
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self.auth_handler = auth_handler.AuthHandler(
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dv_auth, client_auth, self.network)
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else:
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self.auth_handler = None
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def obtain_certificate(self, domains, csr=None):
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"""Obtains a certificate from the ACME server.
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:param str domains: list of domains to get a certificate
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:param csr: CSR must contain requested domains, the key used to generate
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this CSR can be different than self.authkey
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:type csr: :class:`CSR`
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:returns: cert_file, chain_file (paths to respective files)
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:rtype: `tuple` of `str`
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"""
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if self.auth_handler is None:
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logging.warning("Unable to obtain a certificate, because client "
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"does not have a valid auth handler.")
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# Request Challenges
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for name in domains:
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self.auth_handler.add_chall_msg(
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name, self.acme_challenge(name), self.authkey)
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# Perform Challenges/Get Authorizations
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self.auth_handler.get_authorizations()
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# Create CSR from names
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if csr is None:
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csr = init_csr(self.authkey, domains, self.config.cert_dir)
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# Retrieve certificate
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certificate_msg = self.acme_certificate(csr.data)
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# Save Certificate
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cert_file, chain_file = self.save_certificate(
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certificate_msg, self.config.cert_path, self.config.chain_path)
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self.store_cert_key(cert_file, False)
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return cert_file, chain_file
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def acme_challenge(self, domain):
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"""Handle ACME "challenge" phase.
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:returns: ACME "challenge" message.
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:rtype: :class:`letsencrypt.acme.messages.Challenge`
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"""
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return self.network.send_and_receive_expected(
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acme.messages.ChallengeRequest(identifier=domain),
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acme.messages.Challenge)
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def acme_certificate(self, csr_der):
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"""Handle ACME "certificate" phase.
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:param str csr_der: CSR in DER format.
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:returns: ACME "certificate" message.
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:rtype: :class:`letsencrypt.acme.message.Certificate`
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"""
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logging.info("Preparing and sending CSR...")
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return self.network.send_and_receive_expected(
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acme.messages.CertificateRequest.create(
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csr=M2Crypto.X509.load_request_der_string(csr_der),
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key=Crypto.PublicKey.RSA.importKey(self.authkey.pem)),
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acme.messages.Certificate)
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def save_certificate(self, certificate_msg, cert_path, chain_path):
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# pylint: disable=no-self-use
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"""Saves the certificate received from the ACME server.
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:param certificate_msg: ACME "certificate" message from server.
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:type certificate_msg: :class:`letsencrypt.acme.messages.Certificate`
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:param str cert_path: Path to attempt to save the cert file
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:param str chain_path: Path to attempt to save the chain file
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:returns: cert_file, chain_file (absolute paths to the actual files)
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:rtype: `tuple` of `str`
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:raises IOError: If unable to find room to write the cert files
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"""
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cert_chain_abspath = None
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cert_fd, cert_file = le_util.unique_file(cert_path, 0o644)
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cert_fd.write(certificate_msg.certificate.as_pem())
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cert_fd.close()
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logging.info(
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"Server issued certificate; certificate written to %s", cert_file)
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if certificate_msg.chain:
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chain_fd, chain_fn = le_util.unique_file(chain_path, 0o644)
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for cert in certificate_msg.chain:
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chain_fd.write(cert.to_pem())
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chain_fd.close()
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logging.info("Cert chain written to %s", chain_fn)
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# This expects a valid chain file
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cert_chain_abspath = os.path.abspath(chain_fn)
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return os.path.abspath(cert_file), cert_chain_abspath
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def deploy_certificate(self, domains, privkey, cert_file, chain_file=None):
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"""Install certificate
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:param list domains: list of domains to install the certificate
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:param privkey: private key for certificate
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:type privkey: :class:`letsencrypt.client.le_util.Key`
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:param str cert_file: certificate file path
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:param str chain_file: chain file path
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"""
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if self.installer is None:
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logging.warning("No installer specified, client is unable to deploy"
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"the certificate")
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raise errors.LetsEncryptClientError("No installer available")
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chain = None if chain_file is None else os.path.abspath(chain_file)
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for dom in domains:
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self.installer.deploy_cert(dom,
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os.path.abspath(cert_file),
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os.path.abspath(privkey.file),
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chain)
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self.installer.save("Deployed Let's Encrypt Certificate")
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# sites may have been enabled / final cleanup
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self.installer.restart()
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zope.component.getUtility(
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interfaces.IDisplay).success_installation(domains)
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def enhance_config(self, domains, redirect=None):
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"""Enhance the configuration.
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.. todo:: This needs to handle the specific enhancements offered by the
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installer. We will also have to find a method to pass in the chosen
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values efficiently.
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:param list domains: list of domains to configure
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:param redirect: If traffic should be forwarded from HTTP to HTTPS.
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:type redirect: bool or None
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:raises :class:`letsencrypt.client.errors.LetsEncryptClientError`: if
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no installer is specified in the client.
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"""
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if self.installer is None:
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logging.warning("No installer is specified, there isn't any "
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"configuration to enhance.")
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raise errors.LetsEncryptClientError("No installer available")
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if redirect is None:
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redirect = zope.component.getUtility(
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interfaces.IDisplay).redirect_by_default()
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if redirect:
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self.redirect_to_ssl(domains)
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def store_cert_key(self, cert_file, encrypt=False):
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"""Store certificate key. (Used to allow quick revocation)
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:param str cert_file: Path to a certificate file.
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:param bool encrypt: Should the certificate key be encrypted?
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:returns: True if key file was stored successfully, False otherwise.
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:rtype: bool
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"""
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list_file = os.path.join(self.config.cert_key_backup, "LIST")
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le_util.make_or_verify_dir(self.config.cert_key_backup, 0o700)
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idx = 0
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if encrypt:
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logging.error(
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"Unfortunately securely storing the certificates/"
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"keys is not yet available. Stay tuned for the "
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"next update!")
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return False
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if os.path.isfile(list_file):
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with open(list_file, 'r+b') as csvfile:
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csvreader = csv.reader(csvfile)
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for row in csvreader:
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idx = int(row[0]) + 1
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csvwriter = csv.writer(csvfile)
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csvwriter.writerow([str(idx), cert_file, self.authkey.file])
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else:
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with open(list_file, 'wb') as csvfile:
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csvwriter = csv.writer(csvfile)
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csvwriter.writerow(["0", cert_file, self.authkey.file])
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shutil.copy2(self.authkey.file,
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os.path.join(
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self.config.cert_key_backup,
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os.path.basename(self.authkey.file) + "_" + str(idx)))
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shutil.copy2(cert_file,
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os.path.join(
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self.config.cert_key_backup,
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os.path.basename(cert_file) + "_" + str(idx)))
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return True
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def redirect_to_ssl(self, domains):
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"""Redirect all traffic from HTTP to HTTPS
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:param vhost: list of ssl_vhosts
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:type vhost: :class:`letsencrypt.client.interfaces.IInstaller`
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"""
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for dom in domains:
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try:
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self.installer.enhance(dom, "redirect")
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except errors.LetsEncryptConfiguratorError:
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logging.warn('Unable to perform redirect for %s', dom)
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self.installer.save("Add Redirects")
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self.installer.restart()
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def validate_key_csr(privkey, csr=None):
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"""Validate Key and CSR files.
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Verifies that the client key and csr arguments are valid and correspond to
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one another. This does not currently check the names in the CSR due to
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the inability to read SANs from CSRs in python crypto libraries.
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If csr is left as None, only the key will be validated.
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:param privkey: Key associated with CSR
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:type privkey: :class:`letsencrypt.client.le_util.Key`
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:param csr: CSR
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:type csr: :class:`letsencrypt.client.le_util.CSR`
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:raises LetsEncryptClientError: if validation fails
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"""
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# TODO: Handle all of these problems appropriately
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# The client can eventually do things like prompt the user
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# and allow the user to take more appropriate actions
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# Key must be readable and valid.
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if privkey.pem and not crypto_util.valid_privkey(privkey.pem):
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raise errors.LetsEncryptClientError(
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"The provided key is not a valid key")
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if csr:
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if csr.form == "der":
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csr_obj = M2Crypto.X509.load_request_der_string(csr.data)
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csr = le_util.CSR(csr.file, csr_obj.as_pem(), "der")
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# If CSR is provided, it must be readable and valid.
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if csr.data and not crypto_util.valid_csr(csr.data):
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raise errors.LetsEncryptClientError(
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"The provided CSR is not a valid CSR")
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# If both CSR and key are provided, the key must be the same key used
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# in the CSR.
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if csr.data and privkey.pem:
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if not crypto_util.csr_matches_pubkey(
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csr.data, privkey.pem):
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raise errors.LetsEncryptClientError(
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"The key and CSR do not match")
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def init_key(key_size, key_dir):
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"""Initializes privkey.
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Inits key and CSR using provided files or generating new files
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if necessary. Both will be saved in PEM format on the
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filesystem. The CSR is placed into DER format to allow
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the namedtuple to easily work with the protocol.
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:param str key_dir: Key save directory.
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"""
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try:
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key_pem = crypto_util.make_key(key_size)
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except ValueError as err:
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logging.fatal(str(err))
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sys.exit(1)
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# Save file
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le_util.make_or_verify_dir(key_dir, 0o700)
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key_f, key_filename = le_util.unique_file(
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os.path.join(key_dir, "key-letsencrypt.pem"), 0o600)
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key_f.write(key_pem)
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key_f.close()
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logging.info("Generating key (%d bits): %s", key_size, key_filename)
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return le_util.Key(key_filename, key_pem)
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def init_csr(privkey, names, cert_dir):
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"""Initialize a CSR with the given private key.
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:param str cert_dir: Certificate save directory.
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"""
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csr_pem, csr_der = crypto_util.make_csr(privkey.pem, names)
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# Save CSR
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le_util.make_or_verify_dir(cert_dir, 0o755)
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csr_f, csr_filename = le_util.unique_file(
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os.path.join(cert_dir, "csr-letsencrypt.pem"), 0o644)
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csr_f.write(csr_pem)
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csr_f.close()
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logging.info("Creating CSR: %s", csr_filename)
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return le_util.CSR(csr_filename, csr_der, "der")
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# This should be controlled by commandline parameters
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def determine_authenticator(config):
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"""Returns a valid IAuthenticator.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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try:
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return configurator.ApacheConfigurator(config)
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except errors.LetsEncryptNoInstallationError:
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logging.info("Unable to determine a way to authenticate the server")
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def determine_installer(config):
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"""Returns a valid installer if one exists.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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try:
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return configurator.ApacheConfigurator(config)
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except errors.LetsEncryptNoInstallationError:
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logging.info("Unable to find a way to install the certificate.")
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def rollback(checkpoints, config):
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"""Revert configuration the specified number of checkpoints.
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.. note:: If another installer uses something other than the reverter class
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to do their configuration changes, the correct reverter will have to be
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determined.
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.. note:: This function restarts the server even if there weren't any
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rollbacks. The user may be confused or made an error and simply needs
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to restart the server.
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.. todo:: This function will have to change depending on the functionality
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of future installers. Perhaps the interface should define errors that
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are thrown for the various functions.
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:param int checkpoints: Number of checkpoints to revert.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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# Misconfigurations are only a slight problems... allow the user to rollback
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try:
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installer = determine_installer(config)
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except errors.LetsEncryptMisconfigurationError:
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_misconfigured_rollback(checkpoints, config)
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return
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# No Errors occurred during init... proceed normally
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# If installer is None... couldn't find an installer... there shouldn't be
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# anything to rollback
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if installer is not None:
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installer.rollback_checkpoints(checkpoints)
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installer.restart()
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def _misconfigured_rollback(checkpoints, config):
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"""Handles the case where the Installer is misconfigured.
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:param int checkpoints: Number of checkpoints to revert.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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yes = zope.component.getUtility(interfaces.IDisplay).generic_yesno(
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"Oh, no! The web server is currently misconfigured.{0}{0}"
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"Would you still like to rollback the "
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"configuration?".format(os.linesep))
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if not yes:
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logging.info("The error message is above.")
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logging.info("Configuration was not rolled back.")
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return
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logging.info("Rolling back using the Reverter module")
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# recovery routine has probably already been run by installer
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# in the__init__ attempt, run it again for safety... it shouldn't hurt
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# Also... not sure how future installers will handle recovery.
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rev = reverter.Reverter(config)
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rev.recovery_routine()
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rev.rollback_checkpoints(checkpoints)
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# We should try to restart the server
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try:
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installer = determine_installer(config)
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installer.restart()
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logging.info("Hooray! Rollback solved the misconfiguration!")
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logging.info("Your web server is back up and running.")
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except errors.LetsEncryptMisconfigurationError:
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logging.warning(
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"Rollback was unable to solve the misconfiguration issues")
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def revoke(config):
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"""Revoke certificates.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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# Misconfigurations don't really matter. Determine installer better choose
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# correctly though.
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try:
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installer = determine_installer(config)
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except errors.LetsEncryptMisconfigurationError:
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zope.component.getUtility(interfaces.IDisplay).generic_notification(
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"The web server is currently misconfigured. Some "
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"abilities like seeing which certificates are currently "
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"installed may not be available.")
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installer = None
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# This is a temporary fix to avoid errors. The Revoker is not fully
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# developed.
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if installer is None:
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zope.component.getUtility(interfaces.IDisplay).generic_notification(
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"The Let's Encrypt Revoker module does not currently support "
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"revocation without a valid installer. This feature should come "
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"soon.")
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return
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revoc = revoker.Revoker(installer, config)
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revoc.list_certs_keys()
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def view_config_changes(config):
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"""View checkpoints and associated configuration changes.
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.. note:: This assumes that the installation is using a Reverter object.
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:param config: Configuration.
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:type config: :class:`letsencrypt.client.interfaces.IConfig`
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"""
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rev = reverter.Reverter(config)
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rev.recovery_routine()
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rev.view_config_changes()
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