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424 lines
14 KiB
Python
424 lines
14 KiB
Python
"""ACME protocol client class and helper functions."""
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import collections
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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 socket
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import string
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import sys
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import M2Crypto
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import zope.component
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from letsencrypt.client 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 CONFIG
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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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# it's weird to point to chocolate servers via raw IPv6 addresses, and
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# such addresses can be %SCARY in some contexts, so out of paranoia
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# let's disable them by default
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ALLOW_RAW_IPV6_SERVER = False
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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.client.Client.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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"""
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zope.interface.implements(interfaces.IAuthenticator)
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Key = collections.namedtuple("Key", "file pem")
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CSR = collections.namedtuple("CSR", "file data form")
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def __init__(self, server, authkey, dv_auth, installer):
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"""Initialize a client.
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:param str server: CA server to contact
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:param dv_auth: IAuthenticator Interface that can solve the
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CONFIG.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(server)
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self.authkey = authkey
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self.installer = installer
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client_auth = client_authenticator.ClientAuthenticator(server)
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self.auth_handler = auth_handler.AuthHandler(
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dv_auth, client_auth, self.network)
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def obtain_certificate(self, domains, csr=None,
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cert_path=CONFIG.CERT_PATH,
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chain_path=CONFIG.CHAIN_PATH):
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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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:param str cert_path: Full desired path to end certificate.
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:param str chain_path: Full desired path to end chain file.
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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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sanity_check_names(domains)
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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)
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# Retrieve certificate
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certificate_dict = 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_dict, cert_path, 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: dict
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"""
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return self.network.send_and_receive_expected(
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acme.challenge_request(domain), "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: dict
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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.certificate_request(csr_der, self.authkey.pem), "certificate")
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# pylint: disable=no-self-use
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def save_certificate(self, certificate_dict, cert_path, chain_path):
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"""Saves the certificate received from the ACME server.
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:param dict certificate_dict: certificate message from server
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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(
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crypto_util.b64_cert_to_pem(certificate_dict["certificate"]))
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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_dict.get("chain", None):
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chain_fd, chain_fn = le_util.unique_file(chain_path, 0o644)
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for cert in certificate_dict.get("chain", []):
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chain_fd.write(crypto_util.b64_cert_to_pem(cert))
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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:`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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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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: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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"""
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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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# if self.ocsp_stapling is None:
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# q = ("Would you like to protect the privacy of your users "
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# "by enabling OCSP stapling? If so, your users will not have "
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# "to query the Let's Encrypt CA separately about the current "
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# "revocation status of your certificate.")
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# self.ocsp_stapling = self.ocsp_stapling = display.ocsp_stapling(q)
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# if self.ocsp_stapling:
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# # TODO enable OCSP Stapling
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# continue
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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(CONFIG.CERT_KEY_BACKUP, "LIST")
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le_util.make_or_verify_dir(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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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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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.client.Client.Key`
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:param csr: CSR
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:type csr: :class:`letsencrypt.client.client.Client.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 = Client.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):
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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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"""
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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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logging.info("Note: The default RSA key size is %d bits.",
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CONFIG.RSA_KEY_SIZE)
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sys.exit(1)
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# Save file
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le_util.make_or_verify_dir(CONFIG.KEY_DIR, 0o700)
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key_f, key_filename = le_util.unique_file(
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os.path.join(CONFIG.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 Client.Key(key_filename, key_pem)
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def init_csr(privkey, names):
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"""Initialize a CSR with the given private key."""
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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(CONFIG.CERT_DIR, 0o755)
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csr_f, csr_filename = le_util.unique_file(
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os.path.join(CONFIG.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 Client.CSR(csr_filename, csr_der, "der")
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def csr_pem_to_der(csr):
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"""Convert pem CSR to der."""
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csr_obj = M2Crypto.X509.load_request_string(csr.data)
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return Client.CSR(csr.file, csr_obj.as_der(), "der")
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def sanity_check_names(names):
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"""Make sure host names are valid.
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:param list names: List of host names
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"""
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for name in names:
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if not is_hostname_sane(name):
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logging.fatal("%r is an impossible hostname", name)
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sys.exit(81)
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def is_hostname_sane(hostname):
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"""Make sure the given host name is sane.
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Do enough to avoid shellcode from the environment. There's
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no need to do more.
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:param str hostname: Host name to validate
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:returns: True if hostname is valid, otherwise false.
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:rtype: bool
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"""
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# hostnames & IPv4
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allowed = string.ascii_letters + string.digits + "-."
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if all([c in allowed for c in hostname]):
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return True
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if not ALLOW_RAW_IPV6_SERVER:
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return False
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# ipv6 is messy and complicated, can contain %zoneindex etc.
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try:
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# is this a valid IPv6 address?
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socket.getaddrinfo(hostname, 443, socket.AF_INET6)
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return True
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except socket.error:
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return False
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