acme_client
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#!/usr/bin/env python
import argparse, subprocess, json, os, sys, base64, binascii, time, hashlib, re, copy, textwrap, logging
try:
from urllib.request import urlopen # Python 3
from configparser import ConfigParser
except ImportError:
from urllib2 import urlopen # Python 2
from ConfigParser import ConfigParser
try:
config = ConfigParser()
config.read(['/etc/acme.conf'])
DEFAULT_CA = config.get("general", "server_url")
print('server_url =', DEFAULT_CA)
except:
print('Cannot read server_url from section [general] in /etc/acme.conf')
exit(1)
print(DEFAULT_CA)
exit()
with open('/etc/amce.config','r') as f:
output = f.read()
LOGGER = logging.getLogger(__name__)
LOGGER.addHandler(logging.StreamHandler())
LOGGER.setLevel(logging.INFO)
def get_crt(account_key, csr, acme_dir, log=LOGGER, CA=DEFAULT_CA):
# helper function base64 encode for jose spec
def _b64(b):
return base64.urlsafe_b64encode(b).decode('utf8').replace("=", "")
# parse account key to get public key
log.info("Parsing account key...")
proc = subprocess.Popen(["openssl", "rsa", "-in", account_key, "-noout", "-text"],
stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
if proc.returncode != 0:
raise IOError("OpenSSL Error: {0}".format(err))
pub_hex, pub_exp = re.search(
r"modulus:\n\s+00:([a-f0-9\:\s]+?)\npublicExponent: ([0-9]+)",
out.decode('utf8'), re.MULTILINE|re.DOTALL).groups()
pub_exp = "{0:x}".format(int(pub_exp))
pub_exp = "0{0}".format(pub_exp) if len(pub_exp) % 2 else pub_exp
header = {
"alg": "RS256",
"jwk": {
"e": _b64(binascii.unhexlify(pub_exp.encode("utf-8"))),
"kty": "RSA",
"n": _b64(binascii.unhexlify(re.sub(r"(\s|:)", "", pub_hex).encode("utf-8"))),
},
}
accountkey_json = json.dumps(header['jwk'], sort_keys=True, separators=(',', ':'))
thumbprint = _b64(hashlib.sha256(accountkey_json.encode('utf8')).digest())
# helper function make signed requests
def _send_signed_request(url, payload):
payload64 = _b64(json.dumps(payload).encode('utf8'))
protected = copy.deepcopy(header)
protected["nonce"] = urlopen(CA + "/directory").headers['Replay-Nonce']
protected64 = _b64(json.dumps(protected).encode('utf8'))
proc = subprocess.Popen(["openssl", "dgst", "-sha256", "-sign", account_key],
stdin=subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate("{0}.{1}".format(protected64, payload64).encode('utf8'))
if proc.returncode != 0:
raise IOError("OpenSSL Error: {0}".format(err))
data = json.dumps({
"header": header, "protected": protected64,
"payload": payload64, "signature": _b64(out),
})
try:
resp = urlopen(url, data.encode('utf8'))
return resp.getcode(), resp.read()
except IOError as e:
return getattr(e, "code", None), getattr(e, "read", e.__str__)()
# find domains
log.info("Parsing CSR...")
proc = subprocess.Popen(["openssl", "req", "-in", csr, "-noout", "-text"],
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = proc.communicate()
if proc.returncode != 0:
raise IOError("Error loading {0}: {1}".format(csr, err))
domains = set([])
common_name = re.search(r"Subject:.*? CN=([^\s,;/]+)", out.decode('utf8'))
if common_name is not None:
domains.add(common_name.group(1))
subject_alt_names = re.search(r"X509v3 Subject Alternative Name: \n +([^\n]+)\n", out.decode('utf8'), re.MULTILINE|re.DOTALL)
if subject_alt_names is not None:
for san in subject_alt_names.group(1).split(", "):
if san.startswith("DNS:"):
domains.add(san[4:])
# get the certificate domains and expiration
log.info("Registering account...")
code, result = _send_signed_request(CA + "/acme/new-reg", {
"resource": "new-reg",
"agreement": "https://letsencrypt.org/documents/LE-SA-v1.1.1-August-1-2016.pdf",
})
if code == 201:
log.info("Registered!")
elif code == 409:
log.info("Already registered!")
else:
raise ValueError("Error registering: {0} {1}".format(code, result))
# verify each domain
for domain in domains:
log.info("Verifying {0}...".format(domain))
# get new challenge
code, result = _send_signed_request(CA + "/acme/new-authz", {
"resource": "new-authz",
"identifier": {"type": "dns", "value": domain},
})
if code != 201:
raise ValueError("Error requesting challenges: {0} {1}".format(code, result))
# make the challenge file
challenge = [c for c in json.loads(result.decode('utf8'))['challenges'] if c['type'] == "http-01"][0]
token = re.sub(r"[^A-Za-z0-9_\-]", "_", challenge['token'])
keyauthorization = "{0}.{1}".format(token, thumbprint)
wellknown_path = os.path.join(acme_dir, token)
with open(wellknown_path, "w") as wellknown_file:
wellknown_file.write(keyauthorization)
# check that the file is in place
wellknown_url = "http://{0}/.well-known/acme-challenge/{1}".format(domain, token)
try:
resp = urlopen(wellknown_url)
resp_data = resp.read().decode('utf8').strip()
assert resp_data == keyauthorization
except (IOError, AssertionError):
os.remove(wellknown_path)
raise ValueError("Wrote file to {0}, but couldn't download {1}".format(
wellknown_path, wellknown_url))
# notify challenge are met
code, result = _send_signed_request(challenge['uri'], {
"resource": "challenge",
"keyAuthorization": keyauthorization,
})
if code != 202:
raise ValueError("Error triggering challenge: {0} {1}".format(code, result))
# wait for challenge to be verified
while True:
try:
resp = urlopen(challenge['uri'])
challenge_status = json.loads(resp.read().decode('utf8'))
except IOError as e:
raise ValueError("Error checking challenge: {0} {1}".format(
e.code, json.loads(e.read().decode('utf8'))))
if challenge_status['status'] == "pending":
time.sleep(2)
elif challenge_status['status'] == "valid":
log.info("{0} verified!".format(domain))
os.remove(wellknown_path)
break
else:
raise ValueError("{0} challenge did not pass: {1}".format(
domain, challenge_status))
# get the new certificate
log.info("Signing certificate...")
proc = subprocess.Popen(["openssl", "req", "-in", csr, "-outform", "DER"],
stdout=subprocess.PIPE, stderr=subprocess.PIPE)
csr_der, err = proc.communicate()
code, result = _send_signed_request(CA + "/acme/new-cert", {
"resource": "new-cert",
"csr": _b64(csr_der),
})
if code != 201:
raise ValueError("Error signing certificate: {0} {1}".format(code, result))
# return signed certificate!
log.info("Certificate signed!")
return """-----BEGIN CERTIFICATE-----\n{0}\n-----END CERTIFICATE-----\n""".format(
"\n".join(textwrap.wrap(base64.b64encode(result).decode('utf8'), 64)))
def main(argv):
parser = argparse.ArgumentParser(
formatter_class=argparse.RawDescriptionHelpFormatter,
description=textwrap.dedent("""\
This script automates the process of getting a signed TLS certificate from
Let's Encrypt using the ACME protocol. It will need to be run on your server
and have access to your private account key, so PLEASE READ THROUGH IT! It's
only ~200 lines, so it won't take long.
===Example Usage===
python acme_tiny.py --account-key ./account.key --csr ./domain.csr --acme-dir /usr/share/nginx/html/.well-known/acme-challenge/ > signed.crt
===================
===Example Crontab Renewal (once per month)===
0 0 1 * * python /path/to/acme_tiny.py --account-key /path/to/account.key --csr /path/to/domain.csr --acme-dir /usr/share/nginx/html/.well-known/acme-challenge/ > /path/to/signed.crt 2>> /var/log/acme_tiny.log
==============================================
""")
)
parser.add_argument("--account-key", required=True, help="path to your Let's Encrypt account private key")
parser.add_argument("--csr", required=True, help="path to your certificate signing request")
parser.add_argument("--acme-dir", required=True, help="path to the .well-known/acme-challenge/ directory")
parser.add_argument("--quiet", action="store_const", const=logging.ERROR, help="suppress output except for errors")
parser.add_argument("--ca", default=DEFAULT_CA, help="certificate authority, default is Let's Encrypt")
args = parser.parse_args(argv)
LOGGER.setLevel(args.quiet or LOGGER.level)
signed_crt = get_crt(args.account_key, args.csr, args.acme_dir, log=LOGGER, CA=args.ca)
sys.stdout.write(signed_crt)
if __name__ == "__main__": # pragma: no cover
main(sys.argv[1:])