T.: Added a script for generating CAA records

helper-scripts/generate_caa_record.py

@@ -0,0 +1,122 @@
+#!/usr/bin/env python3
+# Based on github.com/diafygi/acme-tiny, original copyright:
+# Copyright Daniel Roesler, under MIT license, see LICENSE at github.com/diafygi/acme-tiny
+import argparse, subprocess, json, os, sys, base64, binascii, time, hashlib, re, copy, textwrap, logging
+try:
+    from urllib.request import urlopen, Request # Python 3
+except ImportError: # pragma: no cover
+    from urllib2 import urlopen, Request # Python 2
+
+DEFAULT_DIRECTORY_URL = "https://acme-v02.api.letsencrypt.org/directory"
+
+LOGGER = logging.getLogger(__name__)
+LOGGER.addHandler(logging.StreamHandler())
+LOGGER.setLevel(logging.INFO)
+
+def get_id(account_key, log=LOGGER, directory_url=DEFAULT_DIRECTORY_URL, contact=None):
+    directory, acct_headers, alg, jwk = None, None, None, None # global variables
+
+    # helper functions - base64 encode for jose spec
+    def _b64(b):
+        return base64.urlsafe_b64encode(b).decode('utf8').replace("=", "")
+
+    # helper function - run external commands
+    def _cmd(cmd_list, stdin=None, cmd_input=None, err_msg="Command Line Error"):
+        proc = subprocess.Popen(cmd_list, stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+        out, err = proc.communicate(cmd_input)
+        if proc.returncode != 0:
+            raise IOError("{0}\n{1}".format(err_msg, err))
+        return out
+
+    # helper function - make request and automatically parse json response
+    def _do_request(url, data=None, err_msg="Error", depth=0):
+        try:
+            resp = urlopen(Request(url, data=data, headers={"Content-Type": "application/jose+json", "User-Agent": "acme-tiny"}))
+            resp_data, code, headers = resp.read().decode("utf8"), resp.getcode(), resp.headers
+        except IOError as e:
+            resp_data = e.read().decode("utf8") if hasattr(e, "read") else str(e)
+            code, headers = getattr(e, "code", None), {}
+        try:
+            resp_data = json.loads(resp_data) # try to parse json results
+        except ValueError:
+            pass # ignore json parsing errors
+        if depth < 100 and code == 400 and resp_data['type'] == "urn:ietf:params:acme:error:badNonce":
+            raise IndexError(resp_data) # allow 100 retrys for bad nonces
+        if code not in [200, 201, 204]:
+            raise ValueError("{0}:\nUrl: {1}\nData: {2}\nResponse Code: {3}\nResponse: {4}".format(err_msg, url, data, code, resp_data))
+        return resp_data, code, headers
+
+    # helper function - make signed requests
+    def _send_signed_request(url, payload, err_msg, depth=0):
+        payload64 = "" if payload is None else _b64(json.dumps(payload).encode('utf8'))
+        new_nonce = _do_request(directory['newNonce'])[2]['Replay-Nonce']
+        protected = {"url": url, "alg": alg, "nonce": new_nonce}
+        protected.update({"jwk": jwk} if acct_headers is None else {"kid": acct_headers['Location']})
+        protected64 = _b64(json.dumps(protected).encode('utf8'))
+        protected_input = "{0}.{1}".format(protected64, payload64).encode('utf8')
+        out = _cmd(["openssl", "dgst", "-sha256", "-sign", account_key], stdin=subprocess.PIPE, cmd_input=protected_input, err_msg="OpenSSL Error")
+        data = json.dumps({"protected": protected64, "payload": payload64, "signature": _b64(out)})
+        try:
+            return _do_request(url, data=data.encode('utf8'), err_msg=err_msg, depth=depth)
+        except IndexError: # retry bad nonces (they raise IndexError)
+            return _send_signed_request(url, payload, err_msg, depth=(depth + 1))
+
+    # helper function - poll until complete
+    def _poll_until_not(url, pending_statuses, err_msg):
+        result, t0 = None, time.time()
+        while result is None or result['status'] in pending_statuses:
+            assert (time.time() - t0 < 3600), "Polling timeout" # 1 hour timeout
+            time.sleep(0 if result is None else 2)
+            result, _, _ = _send_signed_request(url, None, err_msg)
+        return result
+
+    # parse account key to get public key
+    log.info("Parsing account key...")
+    out = _cmd(["openssl", "rsa", "-in", account_key, "-noout", "-text"], err_msg="OpenSSL Error")
+    pub_pattern = r"modulus:[\s]+?00:([a-f0-9\:\s]+?)\npublicExponent: ([0-9]+)"
+    pub_hex, pub_exp = re.search(pub_pattern, 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
+    alg, jwk = "RS256", {
+        "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(jwk, sort_keys=True, separators=(',', ':'))
+    thumbprint = _b64(hashlib.sha256(accountkey_json.encode('utf8')).digest())
+
+    # get the ACME directory of urls
+    log.info("Getting directory...")
+    directory, _, _ = _do_request(directory_url, err_msg="Error getting directory")
+    log.info("Directory found!")
+
+    # create account and get the global key identifier
+    log.info("Registering account...")
+    reg_payload = {"termsOfServiceAgreed": True} if contact is None else {"termsOfServiceAgreed": True, "contact": contact}
+    account, code, acct_headers = _send_signed_request(directory['newAccount'], reg_payload, "Error registering")
+    log.info("Registered!" if code == 201 else "Already registered!")
+
+    return acct_headers['Location']
+
+def main(argv=None):
+    parser = argparse.ArgumentParser(
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        description=textwrap.dedent("""\
+            Generate a CAA record for Mailcow.
+
+            Example Usage: python mailcow_gencaa.py --account-key data/assets/ssl/acme/account.pem
+            """)
+    )
+    parser.add_argument("--account-key", required=True, help="path to your Let's Encrypt account private key")
+    parser.add_argument("--quiet", action="store_const", const=logging.ERROR, help="suppress output except for errors")
+    parser.add_argument("--directory-url", default=DEFAULT_DIRECTORY_URL, help="certificate authority directory url, default is Let's Encrypt")
+    parser.add_argument("--contact", metavar="CONTACT", default=None, nargs="*", help="Contact details (e.g. mailto:aaa@bbb.com) for your account-key")
+
+    args = parser.parse_args(argv)
+    LOGGER.setLevel(args.quiet or LOGGER.level)
+    id = get_id(args.account_key, log=LOGGER, directory_url=args.directory_url, contact=args.contact)
+    print("Use this as your CAA record:")
+    print('issue 128 "letsencrypt.org;accounturi={}"'.format(id))
+
+if __name__ == "__main__": # pragma: no cover
+    main(sys.argv[1:])