add new cliweb command which download/update crl file from caucase

when calling cliweb command with option --updateÃ-cr the crl file
will be downloaded from URL/crl and save only if the previous crl
file don't exists or if there is an old crl file and the new one
is different.
if option --on-crl-update SCRIPT_FILE is passed with --update-crl
SCRIPT_FILE will be executed if the crl is updated.

caucase/cli_flask.py

@@ -26,6 +26,7 @@ import traceback
 import pem
 import json
 import subprocess
+import hashlib
 from OpenSSL import crypto
 from caucase import utils
 from datetime import datetime, timedelta
@@ -64,6 +65,9 @@ def parseArguments():
   parser.add_argument('-s', '--csr-file',
                       default='csr.pem',
                       help='Path where to store csr file. default: %(default)s')
+  parser.add_argument('-r', '--crl-file',
+                      default='crl.pem',
+                      help='Path where to store crl file. default: %(default)s')
   parser.add_argument('--digest',
                       default="sha256",
                       help='Digest used to sign data. default: %(default)s')
@@ -78,6 +82,9 @@ def parseArguments():
   parser.add_argument('--on-renew',
                       help='Path of an executable file to call after certificate'\
                           ' renewal.')
+  parser.add_argument('--on-crl-update',
+                      help='Path of an executable file to call after CRL '\
+                          'file update.')
 
   parser.add_argument('--no-check-certificate',
                       action='store_false', default=True, dest='verify_certificate',
@@ -90,16 +97,14 @@ def parseArguments():
                       help='Revoke existing certificate.')
   group.add_argument('--renew', action='store_true',
                       help='Renew current certificate and and replace with existing files.')
+  group.add_argument('--update-crl', action='store_true',
+                      help='Download and store the new CRL file if there was a new revocation.')
 
   return parser
 
 
 
-def requestCertificate(config):
-
-  ca_request = CertificateAuthorityRequest(config.key_file, config.crt_file,
-          config.ca_crt_file, config.ca_url, digest=config.digest,
-          verify_certificate=config.verify_certificate)
+def requestCertificate(ca_request, config):
 
   # download or update ca crt file
   ca_request.getCACertificateChain()
@@ -116,29 +121,21 @@ def requestCertificate(config):
   ca_request.signCertificate(csr)
 
 
-def revokeCertificate(config):
+def revokeCertificate(ca_revoke, config):
 
   os.close(os.open(config.key_file, os.O_RDONLY))
   os.close(os.open(config.crt_file, os.O_RDONLY))
 
-  ca_revoke = CertificateAuthorityRequest(config.key_file, config.crt_file,
-          config.ca_crt_file, config.ca_url, digest=config.digest,
-          verify_certificate=config.verify_certificate)
-
   # download or update ca crt file
   ca_revoke.getCACertificateChain()
 
   ca_revoke.revokeCertificate()
 
-def renewCertificate(config, backup_dir):
+def renewCertificate(ca_renew, config, backup_dir):
 
   os.close(os.open(config.key_file, os.O_RDONLY))
   os.close(os.open(config.crt_file, os.O_RDONLY))
 
-  ca_renew = CertificateAuthorityRequest(config.key_file, config.crt_file,
-          config.ca_crt_file, config.ca_url, digest=config.digest,
-          verify_certificate=config.verify_certificate)
-
   # download or update ca crt file
   ca_renew.getCACertificateChain()
 
@@ -146,6 +143,7 @@ def renewCertificate(config, backup_dir):
                             backup_dir,
                             config.threshold,
                             after_script=config.on_renew)
+  
 
 def main():
   parser = parseArguments()
@@ -159,16 +157,20 @@ def main():
     parser.print_help()
     exit(1)
 
+  ca_client = CertificateAuthorityRequest(config.key_file, config.crt_file,
+          config.ca_crt_file, config.ca_url, digest=config.digest,
+          verify_certificate=config.verify_certificate)
+
   if config.request:
     if not config.cn:
       parser.error('Option --cn is required for request.')
       parser.print_help()
       exit(1)
 
-    requestCertificate(config)
+    requestCertificate(ca_client, config)
 
   elif config.revoke:
-    revokeCertificate(config)
+    revokeCertificate(ca_client, config)
   
   elif config.renew:
     if not config.threshold:
@@ -184,9 +186,12 @@ def main():
     if os.path.exists(config.csr_file):
       os.unlink(config.csr_file)
 
-    renewCertificate(config, backup_dir)
+    renewCertificate(ca_client, config, backup_dir)
+  elif config.update_crl:
+    ca_client.updateCertificateRevocationList(config.crl_file,
+                                              after_script=config.on_crl_update)
   else:
-    parser.error('Please set one of options: --request | --revoke | --renew.')
+    parser.error('Please set one of options: --request | --revoke | --renew | --update-crl.')
     parser.print_help()
     exit(1)
 
@@ -222,7 +227,7 @@ class CertificateAuthorityRequest(object):
       
 
     if self.logger is None:
-      self.logger = logging.getLogger('Caucase Request')
+      self.logger = logging.getLogger('Caucase Client')
       self.logger.setLevel(logging.DEBUG)
       handler = logging.StreamHandler()
       handler.setLevel(logging.DEBUG)
@@ -694,3 +699,53 @@ class CertificateAuthorityRequest(object):
         if os.path.exists(path):
           os.unlink(path)
 
+
+  def updateCertificateRevocationList(self, crl_file, after_script=''):
+    """
+      Download or update crl. If the crl_file exists, it will be updated if
+      the new CRL has changed.
+    """
+
+    crl_url = '%s/crl' % self.ca_url
+    self.logger.info("Downloading crl file from %s ..." % crl_url)
+    response = self._request('get', crl_url)
+    retry = 1
+
+    while not response or response.status_code != 200:
+      time.sleep(self.sleep_time)
+      response = self._request('get', crl_url)
+      retry += 1
+      if retry > self.max_retry:
+        break
+
+    if not response or response.status_code != 200:
+      raise Exception("ERROR: failed to get crl file after %s retry. Exiting..." % retry)
+
+    crl_string = response.text
+    # load crl string so we are sure that it is a valid crl string
+    crl = crypto.load_crl(crypto.FILETYPE_PEM, crl_string)
+    # Dumped string contain only the CRL without extra info
+    crl_string = crypto.dump_crl(crypto.FILETYPE_PEM, crl)
+    update_crl = False
+    if os.path.exists(crl_file):
+      with open(crl_file) as fcrl:
+        old_checksum = hashlib.md5(fcrl.read()).hexdigest()
+        checksum = hashlib.md5(crl_string).hexdigest()
+        if checksum != old_checksum:
+          update_crl = True
+    else:
+      update_crl = True
+
+    if update_crl:
+      fd = os.open(crl_file, os.O_CREAT | os.O_WRONLY | os.O_TRUNC, 0644)
+      try:
+        os.write(fd, crl_string)
+      finally:
+        os.close(fd)
+      self.logger.info("New CRL file was saved in %s ..." % crl_file)
+      if after_script:
+        output = popenCommunicate([os.path.realpath(after_script)])
+        self.logger.info("Successfully executed script '%s' with output:\n%s" % (
+          after_script, output))
+    else:
+      self.logger.info("crl file don't need to be updated.")