Reducing the stacked exceptions plus a bit of pep8

lemur/certificates/cli.py

@@ -363,7 +363,10 @@ def check_revoked():
             else:
                 status = verify_string(cert.body, "")
 
-            cert.status = 'valid' if status else 'revoked'
+            if status is None:
+                cert.status = 'unknown'
+            else:
+                cert.status = 'valid' if status else 'revoked'
 
         except Exception as e:
             sentry.captureException()

lemur/certificates/verify.py

@@ -7,6 +7,7 @@
 """
 import requests
 import subprocess
+from flask import current_app
 from requests.exceptions import ConnectionError, InvalidSchema
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
@@ -14,6 +15,7 @@ from cryptography.hazmat.backends import default_backend
 from lemur.utils import mktempfile
 from lemur.common.utils import parse_certificate
 
+crl_cache = {}
 
 def ocsp_verify(cert_path, issuer_chain_path):
     """
@@ -29,6 +31,10 @@ def ocsp_verify(cert_path, issuer_chain_path):
     p1 = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     url, err = p1.communicate()
 
+    if not url:
+        current_app.logger.debug("No OCSP URL in certificate")
+        return None
+
     p2 = subprocess.Popen(['openssl', 'ocsp', '-issuer', issuer_chain_path,
                            '-cert', cert_path, "-url", url.strip()], stdout=subprocess.PIPE, stderr=subprocess.PIPE)
 
@@ -57,28 +63,39 @@ def crl_verify(cert_path):
     :raise Exception: If certificate does not have CRL
     """
     with open(cert_path, 'rt') as c:
-        cert = parse_certificate(c.read())
+        try:
+            cert = parse_certificate(c.read())
+        except Exception as e:
+            current_app.logger.error(e)
+            return None
 
-    distribution_points = cert.extensions.get_extension_for_oid(x509.OID_CRL_DISTRIBUTION_POINTS).value
+    try:
+        distribution_points = cert.extensions.get_extension_for_oid(
+                                                    x509.OID_CRL_DISTRIBUTION_POINTS
+                                                ).value
+    except x509.ExtensionNotFound:
+        current_app.logger.warn("No CRLDP extension in certificate")
+        return None
 
     for p in distribution_points:
         point = p.full_name[0].value
 
-        try:
-            response = requests.get(point)
+        if point not in crl_cache:
+            try:
+                response = requests.get(point)
 
-            if response.status_code != 200:
+                if response.status_code != 200:
+                    raise Exception("Unable to retrieve CRL: {0}".format(point))
+            except InvalidSchema:
+                # Unhandled URI scheme (like ldap://); skip this distribution point.
+                continue
+            except ConnectionError:
                 raise Exception("Unable to retrieve CRL: {0}".format(point))
-        except InvalidSchema:
-            # Unhandled URI scheme (like ldap://); skip this distribution point.
-            continue
-        except ConnectionError:
-            raise Exception("Unable to retrieve CRL: {0}".format(point))
 
-        crl = x509.load_der_x509_crl(response.content, backend=default_backend())
+            crl_cache[point] = x509.load_der_x509_crl(response.content, backend=default_backend())
 
-        for r in crl:
-            if cert.serial == r.serial_number:
+        for r in crl_cache[point]:
+            if cert.serial_number == r.serial_number:
                 try:
                     reason = r.extensions.get_extension_for_class(x509.CRLReason).value
                     # Handle "removeFromCRL" revoke reason as unrevoked; continue with the next distribution point.
@@ -86,6 +103,7 @@ def crl_verify(cert_path):
                     if reason == x509.ReasonFlags.remove_from_crl:
                         break
                 except x509.ExtensionNotFound:
+                    current_app.logger.warn("extension not found in CRL?")
                     pass
 
                 return
@@ -103,13 +121,15 @@ def verify(cert_path, issuer_chain_path):
     """
     # OCSP is our main source of truth, in a lot of cases CRLs
     # have been deprecated and are no longer updated
-    try:
-        return ocsp_verify(cert_path, issuer_chain_path)
-    except Exception as e:
-        try:
-            return crl_verify(cert_path)
-        except Exception as e:
-            raise Exception("Failed to verify")
+    verify_result = ocsp_verify(cert_path, issuer_chain_path)
+
+    if verify_result is None:
+        verify_result = crl_verify(cert_path)
+
+    if verify_result is None:
+        current_app.logger.warn("Failed to verify")
+
+    return verify_result
 
 
 def verify_string(cert_string, issuer_string):