Merge pull request #2564 from alex/crl-index-perf

Make indexing a CRL O(1) instead of O(n).

1 files changed, 11 insertions, 2 deletions

diff --git a/src/cryptography/hazmat/backends/openssl/x509.py b/src/cryptography/hazmat/backends/openssl/x509.py
index 7b9f71cd..a470adbd 100644
--- a/src/cryptography/hazmat/backends/openssl/x509.py
+++ b/src/cryptography/hazmat/backends/openssl/x509.py
@@ -6,6 +6,7 @@ from __future__ import absolute_import, division, print_function
 
 import datetime
 import ipaddress
+import operator
 
 from email.utils import parseaddr
 
@@ -872,8 +873,16 @@ class _CertificateRevocationList(object):
             yield self._revoked_cert(i)
 
     def __getitem__(self, idx):
-        # TODO: indexing is O(n)
-        return list(self)[idx]
+        if isinstance(idx, slice):
+            start, stop, step = idx.indices(len(self))
+            return [self._revoked_cert(i) for i in range(start, stop, step)]
+        else:
+            idx = operator.index(idx)
+            if idx < 0:
+                idx += len(self)
+            if not 0 <= idx < len(self):
+                raise IndexError
+            return self._revoked_cert(idx)
 
     def __len__(self):
         revoked = self._backend._lib.X509_CRL_get_REVOKED(self._x509_crl)