add a check to require that the list passed to SAN is all general names

1 files changed, 6 insertions, 0 deletions

diff --git a/src/cryptography/x509.py b/src/cryptography/x509.py
index cdc0e430..898ab6c7 100644
--- a/src/cryptography/x509.py
+++ b/src/cryptography/x509.py
@@ -542,6 +542,12 @@ class IPAddress(object):
 
 class SubjectAlternativeName(object):
     def __init__(self, general_names):
+        if not all(isinstance(x, GeneralName) for x in general_names):
+            raise TypeError(
+                "Every item in the general_names list must be an "
+                "object conforming to the GeneralName interface"
+            )
+
         self._general_names = general_names
 
     def __iter__(self):