Merge pull request #2798 from reaperhulk/110-patch-19

opaque X509_EXTENSION
diff --git a/src/_cffi_src/openssl/x509.py b/src/_cffi_src/openssl/x509.py
index c5eb600..4cdc827 100644
--- a/src/_cffi_src/openssl/x509.py
+++ b/src/_cffi_src/openssl/x509.py
@@ -36,6 +36,8 @@
     ...;
 } X509_CINF;
 
+/* TODO: opaque X509_EXTENSION. Cryptography no longer depends on it being
+   non-opaque but pyOpenSSL needs a release where it doesn't depend on this */
 typedef struct {
     ASN1_OBJECT *object;
     ASN1_BOOLEAN critical;
diff --git a/src/cryptography/hazmat/backends/openssl/decode_asn1.py b/src/cryptography/hazmat/backends/openssl/decode_asn1.py
index 5f828c6..140d3de 100644
--- a/src/cryptography/hazmat/backends/openssl/decode_asn1.py
+++ b/src/cryptography/hazmat/backends/openssl/decode_asn1.py
@@ -198,7 +198,9 @@
             backend.openssl_assert(ext != backend._ffi.NULL)
             crit = backend._lib.X509_EXTENSION_get_critical(ext)
             critical = crit == 1
-            oid = x509.ObjectIdentifier(_obj2txt(backend, ext.object))
+            oid = x509.ObjectIdentifier(
+                _obj2txt(backend, backend._lib.X509_EXTENSION_get_object(ext))
+            )
             if oid in seen_oids:
                 raise x509.DuplicateExtension(
                     "Duplicate {0} extension found".format(oid), oid
@@ -652,9 +654,10 @@
     """
 
     data_ptr_ptr = backend._ffi.new("const unsigned char **")
-    data_ptr_ptr[0] = ext.value.data
+    value = backend._lib.X509_EXTENSION_get_data(ext)
+    data_ptr_ptr[0] = value.data
     gns = backend._lib.d2i_GENERAL_NAMES(
-        backend._ffi.NULL, data_ptr_ptr, ext.value.length
+        backend._ffi.NULL, data_ptr_ptr, value.length
     )
 
     # Check the result of d2i_GENERAL_NAMES() is valid. Usually this is covered