Merge pull request #404 from reaperhulk/commoncrypto-mark

Add mark to skip if binding is not available

2 files changed, 15 insertions, 1 deletions

diff --git a/cryptography/hazmat/bindings/openssl/binding.py b/cryptography/hazmat/bindings/openssl/binding.py
index 4f6b99ae..2a1e1184 100644
--- a/cryptography/hazmat/bindings/openssl/binding.py
+++ b/cryptography/hazmat/bindings/openssl/binding.py
@@ -13,7 +13,9 @@
 
 from __future__ import absolute_import, division, print_function
 
-from cryptography.hazmat.bindings.utils import build_ffi
+from cryptography.hazmat.bindings.utils import (
+    build_ffi, binding_available
+)
 
 _OSX_PRE_INCLUDE = """
 #ifdef __APPLE__
@@ -79,3 +81,7 @@ class Binding(object):
         cls.ffi, cls.lib = build_ffi(cls._module_prefix, cls._modules,
                                      _OSX_PRE_INCLUDE, _OSX_POST_INCLUDE,
                                      ["crypto", "ssl"])
+
+    @classmethod
+    def is_available(cls):
+        return binding_available(cls._ensure_ffi_initialized)
diff --git a/cryptography/hazmat/bindings/utils.py b/cryptography/hazmat/bindings/utils.py
index 9e1d3937..9141c155 100644
--- a/cryptography/hazmat/bindings/utils.py
+++ b/cryptography/hazmat/bindings/utils.py
@@ -86,3 +86,11 @@ def build_ffi(module_prefix, modules, pre_include, post_include, libraries):
                     delattr(lib, name)
 
     return ffi, lib
+
+
+def binding_available(initializer):
+    try:
+        initializer()
+        return True
+    except cffi.VerificationError:
+        return False