Merge pull request #159 from dhermes/speedup-openssl-import

Deferring OpenSSL import until usage.

oauth2client/crypt.py

@@ -16,8 +16,10 @@
 """Crypto-related routines for oauth2client."""
 
 import base64
+import imp
 import json
 import logging
+import os
 import sys
 import time
 
@@ -37,7 +39,9 @@ class AppIdentityError(Exception):
 
 
 try:
-  from OpenSSL import crypto
+  _, _package_dir, _ = imp.find_module('OpenSSL')
+  if not os.path.isfile(os.path.join(_package_dir, 'crypto.py')):
+    raise ImportError('No module named OpenSSL')
 
   class OpenSSLVerifier(object):
     """Verifies the signature on a message."""
@@ -61,6 +65,7 @@ def verify(self, message, signature):
         True if message was signed by the private key associated with the public
         key that this object was constructed with.
       """
+      from OpenSSL import crypto
       try:
         if isinstance(message, six.text_type):
           message = message.encode('utf-8')
@@ -84,6 +89,7 @@ def from_string(key_pem, is_x509_cert):
       Raises:
         OpenSSL.crypto.Error if the key_pem can't be parsed.
       """
+      from OpenSSL import crypto
       if is_x509_cert:
         pubkey = crypto.load_certificate(crypto.FILETYPE_PEM, key_pem)
       else:
@@ -111,6 +117,7 @@ def sign(self, message):
       Returns:
         string, The signature of the message for the given key.
       """
+      from OpenSSL import crypto
       if isinstance(message, six.text_type):
         message = message.encode('utf-8')
       return crypto.sign(self._key, message, 'sha256')
@@ -129,6 +136,7 @@ def from_string(key, password=b'notasecret'):
       Raises:
         OpenSSL.crypto.Error if the key can't be parsed.
       """
+      from OpenSSL import crypto
       parsed_pem_key = _parse_pem_key(key)
       if parsed_pem_key:
         pkey = crypto.load_privatekey(crypto.FILETYPE_PEM, parsed_pem_key)
@@ -149,6 +157,7 @@ def pkcs12_key_as_pem(private_key_text, private_key_password):
     Returns:
       String. PEM contents of ``private_key_text``.
     """
+    from OpenSSL import crypto
     decoded_body = base64.b64decode(private_key_text)
     if isinstance(private_key_password, six.string_types):
       private_key_password = private_key_password.encode('ascii')

tests/test_crypt.py

@@ -58,17 +58,19 @@ def test_succeeds(self):
     self.assertTrue(pem_contents in [pkcs12_key_as_pem, alternate_pem])
 
   def test_without_openssl(self):
-    openssl_mod = sys.modules['OpenSSL']
+    import os
+    path_isfile = os.path.isfile
     try:
-      sys.modules['OpenSSL'] = None
+      os.path.isfile = lambda value: False
       reload(crypt)
       self.assertRaises(NotImplementedError, crypt.pkcs12_key_as_pem,
                         'FOO', 'BAR')
     finally:
-      sys.modules['OpenSSL'] = openssl_mod
+      os.path.isfile = path_isfile
       reload(crypt)
 
   def test_with_nonsense_key(self):
+    from OpenSSL import crypto
     credentials = self._make_signed_jwt_creds(private_key=b'NOT_A_KEY')
-    self.assertRaises(crypt.crypto.Error, crypt.pkcs12_key_as_pem,
+    self.assertRaises(crypto.Error, crypt.pkcs12_key_as_pem,
                       credentials.private_key, credentials.private_key_password)