Factoring out conditional code from `crypt.py`.

Until now, code that depended on PyCrypto or OpenSSL was
defined conditionally (e.g. indented) in `crypt.py`. Rather than
grouping all these together, we factor out the library specific
behavior into standalone modules (but make the modules
private / protected).

In addition, added a `_helpers.py` module with common behavior
that was previously defined in multiple places.

Finally, beefed up some test cases so that the three newly added
modules had 100% test coverage.

Towards #212.

1 files changed, 53 insertions, 0 deletions

diff --git a/oauth2client/_helpers.py b/oauth2client/_helpers.py
new file mode 100644
index 0000000..974d210
--- /dev/null
+++ b/oauth2client/_helpers.py
@@ -0,0 +1,53 @@
+# Copyright 2015 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Helper functions for commonly used utilities."""
+
+import base64
+import json
+import six
+
+
+def _parse_pem_key(raw_key_input):
+  """Identify and extract PEM keys.
+
+  Determines whether the given key is in the format of PEM key, and extracts
+  the relevant part of the key if it is.
+
+  Args:
+    raw_key_input: The contents of a private key file (either PEM or PKCS12).
+
+  Returns:
+    string, The actual key if the contents are from a PEM file, or else None.
+  """
+  offset = raw_key_input.find(b'-----BEGIN ')
+  if offset != -1:
+    return raw_key_input[offset:]
+
+
+def _json_encode(data):
+  return json.dumps(data, separators=(',', ':'))
+
+
+def _urlsafe_b64encode(raw_bytes):
+  if isinstance(raw_bytes, six.text_type):
+    raw_bytes = raw_bytes.encode('utf-8')
+  return base64.urlsafe_b64encode(raw_bytes).decode('ascii').rstrip('=')
+
+
+def _urlsafe_b64decode(b64string):
+  # Guard against unicode strings, which base64 can't handle.
+  if isinstance(b64string, six.text_type):
+    b64string = b64string.encode('ascii')
+  padded = b64string + b'=' * (4 - len(b64string) % 4)
+  return base64.urlsafe_b64decode(padded)