[tor-commits] [bridgedb/master] Add parse.padBase64() function for adding stripped padding '==' back in.

[isis at torproject.org]

commit bc8b04929fccdcf1f7d7f6c162a677cae4ccfa70
Author: Isis Lovecruft <isis at torproject.org>
Date:   Fri Nov 15 15:39:20 2013 +0000

    Add parse.padBase64() function for adding stripped padding '==' back in.
---
 lib/bridgedb/parse/__init__.py |   49 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)

diff --git a/lib/bridgedb/parse/__init__.py b/lib/bridgedb/parse/__init__.py
index e69de29..1fdbd8a 100644
--- a/lib/bridgedb/parse/__init__.py
+++ b/lib/bridgedb/parse/__init__.py
@@ -0,0 +1,49 @@
+# -*- coding: utf-8 -*-
+#
+# This file is part of BridgeDB, a Tor bridge distribution system.
+#
+# :authors: Isis Lovecruft 0xA3ADB67A2CDB8B35 <isis at torproject.org>
+#           please also see AUTHORS file
+# :copyright: (c) 2013 Isis Lovecruft
+#             (c) 2007-2013, The Tor Project, Inc.
+#             (c) 2007-2013, all entities within the AUTHORS file
+# :license: 3-clause BSD, see included LICENSE for information
+
+"""Modules for parsing data.
+
+** Package Overview: **
+
+..
+  parse
+   ||_ parse.addr
+   |   |_ isIPAddress - Check if an arbitrary string is an IP address.
+   |   |_ isIPv4 - Check if an arbitrary string is an IPv4 address.
+   |   |_ isIPv6 - Check if an arbitrary string is an IPv6 address.
+   |   \_ isValidIP - Check that an IP address is valid.
+   |
+   |__ :mod:`bridgedbparse.headers`
+   |__ :mod:`bridgedb.parse.options`
+   \__ :mod:`bridgedb.parse.versions`
+"""
+
+
+def padBase64(b64string):
+    """Re-add any stripped equals sign character padding to a b64 string.
+
+    :param string b64string: A base64-encoded string which might have had its
+        trailing equals sign padding removed.
+    """
+    try:
+        b64string = b64string.strip()
+    except AttributeError:
+        logging.error("Cannot pad base64 string %r: not a string." % b64string)
+    else:
+        addchars  = 0
+        remainder = len(b64string) % 4
+        if 2 <= remainder <= 3:
+            addchars = 4 - remainder
+        else:
+            raise ValueError("Invalid base64-encoded string: %r" % b64string)
+        b64string += '=' * addchars
+    finally:
+        return b64string