Fix JSON binary encode and decode errors
Traverse the objects passed to JSON for encoding and decoding.
When binary data is seen during encode replace the binary
data with a dict {'__base64__' : base64_encoding_of_binary_value}.
On decode if a dict is seen whose single key is '__base64__' replace
that dict with the base64 decoded value of the key's value.
Thanks to Jason for the suggestion (no pun intended :-)
--
John Dennis <jden...@redhat.com>
Looking to carve out IT costs?
www.redhat.com/carveoutcosts/
>From f45be23b3c5f41ee012c51a6d6d3759f92ee48ee Mon Sep 17 00:00:00 2001
From: John Dennis <jden...@redhat.com>
Date: Mon, 1 Mar 2010 18:55:39 -0500
Subject: [PATCH] Fix JSON binary encode and decode errors
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: 8bit
Traverse the objects passed to JSON for encoding and decoding.
When binary data is seen during encode replace the binary
data with a dict {'__base64__' : base64_encoding_of_binary_value}.
On decode if a dict is seen whose single key is '__base64__' replace
that dict with the base64 decoded value of the key's value.
---
ipaserver/rpcserver.py | 100 +++++++++++++++++++++++++++++++++++++++++++++++-
1 files changed, 99 insertions(+), 1 deletions(-)
diff --git a/ipaserver/rpcserver.py b/ipaserver/rpcserver.py
index 4a5040e..96c4d29 100644
--- a/ipaserver/rpcserver.py
+++ b/ipaserver/rpcserver.py
@@ -31,7 +31,7 @@ from ipalib.request import context, Connection, destroy_context
from ipalib.rpc import xml_dumps, xml_loads
from ipalib.util import make_repr
from ipalib.compat import json
-
+import base64
def read_input(environ):
"""
@@ -216,6 +216,102 @@ class xmlserver(WSGIExecutioner):
return xml_dumps(response, methodresponse=True)
+def json_encode_binary(val):
+ '''
+ JSON cannot encode binary values. We encode binary values in Python str
+ objects and text in Python unicode objects. In order to allow a binary
+ object to be passed through JSON we base64 encode it thus converting it to
+ text which JSON can transport. To assure we recognize the value is a base64
+ encoded representation of the original binary value and not confuse it with
+ other text we convert the binary value to a dict in this form:
+
+ {'__base64__' : base64_encoding_of_binary_value}
+
+ This modification of the original input value cannot be done "in place" as
+ one might first assume (e.g. replacing any binary items in a container
+ (e.g. list, tuple, dict) with the base64 dict because the container might be
+ an immutable object (i.e. a tuple). Therefore this function returns a copy
+ of any container objects it encounters with tuples replaced by lists. This
+ is O.K. because the JSON encoding will map both lists and tuples to JSON
+ arrays.
+ '''
+
+ if isinstance(val, dict):
+ new_dict = {}
+ for k,v in val.items():
+ if isinstance(v, str):
+ new_dict[k] = {'__base64__' : base64.b64encode(v)}
+ else:
+ new_dict[k] = json_encode_binary(v)
+ del val
+ return new_dict
+ elif isinstance(val, (list, tuple)):
+ new_list = []
+ n = len(val)
+ i = 0
+ while i < n:
+ v = val[i]
+ if isinstance(v, str):
+ new_list.append({'__base64__' : base64.b64encode(v)})
+ else:
+ new_list.append(json_encode_binary(v))
+ i += 1
+ del val
+ return new_list
+ elif isinstance(val, str):
+ return {'__base64__' : base64.b64encode(val)}
+ else:
+ return val
+
+def json_decode_binary(val):
+ '''
+ JSON cannot transport binary data. In order to transport binary data we
+ convert binary data to a form like this:
+
+ {'__base64__' : base64_encoding_of_binary_value}
+
+ see json_encode_binary()
+
+ After JSON had decoded the JSON stream back into a Python object we must
+ recursively scan the object looking for any dicts which might represent
+ binary values and replace the dict containing the base64 encoding of the
+ binary value with the decoded binary value. Unlike the encoding problem
+ where the input might consist of immutable object, all JSON decoded
+ container are mutable so the conversion could be done in place. However we
+ don't modifying objects in place has side effects which may be
+ dangerous. Thus we elect to spend a few more cycles and avoid the
+ possibility of unintended side effects in favor of robustness.
+ '''
+
+ if isinstance(val, dict):
+ if val.has_key('__base64__'):
+ return base64.b64decode(val['__base64__'])
+ else:
+ new_dict = {}
+ for k,v in val.items():
+ if isinstance(v, dict) and v.has_key('__base64__'):
+ new_dict[k] = base64.b64decode(v['__base64__'])
+ else:
+ new_dict[k] = json_decode_binary(v)
+ del val
+ return new_dict
+ elif isinstance(val, list):
+ new_list = []
+ n = len(val)
+ i = 0
+ while i < n:
+ v = val[i]
+ if isinstance(v, dict) and v.has_key('__base64__'):
+ binary_val = base64.b64decode(v['__base64__'])
+ new_list.append(binary_val)
+ else:
+ new_list.append(json_decode_binary(v))
+ i += 1
+ del val
+ return new_list
+ else:
+ return val
+
class jsonserver(WSGIExecutioner):
"""
JSON RPC server.
@@ -241,6 +337,7 @@ class jsonserver(WSGIExecutioner):
error=error,
id=_id,
)
+ response = json_encode_binary(response)
return json.dumps(response, sort_keys=True, indent=4)
def unmarshal(self, data):
@@ -254,6 +351,7 @@ class jsonserver(WSGIExecutioner):
raise JSONError(error='Request is missing "method"')
if 'params' not in d:
raise JSONError(error='Request is missing "params"')
+ d = json_decode_binary(d)
method = d['method']
params = d['params']
_id = d.get('id')
--
1.6.6.1
_______________________________________________
Freeipa-devel mailing list
Freeipa-devel@redhat.com
https://www.redhat.com/mailman/listinfo/freeipa-devel
