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Fix JSON binary encode and decode errors

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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.
This commit is contained in:
John Dennis
2010-03-01 18:55:39 -05:00
committed by Rob Crittenden
parent 06e5b8bd6b
commit 1289285d49
1 changed files with 99 additions and 2 deletions
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101
ipaserver/rpcserver.py
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@@ -33,7 +33,7 @@ from ipalib.rpc import xml_dumps, xml_loads
from ipalib.util import make_repr
from ipalib.compat import json
from wsgiref.util import shift_path_info
import base64
_not_found_template = """<html>
<head>
@@ -60,7 +60,6 @@ def not_found(environ, start_response):
)
return [output]
def read_input(environ):
"""
Read the request body from environ['wsgi.input'].
@@ -300,6 +299,102 @@ 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 modify objects in place because of 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.
@@ -326,6 +421,7 @@ 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):
@@ -339,6 +435,7 @@ 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')