backend (currently json).
"""
+# pylint: disable-msg=C0103
+
+# C0103: Invalid name, since pylint doesn't see that Dump points to a
+# function and not a constant
import simplejson
import re
+import hmac
+from ganeti import errors
-# Check whether the simplejson module supports indentation
-_JSON_INDENT = 2
try:
- simplejson.dumps(1, indent=_JSON_INDENT)
-except TypeError:
- _JSON_INDENT = None
+ from hashlib import sha1
+except ImportError:
+ import sha as sha1
+
+
+_JSON_INDENT = 2
_RE_EOLSP = re.compile('[ \t]+$', re.MULTILINE)
+def _GetJsonDumpers(_encoder_class=simplejson.JSONEncoder):
+ """Returns two JSON functions to serialize data.
+
+ @rtype: (callable, callable)
+ @return: The function to generate a compact form of JSON and another one to
+ generate a more readable, indented form of JSON (if supported)
+
+ """
+ plain_encoder = _encoder_class(sort_keys=True)
+
+ # Check whether the simplejson module supports indentation
+ try:
+ indent_encoder = _encoder_class(indent=_JSON_INDENT, sort_keys=True)
+ except TypeError:
+ # Indentation not supported
+ indent_encoder = plain_encoder
+
+ return (plain_encoder.encode, indent_encoder.encode)
+
+
+(_DumpJson, _DumpJsonIndent) = _GetJsonDumpers()
+
+
def DumpJson(data, indent=True):
"""Serialize a given object.
@return: the string representation of data
"""
- if not indent or _JSON_INDENT is None:
- txt = simplejson.dumps(data)
+ if indent:
+ fn = _DumpJsonIndent
else:
- txt = simplejson.dumps(data, indent=_JSON_INDENT)
+ fn = _DumpJson
- txt = _RE_EOLSP.sub("", txt)
+ txt = _RE_EOLSP.sub("", fn(data))
if not txt.endswith('\n'):
txt += '\n'
+
return txt
return simplejson.loads(txt)
+def DumpSignedJson(data, key, salt=None):
+ """Serialize a given object and authenticate it.
+
+ @param data: the data to serialize
+ @param key: shared hmac key
+ @return: the string representation of data signed by the hmac key
+
+ """
+ txt = DumpJson(data, indent=False)
+ if salt is None:
+ salt = ''
+ signed_dict = {
+ 'msg': txt,
+ 'salt': salt,
+ 'hmac': hmac.new(key, salt + txt, sha1).hexdigest(),
+ }
+ return DumpJson(signed_dict, indent=False)
+
+
+def LoadSignedJson(txt, key):
+ """Verify that a given message was signed with the given key, and load it.
+
+ @param txt: json-encoded hmac-signed message
+ @param key: shared hmac key
+ @rtype: tuple of original data, string
+ @return: original data, salt
+ @raises errors.SignatureError: if the message signature doesn't verify
+
+ """
+ signed_dict = LoadJson(txt)
+ if not isinstance(signed_dict, dict):
+ raise errors.SignatureError('Invalid external message')
+ try:
+ msg = signed_dict['msg']
+ salt = signed_dict['salt']
+ hmac_sign = signed_dict['hmac']
+ except KeyError:
+ raise errors.SignatureError('Invalid external message')
+
+ if hmac.new(key, salt + msg, sha1).hexdigest() != hmac_sign:
+ raise errors.SignatureError('Invalid Signature')
+
+ return LoadJson(msg), salt
+
+
Dump = DumpJson
Load = LoadJson
+DumpSigned = DumpSignedJson
+LoadSigned = LoadSignedJson