serializer.py 3.13 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
#
#

# Copyright (C) 2007, 2008 Google Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301, USA.

"""Serializer abstraction module

This module introduces a simple abstraction over the serialization
backend (currently json).

"""

import simplejson
import re
30
31
32
import hmac

from ganeti import errors
33

Guido Trotter's avatar
Guido Trotter committed
34
35
36
37
try:
  from hashlib import sha1
except ImportError:
  import sha as sha1
38

39
40
41
42
43
44
45
# Check whether the simplejson module supports indentation
_JSON_INDENT = 2
try:
  simplejson.dumps(1, indent=_JSON_INDENT)
except TypeError:
  _JSON_INDENT = None

46
_RE_EOLSP = re.compile('[ \t]+$', re.MULTILINE)
47
48


49
def DumpJson(data, indent=True):
50
51
  """Serialize a given object.

Iustin Pop's avatar
Iustin Pop committed
52
53
54
55
  @param data: the data to serialize
  @param indent: whether to indent output (depends on simplejson version)

  @return: the string representation of data
56

57
  """
58
  if not indent or _JSON_INDENT is None:
59
60
61
    txt = simplejson.dumps(data)
  else:
    txt = simplejson.dumps(data, indent=_JSON_INDENT)
62

63
  txt = _RE_EOLSP.sub("", txt)
64
65
66
67
68
  if not txt.endswith('\n'):
    txt += '\n'
  return txt


69
def LoadJson(txt):
70
71
  """Unserialize data from a string.

Iustin Pop's avatar
Iustin Pop committed
72
73
74
75
  @param txt: the json-encoded form

  @return: the original data

76
77
  """
  return simplejson.loads(txt)
78
79


80
81
82
83
84
85
86
87
88
89
90
91
92
93
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,
Guido Trotter's avatar
Guido Trotter committed
94
    'hmac': hmac.new(key, salt + txt, sha1).hexdigest(),
95
96
97
98
  }
  return DumpJson(signed_dict)


99
def LoadSignedJson(txt, key):
100
101
102
103
104
  """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
105
  @return: original data, salt
106
107
108
109
110
111
112
113
114
115
116
117
118
  @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')

Guido Trotter's avatar
Guido Trotter committed
119
  if hmac.new(key, salt + msg, sha1).hexdigest() != hmac_sign:
120
121
    raise errors.SignatureError('Invalid Signature')

122
  return LoadJson(msg), salt
123
124


125
126
Dump = DumpJson
Load = LoadJson
127
128
DumpSigned = DumpSignedJson
LoadSigned = LoadSignedJson