4 # Copyright (C) 2007, 2008 Google Inc.
6 # This program is free software; you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation; either version 2 of the License, or
9 # (at your option) any later version.
11 # This program is distributed in the hope that it will be useful, but
12 # WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 # General Public License for more details.
16 # You should have received a copy of the GNU General Public License
17 # along with this program; if not, write to the Free Software
18 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
21 """Serializer abstraction module
23 This module introduces a simple abstraction over the serialization
24 backend (currently json).
27 # pylint: disable-msg=C0103
29 # C0103: Invalid name, since pylint doesn't see that Dump points to a
30 # function and not a constant
35 from ganeti import errors
36 from ganeti import utils
41 _RE_EOLSP = re.compile("[ \t]+$", re.MULTILINE)
44 def _GetJsonDumpers(_encoder_class=simplejson.JSONEncoder):
45 """Returns two JSON functions to serialize data.
47 @rtype: (callable, callable)
48 @return: The function to generate a compact form of JSON and another one to
49 generate a more readable, indented form of JSON (if supported)
52 plain_encoder = _encoder_class(sort_keys=True)
54 # Check whether the simplejson module supports indentation
56 indent_encoder = _encoder_class(indent=_JSON_INDENT, sort_keys=True)
58 # Indentation not supported
59 indent_encoder = plain_encoder
61 return (plain_encoder.encode, indent_encoder.encode)
64 (_DumpJson, _DumpJsonIndent) = _GetJsonDumpers()
67 def DumpJson(data, indent=True):
68 """Serialize a given object.
70 @param data: the data to serialize
71 @param indent: whether to indent output (depends on simplejson version)
73 @return: the string representation of data
81 txt = _RE_EOLSP.sub("", fn(data))
82 if not txt.endswith("\n"):
89 """Unserialize data from a string.
91 @param txt: the json-encoded form
93 @return: the original data
96 return simplejson.loads(txt)
99 def DumpSignedJson(data, key, salt=None, key_selector=None):
100 """Serialize a given object and authenticate it.
102 @param data: the data to serialize
103 @param key: shared hmac key
104 @param key_selector: name/id that identifies the key (in case there are
105 multiple keys in use, e.g. in a multi-cluster environment)
106 @return: the string representation of data signed by the hmac key
109 txt = DumpJson(data, indent=False)
118 signed_dict["key_selector"] = key_selector
122 signed_dict["hmac"] = utils.Sha1Hmac(key, txt, salt=salt + key_selector)
124 return DumpJson(signed_dict, indent=False)
127 def LoadSignedJson(txt, key):
128 """Verify that a given message was signed with the given key, and load it.
130 @param txt: json-encoded hmac-signed message
131 @param key: the shared hmac key or a callable taking one argument (the key
132 selector), which returns the hmac key belonging to the key selector.
133 Typical usage is to pass a reference to the get method of a dict.
134 @rtype: tuple of original data, string
135 @return: original data, salt
136 @raises errors.SignatureError: if the message signature doesn't verify
139 signed_dict = LoadJson(txt)
140 if not isinstance(signed_dict, dict):
141 raise errors.SignatureError("Invalid external message")
143 msg = signed_dict["msg"]
144 salt = signed_dict["salt"]
145 hmac_sign = signed_dict["hmac"]
147 raise errors.SignatureError("Invalid external message")
150 # pylint: disable-msg=E1103
151 key_selector = signed_dict.get("key_selector", None)
152 hmac_key = key(key_selector)
154 raise errors.SignatureError("No key with key selector '%s' found" %
160 if not utils.VerifySha1Hmac(hmac_key, msg, hmac_sign,
161 salt=salt + key_selector):
162 raise errors.SignatureError("Invalid Signature")
164 return LoadJson(msg), salt
169 DumpSigned = DumpSignedJson
170 LoadSigned = LoadSignedJson