X-Git-Url: https://code.grnet.gr/git/ganeti-local/blobdiff_plain/fe26718807f5cd6b8a30aa93770b060753ab91ff..81f7ea25fa942612873eb159e24c44e24ce84e69:/lib/serializer.py

diff --git a/lib/serializer.py b/lib/serializer.py
index a5a9ca4..cbc11fa 100644
--- a/lib/serializer.py
+++ b/lib/serializer.py
@@ -24,42 +24,40 @@ This module introduces a simple abstraction over the serialization
 backend (currently json).
 
 """
-# pylint: disable-msg=C0103
+# pylint: disable=C0103
 
 # C0103: Invalid name, since pylint doesn't see that Dump points to a
 # function and not a constant
 
-import simplejson
 import re
 
+# Python 2.6 and above contain a JSON module based on simplejson. Unfortunately
+# the standard library version is significantly slower than the external
+# module. While it should be better from at least Python 3.2 on (see Python
+# issue 7451), for now Ganeti needs to work well with older Python versions
+# too.
+import simplejson
+
+from ganeti import errors
+from ganeti import utils
 
-# Check whether the simplejson module supports indentation
-_JSON_INDENT = 2
-try:
-  simplejson.dumps(1, indent=_JSON_INDENT)
-except TypeError:
-  _JSON_INDENT = None
 
-_RE_EOLSP = re.compile('[ \t]+$', re.MULTILINE)
+_RE_EOLSP = re.compile("[ \t]+$", re.MULTILINE)
 
 
-def DumpJson(data, indent=True):
+def DumpJson(data):
   """Serialize a given object.
 
   @param data: the data to serialize
-  @param indent: whether to indent output (depends on simplejson version)
-
   @return: the string representation of data
 
   """
-  if not indent or _JSON_INDENT is None:
-    txt = simplejson.dumps(data)
-  else:
-    txt = simplejson.dumps(data, indent=_JSON_INDENT)
+  encoded = simplejson.dumps(data)
+
+  txt = _RE_EOLSP.sub("", encoded)
+  if not txt.endswith("\n"):
+    txt += "\n"
 
-  txt = _RE_EOLSP.sub("", txt)
-  if not txt.endswith('\n'):
-    txt += '\n'
   return txt
 
 
@@ -74,5 +72,75 @@ def LoadJson(txt):
   return simplejson.loads(txt)
 
 
+def DumpSignedJson(data, key, salt=None, key_selector=None):
+  """Serialize a given object and authenticate it.
+
+  @param data: the data to serialize
+  @param key: shared hmac key
+  @param key_selector: name/id that identifies the key (in case there are
+    multiple keys in use, e.g. in a multi-cluster environment)
+  @return: the string representation of data signed by the hmac key
+
+  """
+  txt = DumpJson(data)
+  if salt is None:
+    salt = ""
+  signed_dict = {
+    "msg": txt,
+    "salt": salt,
+    }
+
+  if key_selector:
+    signed_dict["key_selector"] = key_selector
+  else:
+    key_selector = ""
+
+  signed_dict["hmac"] = utils.Sha1Hmac(key, txt, salt=salt + key_selector)
+
+  return DumpJson(signed_dict)
+
+
+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: the shared hmac key or a callable taking one argument (the key
+    selector), which returns the hmac key belonging to the key selector.
+    Typical usage is to pass a reference to the get method of a dict.
+  @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 callable(key):
+    # pylint: disable=E1103
+    key_selector = signed_dict.get("key_selector", None)
+    hmac_key = key(key_selector)
+    if not hmac_key:
+      raise errors.SignatureError("No key with key selector '%s' found" %
+                                  key_selector)
+  else:
+    key_selector = ""
+    hmac_key = key
+
+  if not utils.VerifySha1Hmac(hmac_key, msg, hmac_sign,
+                              salt=salt + key_selector):
+    raise errors.SignatureError("Invalid Signature")
+
+  return LoadJson(msg), salt
+
+
 Dump = DumpJson
 Load = LoadJson
+DumpSigned = DumpSignedJson
+LoadSigned = LoadSignedJson