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#

#

# Copyright (C) 2009 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.

"""Ganeti confd client/server library

"""

from ganeti import constants

_FOURCC_LEN = 4

def PackMagic(payload):

  """Prepend the confd magic fourcc to a payload.

  """

  return ''.join([constants.CONFD_MAGIC_FOURCC, payload])

def UnpackMagic(payload):

  """Unpack and check the confd magic fourcc from a payload.

  """

  if len(payload) < _FOURCC_LEN:

    raise errors.ConfdMagicError("UDP payload too short to contain the"

                                 " fourcc code")

  magic_number = payload[:_FOURCC_LEN]

  if magic_number != constants.CONFD_MAGIC_FOURCC:

    raise errors.ConfdMagicError("UDP payload contains an unkown fourcc")

  return payload[_FOURCC_LEN:]