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# Copyright (C) 2013 Google Inc.

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# 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

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# This program is distributed in the hope that it will be useful, but

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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

# General Public License for more details.

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# 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.

"""Utility functions for security features of Ganeti.

"""

import logging

import OpenSSL

import os

import uuid as uuid_module

from ganeti.utils import io

from ganeti.utils import x509

from ganeti import constants

from ganeti import errors

from ganeti import pathutils

def UuidToInt(uuid):

  uuid_obj = uuid_module.UUID(uuid)

  return uuid_obj.int # pylint: disable=E1101

def AddNodeToCandidateCerts(node_uuid, cert_digest, candidate_certs,

                            info_fn=logging.info, warn_fn=logging.warn):

  """Adds an entry to the candidate certificate map.

  @type node_uuid: string

  @param node_uuid: the node's UUID

  @type cert_digest: string

  @param cert_digest: the digest of the node's client SSL certificate

  @type candidate_certs: dict of strings to strings

  @param candidate_certs: map of node UUIDs to the digests of their client

      SSL certificates, will be manipulated in this function

  @type info_fn: function

  @param info_fn: logging function for information messages

  @type warn_fn: function

  @param warn_fn: logging function for warning messages

  """

  assert candidate_certs is not None

  if node_uuid in candidate_certs:

    old_cert_digest = candidate_certs[node_uuid]

    if old_cert_digest == cert_digest:

      info_fn("Certificate digest for node %s already in config."

              "Not doing anything." % node_uuid)

      return

    else:

      warn_fn("Overriding differing certificate digest for node %s"

              % node_uuid)

  candidate_certs[node_uuid] = cert_digest

def RemoveNodeFromCandidateCerts(node_uuid, candidate_certs,

                                 warn_fn=logging.warn):

  """Removes the entry of the given node in the certificate map.

  @type node_uuid: string

  @param node_uuid: the node's UUID

  @type candidate_certs: dict of strings to strings

  @param candidate_certs: map of node UUIDs to the digests of their client

      SSL certificates, will be manipulated in this function

  @type warn_fn: function

  @param warn_fn: logging function for warning messages

  """

  if node_uuid not in candidate_certs:

    warn_fn("Cannot remove certifcate for node %s, because it's not in the"

            "candidate map." % node_uuid)

    return

  del candidate_certs[node_uuid]

def GetCertificateDigest(cert_filename=pathutils.NODED_CLIENT_CERT_FILE):

  """Reads the SSL certificate and returns the sha1 digest.

  """

  cert_plain = io.ReadFile(cert_filename)

  cert = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM,

                                         cert_plain)

  return cert.digest("sha1")

def GenerateNewSslCert(new_cert, cert_filename, serial_no, log_msg):

  """Creates a new SSL certificate and backups the old one.

  @type new_cert: boolean

  @param new_cert: whether a new certificate should be created

  @type cert_filename: string

  @param cert_filename: filename of the certificate file

  @type serial_no: int

  @param serial_no: serial number of the certificate

  @type log_msg: string

  @param log_msg: log message to be written on certificate creation

  """

  cert_exists = os.path.exists(cert_filename)

  if new_cert or not cert_exists:

    if cert_exists:

      io.CreateBackup(cert_filename)

    logging.debug(log_msg)

    x509.GenerateSelfSignedSslCert(cert_filename, serial_no)

def VerifyCertificate(filename):

  """Verifies a SSL certificate.

  @type filename: string

  @param filename: Path to PEM file

  """

  try:

    cert = OpenSSL.crypto.load_certificate(OpenSSL.crypto.FILETYPE_PEM,

                                           io.ReadFile(filename))

  except Exception, err: # pylint: disable=W0703

    return (constants.CV_ERROR,

            "Failed to load X509 certificate %s: %s" % (filename, err))

  (errcode, msg) = \

    x509.VerifyX509Certificate(cert, constants.SSL_CERT_EXPIRATION_WARN,

                                constants.SSL_CERT_EXPIRATION_ERROR)

  if msg:

    fnamemsg = "While verifying %s: %s" % (filename, msg)

  else:

    fnamemsg = None

  if errcode is None:

    return (None, fnamemsg)

  elif errcode == x509.CERT_WARNING:

    return (constants.CV_WARNING, fnamemsg)

  elif errcode == x509.CERT_ERROR:

    return (constants.CV_ERROR, fnamemsg)

  raise errors.ProgrammerError("Unhandled certificate error code %r" % errcode)