autoupdate.py

# Copyright (c) 2009-2010 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

from buildutil import BuildObject
from xml.dom import minidom

import cherrypy
import os
import shutil
import subprocess
import time


def _LogMessage(message):
  cherrypy.log(message, 'UPDATE')


class Autoupdate(BuildObject):
  """Class that contains functionality that handles Chrome OS update pings.

  Members:
    serve_only: Serve images from a pre-built image.zip file.  static_dir
      must be set to the location of the image.zip.
    factory_config: Path to the factory config file if handling factory
      requests.
    use_test_image: Use chromiumos_test_image.bin rather than the standard.
    static_url_base: base URL, other than devserver, for update images.
    client_prefix: The prefix for the update engine client.
    forced_image: Path to an image to use for all updates.
  """

  def __init__(self, serve_only=None, test_image=False, urlbase=None,
               factory_config_path=None, client_prefix=None, forced_image=None,
               port=8080, src_image='', vm=False, board=None,
               *args, **kwargs):
    super(Autoupdate, self).__init__(*args, **kwargs)
    self.serve_only = serve_only
    self.factory_config = factory_config_path
    self.use_test_image = test_image
    if urlbase:
      self.urlbase = urlbase
    else:
      self.urlbase = None

    self.client_prefix = client_prefix
    self.forced_image = forced_image
    self.src_image = src_image
    self.vm = vm
    self.board = board
    self.crosutils = os.path.join(os.path.dirname(__file__), '../../scripts')

  def _GetSecondsSinceMidnight(self):
    """Returns the seconds since midnight as a decimal value."""
    now = time.localtime()
    return now[3] * 3600 + now[4] * 60 + now[5]

  def _GetDefaultBoardID(self):
    """Returns the default board id stored in .default_board."""
    board_file = '%s/.default_board' % (self.scripts_dir)
    try:
      return open(board_file).read()
    except IOError:
      return 'x86-generic'

  def _GetLatestImageDir(self, board_id):
    """Returns the latest image dir based on shell script."""
    cmd = '%s/get_latest_image.sh --board %s' % (self.scripts_dir, board_id)
    return os.popen(cmd).read().strip()

  def _GetVersionFromDir(self, image_dir):
    """Returns the version of the image based on the name of the directory."""
    latest_version = os.path.basename(image_dir)
    return latest_version.split('-')[0]

  def _CanUpdate(self, client_version, latest_version):
    """Returns true if the latest_version is greater than the client_version.
    """
    client_tokens = client_version.replace('_', '').split('.')
    latest_tokens = latest_version.replace('_', '').split('.')
    _LogMessage('client version %s latest version %s'
                % (client_version, latest_version))
    for i in range(4):
      if int(latest_tokens[i]) == int(client_tokens[i]):
        continue
      return int(latest_tokens[i]) > int(client_tokens[i])
    return False

  def _UnpackZip(self, image_dir):
    """Unpacks an image.zip into a given directory."""
    image = os.path.join(image_dir, self._GetImageName())
    if os.path.exists(image):
      return True
    else:
      # -n, never clobber an existing file, in case we get invoked
      # simultaneously by multiple request handlers. This means that
      # we're assuming each image.zip file lives in a versioned
      # directory (a la Buildbot).
      return os.system('cd %s && unzip -n image.zip' % image_dir) == 0

  def _GetImageName(self):
    """Returns the name of the image that should be used."""
    if self.use_test_image:
      image_name = 'chromiumos_test_image.bin'
    else:
      image_name = 'chromiumos_image.bin'
    return image_name

  def _GetSize(self, update_path):
    """Returns the size of the file given."""
    return os.path.getsize(update_path)

  def _GetHash(self, update_path):
    """Returns the sha1 of the file given."""
    cmd = ('cat %s | openssl sha1 -binary | openssl base64 | tr \'\\n\' \' \';'
           % update_path)
    return os.popen(cmd).read().rstrip()

  def _IsDeltaFormatFile(self, filename):
    try:
      file_handle = open(filename, 'r')
      delta_magic = 'CrAU'
      magic = file_handle.read(len(delta_magic))
      return magic == delta_magic
    except Exception:
      return False

  # TODO(petkov): Consider optimizing getting both SHA-1 and SHA-256 so that
  # it takes advantage of reduced I/O and multiple processors. Something like:
  # % tee < FILE > /dev/null \
  #     >( openssl dgst -sha256 -binary | openssl base64 ) \
  #     >( openssl sha1 -binary | openssl base64 )
  def _GetSHA256(self, update_path):
    """Returns the sha256 of the file given."""
    cmd = ('cat %s | openssl dgst -sha256 -binary | openssl base64' %
           update_path)
    return os.popen(cmd).read().rstrip()

  def _GetMd5(self, update_path):
    """Returns the md5 checksum of the file given."""
    cmd = ("md5sum %s | awk '{print $1}'" % update_path)
    return os.popen(cmd).read().rstrip()

  def _Symlink(self, source, dest):
    """Creates a symlink at dest to source"""
    if os.path.exists(dest):
      os.remove(dest)
    os.symlink(source, dest)

  def GetUpdatePayload(self, hash, sha256, size, url, is_delta_format):
    """Returns a payload to the client corresponding to a new update.

    Args:
      hash: hash of update blob
      sha256: SHA-256 hash of update blob
      size: size of update blob
      url: where to find update blob
    Returns:
      Xml string to be passed back to client.
    """
    delta = 'false'
    if is_delta_format:
      delta = 'true'
    payload = """<?xml version="1.0" encoding="UTF-8"?>
      <gupdate xmlns="http://www.google.com/update2/response" protocol="2.0">
        <daystart elapsed_seconds="%s"/>
        <app appid="{%s}" status="ok">
          <ping status="ok"/>
          <updatecheck
            codebase="%s"
            hash="%s"
            sha256="%s"
            needsadmin="false"
            size="%s"
            IsDelta="%s"
            status="ok"/>
        </app>
      </gupdate>
    """
    return payload % (self._GetSecondsSinceMidnight(),
                      self.app_id, url, hash, sha256, size, delta)

  def GetNoUpdatePayload(self):
    """Returns a payload to the client corresponding to no update."""
    payload = """ < ?xml version = "1.0" encoding = "UTF-8"? >
      < gupdate xmlns = "http://www.google.com/update2/response" protocol = "2.0" >
        < daystart elapsed_seconds = "%s" />
        < app appid = "{%s}" status = "ok" >
          < ping status = "ok" />
          < updatecheck status = "noupdate" />
        </ app >
      </ gupdate >
    """
    return payload % (self._GetSecondsSinceMidnight(), self.app_id)

  def GenerateUpdateFile(self, src_image, image_path, output_dir):
    """Generates an update gz given a full path to an image.

    Args:
      image_path: Full path to image.
    Returns:
      Path to created update_payload or None on error.
    """
    update_path = os.path.join(output_dir, 'update.gz')
    patch_kernel_flag = '--patch_kernel'
    _LogMessage('Generating update image %s' % update_path)

    # Don't patch the kernel for vm images as they don't need the patch.
    if self.vm:
      patch_kernel_flag = ''

    mkupdate_command = (
        '%s/cros_generate_update_payload --image="%s" --output="%s" '
        '%s --noold_style --src_image="%s"' % (
            self.scripts_dir, image_path, update_path, patch_kernel_flag,
            src_image))
    _LogMessage(mkupdate_command)
    if os.system(mkupdate_command) != 0:
      _LogMessage('Failed to create base update file')
      return None

    return update_path

  def GenerateStatefulFile(self, image_path, output_dir):
    """Generates a stateful update payload given a full path to an image.

    Args:
      image_path: Full path to image.
    Returns:
      Path to created stateful update_payload or None on error.
    Raises:
      A subprocess exception if the update generator fails to generate a
      stateful payload.
    """
    output_gz = os.path.join(output_dir, 'stateful.tgz')
    subprocess.check_call(
        ['%s/cros_generate_stateful_update_payload' % self.crosutils,
         '--image=%s' % image_path,
         '--output_dir=%s' % output_dir,
        ])
    return output_gz

  def FindCachedUpdateImageSubDir(self, src_image, dest_image):
    """Find directory to store a cached update.

       Given one, or two images for an update, this finds which
       cache directory should hold the update files, even if they don't exist
       yet. The directory will be inside static_image_dir, and of the form:

       Non-delta updates:
         cache/12345678

       Delta updates:
         cache/12345678_12345678
       """
    # If there is no src, we only have an image file, check image for changes
    if not src_image:
      return os.path.join('cache', self._GetMd5(dest_image))

    # If we have src and dest, we are a delta, and check both for changes
    return os.path.join('cache',
                        "%s_%s" % (self._GetMd5(src_image),
                                   self._GetMd5(dest_image)))

  def GenerateUpdateImage(self, src_image, image_path, output_dir):
    """Force generates an update payload based on the given image_path.

    Args:
      src_image: image we are updating from (Null/empty for non-delta)
      image_path: full path to the image.
      output_dir: the directory to write the update payloads in
    Returns:
      update and stateful payload tuple with full file names
    """
    update_file = None
    stateful_update_file = None

    # Actually do the generation
    _LogMessage('Generating update for image %s' % image_path)
    update_file = self.GenerateUpdateFile(src_image,
                                          image_path,
                                          output_dir)

    if update_file:
      stateful_update_file = self.GenerateStatefulFile(image_path,
                                                       output_dir)

    if update_file and stateful_update_file:
      return update_file, stateful_update_file

    _LogMessage('Failed to generate update')

    # Cleanup incomplete files, if they exist
    if update_file and os.path.exists(update_file):
      os.remove(update_file)

    return None

  def GenerateUpdateImageWithCache(self, image_path, static_image_dir):
    """Force generates an update payload based on the given image_path.

    Args:
      image_path: full path to the image.
      static_image_dir: the directory to move images to after generating.
    Returns:
      update filename (not directory) relative to static_image_dir on success,
        or None
    """
    _LogMessage('Generating update for src %s image %s' % (self.src_image,
                                                           image_path))

    # Which sub_dir of static_image_dir should hold our cached update image
    cache_sub_dir = self.FindCachedUpdateImageSubDir(self.src_image, image_path)
    _LogMessage('Caching in sub_dir "%s"' % cache_sub_dir)

    # The cached payloads exist in a cache dir
    cache_update_payload = os.path.join(static_image_dir,
                                        cache_sub_dir,
                                        'update.gz')
    cache_stateful_payload = os.path.join(static_image_dir,
                                          cache_sub_dir,
                                          'stateful.tgz')

    # The final results (symlinks?) exist directly in static
    update_payload = os.path.join(static_image_dir,
                                  'update.gz')
    stateful_payload = os.path.join(static_image_dir,
                                    'stateful.tgz')

    # If there isn't a cached payload, make one
    if not os.path.exists(cache_update_payload):
      full_cache_dir = os.path.join(static_image_dir, cache_sub_dir)

      # Create the directory for the cache values
      if not os.path.exists(full_cache_dir):
        os.makedirs(full_cache_dir)

      payloads = self.GenerateUpdateImage(self.src_image,
                                          image_path,
                                          full_cache_dir)

      if not payloads:
        # Clean up cache dir if it's not valid
        os.system("rm -rf %s" % os.path.join(static_image_dir, cache_sub_dir))
        return None

      # Verify they were created with the expected names
      new_update_payload, new_stateful_payload = payloads

      _LogMessage('"%s" "%s"' % (new_update_payload, cache_update_payload))
      assert new_update_payload == cache_update_payload
      _LogMessage('"%s" "%s"' % (new_stateful_payload, cache_stateful_payload))
      assert new_stateful_payload == cache_stateful_payload

    # If the generation worked, create symlinks
    self._Symlink(cache_update_payload, update_payload)
    self._Symlink(cache_stateful_payload, stateful_payload)

    # return just the filename which is symlink in static_image_dir
    return 'update.gz'

  def GenerateLatestUpdateImage(self, board_id, client_version,
                                static_image_dir):
    """Generates an update using the latest image that has been built.

    This will only generate an update if the newest update is newer than that
    on the client or client_version is 'ForcedUpdate'.

    Args:
      board_id: Name of the board.
      client_version: Current version of the client or 'ForcedUpdate'
      static_image_dir: the directory to move images to after generating.
    Returns:
      Name of the update image relative to static_image_dir or None
    """
    latest_image_dir = self._GetLatestImageDir(board_id)
    latest_version = self._GetVersionFromDir(latest_image_dir)
    latest_image_path = os.path.join(latest_image_dir, self._GetImageName())

    _LogMessage('Preparing to generate update from latest built image %s.' %
              latest_image_path)

     # Check to see whether or not we should update.
    if client_version != 'ForcedUpdate' and not self._CanUpdate(
        client_version, latest_version):
      _LogMessage('no update')
      return None

    return self.GenerateUpdateImageWithCache(latest_image_path,
                                             static_image_dir=static_image_dir)

  def GenerateImageFromZip(self, static_image_dir):
    """Generates an update from an image zip file.

    This method assumes you have an image.zip in directory you are serving
    from.  If this file is newer than a previously cached file, it will unzip
    this file, create a payload and serve it.

    Args:
      static_image_dir: Directory where the zip file exists.
    Returns:
      Name of the update payload relative to static_image_dir if successful.
    """
    _LogMessage('Preparing to generate update from zip in %s.' %
                static_image_dir)
    image_path = os.path.join(static_image_dir, self._GetImageName())
    zip_file_path = os.path.join(static_image_dir, 'image.zip')

    # TODO(dgarrett): Either work caching into this path before
    #       we unpack, or remove zip support (sosa is considering).
    #       It does currently cache, but after the unpack.

    if not self._UnpackZip(static_image_dir):
      _LogMessage('unzip image.zip failed.')
      return None

    return self.GenerateUpdateImageWithCache(image_path,
                                             static_image_dir=static_image_dir)

  def ImportFactoryConfigFile(self, filename, validate_checksums=False):
    """Imports a factory-floor server configuration file. The file should
    be in this format:
      config = [
        {
          'qual_ids': set([1, 2, 3, "x86-generic"]),
          'factory_image': 'generic-factory.gz',
          'factory_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'release_image': 'generic-release.gz',
          'release_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'oempartitionimg_image': 'generic-oem.gz',
          'oempartitionimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'efipartitionimg_image': 'generic-efi.gz',
          'efipartitionimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'stateimg_image': 'generic-state.gz',
          'stateimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'firmware_image': 'generic-firmware.gz',
          'firmware_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
        },
        {
          'qual_ids': set([6]),
          'factory_image': '6-factory.gz',
          'factory_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'release_image': '6-release.gz',
          'release_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'oempartitionimg_image': '6-oem.gz',
          'oempartitionimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'efipartitionimg_image': '6-efi.gz',
          'efipartitionimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'stateimg_image': '6-state.gz',
          'stateimg_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
          'firmware_image': '6-firmware.gz',
          'firmware_checksum': 'AtiI8B64agHVN+yeBAyiNMX3+HM=',
        },
      ]
    The server will look for the files by name in the static files
    directory.

    If validate_checksums is True, validates checksums and exits. If
    a checksum mismatch is found, it's printed to the screen.
    """
    f = open(filename, 'r')
    output = {}
    exec(f.read(), output)
    self.factory_config = output['config']
    success = True
    for stanza in self.factory_config:
      for key in stanza.copy().iterkeys():
        suffix = '_image'
        if key.endswith(suffix):
          kind = key[:-len(suffix)]
          stanza[kind + '_size'] = self._GetSize(os.path.join(
              self.static_dir, stanza[kind + '_image']))
          if validate_checksums:
            factory_checksum = self._GetHash(os.path.join(self.static_dir,
                                             stanza[kind + '_image']))
            if factory_checksum != stanza[kind + '_checksum']:
              print ('Error: checksum mismatch for %s. Expected "%s" but file '
                     'has checksum "%s".' % (stanza[kind + '_image'],
                                             stanza[kind + '_checksum'],
                                             factory_checksum))
              success = False

    if validate_checksums:
      if success is False:
        raise Exception('Checksum mismatch in conf file.')

      print 'Config file looks good.'

  def GetFactoryImage(self, board_id, channel):
    kind = channel.rsplit('-', 1)[0]
    for stanza in self.factory_config:
      if board_id not in stanza['qual_ids']:
        continue
      if kind + '_image' not in stanza:
        break
      return (stanza[kind + '_image'],
              stanza[kind + '_checksum'],
              stanza[kind + '_size'])
    return (None, None, None)

  def HandleFactoryRequest(self, board_id, channel):
    (filename, checksum, size) = self.GetFactoryImage(board_id, channel)
    if filename is None:
      _LogMessage('unable to find image for board %s' % board_id)
      return self.GetNoUpdatePayload()
    url = '%s/static/%s' % (self.hostname, filename)
    is_delta_format = self._IsDeltaFormatFile(filename)
    _LogMessage('returning update payload ' + url)
    # Factory install is using memento updater which is using the sha-1 hash so
    # setting sha-256 to an empty string.
    return self.GetUpdatePayload(checksum, '', size, url, is_delta_format)

  def GenerateUpdatePayloadForNonFactory(self, board_id, client_version,
                                         static_image_dir):
    """Generates an update for non-factory image.

       Returns:
         file name relative to static_image_dir on success.
    """
    if self.forced_image:
      return self.GenerateUpdateImageWithCache(
          self.forced_image,
          static_image_dir=static_image_dir)
    elif self.serve_only:
      return self.GenerateImageFromZip(static_image_dir)
    else:
      if board_id:
        return self.GenerateLatestUpdateImage(board_id,
                                              client_version,
                                              static_image_dir)

      _LogMessage('You must set --board for pre-generating latest update.')
      return None

  def PreGenerateUpdate(self):
    """Pre-generates an update.  Returns True on success.
    """
     # Does not work with factory config.
    assert(not self.factory_config)
    _LogMessage('Pre-generating the update payload.')
    # Does not work with labels so just use static dir.
    if self.GenerateUpdatePayloadForNonFactory(self.board, '0.0.0.0',
                                               self.static_dir):
      _LogMessage('Pre-generated update successfully.')
      return True
    else:
      _LogMessage('Failed to pre-generate update.')
      return False

  def HandleUpdatePing(self, data, label=None):
    """Handles an update ping from an update client.

    Args:
      data: xml blob from client.
      label: optional label for the update.
    Returns:
      Update payload message for client.
    """
    # Set hostname as the hostname that the client is calling to and set up
    # the url base.
    self.hostname = cherrypy.request.base
    if self.urlbase:
      static_urlbase = self.urlbase
    elif self.serve_only:
      static_urlbase = '%s/static/archive' % self.hostname
    else:
      static_urlbase = '%s/static' % self.hostname

    _LogMessage('Using static url base %s' % static_urlbase)
    _LogMessage('Handling update ping as %s: %s' % (self.hostname, data))

    # Check the client prefix to make sure you can support this type of update.
    update_dom = minidom.parseString(data)
    root = update_dom.firstChild
    if (root.hasAttribute('updaterversion') and
        not root.getAttribute('updaterversion').startswith(self.client_prefix)):
      _LogMessage('Got update from unsupported updater:' +
                root.getAttribute('updaterversion'))
      return self.GetNoUpdatePayload()

    # We only generate update payloads for updatecheck requests.
    update_check = root.getElementsByTagName('o:updatecheck')
    if not update_check:
      _LogMessage('Non-update check received.  Returning blank payload.')
      # TODO(sosa): Generate correct non-updatecheck payload to better test
      # update clients.
      return self.GetNoUpdatePayload()

    # Since this is an updatecheck, get information about the requester.
    query = root.getElementsByTagName('o:app')[0]
    client_version = query.getAttribute('version')
    channel = query.getAttribute('track')
    board_id = (query.hasAttribute('board') and query.getAttribute('board')
                or self._GetDefaultBoardID())

    # Separate logic as Factory requests have static url's that override
    # other options.
    if self.factory_config:
      return self.HandleFactoryRequest(board_id, channel)
    else:
      static_image_dir = self.static_dir
      if label:
        static_image_dir = os.path.join(static_image_dir, label)

      payload_path = self.GenerateUpdatePayloadForNonFactory(board_id,
                                                             client_version,
                                                             static_image_dir)
      if payload_path:
        filename = os.path.join(static_image_dir, payload_path)
        hash = self._GetHash(filename)
        sha256 = self._GetSHA256(filename)
        size = self._GetSize(filename)
        is_delta_format = self._IsDeltaFormatFile(filename)
        if label:
          url = '%s/%s/%s' % (static_urlbase, label, payload_path)
        else:
          url = '%s/%s' % (static_urlbase, payload_path)

        _LogMessage('Responding to client to use url %s to get image.' % url)
        return self.GetUpdatePayload(hash, sha256, size, url, is_delta_format)
      else:
        return self.GetNoUpdatePayload()