glance.py 文件源码

def _download_tarball_and_verify(request, staging_path):
    # NOTE(johngarbutt) By default, there is no timeout.
    # To ensure the script does not hang if we lose connection
    # to glance, we add this socket timeout.
    # This is here so there is no chance the timeout out has
    # been adjusted by other library calls.
    socket.setdefaulttimeout(SOCKET_TIMEOUT_SECONDS)

    try:
        response = urllib2.urlopen(request)
    except urllib2.HTTPError, error:  # noqa
        raise RetryableError(error)
    except urllib2.URLError, error:  # noqa
        raise RetryableError(error)
    except httplib.HTTPException, error:  # noqa
        # httplib.HTTPException and derivatives (BadStatusLine in particular)
        # don't have a useful __repr__ or __str__
        raise RetryableError('%s: %s' % (error.__class__.__name__, error))

    url = request.get_full_url()
    logging.info("Reading image data from %s" % url)

    callback_data = {'bytes_read': 0}
    checksum = md5.new()

    def update_md5(chunk):
        callback_data['bytes_read'] += len(chunk)
        checksum.update(chunk)

    try:
        try:
            utils.extract_tarball(response, staging_path, callback=update_md5)
        except Exception, error:  # noqa
            raise RetryableError(error)
    finally:
        bytes_read = callback_data['bytes_read']
        logging.info("Read %d bytes from %s", bytes_read, url)

    # Use ETag if available, otherwise content-md5(v2) or
    # X-Image-Meta-Checksum(v1)
    etag = response.info().getheader('etag', None)
    if etag is None:
        etag = response.info().getheader('content-md5', None)
    if etag is None:
        etag = response.info().getheader('x-image-meta-checksum', None)

    # Verify checksum using ETag
    checksum = checksum.hexdigest()

    if etag is None:
        msg = "No ETag found for comparison to checksum %(checksum)s"
        logging.info(msg % {'checksum': checksum})
    elif checksum != etag:
        msg = 'ETag %(etag)s does not match computed md5sum %(checksum)s'
        raise RetryableError(msg % {'checksum': checksum, 'etag': etag})
    else:
        msg = "Verified image checksum %(checksum)s"
        logging.info(msg % {'checksum': checksum})