def _ValidateCacheEntryHeader(self, cache_entry_header):
    """Determines whether the values in the cache entry header are valid.

    Args:
      cache_entry_header (firefox_cache1_entry_header): cache entry header.

    Returns:
      bool: True if the cache entry header is valid.
    """
    return (
        cache_entry_header.request_size > 0 and
        cache_entry_header.request_size < self._MAXIMUM_URL_LENGTH and
        cache_entry_header.major_format_version == 1 and
        cache_entry_header.last_fetched_time > 0 and
        cache_entry_header.fetch_count > 0)