if ( ! $wp_last_modified ) {
$wp_last_modified = gmdate( $date_format );
$wp_last_modified .= ' GMT';
$wp_etag = '"' . md5( $wp_last_modified ) . '"';
$headers['Last-Modified'] = $wp_last_modified;
$headers['ETag'] = $wp_etag;
// Support for conditional GET.
if ( isset( $_SERVER['HTTP_IF_NONE_MATCH'] ) ) {
$client_etag = wp_unslash( $_SERVER['HTTP_IF_NONE_MATCH'] );
if ( isset( $_SERVER['HTTP_IF_MODIFIED_SINCE'] ) ) {
$client_last_modified = trim( $_SERVER['HTTP_IF_MODIFIED_SINCE'] );
$client_last_modified = '';
// If string is empty, return 0. If not, attempt to parse into a timestamp.
$client_modified_timestamp = $client_last_modified ? strtotime( $client_last_modified ) : 0;
// Make a timestamp for our most recent modification.
$wp_modified_timestamp = strtotime( $wp_last_modified );
if ( ( $client_last_modified && $client_etag )
? ( ( $client_modified_timestamp >= $wp_modified_timestamp ) && ( $client_etag === $wp_etag ) )
: ( ( $client_modified_timestamp >= $wp_modified_timestamp ) || ( $client_etag === $wp_etag ) )
$post = isset( $wp_query->post ) ? $wp_query->post : null;
// Only set X-Pingback for single posts that allow pings.
if ( $post && pings_open( $post ) ) {
$headers['X-Pingback'] = get_bloginfo( 'pingback_url', 'display' );
// Send nocache headers for password protected posts to avoid unwanted caching.
if ( ! empty( $post->post_password ) ) {
$headers = array_merge( $headers, wp_get_nocache_headers() );
* Filters the HTTP headers before they're sent to the browser.
* @param string[] $headers Associative array of headers to be sent.
* @param WP $wp Current WordPress environment instance.
$headers = apply_filters( 'wp_headers', $headers, $this );
if ( ! empty( $status ) ) {
status_header( $status );
// If Last-Modified is set to false, it should not be sent (no-cache situation).
if ( isset( $headers['Last-Modified'] ) && false === $headers['Last-Modified'] ) {
unset( $headers['Last-Modified'] );
if ( ! headers_sent() ) {
header_remove( 'Last-Modified' );
if ( ! headers_sent() ) {
foreach ( (array) $headers as $name => $field_value ) {
header( "{$name}: {$field_value}" );
* Fires once the requested HTTP headers for caching, content type, etc. have been sent.
* @param WP $wp Current WordPress environment instance (passed by reference).
do_action_ref_array( 'send_headers', array( &$this ) );
* Sets the query string property based off of the query variable property.
* The {@see 'query_string'} filter is deprecated, but still works. Plugins should
* use the {@see 'request'} filter instead.
public function build_query_string() {
$this->query_string = '';
foreach ( (array) array_keys( $this->query_vars ) as $wpvar ) {
if ( '' !== $this->query_vars[ $wpvar ] ) {
$this->query_string .= ( strlen( $this->query_string ) < 1 ) ? '' : '&';
if ( ! is_scalar( $this->query_vars[ $wpvar ] ) ) { // Discard non-scalars.
$this->query_string .= $wpvar . '=' . rawurlencode( $this->query_vars[ $wpvar ] );
if ( has_filter( 'query_string' ) ) { // Don't bother filtering and parsing if no plugins are hooked in.
* Filters the query string before parsing.
* @deprecated 2.1.0 Use {@see 'query_vars'} or {@see 'request'} filters instead.
* @param string $query_string The query string to modify.
$this->query_string = apply_filters_deprecated(
array( $this->query_string ),
parse_str( $this->query_string, $this->query_vars );
* Set up the WordPress Globals.
* The query_vars property will be extracted to the GLOBALS. So care should
* be taken when naming global variables that might interfere with the
* @global WP_Query $wp_query WordPress Query object.
* @global string $query_string Query string for the loop.
* @global array $posts The found posts.
* @global WP_Post|null $post The current post, if available.
* @global string $request The SQL statement for the request.
* @global int $more Only set, if single page or post.
* @global int $single If single page or post. Only set, if single page or post.
* @global WP_User $authordata Only set, if author archive.
public function register_globals() {
// Extract updated query vars back into global namespace.
foreach ( (array) $wp_query->query_vars as $key => $value ) {
$GLOBALS[ $key ] = $value;
$GLOBALS['query_string'] = $this->query_string;
$GLOBALS['posts'] = & $wp_query->posts;
$GLOBALS['post'] = isset( $wp_query->post ) ? $wp_query->post : null;
$GLOBALS['request'] = $wp_query->request;
if ( $wp_query->is_single() || $wp_query->is_page() ) {
if ( $wp_query->is_author() ) {
$GLOBALS['authordata'] = get_userdata( get_queried_object_id() );
* Set up the current user.
* Set up the Loop based on the query variables.
* @global WP_Query $wp_the_query WordPress Query object.
public function query_posts() {
$this->build_query_string();
$wp_the_query->query( $this->query_vars );
* Set the Headers for 404, if nothing is found for requested URL.
* Issue a 404 if a request doesn't match any posts and doesn't match any object
* (e.g. an existing-but-empty category, tag, author) and a 404 was not already issued,
* and if the request was not a search or the homepage.
* Otherwise, issue a 200.
* This sets headers after posts have been queried. handle_404() really means "handle status".
* By inspecting the result of querying posts, seemingly successful requests can be switched to
* a 404 so that canonical redirection logic can kick in.
* @global WP_Query $wp_query WordPress Query object.
public function handle_404() {
* Filters whether to short-circuit default header status handling.
* Returning a non-false value from the filter will short-circuit the handling
* @param bool $preempt Whether to short-circuit default header status handling. Default false.
* @param WP_Query $wp_query WordPress Query object.
if ( false !== apply_filters( 'pre_handle_404', false, $wp_query ) ) {
// If we've already issued a 404, bail.
// Never 404 for the admin, robots, or favicon.
if ( is_admin() || is_robots() || is_favicon() ) {
// If posts were found, check for paged content.
} elseif ( $wp_query->posts ) {
$post = isset( $wp_query->post ) ? $wp_query->post : null;
$next = '<!--nextpage-->';
// Check for paged content that exceeds the max number of pages.
if ( $post && ! empty( $this->query_vars['page'] ) ) {
// Check if content is actually intended to be paged.
if ( str_contains( $post->post_content, $next ) ) {
$page = trim( $this->query_vars['page'], '/' );
$content_found = (int) $page <= ( substr_count( $post->post_content, $next ) + 1 );
// The posts page does not support the <!--nextpage--> pagination.
if ( $wp_query->is_posts_page && ! empty( $this->query_vars['page'] ) ) {
// We will 404 for paged queries, as no posts were found.
} elseif ( ! is_paged() ) {
$author = get_query_var( 'author' );
// Don't 404 for authors without posts as long as they matched an author on this site.
if ( is_author() && is_numeric( $author ) && $author > 0 && is_user_member_of_blog( $author )
// Don't 404 for these queries if they matched an object.
|| ( is_tag() || is_category() || is_tax() || is_post_type_archive() ) && get_queried_object()
// Don't 404 for these queries either.
|| is_home() || is_search() || is_feed()
// Guess it's time to 404.
* Sets up all of the variables required by the WordPress environment.
* The action {@see 'wp'} has one parameter that references the WP object. It
* allows for accessing the properties and methods to further manipulate the
* @param string|array $query_args Passed to parse_request().
public function main( $query_args = '' ) {
$parsed = $this->parse_request( $query_args );
$this->register_globals();
* Fires once the WordPress environment has been set up.
* @param WP $wp Current WordPress environment instance (passed by reference).
do_action_ref_array( 'wp', array( &$this ) );
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
