* prevents penalty for duplicate content by redirecting all incoming links to

function redirect_canonical( $requested_url = null, $do_redirect = true ) {

	if ( is_trackback() || is_search() || is_comments_popup() || is_admin() || !empty($_POST) || is_preview() || is_robots() || $is_IIS )

		$requested_url  = is_ssl() ? 'https://' : 'http://';

	if ( !isset($redirect['path']) )

		$redirect['path'] = '';

	if ( !isset($redirect['query']) )

		$redirect['query'] = '';

	if ( is_feed() && ( $id = get_query_var( 'p' ) ) ) {

		if ( $redirect_url = get_post_comments_feed_link( $id, get_query_var( 'feed' ) ) ) {

			$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type', 'feed'), $redirect_url );

			$redirect['path'] = parse_url( $redirect_url, PHP_URL_PATH );

		}

	}

				$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

		// Redirect ?page_id, ?p=, ?attachment_id= to their respective url's

		$id = max( get_query_var('p'), get_query_var('page_id'), get_query_var('attachment_id') );

		if ( $id && $redirect_post = get_post($id) ) {

			$post_type_obj = get_post_type_object($redirect_post->post_type);

			if ( $post_type_obj->public ) {

				$redirect_url = get_permalink($redirect_post);

				$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

			}

		}

		if ( ! $redirect_url ) {

			if ( $redirect_url = redirect_guess_404_permalink() ) {

				$redirect['query'] = _remove_qs_args_if_not_in_url( $redirect['query'], array( 'page', 'feed', 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ), $redirect_url );

			}

		}

				$redirect['query'] = remove_query_arg(array('p', 'post_type'), $redirect['query']);

		} elseif ( is_page() && !is_feed() && isset($wp_query->queried_object) && 'page' == get_option('show_on_front') && $wp_query->queried_object->ID == get_option('page_on_front')  && ! $redirect_url ) {

			$redirect_url = home_url('/');

		} elseif ( is_home() && !empty($_GET['page_id']) && 'page' == get_option('show_on_front') && get_query_var('page_id') == get_option('page_for_posts')  && ! $redirect_url ) {

			if ( $redirect_url = get_permalink(get_option('page_for_posts')) )

				$redirect['query'] = remove_query_arg('page_id', $redirect['query']);

			if ( ( false !== $author ) && $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_author = %d AND $wpdb->posts.post_status = 'publish' LIMIT 1", $author->ID ) ) ) {

				if ( $redirect_url = get_author_posts_url($author->ID, $author->user_nicename) )

					$redirect['query'] = remove_query_arg('author', $redirect['query']);

			}

		} elseif ( is_category() || is_tag() || is_tax() ) { // Terms (Tags/categories)

			$term_count = 0;

			foreach ( $wp_query->tax_query->queries as $tax_query )

				$term_count += count( $tax_query['terms'] );

			$obj = $wp_query->get_queried_object();

			if ( $term_count <= 1 && !empty($obj->term_id) && ( $tax_url = get_term_link((int)$obj->term_id, $obj->taxonomy) ) && !is_wp_error($tax_url) ) {

				if ( !empty($redirect['query']) ) {

					// Strip taxonomy query vars off the url.

					$qv_remove = array( 'term', 'taxonomy');

					if ( is_category() ) {

						$qv_remove[] = 'category_name';

						$qv_remove[] = 'cat';

					} elseif ( is_tag() ) {

						$qv_remove[] = 'tag';

						$qv_remove[] = 'tag_id';

					} else { // Custom taxonomies will have a custom query var, remove those too:

						$tax_obj = get_taxonomy( $obj->taxonomy );

						if ( false !== $tax_obj->query_var )

							$qv_remove[] = $tax_obj->query_var;

					}

					$rewrite_vars = array_diff( array_keys($wp_query->query), array_keys($_GET) );

					if ( !array_diff($rewrite_vars, array_keys($_GET))  ) { // Check to see if all the Query vars are coming from the rewrite, none are set via $_GET

						$redirect['query'] = remove_query_arg($qv_remove, $redirect['query']); //Remove all of the per-tax qv's

						// Create the destination url for this taxonomy

						$tax_url = parse_url($tax_url);

						if ( ! empty($tax_url['query']) ) { // Taxonomy accessible via ?taxonomy=..&term=.. or any custom qv..

							parse_str($tax_url['query'], $query_vars);

							$redirect['query'] = add_query_arg($query_vars, $redirect['query']);

						} else { // Taxonomy is accessible via a "pretty-URL"

							$redirect['path'] = $tax_url['path'];

						}

					} else { // Some query vars are set via $_GET. Unset those from $_GET that exist via the rewrite

						foreach ( $qv_remove as $_qv ) {

							if ( isset($rewrite_vars[$_qv]) )

								$redirect['query'] = remove_query_arg($_qv, $redirect['query']);

						}

					}

				}

			}

		} elseif ( is_single() && strpos($wp_rewrite->permalink_structure, '%category%') !== false && $cat = get_query_var( 'category_name' ) ) {

			$category = get_category_by_path( $cat );

			$post_terms = wp_get_object_terms($wp_query->get_queried_object_id(), 'category', array('fields' => 'tt_ids'));

			if ( (!$category || is_wp_error($category)) || ( !is_wp_error($post_terms) && !empty($post_terms) && !in_array($category->term_taxonomy_id, $post_terms) ) )

				$redirect_url = get_permalink($wp_query->get_queried_object_id());

		// Post Paging

		if ( is_singular() && ! is_front_page() && get_query_var('page') ) {

				$redirect_url = get_permalink( get_queried_object_id() );

			$redirect_url = trailingslashit( $redirect_url ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );

			$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );

		}

		// paging and feeds

		if ( get_query_var('paged') || is_feed() || get_query_var('cpage') ) {

			while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] ) || preg_match( '#/(comments/?)?(feed|rss|rdf|atom|rss2)(/+)?$#', $redirect['path'] ) || preg_match( '#/comment-page-[0-9]+(/+)?$#', $redirect['path'] ) ) {

				$redirect['path'] = preg_replace("#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path']); // strip off any existing paging

				$redirect['path'] = preg_replace('#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $redirect['path']); // strip off feed endings

				$redirect['path'] = preg_replace('#/comment-page-[0-9]+?(/+)?$#', '/', $redirect['path']); // strip off any existing comment paging

			if ( is_feed() && in_array( get_query_var('feed'), $wp_rewrite->feeds ) ) {

				if ( !is_singular() && get_query_var( 'withcomments' ) )

				if ( ( 'rss' == get_default_feed() && 'feed' == get_query_var('feed') ) || 'rss' == get_query_var('feed') )

					$addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() == 'rss2' ) ? '' : 'rss2' ), 'feed' );

				else

					$addl_path .= user_trailingslashit( 'feed/' . ( ( get_default_feed() ==  get_query_var('feed') || 'feed' == get_query_var('feed') ) ? '' : get_query_var('feed') ), 'feed' );

			} elseif ( is_feed() && 'old' == get_query_var('feed') ) {

				$old_feed_files = array(

					'wp-atom.php'         => 'atom',

					'wp-commentsrss2.php' => 'comments_rss2',

					'wp-feed.php'         => get_default_feed(),

					'wp-rdf.php'          => 'rdf',

					'wp-rss.php'          => 'rss2',

					'wp-rss2.php'         => 'rss2',

				);

				if ( isset( $old_feed_files[ basename( $redirect['path'] ) ] ) ) {

					$redirect_url = get_feed_link( $old_feed_files[ basename( $redirect['path'] ) ] );

					wp_redirect( $redirect_url, 301 );

					die();

				}

						$addl_path = ( !empty( $addl_path ) ? trailingslashit($addl_path) : '' ) . user_trailingslashit("$wp_rewrite->pagination_base/$paged", 'paged');

						$addl_path = !empty( $addl_path ) ? trailingslashit($addl_path) : '';

			$redirect['path'] = user_trailingslashit( preg_replace('|/index.php/?$|', '/', $redirect['path']) ); // strip off trailing /index.php/

			if ( !empty( $addl_path ) && $wp_rewrite->using_index_permalinks() && strpos($redirect['path'], '/index.php/') === false )

				$redirect['path'] = trailingslashit($redirect['path']) . 'index.php/';

				$redirect['path'] = trailingslashit($redirect['path']) . $addl_path;

			$redirect_url = $redirect['scheme'] . '://' . $redirect['host'] . $redirect['path'];

		}

		if ( 'wp-register.php' == basename( $redirect['path'] ) ) {

			if ( is_multisite() )

				$redirect_url = apply_filters( 'wp_signup_location', site_url( 'wp-signup.php' ) );

			else

				$redirect_url = site_url( 'wp-login.php?action=register' );

			wp_redirect( $redirect_url, 301 );

			die();

		parse_str( $redirect['query'], $_parsed_query );

		$redirect = @parse_url($redirect_url);

		if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {

			parse_str( $redirect['query'], $_parsed_redirect_query );

			if ( empty( $_parsed_redirect_query['name'] ) )

				unset( $_parsed_query['name'] );

		}

		$_parsed_query = rawurlencode_deep( $_parsed_query );

		$redirect_url = add_query_arg( $_parsed_query, $redirect_url );

	$user_home = @parse_url(home_url());

		// Redirect obsolete feeds

		$redirect['query'] = preg_replace( '#(^|&)feed=rss(&|$)#', '$1feed=rss2$3', $redirect['query'] );