wp_validate_redirect( string $location, string $default = '' )

Validates a URL for use in a redirect.


Description Description

Checks whether the $location is using an allowed host, if it has an absolute path. A plugin can therefore set or remove allowed host(s) to or from the list.

If the host is not allowed, then the redirect is to $default supplied


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Parameters Parameters

$location

(string) (Required) The redirect to validate

$default

(string) (Optional) The value to return if $location is not allowed

Default value: ''


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Return Return

(string) redirect-sanitized URL


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Source Source

File: wp-includes/pluggable.php

	function wp_validate_redirect( $location, $default = '' ) {
		$location = trim( $location, " \t\n\r\0\x08\x0B" );
		// Browsers will assume 'http' is your protocol, and will obey a redirect to a URL starting with '//'.
		if ( substr( $location, 0, 2 ) == '//' ) {
			$location = 'http:' . $location;
		}

		// In PHP 5 parse_url() may fail if the URL query part contains 'http://'.
		// See https://bugs.php.net/bug.php?id=38143
		$cut  = strpos( $location, '?' );
		$test = $cut ? substr( $location, 0, $cut ) : $location;

		// @-operator is used to prevent possible warnings in PHP < 5.3.3.
		$lp = @parse_url( $test );

		// Give up if malformed URL.
		if ( false === $lp ) {
			return $default;
		}

		// Allow only 'http' and 'https' schemes. No 'data:', etc.
		if ( isset( $lp['scheme'] ) && ! ( 'http' == $lp['scheme'] || 'https' == $lp['scheme'] ) ) {
			return $default;
		}

		if ( ! isset( $lp['host'] ) && ! empty( $lp['path'] ) && '/' !== $lp['path'][0] ) {
			$path = '';
			if ( ! empty( $_SERVER['REQUEST_URI'] ) ) {
				$path = dirname( parse_url( 'http://placeholder' . $_SERVER['REQUEST_URI'], PHP_URL_PATH ) . '?' );
				$path = wp_normalize_path( $path );
			}
			$location = '/' . ltrim( $path . '/', '/' ) . $location;
		}

		// Reject if certain components are set but host is not.
		// This catches URLs like https:host.com for which parse_url() does not set the host field.
		if ( ! isset( $lp['host'] ) && ( isset( $lp['scheme'] ) || isset( $lp['user'] ) || isset( $lp['pass'] ) || isset( $lp['port'] ) ) ) {
			return $default;
		}

		// Reject malformed components parse_url() can return on odd inputs.
		foreach ( array( 'user', 'pass', 'host' ) as $component ) {
			if ( isset( $lp[ $component ] ) && strpbrk( $lp[ $component ], ':/?#@' ) ) {
				return $default;
			}
		}

		$wpp = parse_url( home_url() );

		/**
		 * Filters the whitelist of hosts to redirect to.
		 *
		 * @since 2.3.0
		 *
		 * @param string[] $hosts An array of allowed host names.
		 * @param string   $host  The host name of the redirect destination; empty string if not set.
		 */
		$allowed_hosts = (array) apply_filters( 'allowed_redirect_hosts', array( $wpp['host'] ), isset( $lp['host'] ) ? $lp['host'] : '' );

		if ( isset( $lp['host'] ) && ( ! in_array( $lp['host'], $allowed_hosts ) && strtolower( $wpp['host'] ) !== $lp['host'] ) ) {
			$location = $default;
		}

		return $location;
	}


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Changelog Changelog

Changelog
Version Description
2.8.1 Introduced.

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