functions.photon.php

<?php

use Automattic\Jetpack\Status;

/**
 * Generic functions using the Photon service.
 *
 * Some are used outside of the Photon module being active, so intentionally not within the module.
 *
 * @package jetpack
 */

/**
 * Generates a Photon URL.
 *
 * @see https://developer.wordpress.com/docs/photon/
 *
 * @param string       $image_url URL to the publicly accessible image you want to manipulate.
 * @param array|string $args An array of arguments, i.e. array( 'w' => '300', 'resize' => array( 123, 456 ) ), or in string form (w=123&h=456).
 * @param string|null  $scheme URL protocol.
 * @return string The raw final URL. You should run this through esc_url() before displaying it.
 */
function jetpack_photon_url( $image_url, $args = array(), $scheme = null ) {
	$image_url = trim( $image_url );

	if ( ! defined( 'IS_WPCOM' ) || ! IS_WPCOM ) {
		/**
		 * Disables Photon URL processing for local development
		 *
		 * @module photon
		 *
		 * @since 4.1.0
		 *
		 * @param bool false Result of Automattic\Jetpack\Status->is_development_mode().
		 */
		if ( true === apply_filters( 'jetpack_photon_development_mode', ( new Status() )->is_development_mode() ) ) {
			return $image_url;
		}
	}

	/**
	 * Allow specific image URls to avoid going through Photon.
	 *
	 * @module photon
	 *
	 * @since 3.2.0
	 *
	 * @param bool false Should the image be returned as is, without going through Photon. Default to false.
	 * @param string $image_url Image URL.
	 * @param array|string $args Array of Photon arguments.
	 * @param string|null $scheme Image scheme. Default to null.
	 */
	if ( false !== apply_filters( 'jetpack_photon_skip_for_url', false, $image_url, $args, $scheme ) ) {
		return $image_url;
	}

	/**
	 * Filter the original image URL before it goes through Photon.
	 *
	 * @module photon
	 *
	 * @since 1.9.0
	 *
	 * @param string $image_url Image URL.
	 * @param array|string $args Array of Photon arguments.
	 * @param string|null $scheme Image scheme. Default to null.
	 */
	$image_url = apply_filters( 'jetpack_photon_pre_image_url', $image_url, $args, $scheme );
	/**
	 * Filter the original Photon image parameters before Photon is applied to an image.
	 *
	 * @module photon
	 *
	 * @since 1.9.0
	 *
	 * @param array|string $args Array of Photon arguments.
	 * @param string $image_url Image URL.
	 * @param string|null $scheme Image scheme. Default to null.
	 */
	$args = apply_filters( 'jetpack_photon_pre_args', $args, $image_url, $scheme );

	if ( empty( $image_url ) ) {
		return $image_url;
	}

	$image_url_parts = wp_parse_url( $image_url );

	// Unable to parse.
	if ( ! is_array( $image_url_parts ) || empty( $image_url_parts['host'] ) || empty( $image_url_parts['path'] ) ) {
		return $image_url;
	}

	if ( is_array( $args ) ) {
		// Convert values that are arrays into strings.
		foreach ( $args as $arg => $value ) {
			if ( is_array( $value ) ) {
				$args[ $arg ] = implode( ',', $value );
			}
		}

		// Encode values.
		// See https://core.trac.wordpress.org/ticket/17923 .
		$args = rawurlencode_deep( $args );
	}

	// Don't photon-ize WPCOM hosted images -- we can serve them up from wpcom directly.
	$is_wpcom_image = false;
	if ( wp_endswith( strtolower( $image_url_parts['host'] ), '.files.wordpress.com' ) ) {
		$is_wpcom_image = true;
		if ( isset( $args['ssl'] ) ) {
			// Do not send the ssl argument to prevent caching issues.
			unset( $args['ssl'] );
		}
	}

	/** This filter is documented below. */
	$custom_photon_url = apply_filters( 'jetpack_photon_domain', '', $image_url );
	$custom_photon_url = esc_url( $custom_photon_url );

	// You can't run a Photon URL through Photon again because query strings are stripped.
	// So if the image is already a Photon URL, append the new arguments to the existing URL.
	// Alternately, if it's a *.files.wordpress.com url, then keep the domain as is.
	if (
		in_array( $image_url_parts['host'], array( 'i0.wp.com', 'i1.wp.com', 'i2.wp.com' ), true )
		|| wp_parse_url( $custom_photon_url, PHP_URL_HOST ) === $image_url_parts['host']
		|| $is_wpcom_image
	) {
		/*
		 * VideoPress Poster images should only keep one param, ssl.
		 */
		if (
			is_array( $args )
			&& 'videos.files.wordpress.com' === strtolower( $image_url_parts['host'] )
		) {
			$args = array_intersect_key( array( 'ssl' => 1 ), $args );
		}

		$photon_url = add_query_arg( $args, $image_url );
		return jetpack_photon_url_scheme( $photon_url, $scheme );
	}

	/**
	 * Allow Photon to use query strings as well.
	 * By default, Photon doesn't support query strings so we ignore them and look only at the path.
	 * This setting is Photon Server dependent.
	 *
	 * @module photon
	 *
	 * @since 1.9.0
	 *
	 * @param bool false Should images using query strings go through Photon. Default is false.
	 * @param string $image_url_parts['host'] Image URL's host.
	 */
	if ( ! apply_filters( 'jetpack_photon_any_extension_for_domain', false, $image_url_parts['host'] ) ) {
		// Photon doesn't support query strings so we ignore them and look only at the path.
		// However some source images are served via PHP so check the no-query-string extension.
		// For future proofing, this is a blacklist of common issues rather than a whitelist.
		$extension = pathinfo( $image_url_parts['path'], PATHINFO_EXTENSION );
		if ( empty( $extension ) || in_array( $extension, array( 'php', 'ashx' ), true ) ) {
			return $image_url;
		}
	}

	$image_host_path = $image_url_parts['host'] . $image_url_parts['path'];

	/*
	 * Figure out which CDN subdomain to use.
	 *
	 * The goal is to have the same subdomain for any particular image to prevent multiple runs resulting in multiple
	 * images needing to be downloaded by the browser.
	 *
	 * We are providing our own generated value by taking the modulus of the crc32 value of the URL.
	 *
	 * Valid values are 0, 1, and 2.
	 */
	$subdomain = abs( crc32( $image_host_path ) % 3 );

	/**
	 * Filters the domain used by the Photon module.
	 *
	 * @module photon
	 *
	 * @since 3.4.2
	 *
	 * @param string https://i{$subdomain}.wp.com Domain used by Photon. $subdomain is a random number between 0 and 2.
	 * @param string $image_url URL of the image to be photonized.
	 */
	$photon_domain = apply_filters( 'jetpack_photon_domain', "https://i{$subdomain}.wp.com", $image_url );
	$photon_domain = trailingslashit( esc_url( $photon_domain ) );
	$photon_url    = $photon_domain . $image_host_path;

	/**
	 * Add query strings to Photon URL.
	 * By default, Photon doesn't support query strings so we ignore them.
	 * This setting is Photon Server dependent.
	 *
	 * @module photon
	 *
	 * @since 1.9.0
	 *
	 * @param bool false Should query strings be added to the image URL. Default is false.
	 * @param string $image_url_parts['host'] Image URL's host.
	 */
	if ( isset( $image_url_parts['query'] ) && apply_filters( 'jetpack_photon_add_query_string_to_domain', false, $image_url_parts['host'] ) ) {
		$photon_url .= '?q=' . rawurlencode( $image_url_parts['query'] );
	}

	if ( $args ) {
		if ( is_array( $args ) ) {
			$photon_url = add_query_arg( $args, $photon_url );
		} else {
			// You can pass a query string for complicated requests but where you still want CDN subdomain help, etc.
			$photon_url .= '?' . $args;
		}
	}

	if ( isset( $image_url_parts['scheme'] ) && 'https' === $image_url_parts['scheme'] ) {
		$photon_url = add_query_arg( array( 'ssl' => 1 ), $photon_url );
	}

	return jetpack_photon_url_scheme( $photon_url, $scheme );
}

/**
 * Add an easy way to photon-ize a URL that is safe to call even if Jetpack isn't active.
 *
 * See: https://jetpack.com/2013/07/11/photon-and-themes/
 */
add_filter( 'jetpack_photon_url', 'jetpack_photon_url', 10, 3 );

/**
 * WordPress.com
 *
 * If a cropped WP.com-hosted image is the source image, have Photon replicate the crop.
 */
add_filter( 'jetpack_photon_pre_args', 'jetpack_photon_parse_wpcom_query_args', 10, 2 );

/**
 * Parses WP.com-hosted image args to replicate the crop.
 *
 * @param mixed  $args Args set during Photon's processing.
 * @param string $image_url URL of the image.
 * @return array|string Args for Photon to use for the URL.
 */
function jetpack_photon_parse_wpcom_query_args( $args, $image_url ) {
	$parsed_url = wp_parse_url( $image_url );

	if ( ! $parsed_url ) {
		return $args;
	}

	$image_url_parts = wp_parse_args(
		$parsed_url,
		array(
			'host'  => '',
			'query' => '',
		)
	);

	if ( '.files.wordpress.com' !== substr( $image_url_parts['host'], -20 ) ) {
		return $args;
	}

	if ( empty( $image_url_parts['query'] ) ) {
		return $args;
	}

	$wpcom_args = wp_parse_args( $image_url_parts['query'] );

	if ( empty( $wpcom_args['w'] ) || empty( $wpcom_args['h'] ) ) {
		return $args;
	}

	// Keep the crop by using "resize".
	if ( ! empty( $wpcom_args['crop'] ) ) {
		if ( is_array( $args ) ) {
			$args = array_merge( array( 'resize' => array( $wpcom_args['w'], $wpcom_args['h'] ) ), $args );
		} else {
			$args = 'resize=' . rawurlencode( absint( $wpcom_args['w'] ) . ',' . absint( $wpcom_args['h'] ) ) . '&' . $args;
		}
	} else {
		if ( is_array( $args ) ) {
			$args = array_merge( array( 'fit' => array( $wpcom_args['w'], $wpcom_args['h'] ) ), $args );
		} else {
			$args = 'fit=' . rawurlencode( absint( $wpcom_args['w'] ) . ',' . absint( $wpcom_args['h'] ) ) . '&' . $args;
		}
	}

	return $args;
}

/**
 * Sets the scheme for a URL
 *
 * @param string $url URL to set scheme.
 * @param string $scheme Scheme to use. Accepts http, https, network_path.
 *
 * @return string URL.
 */
function jetpack_photon_url_scheme( $url, $scheme ) {
	if ( ! in_array( $scheme, array( 'http', 'https', 'network_path' ), true ) ) {
		if ( preg_match( '#^(https?:)?//#', $url ) ) {
			return $url;
		}

		$scheme = 'http';
	}

	if ( 'network_path' === $scheme ) {
		$scheme_slashes = '//';
	} else {
		$scheme_slashes = "$scheme://";
	}

	return preg_replace( '#^([a-z:]+)?//#i', $scheme_slashes, $url );
}

/**
 * A wrapper for PHP's parse_url, prepending assumed scheme for network path
 * URLs. PHP versions 5.4.6 and earlier do not correctly parse without scheme.
 *
 * WP ships with a wrapper for parse_url, wp_parse_url, that should be used instead.
 *
 * @see https://php.net/manual/en/function.parse-url.php#refsect1-function.parse-url-changelog
 * @deprecated 7.8.0 Use wp_parse_url instead.
 *
 * @param string  $url The URL to parse.
 * @param integer $component Retrieve specific URL component.
 * @return mixed Result of parse_url
 */
function jetpack_photon_parse_url( $url, $component = -1 ) {
	_deprecated_function( 'jetpack_photon_parse_url', 'jetpack-7.8.0', 'wp_parse_url' );
	return wp_parse_url( $url, $component );
}

add_filter( 'jetpack_photon_skip_for_url', 'jetpack_photon_banned_domains', 9, 2 );

/**
 * Check to skip Photon for a known domain that shouldn't be Photonized.
 *
 * @param bool   $skip If the image should be skipped by Photon.
 * @param string $image_url URL of the image.
 *
 * @return bool Should the image be skipped by Photon.
 */
function jetpack_photon_banned_domains( $skip, $image_url ) {
	$banned_host_patterns = array(
		'/^chart\.googleapis\.com$/',
		'/^chart\.apis\.google\.com$/',
		'/^graph\.facebook\.com$/',
		'/\.fbcdn\.net$/',
		'/\.paypalobjects\.com$/',
		'/\.dropbox\.com$/',
		'/\.cdninstagram\.com$/',
	);

	$host = wp_parse_url( $image_url, PHP_URL_HOST );

	foreach ( $banned_host_patterns as $banned_host_pattern ) {
		if ( 1 === preg_match( $banned_host_pattern, $host ) ) {
			return true;
		}
	}

	return $skip;
}


/**
 * Jetpack Photon - Support Text Widgets.
 *
 * @access public
 * @param string $content Content from text widget.
 * @return string
 */
function jetpack_photon_support_text_widgets( $content ) {
	if ( class_exists( 'Jetpack_Photon' ) && Jetpack::is_module_active( 'photon' ) ) {
		return Jetpack_Photon::filter_the_content( $content );
	}
	return $content;
}
add_filter( 'widget_text', 'jetpack_photon_support_text_widgets' );