class-keycdn.php

<?php
/**
 * A catch-all helper function for flushing URLs from the KeyCDN cache. Determines if the items are URLs, cache tags, or the keyword 'all' to flush the entire cache.
 * @param  array  $items List of items to group by URL or cache tags or the keyword 'all'
 */
function keycdn_flush( $items = array() ) {
	// This function plays traffic cop for different types of flush requests.
	if( is_string( $items ) ) {
		$items = array( $items );
	}

	if( !$items ) {
		return;
	}
	$items = array_map( 'trim', $items );
	$tags = array();
	$urls = array();
	$flush_whole_cache = false;
	foreach( $items as $item ) {
		$lowercase_item = strtolower( $item );
		if( substr( $lowercase_item, 0, 4 ) == 'http' || $lowercase_item[0] == '/' ) {
			$urls[] = $item;
		} else if( $lowercase_item == 'all' ) {
			$flush_whole_cache = true;
		} else {
			$tags[] = $item;
		}
	}

	if( $flush_whole_cache ) {
		keycdn_flush_all();
		return;
	}

	if( !empty( $tags ) ) {
		keycdn_flush_tags( $tags );
	}

	if( !empty( $urls ) ) {
		keycdn_flush_urls( $urls );
	}
}
add_action( 'cdn_integration_flush_urls', 'keycdn_flush' );

/**
 * Flushes the entire KeyCDN cache (zone purge)
 */
function keycdn_flush_all() {
	$options = get_cdn_integration_options();
	$api_secret = $options['keycdn-api-secret'];
	$zone_id = $options['keycdn-zone-id'];
	$zone_url = $options['keycdn-zone-url'];

	if( !$api_secret || !$zone_id || !$zone_url ) {
		throw new Exception( 'Invalid KeyCDN settings!' );
		return;
	}

	$request_url = 'https://api.keycdn.com/zones/purge/' . $zone_id . '.json';
	$args = array(
		'method' => 'GET',
		'headers' => array(
			'Authorization' => 'Basic ' . base64_encode( $api_secret . ':' ),
		),
		'body' => '',
		'timeout' => 30,
	);
	$response = wp_remote_post( $request_url, $args );

	if( is_wp_error( $response ) ) {
		error_log( 'KeyCDN Flush ALL Error: ' . $response->get_error_message() );
	}

	$output = array(
		'url' => $request_url,
		'args' => $args,
		'response' => $response,
	);

	return $output;
}

/**
 * Flushes all URLs from the KeyCDN cache where the "Cache Tag" header contains one or more of the given $tags
 * @param  array  $tags Cache tags that should be flushed
 */
function keycdn_flush_tags( $tags = array() ) {
	if( !$tags ) {
		throw new Exception( '$tags argument passed to keycdn_flush_tags() is FALSE!' );
		return;
	}

	if( is_string( $tags ) ) {
		$tags = array( $tags );
	}

	$options = get_cdn_integration_options();
	$api_secret = $options['keycdn-api-secret'];
	$zone_id = $options['keycdn-zone-id'];
	$zone_url = $options['keycdn-zone-url'];

	if( !$api_secret || !$zone_id || !$zone_url ) {
		throw new Exception( 'Invalid KeyCDN settings!' );
		return;
	}

	$payload= json_encode( array( 'tags' => $tags, ) );

	$request_url = 'https://api.keycdn.com/zones/purgetag/' . $zone_id . '.json';
	$args = array(
		'method' => 'DELETE',
		'headers' => array(
			'Authorization' => 'Basic ' . base64_encode( $api_secret . ':' ),
			'Accept' => 'application/json',
			'Content-Type' => 'application/json',
		),
		'body' => $payload,
	);

	$response = wp_remote_post( $request_url, $args );

	if( is_wp_error( $response ) ) {
		error_log( 'KeyCDN Cache Tag Flush Error: ' . $response->get_error_message() );
	}

	$output = array(
		'url' => $request_url,
		'args' => $args,
		'response' => $response,
	);

	return $output;
}

/**
 * Flushes a list of URLs from the KeyCDN cache
 * @param  array  $urls List of URLs to be flushed
 */
function keycdn_flush_urls( $urls = array() ) {
	if( !$urls ) {
		return;
	}

	$options = get_cdn_integration_options();
	$api_secret = $options['keycdn-api-secret'];
	$zone_id = $options['keycdn-zone-id'];
	$zone_url = $options['keycdn-zone-url'];

	$public_protocol = $options['public-protocol'];
	$public_domain = $options['public-domain'];

	if( !$api_secret || !$zone_id || !$zone_url ) {
		throw new Exception( 'Invalid KeyCDN settings!' );
		return;
	}

	$public_url = $public_protocol . '://' . $public_domain;
	if( !$public_domain ) {
		$public_url = get_site_url();
	}

	foreach( $urls as $i => $url ) {
		$urls[ $i ] = str_replace( $public_url, $zone_url, $url );
	}
	$payload = json_encode( array( 'urls' => $urls, ) );

	$request_url = 'https://api.keycdn.com/zones/purgeurl/' . $zone_id . '.json';
	$args = array(
		'method' => 'DELETE',
		'headers' => array(
			'Authorization' => 'Basic ' . base64_encode( $api_secret . ':' ),
			'Accept' => 'application/json',
			'Content-Type' => 'application/json',
		),
		'body' => $payload,
	);
	$response = wp_remote_post( $request_url, $args );

	if( is_wp_error( $response ) ) {
		error_log( 'KeyCDN URL Flush Error: ' . $response->get_error_message() );
	}

	$output = array(
		'url' => $request_url,
		'args' => $args,
		'response' => $response,
	);

	return $output;
}

/**
 * Helper conditional to determne if the request is coming from a KeyCDN edge server
 * See https://www.keycdn.com/support/frequently-asked-questions/#request-header-edge-server
 */
function is_keycdn_request() {
	return ( isset( $_SERVER['HTTP_X_PULL'] ) && $_SERVER['HTTP_X_PULL'] == 'KeyCDN' );
}
/**
 * If the request is from KeyCDN then use output buffering so the page response can be cached
 * @return bool Whether the request is from KeyCDN
 */
function keycdn_output_buffering() {
	return is_keycdn_request();
}
add_filter( 'continue_cdn_integration_buffering', 'keycdn_output_buffering' );

/**
 * Adds the "Cache Tag" header to the request based on what kind of page is being served. This enables the flushing of specific subsets of pages in one go.
 */
function add_keycdn_cache_tags() {
	if( is_admin() ) {
		return;
	}

	$cache_tags = array( 'html' );
	if( is_home() ) {
		$cache_tags[] = 'home';
	}
	if( is_archive() ) {
		$cache_tags[] = 'archive';
	}
	if( is_singular() ) {
		$post = get_post();
		$cache_tags[] = 'singlular';
		$cache_tags[] = 'single-' . $post->post_type;
	}
	$cache_tags = apply_filters( 'keycdn_cache_tags', $cache_tags );

	if( !headers_sent() ) {
		header( 'Cache-Tag: ' . implode( ' ', $cache_tags ) );
	}
}
add_action( 'wp', 'add_keycdn_cache_tags' );

/**
 * Modify the HTTP headers WordPress sends for a page request.
 * Allows us to specify caching headers for KeyCDN.
 * @param  array $headers The headers we will modify
 * @return array          The modified headers
 */
function keycdn_filter_wp_headers( $headers = array() ) {
	$old_cache_control_values = array();
	$new_max_age_value = apply_filters( 'keycdn_max_age', 10 );
	$new_max_age_value = intval( $new_max_age_value );
	$new_s_max_age_value = apply_filters( 'keycdn_s_max_age', DAY_IN_SECONDS );
	$new_s_max_age_value = intval( $new_s_max_age_value );

	// Provide an opportunity to prevent adding Cache-Control headers
	if( $new_max_age_value == -1 || $new_s_max_age_value == -1 ) {
		return $headers;
	}

	if( isset( $headers['Cache-Control'] ) ) {
		$old_cache_control = $headers['Cache-Control'];
		$old_cache_control_values = explode( ',', $old_cache_control );
		$old_cache_control_values = array_map( 'trim', $old_cache_control_values );

		// If the response is supposed to not be cached then bail
		if(
			in_array( 'no-cache', $old_cache_control_values ) ||
			in_array( 'max-age=0', $old_cache_control_values )
		) {
			return $headers;
		}

		foreach( $old_cache_control_values as $index => $val ) {
			if(
				stristr( $val, 'max-age' ) ||
				stristr( $val, 's-maxage' ) ||
				stristr( $val, 'public' )
			) {
				unset( $old_cache_control_values[ $index ] );
			}
		}
	}

	$old_cache_control_values[] = 'max-age=' . intval( $new_max_age_value );
	$old_cache_control_values[] = 's-maxage=' . intval( $new_s_max_age_value );
	$old_cache_control_values[] = 'public';
	$headers['Cache-Control'] = implode( ', ', $old_cache_control_values );

	return $headers;
}
add_filter( 'wp_headers', 'keycdn_filter_wp_headers' );

/**
 * Compare paths of the request and determine if we need to redirect
 * @param  string $redirect_url Proposed URL to redirect to
 * @param  string $request_url  The Requested URL
 * @return string/bool           The URL to redirect to or false if no redirect should occur
 */
function keycdn_maybe_do_canonical_redirect( $redirect_url = '', $request_url = '' ) {
	if( !is_keycdn_request() ) {
		return $redirect_url;
	}
	$parts = parse_url( $redirect_url );
	$redirect_path = '';
	if ( isset( $parts['path'] ) && ! empty( $parts['path'] ) ) {
		$redirect_path .= $parts['path'];
	}
	if ( isset( $parts['query'] ) && ! empty( $parts['query'] ) ) {
		$redirect_path .= '?' . $parts['query'];
	}

	$parts = parse_url( $request_url );
	$request_path = '';
	if ( isset( $parts['path'] ) && ! empty( $parts['path'] ) ) {
		$request_path .= $parts['path'];
	}
	if ( isset( $parts['query'] ) && ! empty( $parts['query'] ) ) {
		$request_path .= '?' . $parts['query'];
	}

	if ( $redirect_path == $request_path ) {
		return false;
	}

	return $redirect_url;
}
add_filter( 'redirect_canonical', 'keycdn_maybe_do_canonical_redirect', 10, 2 );