Dynamic Cacher

<?php

set_time_limit(3600);

global $fp, $headers;
$fp = null; $headers = array();

$url = 'http://milk-hub.net/'.($path = trim($_SERVER['REQUEST_URI'], '/'));
if ($path == '') $path = 'index';
$nfopath = dirname($path).'/._'.basename($path);

if ($path[0] == '.' || $path == 'index.php') {
	header('HTTP/1.0 403 '.statusmessage(403));
	echo '403 '. statusmessage(403);
	exit;
}
else if (is_dir($path)) {
	header('HTTP/1.0 403 '.statusmessage(403));
	echo '403 '. statusmessage(403);
	exit;
}

// Make dir for file
if (!is_dir(dirname($path))) mkdir(dirname($path), 0755, true);

// Do the fetch
$date = (file_exists($path) && file_exists($nfopath)) ? filemtime($path) : false;

if ($date < time() - 60*60*24 || $_GET['nocache']) {
	$date = $date ? date('r', $date) : false;

	if (file_exists($path))    unlink($path);
	if (file_exists($nfopath)) unlink($nfopath);

	if ($fp = fopen($path, 'wb')) {
		ignore_user_abort(true); // Even if the user stops fetching the file we need to finish caching it!

		$info = download($url, $date);
		$info['headers'] = $headers;
		file_put_contents($nfopath, serialize($info));

		fclose($fp);
		chmod($path, 0644);
	}
	else {
		header('HTTP/1.0 500 '.statusmessage(500));
		echo '500 '. statusmessage(500);
		exit;
	}
}
else {
	$info = unserialize(file_get_contents($nfopath));

	header('HTTP/1.0 '.$info['http_code'].' '.statusmessage($info['http_code']));
	if (is_array($info['headers'])) {
		foreach ($info['headers'] as $header) {
			header($header);
		}
	}
	else {
		header('Content-type: '.$info['content_type']);
		header('Content-Length: '.$info['download_content_length']);
		header('Last-Modified: '.date('r', filemtime($path)));
		header('Content-Disposition: inline; filename='.basename($path));
	}
	readfile($path);
}

$fsize = filesize($path);
if ($info['http_code'] < 200 || $info['http_code'] >= 400 || $info['download_content_length'] != $fsize || $fsize == 0) {
	if (file_exists($path))    unlink($path);
	if (file_exists($nfopath)) unlink($nfopath);
}

exit;

function download($url, $date) {
	global $fp;
	
	$ch = curl_init($url);

	$header = array(
		'Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5',
		'Cache-Control: max-age=0',
		'Connection: keep-alive',
		'Keep-Alive: 300',
		'Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.7',
		'Accept-Language: en-us,en;q=0.5',
		'Pragma: ', // browsers keep this blank.
	);
	if ($date) {
		$header[] = 'If-Modified-Since: '.$date;
	}
	
	curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
	curl_setopt($ch, CURLOPT_ENCODING,    'gzip,deflate');
	curl_setopt($ch, CURLOPT_FILE, $fp);
	curl_setopt($ch, CURLOPT_HTTPHEADER,  $header);
	curl_setopt($ch, CURLOPT_REFERER,     $_SERVER['HTTP_REFERER']);
	// curl_setopt($ch, CURLOPT_TIMEOUT,     10);
	curl_setopt($ch, CURLOPT_USERAGENT,  'CacheBot/1.0 (+http://cache.milk-hub.net)');

	curl_setopt($ch, CURLOPT_HEADERFUNCTION, 'read_header');
	curl_setopt($ch, CURLOPT_WRITEFUNCTION, 'read_body');

	curl_exec($ch);
	$info = curl_getinfo($ch);
	curl_close($ch);

	return $info;
}

function read_header($ch, $data) {
	global $headers;

	list($field, $value) = explode(':', $data, 2);

	switch ($field) {
		case 'Content-type':
		case 'Content-Disposition':
		case 'Content-Length':
		case 'Last-Modified':
			header($data);
			$headers[] = $data;
		break;
	}

	return strlen($data);
}

function read_body($ch, $data) {
	global $fp;
	
	fwrite($fp, $data);
	echo $data; flush();
	
	return strlen($data);
}

function statusmessage($statuscode) {
	switch($statuscode) {
		case 100:
			return 'Continue';
		case 101:
			return 'Switching Protocols';
		case 200:
			return 'OK';
		case 201:
			return 'Created';
		case 202:
			return 'Accepted';
		case 203:
			return 'Non-Authoritative Information';
		case 204:
			return 'No Content';
		case 205:
			return 'Reset Content';
		case 206:
			return 'Partial Content';
		case 300:
			return 'Multiple Choices';
		case 301:
			return 'Moved Permanently';
		case 302:
			return 'Found';
		case 303:
			return 'See Other';
		case 304:
			return 'Not Modified';
		case 305:
			return 'Use Proxy';
		case 306:
			return 'No Longer Used';
		case 307:
			return 'Temporary Redirect';
		case 400:
			return 'Bad Request';
		case 401:
			return 'Not Authorised';
		case 402:
			return 'Payment Required';
		case 403:
			return 'Forbidden';
		case 404:
			return 'Not Found';
		case 405:
			return 'Method Not Allowed';
		case 406:
			return 'Not Acceptable';
		case 407:
			return 'Proxy Authentication Required';
		case 408:
			return 'Request Timeout';
		case 409:
			return 'Conflict';
		case 410:
			return 'Gone';
		case 411:
			return 'Length Required';
		case 412:
			return 'Precondition Failed';
		case 413:
			return 'Request Entity Too Large';
		case 414:
			return 'Request URI Too Long';
		case 415:
			return 'Unsupported Media Type';
		case 416:
			return 'Requested Range Not Satisfiable';
		case 417:
			return 'Expectation Failed';
		case 500:
			return 'Internal Server Error';
		case 501:
			return 'Not Implemented';
		case 502:
			return 'Bad Gateway';
		case 503:
			return 'Service Unavailable';
		case 504:
			return 'Gateway Timeout';
		case 505:
			return 'HTTP Version Not Supported ';
		default:
			return 'Unknown';
	}
}

Created by Phill Sparks on 2nd October 2007. Last updated on 1st November 2008.