5 * This class is designed to take advantage of parallel HTTP requests
6 * offered by PHP's PECL HTTP extension or the curl_multi_* functions.
7 * For environments which do not have these options, it reverts to standard sequential
8 * requests (using file_get_contents())
12 * @see http://php.net/HttpRequestPool
13 * @author Keyvan Minoukadeh
14 * @copyright 2011-2012 Keyvan Minoukadeh
15 * @license http://www.gnu.org/licenses/agpl-3.0.html AGPL v3
20 const METHOD_REQUEST_POOL
= 1;
21 const METHOD_CURL_MULTI
= 2;
22 const METHOD_FILE_GET_CONTENTS
= 4;
23 //const UA_BROWSER = 'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1';
24 const UA_BROWSER
= 'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/535.2 (KHTML, like Gecko) Chrome/15.0.874.92 Safari/535.2';
25 const UA_PHP
= 'PHP/5.2';
26 const REF_GOOGLE
= 'http://www.google.co.uk/url?sa=t&source=web&cd=1';
28 protected $requests = array();
29 protected $redirectQueue = array();
30 protected $requestOptions;
31 protected $maxParallelRequests = 5;
32 protected $cache = null; //TODO
33 protected $httpContext;
34 protected $minimiseMemoryUse = false; //TODO
35 protected $debug = false;
38 public $rewriteHashbangFragment = true; // see http://code.google.com/web/ajaxcrawling/docs/specification.html
39 public $maxRedirects = 5;
40 public $userAgentMap = array();
41 public $rewriteUrls = array();
42 public $userAgentDefault;
44 //public $userAgent = 'Mozilla/5.0';
46 // Prevent certain file/mime types
47 // HTTP responses which match these content types will
48 // be returned without body.
49 public $headerOnlyTypes = array();
50 // URLs ending with one of these extensions will
51 // prompt Humble HTTP Agent to send a HEAD request first
52 // to see if returned content type matches $headerOnlyTypes.
53 public $headerOnlyClues = array('pdf','mp3','zip','exe','gif','gzip','gz','jpeg','jpg','mpg','mpeg','png','ppt','mov');
55 //TODO: set max file size
56 //TODO: normalise headers
58 function __construct($requestOptions=null, $method=null) {
59 $this->userAgentDefault
= self
::UA_BROWSER
;
60 $this->referer
= self
::REF_GOOGLE
;
61 // set the request method
62 if (in_array($method, array(1,2,4))) {
63 $this->method
= $method;
65 if (class_exists('HttpRequestPool')) {
66 $this->method
= self
::METHOD_REQUEST_POOL
;
67 } elseif (function_exists('curl_multi_init')) {
68 $this->method
= self
::METHOD_CURL_MULTI
;
70 $this->method
= self
::METHOD_FILE_GET_CONTENTS
;
73 if ($this->method
== self
::METHOD_CURL_MULTI
) {
74 require_once(dirname(__FILE__
).'/RollingCurl.php');
77 $this->cookieJar
= new CookieJar();
78 // set request options (redirect must be 0)
79 $this->requestOptions
= array(
81 'redirect' => 0 // we handle redirects manually so we can rewrite the new hashbang URLs that are creeping up over the web
82 // TODO: test onprogress?
84 if (is_array($requestOptions)) {
85 $this->requestOptions
= array_merge($this->requestOptions
, $requestOptions);
87 $this->httpContext
= array(
89 'ignore_errors' => true,
90 'timeout' => $this->requestOptions
['timeout'],
91 'max_redirects' => $this->requestOptions
['redirect'],
92 'header' => "Accept: */*\r\n"
97 protected function debug($msg) {
99 $mem = round(memory_get_usage()/1024, 2);
100 $memPeak = round(memory_get_peak_usage()/1024, 2);
102 echo ' - mem used: ',$mem," (peak: $memPeak)\n";
108 protected function getUserAgent($url, $asArray=false) {
109 $host = @parse_url($url, PHP_URL_HOST
);
110 if (strtolower(substr($host, 0, 4)) == 'www.') {
111 $host = substr($host, 4);
115 $split = explode('.', $host);
116 if (count($split) > 1) {
118 $try[] = '.'.implode('.', $split);
120 foreach ($try as $h) {
121 if (isset($this->userAgentMap
[$h])) {
122 $ua = $this->userAgentMap
[$h];
127 if (!isset($ua)) $ua = $this->userAgentDefault
;
129 return array('User-Agent' => $ua);
131 return 'User-Agent: '.$ua;
135 public function rewriteHashbangFragment($url) {
136 // return $url if there's no '#!'
137 if (strpos($url, '#!') === false) return $url;
138 // split $url and rewrite
139 // TODO: is SimplePie_IRI included?
140 $iri = new SimplePie_IRI($url);
141 $fragment = substr($iri->fragment
, 1); // strip '!'
142 $iri->fragment
= null;
143 if (isset($iri->query
)) {
144 parse_str($iri->query
, $query);
148 $query['_escaped_fragment_'] = (string)$fragment;
149 $iri->query
= str_replace('%2F', '/', http_build_query($query)); // needed for some sites
150 return $iri->get_iri();
153 public function removeFragment($url) {
154 $pos = strpos($url, '#');
155 if ($pos === false) {
158 return substr($url, 0, $pos);
162 public function rewriteUrls($url) {
163 foreach ($this->rewriteUrls
as $find => $action) {
164 if (strpos($url, $find) !== false) {
165 if (is_array($action)) {
166 return strtr($url, $action);
173 public function enableDebug($bool=true) {
174 $this->debug
= (bool)$bool;
177 public function minimiseMemoryUse($bool = true) {
178 $this->minimiseMemoryUse
= $bool;
181 public function setMaxParallelRequests($max) {
182 $this->maxParallelRequests
= $max;
185 public function validateUrl($url) {
186 $url = filter_var($url, FILTER_SANITIZE_URL
);
187 $test = filter_var($url, FILTER_VALIDATE_URL
, FILTER_FLAG_SCHEME_REQUIRED
);
188 // deal with bug http://bugs.php.net/51192 (present in PHP 5.2.13 and PHP 5.3.2)
189 if ($test === false) {
190 $test = filter_var(strtr($url, '-', '_'), FILTER_VALIDATE_URL
, FILTER_FLAG_SCHEME_REQUIRED
);
192 if ($test !== false && $test !== null && preg_match('!^https?://!', $url)) {
199 public function fetchAll(array $urls) {
200 $this->fetchAllOnce($urls, $isRedirect=false);
202 while (!empty($this->redirectQueue
) && ++
$redirects <= $this->maxRedirects
) {
203 $this->debug("Following redirects #$redirects...");
204 $this->fetchAllOnce($this->redirectQueue
, $isRedirect=true);
208 // fetch all URLs without following redirects
209 public function fetchAllOnce(array $urls, $isRedirect=false) {
210 if (!$isRedirect) $urls = array_unique($urls);
211 if (empty($urls)) return;
213 //////////////////////////////////////////////////////
214 // parallel (HttpRequestPool)
215 if ($this->method
== self
::METHOD_REQUEST_POOL
) {
216 $this->debug('Starting parallel fetch (HttpRequestPool)');
218 while (count($urls) > 0) {
219 $this->debug('Processing set of '.min($this->maxParallelRequests
, count($urls)));
220 $subset = array_splice($urls, 0, $this->maxParallelRequests
);
221 $pool = new HttpRequestPool();
222 foreach ($subset as $orig => $url) {
223 if (!$isRedirect) $orig = $url;
224 unset($this->redirectQueue
[$orig]);
225 $this->debug("...$url");
226 if (!$isRedirect && isset($this->requests[$url])) {
227 $this->debug("......in memory
");
229 } elseif ($this->isCached($url)) {
230 $this->debug("......is cached
");
231 if (!$this->minimiseMemoryUse) {
232 $this->requests[$url] = $this->getCached($url);
236 $this->debug("......adding to pool
");
237 $req_url = $this->rewriteUrls($url);
238 $req_url = ($this->rewriteHashbangFragment) ? $this->rewriteHashbangFragment($req_url) : $req_url;
239 $req_url = $this->removeFragment($req_url);
240 if (!empty($this->headerOnlyTypes) && !isset($this->requests[$orig]['wrongGuess']) && $this->possibleUnsupportedType($req_url)) {
241 $_meth = HttpRequest::METH_HEAD;
243 $_meth = HttpRequest::METH_GET;
244 unset($this->requests[$orig]['wrongGuess']);
246 $httpRequest = new HttpRequest($req_url, $_meth, $this->requestOptions);
247 // send cookies, if we have any
248 if ($cookies = $this->cookieJar->getMatchingCookies($req_url)) {
249 $this->debug("......sending cookies
: $cookies");
250 $httpRequest->addHeaders(array('Cookie' => $cookies));
252 //$httpRequest->addHeaders(array('User-Agent' => $this->userAgent));
253 $httpRequest->addHeaders($this->getUserAgent($req_url, true));
254 // add referer for picky sites
255 $httpRequest->addheaders(array('Referer' => $this->referer
));
256 $this->requests
[$orig] = array('headers'=>null, 'body'=>null, 'httpRequest'=>$httpRequest);
257 $this->requests
[$orig]['original_url'] = $orig;
258 $pool->attach($httpRequest);
261 // did we get anything into the pool?
262 if (count($pool) > 0) {
263 $this->debug('Sending request...');
266 } catch (HttpRequestPoolException
$e) {
269 $this->debug('Received responses');
270 foreach($subset as $orig => $url) {
271 if (!$isRedirect) $orig = $url;
272 $request = $this->requests
[$orig]['httpRequest'];
273 //$this->requests[$orig]['headers'] = $this->headersToString($request->getResponseHeader());
274 // getResponseHeader() doesn't return status line, so, for consistency...
275 $this->requests
[$orig]['headers'] = substr($request->getRawResponseMessage(), 0, $request->getResponseInfo('header_size'));
276 // check content type
277 // TODO: use getResponseHeader('content-type') or getResponseInfo()
278 if ($this->headerOnlyType($this->requests
[$orig]['headers'])) {
279 $this->requests
[$orig]['body'] = '';
280 $_header_only_type = true;
281 $this->debug('Header only type returned');
283 $this->requests
[$orig]['body'] = $request->getResponseBody();
284 $_header_only_type = false;
286 $this->requests
[$orig]['effective_url'] = $request->getResponseInfo('effective_url');
287 $this->requests
[$orig]['status_code'] = $status_code = $request->getResponseCode();
289 if ((in_array($status_code, array(300, 301, 302, 303, 307)) || $status_code > 307 && $status_code < 400) && $request->getResponseHeader('location')) {
290 $redirectURL = $request->getResponseHeader('location');
291 if (!preg_match('!^https?://!i', $redirectURL)) {
292 $redirectURL = SimplePie_Misc
::absolutize_url($redirectURL, $url);
294 if ($this->validateURL($redirectURL)) {
295 $this->debug('Redirect detected. Valid URL: '.$redirectURL);
297 $cookies = $request->getResponseHeader('set-cookie');
298 if ($cookies && !is_array($cookies)) $cookies = array($cookies);
299 if ($cookies) $this->cookieJar
->storeCookies($url, $cookies);
300 $this->redirectQueue
[$orig] = $redirectURL;
302 $this->debug('Redirect detected. Invalid URL: '.$redirectURL);
304 } elseif (!$_header_only_type && $request->getMethod() === HttpRequest
::METH_HEAD
) {
305 // the response content-type did not match our 'header only' types,
306 // but we'd issues a HEAD request because we assumed it would. So
307 // let's queue a proper GET request for this item...
308 $this->debug('Wrong guess at content-type, queing GET request');
309 $this->requests
[$orig]['wrongGuess'] = true;
310 $this->redirectQueue
[$orig] = $this->requests
[$orig]['effective_url'];
312 //die($url.' -multi- '.$request->getResponseInfo('effective_url'));
313 $pool->detach($request);
314 unset($this->requests
[$orig]['httpRequest'], $request);
316 if ($this->minimiseMemoryUse) {
317 if ($this->cache($url)) {
318 unset($this->requests[$url]);
325 } catch (HttpException
$e) {
331 //////////////////////////////////////////////////////////
332 // parallel (curl_multi_*)
333 elseif ($this->method
== self
::METHOD_CURL_MULTI
) {
334 $this->debug('Starting parallel fetch (curl_multi_*)');
335 while (count($urls) > 0) {
336 $this->debug('Processing set of '.min($this->maxParallelRequests
, count($urls)));
337 $subset = array_splice($urls, 0, $this->maxParallelRequests
);
338 $pool = new RollingCurl(array($this, 'handleCurlResponse'));
339 $pool->window_size
= count($subset);
341 foreach ($subset as $orig => $url) {
342 if (!$isRedirect) $orig = $url;
343 unset($this->redirectQueue
[$orig]);
344 $this->debug("...$url");
345 if (!$isRedirect && isset($this->requests[$url])) {
346 $this->debug("......in memory
");
348 } elseif ($this->isCached($url)) {
349 $this->debug("......is cached
");
350 if (!$this->minimiseMemoryUse) {
351 $this->requests[$url] = $this->getCached($url);
355 $this->debug("......adding to pool
");
356 $req_url = $this->rewriteUrls($url);
357 $req_url = ($this->rewriteHashbangFragment) ? $this->rewriteHashbangFragment($req_url) : $req_url;
358 $req_url = $this->removeFragment($req_url);
359 if (!empty($this->headerOnlyTypes) && !isset($this->requests[$orig]['wrongGuess']) && $this->possibleUnsupportedType($req_url)) {
363 unset($this->requests[$orig]['wrongGuess']);
366 //$headers[] = 'User-Agent: '.$this->userAgent;
367 $headers[] = $this->getUserAgent($req_url);
368 // add referer for picky sites
369 $headers[] = 'Referer: '.$this->referer;
370 // send cookies, if we have any
371 if ($cookies = $this->cookieJar->getMatchingCookies($req_url)) {
372 $this->debug("......sending cookies
: $cookies");
373 $headers[] = 'Cookie: '.$cookies;
375 $httpRequest = new RollingCurlRequest($req_url, $_meth, null, $headers, array(
376 CURLOPT_CONNECTTIMEOUT
=> $this->requestOptions
['timeout'],
377 CURLOPT_TIMEOUT
=> $this->requestOptions
['timeout']
379 $httpRequest->set_original_url($orig);
380 $this->requests
[$orig] = array('headers'=>null, 'body'=>null, 'httpRequest'=>$httpRequest);
381 $this->requests
[$orig]['original_url'] = $orig; // TODO: is this needed anymore?
382 $pool->add($httpRequest);
385 // did we get anything into the pool?
386 if (count($pool) > 0) {
387 $this->debug('Sending request...');
388 $pool->execute(); // this will call handleCurlResponse() and populate $this->requests[$orig]
389 $this->debug('Received responses');
390 foreach($subset as $orig => $url) {
391 if (!$isRedirect) $orig = $url;
392 // $this->requests[$orig]['headers']
393 // $this->requests[$orig]['body']
394 // $this->requests[$orig]['effective_url']
395 // check content type
396 if ($this->headerOnlyType($this->requests
[$orig]['headers'])) {
397 $this->requests
[$orig]['body'] = '';
398 $_header_only_type = true;
399 $this->debug('Header only type returned');
401 $_header_only_type = false;
403 $status_code = $this->requests
[$orig]['status_code'];
404 if ((in_array($status_code, array(300, 301, 302, 303, 307)) || $status_code > 307 && $status_code < 400) && isset($this->requests
[$orig]['location'])) {
405 $redirectURL = $this->requests
[$orig]['location'];
406 if (!preg_match('!^https?://!i', $redirectURL)) {
407 $redirectURL = SimplePie_Misc
::absolutize_url($redirectURL, $url);
409 if ($this->validateURL($redirectURL)) {
410 $this->debug('Redirect detected. Valid URL: '.$redirectURL);
412 $cookies = $this->cookieJar
->extractCookies($this->requests
[$orig]['headers']);
413 if (!empty($cookies)) $this->cookieJar
->storeCookies($url, $cookies);
414 $this->redirectQueue
[$orig] = $redirectURL;
416 $this->debug('Redirect detected. Invalid URL: '.$redirectURL);
418 } elseif (!$_header_only_type && $this->requests
[$orig]['method'] == 'HEAD') {
419 // the response content-type did not match our 'header only' types,
420 // but we'd issues a HEAD request because we assumed it would. So
421 // let's queue a proper GET request for this item...
422 $this->debug('Wrong guess at content-type, queing GET request');
423 $this->requests
[$orig]['wrongGuess'] = true;
424 $this->redirectQueue
[$orig] = $this->requests
[$orig]['effective_url'];
426 // die($url.' -multi- '.$request->getResponseInfo('effective_url'));
427 unset($this->requests
[$orig]['httpRequest'], $this->requests
[$orig]['method']);
433 //////////////////////////////////////////////////////
434 // sequential (file_get_contents)
436 $this->debug('Starting sequential fetch (file_get_contents)');
437 $this->debug('Processing set of '.count($urls));
438 foreach ($urls as $orig => $url) {
439 if (!$isRedirect) $orig = $url;
440 unset($this->redirectQueue
[$orig]);
441 $this->debug("...$url");
442 if (!$isRedirect && isset($this->requests[$url])) {
443 $this->debug("......in memory
");
445 } elseif ($this->isCached($url)) {
446 $this->debug("......is cached
");
447 if (!$this->minimiseMemoryUse) {
448 $this->requests[$url] = $this->getCached($url);
452 $this->debug("Sending request
for $url");
453 $this->requests
[$orig]['original_url'] = $orig;
454 $req_url = $this->rewriteUrls($url);
455 $req_url = ($this->rewriteHashbangFragment
) ? $this->rewriteHashbangFragment($req_url) : $req_url;
456 $req_url = $this->removeFragment($req_url);
457 // send cookies, if we have any
458 $httpContext = $this->httpContext
;
459 $httpContext['http']['header'] .= $this->getUserAgent($req_url)."\r\n";
460 // add referer for picky sites
461 $httpContext['http']['header'] .= 'Referer: '.$this->referer
."\r\n";
462 if ($cookies = $this->cookieJar
->getMatchingCookies($req_url)) {
463 $this->debug("......sending cookies: $cookies");
464 $httpContext['http']['header'] .= 'Cookie: '.$cookies."\r\n
";
466 if (false !== ($html = @file_get_contents($req_url, false, stream_context_create($httpContext)))) {
467 $this->debug('Received response');
469 if (!isset($http_response_header[0]) || !preg_match('!^HTTP/\d+\.\d+\s+(\d+)!', trim($http_response_header[0]), $match)) {
470 $this->debug('Error: no status code found');
471 // TODO: handle error - no status code
473 $this->requests[$orig]['headers'] = $this->headersToString($http_response_header, false);
474 // check content type
475 if ($this->headerOnlyType($this->requests[$orig]['headers'])) {
476 $this->requests[$orig]['body'] = '';
478 $this->requests[$orig]['body'] = $html;
480 $this->requests[$orig]['effective_url'] = $req_url;
481 $this->requests[$orig]['status_code'] = $status_code = (int)$match[1];
484 if (preg_match('/^Location:(.*?)$/m', $this->requests[$orig]['headers'], $match)) {
485 $this->requests[$orig]['location'] = trim($match[1]);
487 if ((in_array($status_code, array(300, 301, 302, 303, 307)) || $status_code > 307 && $status_code < 400) && isset($this->requests[$orig]['location'])) {
488 $redirectURL = $this->requests[$orig]['location'];
489 if (!preg_match('!^https?://!i', $redirectURL)) {
490 $redirectURL = SimplePie_Misc::absolutize_url($redirectURL, $url);
492 if ($this->validateURL($redirectURL)) {
493 $this->debug('Redirect detected. Valid URL: '.$redirectURL);
495 $cookies = $this->cookieJar->extractCookies($this->requests[$orig]['headers']);
496 if (!empty($cookies)) $this->cookieJar->storeCookies($url, $cookies);
497 $this->redirectQueue[$orig] = $redirectURL;
499 $this->debug('Redirect detected. Invalid URL: '.$redirectURL);
504 $this->debug('Error retrieving URL');
506 //print_r($http_response_header);
509 // TODO: handle error - failed to retrieve URL
516 public function handleCurlResponse($response, $info, $request) {
517 $orig = $request->url_original;
518 $this->requests[$orig]['headers'] = substr($response, 0, $info['header_size']);
519 $this->requests[$orig]['body'] = substr($response, $info['header_size']);
520 $this->requests[$orig]['method'] = $request->method;
521 $this->requests[$orig]['effective_url'] = $info['url'];
522 $this->requests[$orig]['status_code'] = (int)$info['http_code'];
523 if (preg_match('/^Location:(.*?)$/m', $this->requests[$orig]['headers'], $match)) {
524 $this->requests[$orig]['location'] = trim($match[1]);
528 protected function headersToString(array $headers, $associative=true) {
530 return implode("\n
", $headers);
533 foreach ($headers as $key => $val) {
534 if (is_array($val)) {
535 foreach ($val as $v) $str .= "$key: $v\n";
537 $str .= "$key: $val\n";
544 public function get($url, $remove=false, $gzdecode=true) {
546 if (isset($this->requests
[$url]) && isset($this->requests
[$url]['body'])) {
547 $this->debug("URL already fetched - in memory ($url, effective: {$this->requests[$url]['effective_url']})");
548 $response = $this->requests
[$url];
550 } elseif ($this->isCached($url)) {
551 $this->debug("URL already fetched - in disk cache ($url)");
552 $response = $this->getCached($url);
553 $this->requests[$url] = $response;
556 $this->debug("Fetching URL ($url)");
557 $this->fetchAll(array($url));
558 if (isset($this->requests
[$url]) && isset($this->requests
[$url]['body'])) {
559 $response = $this->requests
[$url];
561 $this->debug("Request failed");
566 if ($this->minimiseMemoryUse && $response) {
568 unset($this->requests[$url]);
571 if ($remove && $response) unset($this->requests
[$url]);
572 if ($gzdecode && stripos($response['headers'], 'Content-Encoding: gzip')) {
573 if ($html = gzdecode($response['body'])) {
574 $response['body'] = $html;
580 public function parallelSupport() {
581 return class_exists('HttpRequestPool') || function_exists('curl_multi_init');
584 private function headerOnlyType($headers) {
585 if (preg_match('!^Content-Type:\s*(([a-z-]+)/([^;\r\n ]+))!im', $headers, $match)) {
586 // look for full mime type (e.g. image/jpeg) or just type (e.g. image)
587 $match[1] = strtolower(trim($match[1]));
588 $match[2] = strtolower(trim($match[2]));
589 foreach (array($match[1], $match[2]) as $mime) {
590 if (in_array($mime, $this->headerOnlyTypes
)) return true;
596 private function possibleUnsupportedType($url) {
597 $path = @parse_url($url, PHP_URL_PATH
);
598 if ($path && strpos($path, '.') !== false) {
599 $ext = strtolower(trim(pathinfo($path, PATHINFO_EXTENSION
)));
600 return in_array($ext, $this->headerOnlyClues
);
606 // gzdecode from http://www.php.net/manual/en/function.gzdecode.php#82930
607 if (!function_exists('gzdecode')) {
608 function gzdecode($data,&$filename='',&$error='',$maxlength=null)
610 $len = strlen($data);
611 if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) {
612 $error = "Not in GZIP format.";
613 return null; // Not GZIP format (See RFC 1952)
615 $method = ord(substr($data,2,1)); // Compression method
616 $flags = ord(substr($data,3,1)); // Flags
617 if ($flags & 31 != $flags) {
618 $error = "Reserved bits not allowed.";
621 // NOTE: $mtime may be negative (PHP integer limitations)
622 $mtime = unpack("V", substr($data,4,4));
624 $xfl = substr($data,8,1);
625 $os = substr($data,8,1);
630 // 2-byte length prefixed EXTRA data in header
631 if ($len - $headerlen - 2 < 8) {
632 return false; // invalid
634 $extralen = unpack("v",substr($data,8,2));
635 $extralen = $extralen[1];
636 if ($len - $headerlen - 2 - $extralen < 8) {
637 return false; // invalid
639 $extra = substr($data,10,$extralen);
640 $headerlen +
= 2 +
$extralen;
646 if ($len - $headerlen - 1 < 8) {
647 return false; // invalid
649 $filenamelen = strpos(substr($data,$headerlen),chr(0));
650 if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) {
651 return false; // invalid
653 $filename = substr($data,$headerlen,$filenamelen);
654 $headerlen +
= $filenamelen +
1;
659 // C-style string COMMENT data in header
660 if ($len - $headerlen - 1 < 8) {
661 return false; // invalid
663 $commentlen = strpos(substr($data,$headerlen),chr(0));
664 if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) {
665 return false; // Invalid header format
667 $comment = substr($data,$headerlen,$commentlen);
668 $headerlen +
= $commentlen +
1;
672 // 2-bytes (lowest order) of CRC32 on header present
673 if ($len - $headerlen - 2 < 8) {
674 return false; // invalid
676 $calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;
677 $headercrc = unpack("v", substr($data,$headerlen,2));
678 $headercrc = $headercrc[1];
679 if ($headercrc != $calccrc) {
680 $error = "Header checksum failed.";
681 return false; // Bad header CRC
686 $datacrc = unpack("V",substr($data,-8,4));
687 $datacrc = sprintf('%u',$datacrc[1] & 0xFFFFFFFF);
688 $isize = unpack("V",substr($data,-4));
691 $bodylen = $len-$headerlen-8;
693 // IMPLEMENTATION BUG!
696 $body = substr($data,$headerlen,$bodylen);
701 // Currently the only supported compression method:
702 $data = gzinflate($body,$maxlength);
705 $error = "Unknown compression method.";
708 } // zero-byte body content is allowed
710 $crc = sprintf("%u",crc32($data));
711 $crcOK = $crc == $datacrc;
712 $lenOK = $isize == strlen($data);
713 if (!$lenOK || !$crcOK) {
714 $error = ( $lenOK ? '' : 'Length check FAILED. ') . ( $crcOK ? '' : 'Checksum FAILED.');