get_headers

(PHP 5)

get_headers — 取得服务器响应一个 HTTP 请求所发送的所有标头

说明

array get_headers ( string $url [, int $format = 0 ] )

get_headers() 返回一个数组，包含有服务器响应一个 HTTP 请求所发送的标头。

参数

url: 目标 URL。
format: 如果将可选的 format 参数设为 1，则 get_headers() 会解析相应的信息并设定数组的键名。

返回值

返回包含有服务器响应一个 HTTP 请求所发送标头的索引或关联数组，如果失败则返回 FALSE 。

更新日志

版本	说明
5.1.3	自 PHP 5.1.3 起本函数使用默认的流上下文，其可以用 stream_context_get_default() 函数设定和修改。

范例

Example #1 get_headers() 例子

  <?php
$url  =  'http://www.example.com' ;

 print_r ( get_headers ( $url ));

 print_r ( get_headers ( $url ,  1 ));
 ?>

以上例程的输出类似于：

Array
(
    [0] => HTTP/1.1 200 OK
    [1] => Date: Sat, 29 May 2004 12:28:13 GMT
    [2] => Server: Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [3] => Last-Modified: Wed, 08 Jan 2003 23:11:55 GMT
    [4] => ETag: "3f80f-1b6-3e1cb03b"
    [5] => Accept-Ranges: bytes
    [6] => Content-Length: 438
    [7] => Connection: close
    [8] => Content-Type: text/html
)Array
(
    [0] => HTTP/1.1 200 OK
    [Date] => Sat, 29 May 2004 12:28:14 GMT
    [Server] => Apache/1.3.27 (Unix)  (Red-Hat/Linux)
    [Last-Modified] => Wed, 08 Jan 2003 23:11:55 GMT
    [ETag] => "3f80f-1b6-3e1cb03b"
    [Accept-Ranges] => bytes
    [Content-Length] => 438
    [Connection] => close
    [Content-Type] => text/html
)

Example #2 get_headers() using HEAD example

  <?php
 // By default get_headers uses a GET request to fetch the headers. If you
// want to send a HEAD request instead, you can do so using a stream context:
 stream_context_set_default (
    array(
         'http'  => array(
             'method'  =>  'HEAD'
         )
    )
);
 $headers  =  get_headers ( 'http://example.com' );
 ?>

参见

apache_request_headers() - 获取全部 HTTP 请求头信息

用户评论:

[#1] bobray at softville dot com [2015-05-11 05:29:00]

Testing the validity of a URL that is preceded by one or more server redirects is tricky. There will be more than one status code returned and all but the first will be redirect codes.

This function will return an integer containing the three digit status code of the last code returned, which is what you want.

    function getStatus($url) {
        $headers = @get_headers($url, true);
        $value = NULL;
        if ($headers === false) {
            return $headers;
        }
        foreach ($headers as $k => $v) {
            if (!is_int($k)) {
                continue;
            }
            $value = $v;
        }

        return (int) substr($value, strpos($value, ' ', 8) + 1, 3);
     }

If getHeaders() fails, PHP will throw an error. Test the return value for === false.

[#2] pegasus at vaultwiki dot org [2015-04-29 14:41:26]

Note that get_headers should not be used against a URL that was gathered via user input. The timeout option in the stream context only affects the idle time between data in the stream. It does not affect connection time or the overall time of the request.

(Unfortunately, this is not mentioned in the docs for the timeout option, but has been discussed in a number of code discussions elsewhere, and I have done my own tests to confirm the conclusions of those discussions.)

Thus it is very easy for a user to give you a URL that acts like a Slowloris attack - feeding your get_headers function 1 header only often enough to avoid the stream timeout.

If you are publishing your code, even default_socket_timeout cannot be relied on to remedy this, because it is broken for the HTTPS protocol on many but the more recent versions of PHP: https://bugs.php.net/bug.php?id=41631

With get_headers accepting user input, it can be very easy for an attacker to make all of your PHP child processes become busy.

Instead, use cURL functions to get headers for a URL provided by the user and parse those headers manually, as CURLOPT_TIMEOUT applies to the entire request.

[#3] cees at cornelisdigitaal dot nl [2015-02-23 09:20:33]

@Jim Greene:

if the URL does not exist, it returns incomplete headers, making the substring default to rubbish.

The integer value of rubbish is always 0. So your lower than 400 does not always means it exists!

[#4] Kubo2 [2013-11-24 09:55:39]

If you don't want to display Warning when get_headers() function fails, you can simply add at-sign (@) before it.

<?php // in failure, Warning will be hidden and false returned $withoutWarning = @get_headers("http://www.some-domain.com"); // in failure, Warning displays and false will be returned, too $withWarning = get_headers("http://www.some-domain.com"); // bool(false) var_dump($withoutWarning); // bool(false) var_dump($withWarning); ?>

[#5] Jim Greene [2013-07-09 14:47:55]

I know you're not supposed to reference other notes, but sincere props to Nick at Innovaweb's comment, for which I base this addition to his idea:

If you use that function, it will return a string, which is great if you are checking for only files that return 404, or 200, or whatnot. If you cast the string value to an integer, you can perform mathematical comparison on it.

For example:

<?php function get_http_response_code($theURL) { $headers = get_headers($theURL); return substr($headers[0], 9, 3); } if(intval(get_http_response_code('filename.jpg')) < 400){ // File exists, huzzah! } ?>

Rule of thumb is if the response is less than 400, then the file's there, even if it doesn't return 200.

[#6] Backslider [2012-02-15 19:06:56]

It should be noted that rather than returning "false" on failure, this function (and others) return a big phat WARNING that will halt your script in its tracks if you do not have error reporting /warning turned off.

Thats just insane! Any function that does something like fetch a URL should simply return false, without a warning, if the URL fails for whatever reason other than it is badly formatted.

[#7] damolp at hotmail dot com [2011-07-03 17:43:51]

I found that this function is the slowest in obtaining the headers of a page probably because it uses a GET request rather then a HEAD request. Over 10,000,000 trials of obtaining the headers of a page from a server i found the following (results in seconds).

cURL: Mean: 0.584127946. Sigma: 0.050581736.
fsocketopen: Mean: 0.622114251. Sigma: 0.263170424.
get_headers: Mean: 0.90375551. Sigma: 0.273823419.

cURL was the fastest with fsocketopens being the second fastest. I noticed as well that fsocketopen had some outliers where as cURL did not.

[#8] Lukas Najduk [2011-01-11 03:36:50]

Unfortunately there is still no useful output format to handle redirects.

This function will bring all non-broken headers into a usable format. Too bad it has to call the get_headers() funtion 2 times, but i dont see any other possibility right now.

<?php function page_get_headers($crawl_uri) { // get the array values where to split the second get headers return $headers = get_headers($crawl_uri, 1); if (empty($headers)) { return array(); } $splitmarks = array(); foreach ($headers as $key=>$h) { if (is_numeric($key)) { array_push($splitmarks, $h); } } // get the "real" headers $headers_final = array(); $i = 0; $headers = get_headers($crawl_uri); foreach ($headers as $head) { // if the value is one of the splitmarks, start the next header if (array_key_exists($i, $splitmarks) && $head === $splitmarks[$i]) { $i++; } else { // get the headers name $tmp = explode(": ", $head, 2); // check if the header is already existing, if yes, parse the similar header to an array if (!empty($headers_final[$i-1][$tmp[0]])) { if (is_array($headers_final[$i-1][$tmp[0]])) { array_push($headers_final[$i-1][$tmp[0]], $tmp[1]); } else { $headers_final[$i-1][$tmp[0]] = array($headers_final[$i-1][$tmp[0]], $tmp[1]); } } else { $headers_final[$i-1][$tmp[0]] = $tmp[1]; } } } return $headers_final; } ?>

[#9] Weboide [2010-09-25 18:13:47]

Note that get_headers **WILL follow redirections** (HTTP redirections). New headers will be appended to the array if $format=0. If $format=1 each redundant header will be an array of multiple values, one for each redirection.

For example:

<?php $url = 'http://google.com'; var_dump(get_headers($url,0)); var_dump(get_headers($url,1)); ?>

[#10] nick at innovaweb dot co dot uk [2010-05-02 17:28:29]

Seems like there are some people who are looking for only the 3-digit HTTP response code - here is a quick and nasty solution:

<?php function get_http_response_code($theURL) { $headers = get_headers($theURL); return substr($headers[0], 9, 3); } ?>

How easy is that? Echo the function containing the URL you want to check the response code for, and voil??. Custom redirects, alternative for blocked is_file() or flie_exists() functions (like I seem to have on my servers) hence the cheap workaround. But hey - it works!

Pudding

[#11] php at hm2k dot org [2010-01-28 10:20:25]

<?php function get_real_headers($url,$format=0,$follow_redirect=0) { if (!$follow_redirect) { //set new default options $opts = array('http' => array('max_redirects'=>1,'ignore_errors'=>1) ); stream_context_get_default($opts); } //get headers $headers=get_headers($url,$format); //restore default options if (isset($opts)) { $opts = array('http' => array('max_redirects'=>20,'ignore_errors'=>0) ); stream_context_get_default($opts); } //return return $headers; } ?>

[#12] gabe at vtunnel dot com [2009-04-22 01:23:51]

In some cases, you don't want get_headers to follow redirects. For example, some of my servers can access a particular website, which sends a redirect header. The site it is redirected to, however, has me firewalled. I need to take the 302 redirected url, and do something to it to give me a new url that I *can* connect to.

The following will give you output similar to get_headers, except it has a timeout, and it doesn't follow redirects:

<?php function get_headers_curl($url) { $ch = curl_init(); curl_setopt($ch, CURLOPT_URL, $url); curl_setopt($ch, CURLOPT_HEADER, true); curl_setopt($ch, CURLOPT_NOBODY, true); curl_setopt($ch, CURLOPT_RETURNTRANSFER, true); curl_setopt($ch, CURLOPT_TIMEOUT, 15); $r = curl_exec($ch); $r = split("\n", $r); return $r; } If you do want to follow redirects, you can do something like this: $go = 1; $i = 1; while ($go && $i < 6) { $headers = get_headers_curl($url); $go = getNextLocation($headers); if ($go) { $url = modifyUrl($go); } $i++; } function getNextLocation($headers) { $array = $headers; $count = count($array); for ($i=0; $i < $count; $i++) { if (strpos($array[$i], "ocation:")) { $url = substr($array[$i], 10); } } if ($url) { return $url; } else { return 0; } } ?>

[#13] info at marc-gutt dot de [2008-06-21 05:04:49]

Should be the same than the original get_headers():

<?php if (!function_exists('get_headers')) { function get_headers($url, $format=0) { $headers = array(); $url = parse_url($url); $host = isset($url['host']) ? $url['host'] : ''; $port = isset($url['port']) ? $url['port'] : 80; $path = (isset($url['path']) ? $url['path'] : '/') . (isset($url['query']) ? '?' . $url['query'] : ''); $fp = fsockopen($host, $port, $errno, $errstr, 3); if ($fp) { $hdr = "GET $path HTTP/1.1\r\n"; $hdr .= "Host: $host \r\n"; $hdr .= "Connection: Close\r\n\r\n"; fwrite($fp, $hdr); while (!feof($fp) && $line = trim(fgets($fp, 1024))) { if ($line == "\r\n") break; list($key, $val) = explode(': ', $line, 2); if ($format) if ($val) $headers[$key] = $val; else $headers[] = $key; else $headers[] = $line; } fclose($fp); return $headers; } return false; } } ?>

[#14] php dot sirlancelot at spamgourmet dot com [2008-06-05 13:59:32]

I tried to replicate the native behavior as much as possible for systems that don't have the get_headers() function. Here it is:
<?php if (!function_exists('get_headers')) { function get_headers($Url, $Format= 0, $Depth= 0) { if ($Depth > 5) return; $Parts = parse_url($Url); if (!array_key_exists('path', $Parts)) $Parts['path'] = '/'; if (!array_key_exists('port', $Parts)) $Parts['port'] = 80; if (!array_key_exists('scheme', $Parts)) $Parts['scheme'] = 'http'; $Return = array(); $fp = fsockopen($Parts['host'], $Parts['port'], $errno, $errstr, 30); if ($fp) { $Out = 'GET '.$Parts['path'].(isset($Parts['query']) ? '?'.@$Parts['query'] : '')." HTTP/1.1\r\n". 'Host: '.$Parts['host'].($Parts['port'] != 80 ? ':'.$Parts['port'] : '')."\r\n". 'Connection: Close'."\r\n"; fwrite($fp, $Out."\r\n"); $Redirect = false; $RedirectUrl = ''; while (!feof($fp) && $InLine = fgets($fp, 1280)) { if ($InLine == "\r\n") break; $InLine = rtrim($InLine); list($Key, $Value) = explode(': ', $InLine, 2); if ($Key == $InLine) { if ($Format == 1) $Return[$Depth] = $InLine; else $Return[] = $InLine; if (strpos($InLine, 'Moved') > 0) $Redirect = true; } else { if ($Key == 'Location') $RedirectUrl = $Value; if ($Format == 1) $Return[$Key] = $Value; else $Return[] = $Key.': '.$Value; } } fclose($fp); if ($Redirect && !empty($RedirectUrl)) { $NewParts = parse_url($RedirectUrl); if (!array_key_exists('host', $NewParts)) $RedirectUrl = $Parts['host'].$RedirectUrl; if (!array_key_exists('scheme', $NewParts)) $RedirectUrl = $Parts['scheme'].'://'.$RedirectUrl; $RedirectHeaders = get_headers($RedirectUrl, $Format, $Depth+1); if ($RedirectHeaders) $Return = array_merge_recursive($Return, $RedirectHeaders); } return $Return; } return false; }} ?>
The function will handle up to five redirects.
Enjoy!

[#15] dxtrim at yahoo dot com [2008-01-17 01:16:11]

Content-Type returns a value depending only on the extension and not the real MIME TYPE.

So, bad_file.exe renamed to good_file.doc will return application/msword

A file without extension returns a 404.

[#16] [2006-11-13 00:29:21]

I've noticed it.
Some Server will simply return the false reply header if you sent 'HEAD' request instead of 'GET'. The 'GET' request header always receiving the most actual HTTP header instead of 'HEAD' request header. But If you don't mind for a fast but risky method then 'HEAD' request is better for you.

btw ... this is get header with additional information such as User, Pass & Refferer. ...
<?php     function get_headers_x($url,$format=0, $user='', $pass='', $referer='') {         if (!empty($user)) {             $authentification = base64_encode($user.':'.$pass);             $authline = "Authorization: Basic $authentification\r\n";         }         if (!empty($referer)) {             $refererline = "Referer: $referer\r\n";         }         $url_info=parse_url($url);         $port = isset($url_info['port']) ? $url_info['port'] : 80;         $fp=fsockopen($url_info['host'], $port, $errno, $errstr, 30);         if($fp) {             $head = "GET ".@$url_info['path']."?".@$url_info['query']." HTTP/1.0\r\n";             if (!empty($url_info['port'])) {                 $head .= "Host: ".@$url_info['host'].":".$url_info['port']."\r\n";             } else {                 $head .= "Host: ".@$url_info['host']."\r\n";             }             $head .= "Connection: Close\r\n";             $head .= "Accept: *     function get_headers($url,$format=0) {         $url_info=parse_url($url);         $port = isset($url_info['port']) ? $url_info['port'] : 80;         $fp=fsockopen($url_info['host'], $port, $errno, $errstr, 30);         if($fp) {             $head = "HEAD ".@$url_info['path']."?".@$url_info['query'];             $head .= " HTTP/1.0\r\nHost: ".@$url_info['host']."\r\n\r\n";             fputs($fp, $head);             while(!feof($fp)) {                 if($header=trim(fgets($fp, 1024))) {                     if($format == 1) {                         $h2 = explode(':',$header);                         // the first element is the http header type, such as HTTP/1.1 200 OK,                         // it doesn't have a separate name, so we have to check for it.                         if($h2[0] == $header) {                             $headers['status'] = $header;                         }                         else {                             $headers[strtolower($h2[0])] = trim($h2[1]);                         }                     }                     else {                         $headers[] = $header;                     }                 }             }             return $headers;         }         else {             return false;         }     } } ?>

OK?  Here's the usage:

<?php $response = get_headers('http://www.example.com/', 1); if (!$response) {     echo 'Unable to initiate connection.'; } else {     print_r($response); } ?>

[#22] aeontech at gmail dot com [2004-12-23 17:20:18]

In response to dotpointer's modification of Jamaz' solution...

Here is a small modification of your function, this adds the emulation of the optional $format parameter.

<?php if(!function_exists('get_headers')) { function get_headers($url,$format=0) { $url_info=parse_url($url); $port = isset($url_info['port']) ? $url_info['port'] : 80; $fp=fsockopen($url_info['host'], $port, $errno, $errstr, 30); if($fp) { $head = "HEAD ".@$url_info['path']."?".@$url_info['query']." HTTP/1.0\r\nHost: ".@$url_info['host']."\r\n\r\n"; fputs($fp, $head); while(!feof($fp)) { if($header=trim(fgets($fp, 1024))) { if($format == 1) { $key = array_shift(explode(':',$header)); // the first element is the http header type, such as HTTP 200 OK, // it doesn't have a separate name, so we have to check for it. if($key == $header) { $headers[] = $header; } else { $headers[$key]=substr($header,strlen($key)+2); } unset($key); } else { $headers[] = $header; } } } return $headers; } else { return false; } } } ?>