PHP: Ajax script for making cURL HEAD requests
This article presents a simple PHP script that executes a cURL HEAD request for the supplied URL, and then uses our AjaxResponseXML PHP class to return the output to the calling page.
PHP Source Code
The code presented below accepts a single 'url' parameter and checks that it starts with a HTTP or HTTPS protocol. The path to cURL is hard-coded, and all user-supplied arguments are escaped.
Still, you may want to add extra filters and checks to improve security, and to restrict which URLs can be requested.
curl-head.xml.php:
<?PHP
if(!isset($_POST['url']) || !preg_match("@^https?://\S+$@", $url)) {
die("Invalid URL supplied: {$url}")
}
$CURL = "/usr/bin/curl --silent --user-agent " . escapeshellarg($_SERVER['HTTP_USER_AGENT']);
$cmd = "{$CURL} --location --head " . escapeshellarg($url);
exec($cmd, $out, $ret);
$response = [];
$http_code = NULL;
foreach($out as $line) {
if(preg_match("@^HTTP/\S+ (\d{3})@", $line, $regs)) {
// new set of headers, starting with response three-digit code
if($response) {
$responses[] = $response;
}
$http_code = $regs[1];
$response = [
$http_code,
];
}
if($http_code) {
// include only matching headers in payload
if(preg_match("/^(Server|Location|Content-(Type|Length)): /i", $line)) {
$response[] = $line;
}
}
}
if($response) {
$responses[] = $response;
}
$xml = new \Chirp\AjaxResponseXML();
$xml->start();
$xml->command('callback', [
'params' => [
$url,
json_encode($responses)
],
]);
$xml->end();
exit;
Sample Output
As previously discussed, the output is an XML document containing parameters to be returned to the AjaxRequestXML JavaScript class from where the Ajax request was initiated:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<response>
<command method="callback">
<params>https://www.the-art-of-web.com/javascript/curl-head-ajax/</params>
<params>[["200","Server: Apache\/2.4","Content-Type: text\/html; charset=UTF-8"]]</params>
</command>
</response>
Each response, because there will be multiple where redirects are followed, is encoded as a JSON array starting with the response code, follwed by selected headers.
For more details, and a demonstration, refer to the accompanying article containing the HTML and JavaScript components that tie this all together.
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