Using PHP to check response time of HTTP-server

I must start off with admiting that my PHP skills are very limited, however being a very experienced Perl hacker this is very similar to me.

I needed a script that checked for a normal HTTP response from another server, a status script to see if the other server(s) where behaving as they should.

The resources on-line for PHP are great and I quickly found the code needed to retrieve a remote page and read the contents. I also found some tutorials describing how to use this code. My version ended up looking like this (thanks phptoys.com for the tutorial!):

<?php
// check responsetime for a webbserver
function pingDomain($domain){
    $starttime = microtime(true);
    $file      = fsockopen ($domain, 80, $errno, $errstr, 10);
    $stoptime  = microtime(true);
    $status    = 0;

    if (!$file){
        $status = -1;  // Site is down
    }
    else{
        fclose($file);
        $status = ($stoptime - $starttime) * 1000;
        $status = floor($status);
    }
    return $status;
}
?>

This code works just fine as long as the server is up, but fsockopen generates an error message when the server is down. Here is the problem: the code is intended to verify that the server is up and take action when it is not and therefore I do not want to display the error message (as I half expect it).

I’ve tried to find a way to supress this error message (that I know will occur at some point) but could find no on-line resource describing it. In lack of a proper solution I instead made a hack innovative solution. I know when the error message will show up and that it will be written to output, to avoid this I simply put the function call in an “invisible” space of HTML:

<div style="display:none;">
<?php
$status = pingDomain('www.fireflake.com');
?>
</div>

Sure, it will still show up in the code but after this code is run you will have the response time in the $status variable and the possible error message will only be visible to someone who inspects the code! If $status is -1 the server is unreachable and 0 and up is the response time.

Also, due to the fact that DNS servers usually return a “search engine” response when a domain is unknown, you are better of using IP-numbers for checking that servers are truly on-line or not (I hope they have a fixed IP!). If not you would have to read a file from the server and make sure it has the contents you expect to be sure you are on the right server and your DNS isn’t fooling you.

EDIT:  Thx for adding the tip to use @ to supress error messages. Just use @fsockopen to supress the inevitable error message.