[PHP] Urgent help - Token Generation code!

[Shreyas Agasthya]

I am re-visiting the world of PHP after a really big hiatus and I am finding
things veryslippery. Can someone please help me with the below code and let
me know how I can print the token that is getting generated?

I am using EasyPHP and I am trying to echo the $token but it wouldn't print
anything. I am trying it as : http://localhost/token/URLToken.php. May I
know where all I am going wrong here in my approach?

<?php

                          $sUrl = "/tstd_c_b1@s54782";
                           $sParam = "primaryToken";
                           $nTime = time();
                           $nEventDuration = 86400;
                           $nWindow = $nTime + $nEventDuration;
                           $sSalt = "akamai123!";
                           $sExtract = ""; // optional


function urlauth_gen_url($sUrl, $sParam, $nWindow,
                         $sSalt, $sExtract, $nTime) {



$sToken = urlauth_gen_token($sUrl, $nWindow, $sSalt,
                                    $sExtract, $nTime);
 echo $token;
 if ($sToken == null) {
return ;
}

if (($sParam == "") || (!is_string($sParam))) {
$sParam = "__gda__";
}

    if ((strlen($sParam) < 5) || (strlen($sParam) > 12)) {
        return;
    }

if (($nWindow < 0) || (!is_integer($nWindow))) {
return;
}

if (($nTime <= 0) || (!is_integer($nTime))) {
$nTime = time();
}

$nExpires = $nWindow + $nTime;

if (strpos($sUrl, "?") === false) {
$res = $sUrl . "?" . $sParam . "=" . $nExpires . "_" . $sToken;
} else {
$res = $sUrl . "&" . $sParam . "=" . $nExpires . "_" . $sToken;
}

return $res;
}

/**
 * Returns the hash portion of the token. This function should not be
 *   called directly.
 */
function urlauth_gen_token($sUrl, $nWindow, $sSalt,
                           $sExtract, $nTime) {


if (($sUrl == "") || (!is_string($sUrl))) {
return;
}

if (($nWindow < 0) || (!is_integer($nWindow))) {
return;
}

if (($sSalt == "") || (!is_string($sSalt))) {
return;
}

if (!is_string($sExtract)) {
$sExtract = "";
}

if (($nTime <= 0) || (!is_integer($nTime))) {
$nTime = time();
}

$nExpires = $nWindow + $nTime;
$sExpByte1 = chr($nExpires & 0xff);
$sExpByte2 = chr(($nExpires >> 8) & 0xff);
$sExpByte3 = chr(($nExpires >> 16) & 0xff);
$sExpByte4 = chr(($nExpires >> 24) & 0xff);

$sData = $sExpByte1 . $sExpByte2 . $sExpByte3 . $sExpByte4
                 . $sUrl . $sExtract . $sSalt;

$sHash = _unHex(md5($sData));

$sToken = md5($sSalt . $sHash);
return $sToken;
}

/**
 * Helper function used to translate hex data to binary
 */
function _unHex($str) {
$res = "";
for ($i = 0; $i < strlen($str); $i += 2) {
        $res .= chr(hexdec(substr($str, $i, 2)));
}
return $res;
}

?>

-- 
Regards,
Shreyas Agasthya