Banning Specific Referers

OK, i've been trying to make a function like checkipban(); but that checks the referring site and if listed like IP's then it shows a vB Error message, heres what I got so far, It either bans every referrer or bans no referrer :ermm:

PHP Code:

// ###################### Start checkreferrerban #######################
function checkreferrerban() {
 // checks to see if the referring site is banned
 global $enablebanning,$banreferrer,$webmasteremail,$session;

 $banreferrer = trim($banreferrer);
 if ($enablebanning==1 and $banreferrer!="") {
    // get referring sites address
    $referreraddress=getenv("$HTTP_REFERER");
    // get all banned referrers from the db
    $dbdomain=explode(" ", preg_replace("/[[:space:]]+/", " ", $banreferrer) );
    // get domain for all banned  referrers
    while (list($key,$val)=each($dbdomain)) {
    //get referring host name from URL
    preg_match("/^(http:\/\/)?([^\/]+)/i", ".$referreraddress", $matches);
    $host = $matches[2];
    //get domain name from URL
    preg_match("/[^\.\/]+\.[^\.\/]+$/",$host,$matches);
    $match=$matches[0];
    $hostdomain=explode(" ", $match);
    //check against each banned referrer in the db
    while (list($key,$val)=each($hostdomain)) {
    if (strstr(" ".$match," ".trim($val))!="") {
   eval("standarderror(\"".gettemplate("error_banref")."\");");
          } 
     }
    }
  }
} 

Its based on this fucnction:

PHP Code:

// ###################### Start checkipban #######################
function checkipban() {
  // checkes to see if the current ip address is banned
  global $enablebanning,$banip,$webmasteremail,$session;

  $banip = trim($banip);
  if ($enablebanning==1 and $banip!="") {
    $ipaddress=getenv("REMOTE_ADDR");

    $addresses=explode(" ", preg_replace("/[[:space:]]+/", " ", $banip) );
    while (list($key,$val)=each($addresses)) {
      if (strstr(" ".$ipaddress," ".trim($val))!="") {
        eval("standarderror(\"".gettemplate("error_banip")."\");");
      }
    }
  }
} 

Any help would be appriciated

[Erwin]

You can ban referrers with .htaccess already. But you probably knew that, and want a PHP version for those without .htaccess.