<?php
//ip address array (change or add them as necessary)
$IP_Array = array('173.8.241.122', '173.8.241.123');

//function to get the current pages URL
function curPageURL() {
    $pageURL = 'http';
    if ($_SERVER["HTTPS"] == "on") {
        $pageURL .= "s";
    }
    $pageURL .= "://";
    if ($_SERVER["SERVER_PORT"] != "80") {
        $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
    }
    else {
        $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
    }
    return $pageURL;
}

//set url to current page URL
$url = curPageURL();

//get referrer url
if (!isset($url))
    $url = $_SERVER["HTTP_REFERER"];

//get the lander and image from the url
$last = parse_url($url, PHP_URL_PATH);

$lander = substr($last, -16, 7);
$image = substr($last, -8, 4);

//get the users ip address
$IP_Address = $_SERVER["REMOTE_ADDR"];

if(in_array($IP_Address, $IP_Array)) {
    //ip matches do nothing
}
//ip does not match send to someplace else
elseif ($lander == 'lander1') {
    header( 'Location: http://domain.com/base.php?c=112&key=123456789&keyword='.$image );
}
elseif ($lander == 'lander2') {
    header( 'Location: http://domain.com/base.php?c=112&key=abcdefghi&keyword='.$image );
}
?>