In-depth knowledge of how Empire CMS jumps to different pages based on IP address

<?php
//php获取ip的算法
$user_IP = ($_SERVER["HTTP_VIA"]) ? $_SERVER["HTTP_X_FORWARDED_FOR"] : $_SERVER["REMOTE_ADDR"];
$user_IP = ($user_IP) ? $user_IP : $_SERVER["REMOTE_ADDR"];
//echo $user_IP;
?>

//===================================
// 功能：IP地址获取真实地址函数
// 参数：$ip - IP地址
//===================================
function convertip($ip) {
//IP数据文件路径
$dat_path = 'QQWry.dat';
//检查IP地址
if(!ereg("^([0-9]{1,3}.){3}[0-9]{1,3}$", $ip)){
return 'IP Address Error';
}
//打开IP数据文件
if(!$fd = @fopen($dat_path, 'rb')){
return 'IP date file not exists or access denied';
}
//分解IP进行运算，得出整形数
$ip = explode('.', $ip);
$ipNum = $ip[0] * 16777216 + $ip[1] * 65536 + $ip[2] * 256 + $ip[3];
//获取IP数据索引开始和结束位置
$DataBegin = fread($fd, 4);
$DataEnd = fread($fd, 4);
$ipbegin = implode('', unpack('L', $DataBegin));
if($ipbegin < 0) $ipbegin += pow(2, 32);
$ipend = implode(&#39;&#39;, unpack(&#39;L&#39;, $DataEnd));
if($ipend < 0) $ipend += pow(2, 32);
$ipAllNum = ($ipend - $ipbegin) / 7 + 1;
$BeginNum = 0;
$EndNum = $ipAllNum;
//使用二分查找法从索引记录中搜索匹配的IP记录
while($ip1num>$ipNum || $ip2num<$ipNum) {
$Middle= intval(($EndNum + $BeginNum) / 2);
//偏移指针到索引位置读取4个字节
fseek($fd, $ipbegin + 7 * $Middle);
$ipData1 = fread($fd, 4);
if(strlen($ipData1) < 4) {
fclose($fd);
return &#39;System Error&#39;;
}
//提取出来的数据转换成长整形，如果数据是负数则加上2的32次幂
$ip1num = implode(&#39;&#39;, unpack(&#39;L&#39;, $ipData1));
if($ip1num < 0) $ip1num += pow(2, 32);
//提取的长整型数大于我们IP地址则修改结束位置进行下一次循环
if($ip1num > $ipNum) {
$EndNum = $Middle;
continue;
}
//取完上一个索引后取下一个索引
$DataSeek = fread($fd, 3);
if(strlen($DataSeek) < 3) {
fclose($fd);
return &#39;System Error&#39;;
}
$DataSeek = implode(&#39;&#39;, unpack(&#39;L&#39;, $DataSeek.chr(0)));
fseek($fd, $DataSeek);
$ipData2 = fread($fd, 4);
if(strlen($ipData2) < 4) {
fclose($fd);
return &#39;System Error&#39;;
}
$ip2num = implode(&#39;&#39;, unpack(&#39;L&#39;, $ipData2));
if($ip2num < 0) $ip2num += pow(2, 32);
//没找到提示未知
if($ip2num < $ipNum) {
if($Middle == $BeginNum) {
fclose($fd);
return &#39;Unknown&#39;;
}
$BeginNum = $Middle;
}
}
//下面的代码读晕了，没读明白，有兴趣的慢慢读
$ipFlag = fread($fd, 1);
if($ipFlag == chr(1)) {
$ipSeek = fread($fd, 3);
if(strlen($ipSeek) < 3) {
fclose($fd);
return &#39;System Error&#39;;
}
$ipSeek = implode(&#39;&#39;, unpack(&#39;L&#39;, $ipSeek.chr(0)));
fseek($fd, $ipSeek);
$ipFlag = fread($fd, 1);
}
if($ipFlag == chr(2)) {
$AddrSeek = fread($fd, 3);
if(strlen($AddrSeek) < 3) {
fclose($fd);
return &#39;System Error&#39;;
}
$ipFlag = fread($fd, 1);
if($ipFlag == chr(2)) {
$AddrSeek2 = fread($fd, 3);
if(strlen($AddrSeek2) < 3) {
fclose($fd);
return &#39;System Error&#39;;
}
$AddrSeek2 = implode(&#39;&#39;, unpack(&#39;L&#39;, $AddrSeek2.chr(0)));
fseek($fd, $AddrSeek2);
} else {
fseek($fd, -1, SEEK_CUR);
}
while(($char = fread($fd, 1)) != chr(0))
$ipAddr2 .= $char;
$AddrSeek = implode(&#39;&#39;, unpack(&#39;L&#39;, $AddrSeek.chr(0)));
fseek($fd, $AddrSeek);
while(($char = fread($fd, 1)) != chr(0))
$ipAddr1 .= $char;
} else {
fseek($fd, -1, SEEK_CUR);
while(($char = fread($fd, 1)) != chr(0))
$ipAddr1 .= $char;
$ipFlag = fread($fd, 1);
if($ipFlag == chr(2)) {
$AddrSeek2 = fread($fd, 3);
if(strlen($AddrSeek2) < 3) {
fclose($fd);
return &#39;System Error&#39;;
}
$AddrSeek2 = implode(&#39;&#39;, unpack(&#39;L&#39;, $AddrSeek2.chr(0)));
fseek($fd, $AddrSeek2);
} else {
fseek($fd, -1, SEEK_CUR);
}
while(($char = fread($fd, 1)) != chr(0)){
$ipAddr2 .= $char;
}
}
fclose($fd);
//最后做相应的替换操作后返回结果
if(preg_match(&#39;/http/i&#39;, $ipAddr2)) {
$ipAddr2 = &#39;&#39;;
}
$ipaddr = "$ipAddr1 $ipAddr2";
$ipaddr = preg_replace(&#39;/CZ88.Net/is&#39;, &#39;&#39;, $ipaddr);
$ipaddr = preg_replace(&#39;/^s*/is&#39;, &#39;&#39;, $ipaddr);
$ipaddr = preg_replace(&#39;/s*$/is&#39;, &#39;&#39;, $ipaddr);
if(preg_match(&#39;/http/i&#39;, $ipaddr) || $ipaddr == &#39;&#39;) {
$ipaddr = &#39;Unknown&#39;;
}
return $ipaddr;
}
?>

var sf='';//此处的sf变量可保存PHP函数获取到的真实地址
if(sf.indexOf("香港")>=0){
window.location.href="http://www.****.com/?香港";
}
else if(sf.indexOf("广东省")>=0){
window.location.href="http://www.****.com/?广东";
}