php实现根据ip跳转的方法

<?php
//返回当前IP的城市字符串
function convertip($ip) {
    //IP数据文件路径
    $dat_path = 'QQWry.Dat';
    //检查IP地址
    if(!preg_match("/^(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])\.(\d{1,2}|1\d\d|2[0-4]\d|25[0-5])$/", $ip)) {
        return 'IP Address Error';
    }
    //打开IP数据文件
    if(!$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('', unpack('L', $DataEnd));
    if($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 'System Error';
        }
        //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('', unpack('L', $ipData1));
        if($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 'System Error';
        }
        $DataSeek = implode('', unpack('L', $DataSeek.chr(0)));
        fseek($fd, $DataSeek);
        $ipData2 = fread($fd, 4);
        if(strlen($ipData2) < 4) {
            fclose($fd);
            return 'System Error';
        }
        $ip2num = implode('', unpack('L', $ipData2));
        if($ip2num < 0) $ip2num += pow(2, 32);
        //没找到提示未知
        if($ip2num < $ipNum) {
            if($Middle == $BeginNum) {
                fclose($fd);
                return 'Unknown';
            }
            $BeginNum = $Middle;
        }
    }
    $ipFlag = fread($fd, 1);
    if($ipFlag == chr(1)) {
        $ipSeek = fread($fd, 3);
        if(strlen($ipSeek) < 3) {
            fclose($fd);
            return 'System Error';
        }
        $ipSeek = implode('', unpack('L', $ipSeek.chr(0)));
        fseek($fd, $ipSeek);
        $ipFlag = fread($fd, 1);
    }
    if($ipFlag == chr(2)) {
        $AddrSeek = fread($fd, 3);
        if(strlen($AddrSeek) < 3) {
            fclose($fd);
            return 'System Error';
        }
        $ipFlag = fread($fd, 1);
        if($ipFlag == chr(2)) {
            $AddrSeek2 = fread($fd, 3);
            if(strlen($AddrSeek2) < 3) {
                fclose($fd);
                return 'System Error';
            }
            $AddrSeek2 = implode('', unpack('L', $AddrSeek2.chr(0)));
            fseek($fd, $AddrSeek2);
        } else {
            fseek($fd, -1, SEEK_CUR);
        }
        while(($char = fread($fd, 1)) != chr(0))
            $ipAddr2 .= $char;
        $AddrSeek = implode('', unpack('L', $AddrSeek.chr(0)));
        fseek($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 'System Error';
            }
            $AddrSeek2 = implode('', unpack('L', $AddrSeek2.chr(0)));
            fseek($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('/http/i', $ipAddr2)) {
        $ipAddr2 = '';
    }
    $ipaddr = "$ipAddr1 $ipAddr2";
    $ipaddr = preg_replace('/CZ88.Net/is', '', $ipaddr);
    $ipaddr = preg_replace('/^s*/is', '', $ipaddr);
    $ipaddr = preg_replace('/s*$/is', '', $ipaddr);
    if(preg_match('/http/i', $ipaddr) || $ipaddr == '') {
        $ipaddr = 'Unknown';
    }
    return $ipaddr;
}
//查找字符串
function  findstr($str, $substr)
{
         $m = strlen($str);
        $n = strlen($substr );
        if ($m < $n) return false ;
        for ($i=0; $i <=($m-$n+1); $i ++){
                $sub = substr( $str, $i, $n);
                if ( strcmp($sub, $substr) ==  0)  return true;
        }
        return false ;
}
 
$xp_UserIp = ($_SERVER["HTTP_VIA"]) ? $_SERVER["HTTP_X_FORWARDED_FOR"] : $_SERVER["REMOTE_ADDR"];
$Clientip = ($xp_UserIp) ? $xp_UserIp : $_SERVER["REMOTE_ADDR"];
$ClientSity=convertip($Clientip);
if (findstr($ClientSity,"北京")){
    //out.print("beijing");
    Header("Location: http://www.qq.com");
}else{
    //out.print("false beijing");
    Header("Location: http://www.163.com");
}
?>