php如何根据IP地址获取所在城市

<?php
header('Content-Type:text/html;Charset=utf-8');
function GetIp(){
    $realip = '';
    $unknown = 'unknown';
    if (isset($_SERVER)){
        if(isset($_SERVER['HTTP_X_FORWARDED_FOR']) && !empty($_SERVER['HTTP_X_FORWARDED_FOR']) && strcasecmp($_SERVER['HTTP_X_FORWARDED_FOR'], $unknown)){
            $arr = explode(',', $_SERVER['HTTP_X_FORWARDED_FOR']);
            foreach($arr as $ip){
                $ip = trim($ip);
                if ($ip != 'unknown'){
                    $realip = $ip;
                    break;
                }
            }
        }else if(isset($_SERVER['HTTP_CLIENT_IP']) && !empty($_SERVER['HTTP_CLIENT_IP']) && strcasecmp($_SERVER['HTTP_CLIENT_IP'], $unknown)){
            $realip = $_SERVER['HTTP_CLIENT_IP'];
        }else if(isset($_SERVER['REMOTE_ADDR']) && !empty($_SERVER['REMOTE_ADDR']) && strcasecmp($_SERVER['REMOTE_ADDR'], $unknown)){
            $realip = $_SERVER['REMOTE_ADDR'];
        }else{
            $realip = $unknown;
        }
    }else{
        if(getenv('HTTP_X_FORWARDED_FOR') && strcasecmp(getenv('HTTP_X_FORWARDED_FOR'), $unknown)){
            $realip = getenv("HTTP_X_FORWARDED_FOR");
        }else if(getenv('HTTP_CLIENT_IP') && strcasecmp(getenv('HTTP_CLIENT_IP'), $unknown)){
            $realip = getenv("HTTP_CLIENT_IP");
        }else if(getenv('REMOTE_ADDR') && strcasecmp(getenv('REMOTE_ADDR'), $unknown)){
            $realip = getenv("REMOTE_ADDR");
        }else{
            $realip = $unknown;
        }
    }
    $realip = preg_match("/[\d\.]{7,15}/", $realip, $matches) ? $matches[0] : $unknown;
    return $realip;
}

function GetIpLookup($ip = ''){
    if(empty($ip)){
        $ip = GetIp();
    }
    $res = @file_get_contents('http://int.dpool.sina.com.cn/iplookup/iplookup.php?format=js&ip=' . $ip);
    if(empty($res)){ return false; }
    $jsonMatches = array();
    preg_match('#\{.+?\}#', $res, $jsonMatches);
    if(!isset($jsonMatches[0])){ return false; }
    $json = json_decode($jsonMatches[0], true);
    if(isset($json['ret']) && $json['ret'] == 1){
        $json['ip'] = $ip;
        unset($json['ret']);
    }else{
        return false;
    }
    return $json;
}


$ipInfos = GetIpLookup('123.125.114.144'); //baidu.com IP鍦板潃
var_dump($ipInfos);
?>