纯真IP地址数据库应该是国内最流行的IP地址数据库
纯真IP地址数据库（官方下载）
http://www.cz88.net/fox/ipdat.shtml<?php
/*--------------------------------------------------ip2address [qqwry.dat]
--------------------------------------------------*/class ip {var $fh; //IP数据库文件句柄var $first; //第一条索引var $last; //最后一条索引var $total; //索引总数//构造函数function __construct() {$this->fh = fopen('qqwry.dat', 'rb'); //qqwry.dat文件$this->first = $this->getLong4();$this->last = $this->getLong4();$this->total = ($this->last - $this->first) / 7; //每条索引7字节}//检查IP合法性function checkIp($ip) {$arr = explode('.',$ip);if(count($arr) !=4 ) {return false;} else {for ($i=0; $i < 4; $i++) {if ($arr[$i] <'0' || $arr[$i] > '255') {return false;}}}return true;}function getLong4() {//读取little-endian编码的4个字节转化为长整型数$result = unpack('Vlong', fread($this->fh, 4));return $result['long'];}function getLong3() {//读取little-endian编码的3个字节转化为长整型数$result = unpack('Vlong', fread($this->fh, 3).chr(0));return $result['long'];}//查询信息function getInfo($data = "") {$char = fread($this->fh, 1);while (ord($char) != 0) { //国家地区信息以0结束$data .= $char;$char = fread($this->fh, 1);}return $data;}//查询地区信息function getArea() {$byte = fread($this->fh, 1); //标志字节switch (ord($byte)) {case 0: $area = ''; break; //没有地区信息case 1: //地区被重定向fseek($this->fh, $this->getLong3());$area = $this->getInfo(); break;case 2: //地区被重定向fseek($this->fh, $this->getLong3());$area = $this->getInfo(); break;default: $area = $this->getInfo($byte);  break; //地区没有被重定向}return $area;}function ip2addr($ip) {if(!$this -> checkIp($ip)){return false;}$ip = pack('N', intval(ip2long($ip)));//二分查找$l = 0;$r = $this->total;while($l <= $r) {$m = floor(($l + $r) / 2); //计算中间索引fseek($this->fh, $this->first + $m * 7);$beginip = strrev(fread($this->fh, 4)); //中间索引的开始IP地址fseek($this->fh, $this->getLong3());$endip = strrev(fread($this->fh, 4)); //中间索引的结束IP地址if ($ip < $beginip) { //用户的IP小于中间索引的开始IP地址时$r = $m - 1;} else {if ($ip > $endip) { //用户的IP大于中间索引的结束IP地址时$l = $m + 1;} else { //用户IP在中间索引的IP范围内时$findip = $this->first + $m * 7;break;}}}//查询国家地区信息fseek($this->fh, $findip);$location['beginip'] = long2ip($this->getLong4()); //用户IP所在范围的开始地址$offset = $this->getlong3();fseek($this->fh, $offset);$location['endip'] = long2ip($this->getLong4()); //用户IP所在范围的结束地址$byte = fread($this->fh, 1); //标志字节switch (ord($byte)) {case 1:  //国家和区域信息都被重定向$countryOffset = $this->getLong3(); //重定向地址fseek($this->fh, $countryOffset);$byte = fread($this->fh, 1); //标志字节switch (ord($byte)) {case 2: //国家信息被二次重定向fseek($this->fh, $this->getLong3());$location['country'] = $this->getInfo();fseek($this->fh, $countryOffset + 4);$location['area'] = $this->getArea();break;default: //国家信息没有被二次重定向$location['country'] = $this->getInfo($byte);$location['area'] = $this->getArea();break;}break;case 2: //国家信息被重定向fseek($this->fh, $this->getLong3());$location['country'] = $this->getInfo();fseek($this->fh, $offset + 8);$location['area'] = $this->getArea();break;default: //国家信息没有被重定向$location['country'] = $this->getInfo($byte);$location['area'] = $this->getArea();break;}//gb2312 to utf-8（去除无信息时显示的CZ88.NET）foreach ($location as $k => $v) {$location[$k] = str_replace('CZ88.NET','',iconv('gb2312', 'utf-8', $v));}return $location;}//析构函数function __destruct() {fclose($this->fh);}
}$ip = new ip();
$addr = $ip -> ip2addr('IP地址');
print_r($addr);
?>