php IP取得城市API(純真IP資料庫)

/**
* 依IP位址取得城市名稱 純真IP資料庫
* edit: bbs.it-home.org
*/
 function convertip($ip) {
 //IP資料檔路徑
 $dat_path = 'QQWry.Dat';

 //檢查IP位址
 if(!filter_var($ip, FILTER_VALIDATE_IP)) {
 return 'IP Address Error';
 }
 return 'IP Address Error';
 }
 }
 //開啟IP資料檔
 if(!$fd = @fopen($dat_path, 'rb')){
 return 'IP date file not exists or access denied';
 }

 //分解IP進行運算，得出整形數
 $ipNum = ip2long($ip);

 //取得IP資料索引開始與結束位置
 $DataBegin = fread($fd, 4);
 $DataEnd = fread($fd, 4);
 $ipbegin = implode('', unpack('L', $DataBegin));
 if($ ipbegin  $ipend = implode('', unpack('L', $DataEnd));
 if($ipend $ipNum || $ip2num $Middle= intval(($EndNum + $BeginNum) / 2);

 //偏移指標到索引位置讀取4個位元組
 fseek($fd, $ipbegin + 7 * $Middle);
 $ipData1 = fread($fd, 4);
 if(strlen($ipData1)  fclose($fd);
 return 'System Error';
 }
 //提取出來的資料轉換成長整形，如果資料是負數則加上2的32次方
 $ ip1num = implode('', unpack('L', $ipData1));
 if($ip1num  $ipNum) {
 $EndNum = $Middle;
 continue;
 }

 //取完上一個索引後取下一個索引
 $DataSeek = fread($fd, 3);
 if(strlen($DataSeek)  fclose($fd);
 return 'System Error';
 }
 $DataSeek = implode('', unpack('L', $DataSeek.chr(0)));
 fseek($fd, $DataSeek);
 $ipData2 = fread ($fd, 4);
 if(strlen($ipData2)  fclose($fd);
 return 'System Error';
 }
 $ip2num = implode ('', unpack('L', $ipData2));
 if($ip2num
 //找不到提示未知
 if($ip2num  if($Middle == $BeginNum) {
 fclose($fd);
 return 'Unknown';
 }
 $BeginNum = $Middle;
 }
 }

 //下面的程式碼讀暈了，沒讀明白，有興趣的慢慢讀
 $ipFlag = fread($fd, 1);
 if($ipFlag == chr(1)) {
 $ipSeek = fread($fd, 3);
 if(strlen($ipSeek)  fclose($fd );
 return 'System Error';
 }
 $ipSeek = implode('', unpack('L', $ipSeek.chr(0)));
 fseek($fd, $ipSeek.chr(0)));
 fseek($fd, $ipSeek);
 $ipFlag = fread($fd, 1);
 }

 if($ipFlag == chr(2)) {
 $AddrSeek = fread($fd , 3);
 if(strlen($AddrSeek)  fclose($fd);
 return 'System Error';
 }
 $ipFlag = fread($fd , 1);
 if($ipFlag == chr(2)) {
 $AddrSeek2 = fread($fd, 3);
 if(strlen($AddrSeek2)  fclose($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($AddrSeek2)  fclose($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);

 //最後做對應的替換操作後回傳結果
 if(preg_match('/http/i', $ipAddr2)) {
 $ipAddr2 = '';
 }
 $ipaddr = "$ipAddr1 $ipAddr2";
 $ipaddr = preg_replace('/CZ88.Net/is', '', $ipaddr);
 $ipaddrdr = preg_replace('/^s*/is', '', $ipaddr);
 $ipaddr = preg_replace('/s*$/is', '', $ipaddr);
 if(preg_match( '/http/i', $ipaddr) || $ipaddr == '') {
 $ipaddr = '未知';
 }

 return $ipaddr;
}
header("內容類型：text/html; charset=utf-8");
$ip = $_SERVER['HTTP_X_FORWARDED_FOR'];
if(isset($_GET['q'])) {
 $ip = $_GET['q'];
 if(filter_var("http://".$ip,FILTER_VALIDATE_URL,FILTER_FLAG_HOST_REQUIRED)){
 $ip = gethostbyname($ip); 🎜> }
}
echo "$ip,".mb_convert_encoding(convertip($ip),"utf-8","gb2312");

?>