class ipCity {

/**
* 根据ip地址获取对应所在城市
* @param type $userip 用户IP地址
* @return string
*/
public function getCity( $userip,$dat_path = '' ) {
//IP数据库路径，这里用的是QQ IP数据库 20110405 纯真版
empty( $dat_path ) && $dat_path = FCPATH . 'plugin/ipLocation/qqwry/QQWry.Dat';
//判断IP地址是否有效
if ( preg_match( "/^([0-9]{1,3}.){3}[0-9]{1,3}$/",$userip ) == 0 ) {
return 'IP Address Invalid';
}
//打开IP数据库
if ( !$fd = @fopen( $dat_path,'rb' ) ) {
return 'IP data file not exists or access denied';
}
//explode函数分解IP地址，运算得出整数形结果
$userip = explode( '.',$userip );
$useripNum = $userip[0] * 16777216 + $userip[1] * 65536 + $userip[2] * 256 + $userip[3];
//获取IP地址索引开始和结束位置
$DataBegin = fread( $fd,4 );
$DataEnd = fread( $fd,4 );
$useripbegin = implode( '',unpack( 'L',$DataBegin ) );
if ( $useripbegin < 0 )
$useripbegin += pow( 2,32 );
$useripend = implode( '',$DataEnd ) );
if ( $useripend < 0 )
$useripend += pow( 2,32 );
$useripAllNum = ($useripend - $useripbegin) / 7 + 1;
$BeginNum = 0;
$EndNum = $useripAllNum;
//使用二分查找法从索引记录中搜索匹配的IP地址记录
while ( $userip1num > $useripNum || $userip2num < $useripNum ) {
$Middle = intval( ($EndNum + $BeginNum) / 2 );
//偏移指针到索引位置读取4个字节
fseek( $fd,$useripbegin + 7 * $Middle );
$useripData1 = fread( $fd,4 );
if ( strlen( $useripData1 ) < 4 ) {
fclose( $fd );
return 'File 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
$userip1num = implode( '',$useripData1 ) );
if ( $userip1num < 0 )
$userip1num += 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 ( $userip1num > $useripNum ) {
$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 'File Error';
}
$DataSeek = implode( '',$DataSeek . chr( 0 ) ) );
fseek( $fd,$DataSeek );
$useripData2 = fread( $fd,4 );
if ( strlen( $useripData2 ) < 4 ) {
fclose( $fd );
return 'File Error';
}
$userip2num = implode( '',$useripData2 ) );
if ( $userip2num < 0 )
$userip2num += pow( 2,32 );
//找不到IP地址对应城市
if ( $userip2num < $useripNum ) {
if ( $Middle == $BeginNum ) {
fclose( $fd );
return 'No Data';
}
$BeginNum = $Middle;
}
}
$useripFlag = fread( $fd,1 );
if ( $useripFlag == chr( 1 ) ) {
$useripSeek = fread( $fd,3 );
if ( strlen( $useripSeek ) < 3 ) {
fclose( $fd );
return 'System Error';
}
$useripSeek = implode( '',$useripSeek . chr( 0 ) ) );
fseek( $fd,$useripSeek );
$useripFlag = fread( $fd,1 );
}
if ( $useripFlag == chr( 2 ) ) {
$AddrSeek = fread( $fd,3 );
if ( strlen( $AddrSeek ) < 3 ) {
fclose( $fd );
return 'System Error';
}
$useripFlag = fread( $fd,1 );
if ( $useripFlag == chr( 2 ) ) {
$AddrSeek2 = fread( $fd,3 );
if ( strlen( $AddrSeek2 ) < 3 ) {
fclose( $fd );
return 'System Error';
}
$AddrSeek2 = implode( '',$AddrSeek2 . chr( 0 ) ) );
fseek( $fd,$AddrSeek2 );
} else {
fseek( $fd,-1,SEEK_CUR );
}
while ( ($char = fread( $fd,1 )) != chr( 0 ) )
$useripAddr2 .= $char;
$AddrSeek = implode( '',$AddrSeek . chr( 0 ) ) );
fseek( $fd,$AddrSeek );
while ( ($char = fread( $fd,1 )) != chr( 0 ) )
$useripAddr1 .= $char;
} else {
fseek( $fd,SEEK_CUR );
while ( ($char = fread( $fd,1 )) != chr( 0 ) )
$useripAddr1 .= $char;
$useripFlag = fread( $fd,1 )) != chr( 0 ) ) {
$useripAddr2 .= $char;
}
}
fclose( $fd );
//返回IP地址对应的城市结果
if ( preg_match( '/http/i',$useripAddr2 ) ) {
$useripAddr2 = '';
}
$useripaddr = "$useripAddr1 $useripAddr2";
$useripaddr = preg_replace( '/CZ88.Net/is','',$useripaddr );
$useripaddr = preg_replace( '/^s*/is',$useripaddr );
$useripaddr = preg_replace( '/s*$/is',$useripaddr );
if ( preg_match( '/http/i',$useripaddr ) || $useripaddr == '' ) {
$useripaddr = 'No Data';
} elseif ( !$this->is_utf8( $useripaddr ) ) {
$useripaddr = iconv( 'GBK','UTF-8',$useripaddr );
}
return $useripaddr;
}

/**
* 判断是否我utf-8编码的字符串
* @param type $string
* @return boolean
*/
private function is_utf8( $string ) {
if ( preg_match( "/^([" . chr( 228 ) . "-" . chr( 233 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}){1}/",$string ) == true || preg_match( "/([" . chr( 228 ) . "-" . chr( 233 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}){1}$/",$string ) == true || preg_match( "/([" . chr( 228 ) . "-" . chr( 233 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}[" . chr( 128 ) . "-" . chr( 191 ) . "]{1}){2,}/",$string ) == true ) {
return true;
} else {
return false;
}
}

}