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PHP判断是否中国大陆IP
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<?php | |
/* | |
需要存放IP段起止地址的二进制文件cnips.dat | |
*/ | |
/** | |
* 二分(折半)查找算法 | |
*/ | |
function binary_search($total, $callback) | |
{ | |
$args = func_get_args(); | |
array_shift($args); | |
$step = $total; | |
$offset = 0; | |
$sign = 1; | |
do { | |
$step = ceil($step / 2); | |
$offset += $sign * $step; | |
$args[0] = $offset; | |
$sign = call_user_func_array($callback, $args); | |
} while ($sign !== 0 && $step > 1); | |
return $sign === 0; | |
} | |
function compare_ip($offset, $ip, $fp) | |
{ | |
fseek($fp, ($offset - 1) * 8); | |
$start_ip = fread($fp, 4); //读取之后0-4个字节 | |
$end_ip = fread($fp, 4); //读取之后4-8个字节 | |
$sign = strcmp($ip, bin2hex($start_ip)); | |
if ($sign >= 0 && strcmp($ip, bin2hex($end_ip)) <= 0) { | |
return 0; //在IP段范围内(含两端) | |
} | |
else { //指出下次偏移的方向 | |
return $sign; | |
} | |
} | |
/** | |
* 是否中国大陆IP | |
*/ | |
function ip_in_china($ip_address) | |
{ | |
//IP段数据文件,每个IP表示成一个8位hex整数,不足8位的前面补0 | |
$datfile = 'cnips.dat'; | |
$total = floor(filesize($datfile) / 8); //IP段总数 | |
//将要判断的IP转为8位hex整数 | |
$ip = sprintf('%08x', ip2long($ip_address)); | |
$fp = fopen($datfile, 'rb'); | |
//比较IP并决定方向 | |
$result = binary_search($total, 'compare_ip', $ip, $fp); //请在这以后关闭文件 | |
fclose($fp); | |
return $result; | |
} |
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IP段起止地址的二进制文件cnips.dat 在哪里可以下载到呢