Question

我的输入数据，例如：

$ip = '2001:db8::1428:54ab';
$prefix = 64; // 64 bits for addresses, 0 bits in addr ip

第一步，我使用inet_pton（$ ip）转换为bin表示
然后我需要删除最后64位，我该怎么做？当我回应inet_pton（$ ip）时，我得到了难以理解的乱语
，我认为我们需要使用inet_ntop函数来获取可读的十六进制地址

需要帮助！，如何通过擦除位来做这个逻辑，也许我需要使用另一个功能？ thansk！

Answer 1

难以理解的乱码是你要求的二进制数据： - ）

以下是执行/64的示例：

$address = '2001:db8:1234:abcd:aabb:ccdd:eeff:7711';

echo "Original: $address\n";

$address_bin = inet_pton($address);  
$address_hex = bin2hex($address_bin);
echo "Address (hex): $address_hex\n";

// Getting the /64 is easy because it is on a byte boundary  
$prefix_bin = substr($address_bin, 0, 8) . "\x00\x00\x00\x00\x00\x00\x00\x00";
$prefix_hex = bin2hex($prefix_bin);
echo "Prefix (hex):  $prefix_hex\n";

$prefix_str = inet_ntop($prefix_bin);
echo "Prefix: $prefix_str/64\n";

这会给你：

Original: 2001:db8:1234:abcd:aabb:ccdd:eeff:7711
Address (hex): 20010db81234abcdaabbccddeeff7711
Prefix (hex):  20010db81234abcd0000000000000000
Prefix: 2001:db8:1234:abcd::/64

如果你想要任意前缀长度，那就更难了：

$address = '2001:db8:1234:abcd:aabb:ccdd:eeff:7711';
$prefix_len = 61;

echo "Original: $address\n";

$address_bin = inet_pton($address);  
$address_hex = bin2hex($address_bin);
echo "Address (hex): $address_hex\n";

// If you want arbitrary prefix lengths it is more difficult
$prefix_bin = '';
$remaining_bits = $prefix_len;
for ($byte=0; $byte<16; ++$byte) {
  // Get the source byte
  $current_byte = ord(substr($address_bin, $byte, 1));

  // Get the bit-mask based on how many bits we want to copy
  $copy_bits = max(0, min(8, $remaining_bits));
  $mask = 256 - pow(2, 8-$copy_bits);

  // Apply the mask to the byte
  $current_byte &= $mask;

  // Append the byte to the prefix
  $prefix_bin .= chr($current_byte);

  // 1 byte = 8 bits done
  $remaining_bits -= 8;
}

$prefix_hex = bin2hex($prefix_bin);
echo "Prefix (hex):  $prefix_hex\n";

$prefix_str = inet_ntop($prefix_bin);
echo "Prefix: $prefix_str/$prefix_len\n";

这将显示：

Original: 2001:db8:1234:abcd:aabb:ccdd:eeff:7711
Address (hex): 20010db81234abcdaabbccddeeff7711
Prefix (hex):  20010db81234abc80000000000000000
Prefix: 2001:db8:1234:abc8::/61

PHP中前缀的IPv6转换

1 个答案: