子网（C）中的所有IP [英] All IP's in a subnet (C)

问题描述

有人能很好地说明我如何使用带有CIDR的IP地址（例如 192.168.1.1/24 ）并返回其中的所有IP地址范围例如 192.168.1.1、192.168.1.2、192.168.1.3 ...

Does someone have a good example of a way I could take a IP address with a CIDR such as 192.168.1.1/24 and return all the ip addresses inside of that range such as 192.168.1.1, 192.168.1.2, 192.168.1.3 ...

我很好它以 unsigned long ， char 或类似

/* Pseudocode */
while(currnetip <= finalip) { 
    print(currnetip); 
    currnetip++; 
}

只要我能理解就可以了。

As long as I can understand it its fine.

如果您认为它可以帮助我，请随意评论帖子的链接。

Feel free to comment a link to a post if you think it could help me.

编辑：可能值得一提，我已经找到了我只是不确定如何将所有这些功能链接在一起。

Probably worth mentioning I've found lots of stuff that calculated the broadcast address ect I'm just not sure how to link all those functions together.

推荐答案

首先，将您的IPv4地址打包到 uint32_t （在< stdint.h> 中定义）中，将最左边的八位字节加点-将十进制表示法转换为最高有效位。例如，

First, pack your IPv4 address into an uint32_t (defined in <stdint.h>), putting the leftmost octet in dotted-decimal notation into the most significat bits. For example,

uint32_t ipv4_pack(const uint8_t octet1,
                   const uint8_t octet2,
                   const uint8_t octet3,
                   const uint8_t octet4)
{
    return (((uint32_t)octet1) << 24)
         | (((uint32_t)octet2) << 16)
         | (((uint32_t)octet3) <<  8)
         |  ((uint32_t)octet4);
}

及其反函数，

unsigned char *ipv4_unpack(unsigned char *addr, const uint32_t packed)
{
    addr[3] = (uint8_t)(packed);
    addr[2] = (uint8_t)(packed >> 8);
    addr[1] = (uint8_t)(packed >> 16);
    addr[0] = (uint8_t)(packed >> 24);
    return addr;
}

128.64.32.16 包装为 0x80402010 （128 == 80 16 ，64 == 40 16 ，32 == 20 16 ，和16 == 10 16 ）。

An address like 128.64.32.16 is packed into 0x80402010 (128 == 80₁₆, 64 == 40₁₆, 32 == 20₁₆, and 16 == 10₁₆).

您还需要将 CIDR 前缀大小（1到32）转换为二进制设置的那个最高位的掩码：

You need to also convert the CIDR prefix size (1 to 32) into a binary mask of that many highest bits set:

uint32_t ipv4_mask(const int prefix_size)
{
    if (prefix_size > 31)
        return (uint32_t)0xFFFFFFFFU;
    else
    if (prefix_size > 0)
        return ((uint32_t)0xFFFFFFFFU) << (32 - prefix_size);
    else
        return (uint32_t)0U;
}

前缀24对应于二进制掩码11111111111111111111111100000000，十六进制为0xFFFFFF00。

Prefix 24 corresponds to a mask of 11111111111111111111111100000000 in binary, and 0xFFFFFF00 in hexadecimal.

前缀28对应掩码为11111111111111111111111111111110000的掩码，十六进制为0xFFFFFFF0。

Prefix 28 corresponds to a mask of 11111111111111111111111111110000 in binary, and 0xFFFFFFF0 in hexadecimal.

对于地址 addr1.addr2.addr3.addr4 / prefix ，范围中的第一个地址（通常是该范围的网关地址）是

For address addr1.addr2.addr3.addr4/prefix, the first address in a range (typically the gateway address for said range) is

uint32_t first = ipv4_pack(addr1, addr2, addr3, addr4) & ipv4_mask(prefix);

最后一个地址（通常是该范围的广播地址）是

and the last address (typically the broadcast address for said range) is

uint32_t last = ipv4_pack(addr1, addr2, addr3, addr4) | (~ipv4_mask(prefix));

在所有情况下， first< = last ，然后从 first 迭代到 last （包括两端），并调用 ipv4_unpack（）将该值解压缩为点分十进制格式），将产生该范围内的所有IPv4地址。

In all cases, first <= last, and iterating from first to last, inclusive, and calling ipv4_unpack() to unpack the value into dotted-decimal notation), yields all IPv4 addresses within the range.

相同的方法适用于IPv6，但需要类似 uint128_t 类型的内容。 （当然，可以使用更小的无符号整数类型来模拟它，当然，它需要更多的指令，但是逻辑保持不变。）

The same would work for IPv6, but requires something like an uint128_t type. (It can be emulated with smaller unsigned integer types, of course, taking a few more instructions, but the logic stays the same.)

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