C++判断ip是否为保留ip

版权声明：长风原创 https://blog.csdn.net/u012846486/article/details/53031961

bool isReservedIp(const char *ip)
{
    static const char *address_blocks[] = {
        "0.0.0.0/8",
        "10.0.0.0/8",
        "100.64.0.0/10",
        "127.0.0.0/8",
        "169.254.0.0/16",
        "172.16.0.0/12",
        "192.0.0.0/24",
        "192.0.2.0/24",
        "192.88.99.0/24",
        "192.168.0.0/16",
        "198.18.0.0/15",
        "198.51.100.0/24",
        "203.0.113.0/24",
        "224.0.0.0/4",
        "240.0.0.0/4",
        "255.255.255.255/32"
    };

    static const int blk_nums = sizeof(address_blocks) / sizeof(*address_blocks);
    static __thread char buf[40];

    for (int i = 0; i < blk_nums; ++i) {
        strncpy(buf, address_blocks[i], sizeof(buf));
        char *pos = strchr(buf, '/');
        assert(pos != NULL);
        *pos = '\0';

        uint32_t val = ntohl(inet_addr(buf)); // little endian
        uint32_t msk = atoi(pos + 1);
        uint32_t offset = 32 - msk;

        uint32_t tar = ntohl(inet_addr(ip));

        if ((val >> offset) == (tar >> offset))
            return true;
    }

    return false;
}

bool isReservedIp(uint32_t ip) // little endian
{
    static const char *address_blocks[] = {
        "0.0.0.0/8",
        "10.0.0.0/8",
        "100.64.0.0/10",
        "127.0.0.0/8",
        "169.254.0.0/16",
        "172.16.0.0/12",
        "192.0.0.0/24",
        "192.0.2.0/24",
        "192.88.99.0/24",
        "192.168.0.0/16",
        "198.18.0.0/15",
        "198.51.100.0/24",
        "203.0.113.0/24",
        "224.0.0.0/4",
        "240.0.0.0/4",
        "255.255.255.255/32"
    };

    static const int blk_nums = sizeof(address_blocks) / sizeof(*address_blocks);
    static __thread char buf[40];

    for (int i = 0; i < blk_nums; ++i) {
        strncpy(buf, address_blocks[i], sizeof(buf));
        char *pos = strchr(buf, '/');
        assert(pos != NULL);
        *pos = '\0';

        uint32_t val = ntohl(inet_addr(buf)); // little endian
        uint32_t msk = atoi(pos + 1);
        uint32_t offset = 32 - msk;

        if ((val >> offset) == (ip >> offset))
            return true;
    }

    return false;
}