与C linux中的ipv6范围相比，如何查找ipv4地址的范围名称（链接，主机和全局）

Question

Here i am not talking about the scope id its about the scope name (host, link, site or global). How to compare/get scopes of ipv4 address as well as for ipv6.

Answer 1

直接解决方案是将地址与Wikipedia上此列表中的前缀进行比较。

Answer 2

To match my IP6 answer : however as noted IP4 the classifications are a recommendation that have been enshrined in the IP6 protocol so not completely equivalent.

There are helper macros to assist:

#define IN_LINKLOCAL(i) (((uint32_t)(i) & 0xffff0000) == 0xa9fe0000)
#define IN_PRIVATE(i)   ((((uint32_t)(i) & 0xff000000) == 0x0a000000) || \
                         (((uint32_t)(i) & 0xfff00000) == 0xac100000) || \
                         (((uint32_t)(i) & 0xffff0000) == 0xc0a80000))

struct sockaddr_in s4;
if (IN_LOOPBACK(ntohl(s4->sin_addr.s_addr)) {
  puts ("loopback");
} else if (IN_MULTICAST(ntohl(s4->sin_addr.s_addr)) {
  puts ("multicast");
} else if (IN_BADCLASS(ntohl(s4->sin_addr.s_addr)) {
  puts ("reserved");
} else if (IN_LINKLOCAL(ntohl(s4->sin_addr.s_addr)) {
  puts ("link-local");
} else if (IN_PRIVATE(ntohl(s4->sin_addr.s_addr)) {
  puts ("private");
} else {
  puts ("global");
}