一些网络相关的代码

check_special_ip.c

// 判断一个IP地址，是否属于以下网段：
// 10.0.0.0/8, 169.254.0.0/16, 172.16.0.0/12, 192.168.0.0/16, 224.0.0.0/4, 255.255.255.255/32, fc00::/7, fe80::/10, ff00::/8
#include <stdint.h>
#include <arpa/inet.h>

int is_special_ip(uint32_t ipv4) {
  uint8_t first_octet = ipv4 >> 24;

  if (first_octet == 10) return 1; 
  if (first_octet == 169 && (ipv4 & 0xFFFF0000) == 0xA9FE0000) return 1;
  if (first_octet == 172 && (ipv4 & 0xFFF00000) == 0xAC100000) return 1;
  if (first_octet == 192 && (ipv4 & 0xFFFF0000) == 0xC0A80000) return 1;
  if (first_octet >= 224 && first_octet <= 239) return 1;
  if (ipv4 == 0xFFFFFFFF) return 1;

  return 0;
}

int is_special_ip6(struct in6_addr *addr) {
  uint16_t *words = (uint16_t*)addr;

  if (words[0] == 0xFC00) return 1; 
  if (words[0] == 0xFE80) return 1;
  if (words[0] == 0xFF00) return 1;

  return 0; 
}