本文最后更新于 130 天前，其中的信息可能已经有所发展或是发生改变。
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netdb.h>
#include <arpa/inet.h>
int main(int argc, char *argv[])
{
if (argc != 2)
{
fprintf(stderr, "Usage: %s <domain>\n", argv[0]);
return 1;
}
struct addrinfo hints, *res, *p;
char ipstr[INET6_ADDRSTRLEN];
int status;
memset(&hints, 0, sizeof hints);
hints.ai_family = AF_UNSPEC; // 不限制 IPv4 或 IPv6，全部返回
hints.ai_socktype = SOCK_STREAM; // 通常设为 SOCK_STREAM，对地址解析不影响
if ((status = getaddrinfo(argv[1], NULL, &hints, &res)) != 0)
{
fprintf(stderr, "getaddrinfo error: %s\n", gai_strerror(status));
return 1;
}
printf("IP addresses for %s:\n", argv[1]);
for (p = res; p != NULL; p = p->ai_next)
{
void *addr;
char *ipver;
if (p->ai_family == AF_INET)
{ // IPv4
struct sockaddr_in *ipv4 = (struct sockaddr_in *)p->ai_addr;
addr = &(ipv4->sin_addr);
ipver = "IPv4";
}
else
{ // IPv6
struct sockaddr_in6 *ipv6 = (struct sockaddr_in6 *)p->ai_addr;
addr = &(ipv6->sin6_addr);
ipver = "IPv6";
}
inet_ntop(p->ai_family, addr, ipstr, sizeof ipstr);
printf("%s: %s\n", ipver, ipstr);
}
freeaddrinfo(res);
return 0;
}
