获取网卡地址 mac or ip or net mask

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <netinet/in.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <arpa/inet.h>
#include <errno.h>

#define ETH_NAME "eth0"

int main()
{
int sock;
struct sockaddr_in sin;
struct sockaddr sa;
struct ifreq ifr;
unsigned char mac[6];

sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock == -1)
{
perror("socket");
return -1;
}

strncpy(ifr.ifr_name, ETH_NAME, IFNAMSIZ);
ifr.ifr_name[IFNAMSIZ - 1] = 0;

if (ioctl(sock, SIOCGIFADDR, &ifr) < 0)
{
perror("ioctl");
return -1;
}

memcpy(&sin, &ifr.ifr_addr, sizeof(sin));
fprintf(stdout, "%s ip: %s/n", ETH_NAME, inet_ntoa(sin.sin_addr));

memset(mac, 0, sizeof(mac));
if (ioctl(sock, SIOCGIFHWADDR, &ifr) < 0)
{
perror("ioctl");
return -1;
}

memcpy(&sa, &ifr.ifr_addr, sizeof(sin));
memcpy(mac, sa.sa_data, sizeof(mac));
fprintf(stdout, "%s mac: %.2X:%.2X:%.2X:%.2X:%.2X:%.2X/n", ETH_NAME, mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
return 0;
}