学步园

#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 ifreq ifr;
        
        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, "eth0: %s\n", inet_ntoa(sin.sin_addr));
        
        return 0;
}