获取本机ip地址

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

int main()
{
	int inet_sock;
	struct ifreq ifr;
	inet_sock = socket(AF_INET, SOCK_DGRAM, 0);
	char current_osd_ip[20];

	strcpy(ifr.ifr_name, "eth1");
	if (ioctl(inet_sock, SIOCGIFADDR, &ifr) < 0){
		perror("ioctl");
		
		strcpy(ifr.ifr_name, "eth0");
		if (ioctl(inet_sock, SIOCGIFADDR, &ifr) < 0){
			perror("ioctl");
			goto ip_error;
		}
	}
	strcpy(current_osd_ip, inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr));
	printf("\nValid IP address of this machine is: %s\n", inet_ntoa(((struct sockaddr_in*)&(ifr.ifr_addr))->sin_addr));

	return 0;
ip_error:
	printf("\nNO valid ip address on this machine...\n");
	return 0;
}