#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <pcap.h>

void die()
{
    exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
    int sock;
    char errbuf[PCAP_ERRBUF_SIZE], *dev = NULL;
    bpf_u_int32 network, netmask;
    struct in_addr netmask_ip, network_ip;
    struct ifreq hw;

    if(argc < 2)
    {
	if((dev = pcap_lookupdev(errbuf)) == NULL)
	    die(printf("[!] %s\n",errbuf));
	printf("[+] No device passed as argument, using default device: %s\n",dev);
    }

    if(dev == NULL)
	dev = strdup(argv[1]);

    if(pcap_lookupnet(dev,&network,&netmask,errbuf) == -1) /* per avere netmask e network facilmente */
	die(printf("[!] %s\n",errbuf));

    if((sock = socket(AF_INET,SOCK_STREAM,0))<0) /* socket per comunicare con ioctl */
	die(printf("[!] %s\n",strerror(errno)));

    memcpy(hw.ifr_name,dev,strlen(dev));  /* Nome dell'interfaccia di rete in hw.ifr_name */
    hw.ifr_addr.sa_family = AF_INET; /* Utilizza la famiglia di indirizzi di tipo AF_INET */

    if((ioctl(sock,SIOCGIFHWADDR,&hw)) == -1) /* Richiesta: SIOCGIFHWADDR, per avere il MAC in hw.ifr_hwaddr.sa_data[14] */
	die(printf("[!] %s\n",strerror(errno)));

    netmask_ip.s_addr = netmask; /* lo diamo in pasto ad una struct in_addr per la inet_ntoa successiva */
    network_ip.s_addr = network; /* ^ */

    printf("%s\nMAC: %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\nNetmask: %s\n",
	    dev,
	    (unsigned int) hw.ifr_hwaddr.sa_data[0],
	    (unsigned int) hw.ifr_hwaddr.sa_data[1],
	    (unsigned int) hw.ifr_hwaddr.sa_data[2],
	    (unsigned int) hw.ifr_hwaddr.sa_data[3],
	    (unsigned int) hw.ifr_hwaddr.sa_data[4],
	    (unsigned int) hw.ifr_hwaddr.sa_data[5],
	    inet_ntoa(netmask_ip));

    printf("Network: %s\n",inet_ntoa(network_ip));
    close(sock);
    free(dev);
    return EXIT_SUCCESS;
}