mac broadcast flooding

#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <netdb.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <sys/un.h>
#include <netdb.h>
#include <sys/ioctl.h>
#include <stdarg.h>
#include <net/if.h>
#include <netinet/ip.h>
#define __FAVOR_BSD
#include <netinet/tcp.h>
#define ETH_P_ARP 0x0806
#define MAX_PACK_LEN 2000
#define ETHER_HEADER_LEN 14
#define ARPREQUEST 1
#define ARPREPLY 2
#define perr(s) fprintf(stderr,s)

struct arp_struct
{
 u_char dst_mac[6];
 u_char src_mac[6];
 u_short pkt_type;
 u_short hw_type;
 u_short pro_type;
 u_char hw_len;
 u_char pro_len;
 u_short arp_op;
 u_char sender_eth[6];
 u_char sender_ip[4];
 u_char target_eth[6];
 u_char target_ip[4];
};
union
{
 u_char full_packet[MAX_PACK_LEN];
 struct arp_struct arp_pkt;
}
a;
#define full_packet a.full_packet
#define arp_pkt a.arp_pkt
void get_hw_addr (char *, char *);
char *
inetaddr ( u_int32_t ip )
{
 struct in_addr in;
 in.s_addr = ip;
 return inet_ntoa(in);
}
char *
hwaddr (u_char * s)
{
 static char buf[30];
 sprintf (buf, "%02X:%02X:%02X:%02X:%02X:%02X", s[0], s[1], s[2], s[3], s[4], s[5]);
 return buf;
}
int 
main (int argc, char **argv)
{
 int rec;
 int len, from_len, rsflags;
 struct ifreq if_data;
 struct sockaddr from;
 u_int8_t myMAC[6];
 u_int32_t myIP, myNETMASK, myBROADCAST, ip, dip, sip;
 char * macaddr;
 if (getuid () != 0)
 {
 perr ("You must be root to run this program!\n");
 exit (0);
 }
 if (argc != 2)
 {
 fprintf(stderr,"Usage: %s Macaddr\n", argv[0]);
 exit (0);
 } 
 if ((rec = socket (AF_INET, SOCK_PACKET, htons (ETH_P_ARP))) < 0)
 {
 perror("socket");
 exit (0);
 }
 printf ("----------------------------------------------------------\n");
 strcpy (if_data.ifr_name, "eth0");
 if (ioctl (rec, SIOCGIFHWADDR, &if_data) < 0) {
 perr ("can't get HW addres of my interface!\n");
 exit(1);
 } //if (ioctl (rec, SIOCGIFHWADDR, &if_data) < 0) 
 memcpy (myMAC, if_data.ifr_hwaddr.sa_data, 6);
 printf ("> My HW Addr: %s\n", hwaddr (myMAC));
 if (ioctl (rec, SIOCGIFADDR, &if_data) < 0) {
 perr ("can't get IP addres of my interface!\n");
 exit(1);
 } //if (ioctl (rec, SIOCGIFADDR, &if_data) < 0) 
 memcpy ((void *) &ip, (void *) &if_data.ifr_addr.sa_data + 2, 4);
 myIP = ntohl (ip); //change ip to spoof
 printf ("> My IP Addr: %s\n", inetaddr(ip));
 if (ioctl (rec, SIOCGIFNETMASK, &if_data) < 0)
 perr ("can't get NETMASK addres of my interface!\n");
 memcpy ((void *) &ip, (void *) &if_data.ifr_netmask.sa_data + 2, 4);
 myNETMASK = ntohl (ip);
 printf ("> My NETMASK: %s\n", inetaddr(ip));
 if (ioctl (rec, SIOCGIFBRDADDR, &if_data) < 0)
 perr ("can't get BROADCAST addres of my interface!\n");
 memcpy ((void *) &ip, (void *) &if_data.ifr_broadaddr.sa_data + 2, 4);
 myBROADCAST = ntohl (ip);
 printf ("> My BROADCAST: %s\n", inetaddr(ip));
 if ((rsflags = fcntl (rec, F_GETFL)) == -1)
 {
 perror ("fcntl F_GETFL");
 exit (1);
 } 
 if (fcntl (rec, F_SETFL, rsflags | O_NONBLOCK) == -1)
 {
 perror ("fcntl F_SETFL");
 exit (1);
 }
 printf ("----------------------------------------------------------\n");
 printf ("Scanning");
 for (dip = (myIP & myNETMASK) + 1; dip < myBROADCAST; dip++)
 {
 bzero(full_packet, MAX_PACK_LEN);
 //memcpy (arp_pkt.dst_mac,"\255\255\255\255\255\0", 6); 
 memcpy (arp_pkt.dst_mac, "\xff\xff\xff\xff\xff\xff", 6); 
 //get_hw_addr(arp_pkt.dst_mac,"FF:FF:FF:FF:FF:FF");
 /* ff:ff:ff:ff:ff:ff:)*/
 memcpy (arp_pkt.src_mac, myMAC, 6);
 arp_pkt.pkt_type = htons( ETH_P_ARP );
 arp_pkt.hw_type = htons( 0x0001 );
 arp_pkt.hw_len = 6;
 arp_pkt.pro_type = htons( 0x0800 );
 arp_pkt.pro_len = 4;
 arp_pkt.arp_op = htons (ARPREQUEST);
 memcpy (arp_pkt.sender_eth, myMAC, 6);
 ip = htonl (myIP);
 memcpy (arp_pkt.sender_ip, &ip, 4);
 memcpy (arp_pkt.target_eth, "\0\0\0\0\0\0", 6);
 ip = htonl (dip);
 memcpy (arp_pkt.target_ip, &ip, 4);
 strcpy(from.sa_data, "eth0");
 from.sa_family = 1;
 if( sendto (rec, full_packet, sizeof (struct arp_struct), 0, &from,sizeof(from)) < 0)
 perror ("sendto");
 usleep (50);
 len = recvfrom (rec, full_packet, MAX_PACK_LEN, 0, &from, &from_len);
 if (len <= ETHER_HEADER_LEN)
 continue;
 memcpy (&ip, arp_pkt.target_ip, 4);
 memcpy (&sip, arp_pkt.sender_ip, 4);

 if (ntohs (arp_pkt.arp_op) == ARPREPLY
 && ( dip - ntohl(sip) >= 0 )
 && ( dip - ntohl(sip) <= 2 ) )
 {
 macaddr=hwaddr(arp_pkt.sender_eth);
 if (!strncmp(macaddr,argv[1],17))
 {
 printf ("\nMAC: %s ---------> HOST: %s \n",macaddr,inetaddr (sip));
 exit(0);
 } 
 } 
 else
 printf("."),fflush(stdout);
 } 
 printf ("End\n");
 return;
} 

void get_hw_addr (char *buf, char *str)
{
 int i;
 char c, val;
 for(i = 0; i < 6; i++)
 {
 if (!(c = tolower(*str++)));
 if (isdigit(c))
 val = c - '0';
 else if (c >= 'a' && c <= 'f')
 val = c-'a'+10;
 *buf = val << 4;
 if (!(c = tolower(*str++)));
 if (isdigit(c))
 val = c - '0';
 else if (c >= 'a' && c <= 'f')
 val = c-'a'+10;
 *buf++ |= val;
 if (*str == ':')
 str++;
 } 
}