#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/time.h>#include <sys/socket.h>#include <net/ethernet.h>#include <netinet/in_systm.h>#include <netinet/in.h>#include <netinet/ip.h>#include <netinet/ip_icmp.h>#include <getopt.h> //added for getopt()&&optarg,optind#define __FAVOR_BSD //due to some BSD style structure,tcphdr#include <netinet/tcp.h>#include <netinet/udp.h>#include <netinet/if_ether.h>#include <arpa/inet.h>#ifdef __linux#include <linux/sockios.h>#include <linux/if.h>#else#include <sys/ioctl.h>#include <net/bpf.h>#include <net/if.h>#include <fcntl.h>#endif#define MAXSIZE 4096#define OPTNUM 8#define ON 1#define OFF 0enum{ ETHER, ARP, IP, TCP, UDP, ICMP, DUMP, ALL };#ifdef __linuxint open_bpf (char *ifname);#endifvoid print_ethernet (struct ether_header *eth);void print_arp (struct ether_arp *arp);void print_ip (struct ip *ip);void print_icmp (struct icmp *icmp);void print_tcp (struct tcphdr *tcp);void print_udp (struct udphdr *udp);void dump_packet (unsigned char *buff, int len);char *mac_ntoa (u_char * d);char *tcp_ftoa (int flag);char *ip_ttoa (int flag);char *ip_ftoa (int flag);void help (char *cmd);struct ip *ip; //this structure can be used for allintmain (int argc, char *argv[]){	struct ether_header *eth;	struct ether_arp *arp;	//struct ip *ip;	struct icmp *icmp;	struct tcphdr *tcp;	struct udphdr *udp;	int s; //socket 	int len; //received len	int c; //char from getopt()	int disp; //flg of displaying on screen	char buff[MAXSIZE]; //recv buffer	char *p; //datagram header pointer 	char *p0; //datagram pointer	char ifname[256] = "x10"; //FreeBSD socket	int opt[OPTNUM]; //area flag	//extern int optind; //getopt() variable#ifndef __linux	int bpf_len; //len received from BPF	struct bpf_hdr *bp; //BPF header struct#endif	//init value of every type packet	//setbuf(stdout,NULL);	opt[ETHER] = OFF;	opt[ARP] = ON;	opt[IP] = ON;	opt[TCP] = ON;	opt[UDP] = ON;	opt[ICMP] = ON;	opt[DUMP] = OFF;	opt[ALL] = OFF;while ((c = getopt (argc, argv, "aei:p:dh") != EOF)) //command parameter process		{			switch (c)			{			case 'a': //all				{					opt[ALL] = ON;					break;				}			case 'i': //ifname 				{					strcpy (ifname, optarg);					break;				}			case 'e': //ethernet				{					opt[ETHER] = ON;					break;				}			case 'd': //dump 				{					opt[DUMP] = ON;					break;				}			case 'p': //protocol				{					opt[ARP] = OFF;					opt[IP] = OFF;					opt[TCP] = OFF;					opt[UDP] = OFF;					opt[ICMP] = OFF;					optind--;					while (argv[optind] != NULL && argv[optind][0] != '-')					{						if (strcmp (argv[optind], "arp" == 0)) //arp							opt[ARP] = ON;						else if (strcmp (argv[optind], "ip" == 0)) //ip							opt[IP] = ON;						else if (strcmp (argv[optind], "tcp" == 0)) //tcp							opt[TCP] = ON;						else if (strcmp (argv[optind], "udp" == 0)) //udp							opt[UDP] = ON;						else if (strcmp (argv[optind], "icmp" == 0)) //icmp							opt[ICMP] = ON;						else if (strcmp (argv[optind], "other" == 0)) //other							;						else						{							help (argv[0]);							exit (EXIT_FAILURE);						}						optind ;					}					break;				}			case 'h': //help			case '?':			default:				{					help (argv[0]);					exit (EXIT_FAILURE);					break;				}			}		} 	if (optind < argc)		{			while (optind < argc)			{				printf ("%s", argv[optind ]);			}			printf ("\n");				help (argv[0]);			exit (EXIT_FAILURE);		}#ifdef __linux		//***********open socket with promiscuous***************		if ((s = socket (AF_INET, SOCK_PACKET, htons (ETH_P_ALL))) < 0)			//if ((s = socket (AF_INET, SOCK_STREAM, 0)) < 0)		{			perror ("socket");				exit (EXIT_FAILURE);		}		if (strcmp (ifname, "x10") != 0)		{			struct sockaddr sa;			memset (&sa, 0, sizeof sa);			sa.sa_family = AF_INET;			strcpy (sa.sa_data, ifname);			if (bind (s, &sa, sizeof sa) < 0)			{				perror ("bind");					exit (EXIT_FAILURE);			}		}#else		if ((s = open_bpf (ifname)) < 0)		{			exit (EXIT_FAILURE);		}		bpf_len = 0;#endif 		 while (1)		{#ifndef __linux			//******input from UNIX bpf*******			if (bpf_len <= 0)			{				//*********get some packet at onece********				if ((bpf_len = read (s, buff, MAXSIZE)) < 0)				{					perror ("read");						exit (EXIT_FAILURE);				}				bp = (struct bpf_hdr *) buff;			}			else			{				//*********move the next bpf pointer*******				bp = (struct bpf hdr *) ((char *) bp+ bp->bh_hdrlen+ 					bp->bh_caplen);				bp = (struct bpf hdr *) BPF_WORDALIGN ((int) bp);			}			//*******init Ethernet header pointer********			p = p0 = (char *) bp+ bp->bh_hdrlen;			len = bp->bh_caplen;#ifdef DEBUG			//*******display BPF header struct***********							printf ("hdrlen=%d,", bp->bh_hdrlen);			printf ("caplen=%d,", bp->bh_caplen);			printf ("datalen=%d\n", bp->bh_datalen);#endif			//*******process unit before next while loop**			bpf_len -= BPF_WORDALIGN (bp->bh_hdrlen bp->bh_caplen);#else			//*******input from Linux SOCK_PACKET********			if ((len = read (s, buff, MAXSIZE)) < 0)			{				perror ("read");					exit (EXIT_FAILURE);			}			//*******init Ethernet header pointer*********			p = p0 = buff;#endif			//*******packet displaying process unit*******			disp = OFF; //flag of whether display on screen			//*******set the header of Ethernet's struct***			eth = (struct ether_header *) p;			p = p + sizeof (struct ether_header); //ethernet datagram pointer			if (ntohs (eth->ether_type) == ETHERTYPE_ARP) //arp packet			{				if (opt[ARP] == ON)				{					if (opt[ETHER] == ON)					{						print_ethernet (eth);					}					arp = (struct ether_arp *) p;					print_arp (arp);					disp = ON;				}			}  			else if ((ntohs (eth->ether_type) == ETHERTYPE_IP) && (eth->ether_dhost != eth->ether_shost)) //ip packet			{				ip = (struct ip *) p;				if (strcmp					(inet_ntoa (*(struct in_addr *) &(ip->ip_src)),					"127.0.0.1" != 0))				{					p = p + ((int) (ip->ip_hl) << 2);					if (opt[IP] == ON && opt[TCP] == OFF						&& opt[UDP] == OFF && opt[ICMP] == OFF)					{						if (opt[ETHER] == ON)						{							print_ethernet (eth);						}						print_ip (ip);						disp = ON;					}					switch (ip->ip_p)					{					case IPPROTO_TCP:						tcp = (struct tcphdr *) p;						p = p + ((int) (tcp->th_off) << 2);						if (opt[TCP] == ON)						{							if (opt[IP] == ON)							{								if (opt[ETHER] == ON)								{									print_ethernet(eth);																		}								print_ip (ip);							}							print_tcp (tcp);							disp = ON;						}						break;					case IPPROTO_UDP:						udp = (struct udphdr *) p;						p = p + sizeof (struct udphdr);						if (opt[UDP] == ON)						{							if (opt[IP] == ON)							{								if (opt[ETHER] == ON)								{									print_ethernet										(eth);								}								print_ip (ip);							}							print_udp (udp);							disp = ON;						}						break;					case IPPROTO_ICMP:						icmp = (struct icmp *) p;						p = p + sizeof (struct udphdr);						if (opt[ICMP] == ON)						{							if (opt[IP] == ON)							{								if (opt[ETHER] == ON)								{									print_ethernet										(eth);								}								print_ip (ip);							}							print_icmp (icmp);							disp = ON;						}						break;					default:						if (opt[ALL] == ON)						{							if (opt[IP] == ON)							{								if (opt[ETHER] == ON)								{									print_ethernet										(eth);								}								print_ip (ip);							}							printf ("IP Protocol : unknown\n");								disp = ON;						}						break;					}				} 				 else				{					if (opt[ALL] == ON)					{						if (opt[ETHER] == ON)						{							print_ethernet (eth);						}						printf ("Ethernet protocol:unknow\n");							disp = ON;					}				}				if (disp == ON)				{					if (opt[DUMP] == ON)					{						dump_packet (p0, len);					}					printf ("\n");				}			}		}		return EXIT_SUCCESS;}/************************************************convert mac add. to str************************************************/char *mac_ntoa (u_char * d){	static char str[50];	sprintf (str, "%02x:%02x:%02x:%02x:%02x:%02x",		d[0], d[1], d[2], d[3], d[4], d[5]);	return str;}/************************************************disp Ethernet header************************************************/voidprint_ethernet (struct ether_header *eth){	int type = ntohs (eth->ether_type); //Ethernet type	if (type <= 1500)	{		printf ("IEEE 802.3 Ethernet Frame:\n");	}	else	{		printf ("Ethernet Frame:\n");	}	printf (" ------------------------------------------ \n");		printf ("|Destination MAC Address: %      17s|\n",		mac_ntoa (eth->ether_dhost));	printf (" ------------------------------------------ \n");		printf ("|Source MAC Address:%            17s|\n",