/**************************************************************************** ** File: ethernet.c**** Author: Mike Borella**** Comments: Dump ethernet packets*******************************************************************************/#include <stdio.h>#include <unistd.h>#include <pcap.h>#include <netinet/in.h>#include "ethernet.h"#include "config.h"u_char *packet_ptr;u_char *packet_end;extern struct arg_t *my_args;/*----------------------------------------------------------------------------**** dump_ethernet()**** Process packets from the DLT_EN10MB interface type****----------------------------------------------------------------------------*/void dump_ethernet(u_char *user, const struct pcap_pkthdr *h, u_char *p){  int length;   int caplen;  int ether_type;  EtherHdr *ep;  void dump_ip(u_char *, int);  void dump_ipx(u_char *, int);  void dump_arp(u_char *, int, int);  char *etheraddr_string(u_char *);  char *etherproto_string(u_short);  /*   * Get total packet length and length of the captured section   */  length = h->len;  caplen = h->caplen;  /*   * Dump header announcement   */  if (!my_args->l)    {      printf("=================================================================\n");      printf("                        Ethernet Header(%u.%06u)\n",	     (u_int32_t) h->ts.tv_sec, (u_int32_t) h->ts.tv_usec);      printf("-----------------------------------------------------------------\n");    }  /*   * Check for truncated header    */  if (caplen < sizeof(EtherHdr))     {      printf("Ethernet header too short! (%d bytes)\n", length);      return;    }  /*   * Dump header fields   */  ep = (EtherHdr *) p;    ether_type = ntohs(ep->ether_type);  if (!my_args->l)    {      printf("Hardware source:        %s\n", 	     etheraddr_string(ep->ether_src));      printf("Hardware destination:   %s\n", 	     etheraddr_string(ep->ether_dst));      printf("Protocol type:          %xH (%s)\n", ether_type, 	     etherproto_string(ep->ether_type));      printf("Length:                 %d\n", length+4); /* add FCS */    }   /*   * Some printers want to get back at the link level addresses,   * and/or check that they're not walking off the end of the packet.   * Rather than pass them all the way down, we set these globals.   */     packet_ptr = p;  packet_end = p + caplen;  /*   * Check for IEEE 802 (LLC) encapsulation.  If not, assume regular ethernet   */  p += sizeof(EtherHdr);  if (ether_type <= ETHERMTU)     {      /* XXX do something intelligent with LLC */    }  else     {      switch (ether_type)	{        case ETHERTYPE_IP:	  dump_ip(p, length);	  return;	case ETHERTYPE_ARP:        case ETHERTYPE_REVARP:	  dump_arp(p, length, caplen);	  return;	case ETHERTYPE_IPX:	  dump_ipx(p, length-sizeof(EtherHdr));	  return;        default:	  return;	  	}    } /* else */  if(my_args->f)    {      /* flush stdout */      fflush(stdout);    }}