packet_capture

packet_capture.c

#include <stdio.h>
#include <linux/if_vlan.h>
#include <netinet/ether.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <arpa/inet.h>
#include <net/ethernet.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <linux/if.h>
#include <linux/if_packet.h>

#define BUFFER_SIZE 4096
#define VLAN_VID_MASK		0x0fff	/* VLAN Identifier */
struct vlan_header
{
  __be16 vlan_tci;
  __be16 vlan_proto;
};

int
main (int argc, char *argv[])
{
  int sock, ifindex, read_size;
  char *buffer;
  struct ifreq ifr;
  struct sockaddr_ll saddr;
  socklen_t saddr_size = sizeof (saddr);

  uint64_t length = 0;
  // create socket
  if ((sock = socket (AF_PACKET, SOCK_RAW, htons (ETH_P_ALL))) < 0)
    {
      perror ("socket()");
      exit (EXIT_FAILURE);
    }

  // get interface index
  strncpy (ifr.ifr_name, "enp4s0d1.100", IFNAMSIZ);
  if (ioctl (sock, SIOCGIFINDEX, &ifr) < 0)
    {
      perror ("ioctl()");
      exit (EXIT_FAILURE);
    }
  ifindex = ifr.ifr_ifindex;

  // get MAC address
  if (ioctl (sock, SIOCGIFHWADDR, &ifr) < 0)
    {
      perror ("ioctl()");
      exit (EXIT_FAILURE);
    }

  // bind to interface
  memset (&saddr, 0, sizeof (saddr));
  saddr.sll_family = AF_PACKET;
  saddr.sll_ifindex = ifindex;
  saddr.sll_protocol = htons (ETH_P_ALL);
  if (bind (sock, (struct sockaddr *) &saddr, sizeof (saddr)) < 0)
    {
      perror ("bind()");
      exit (EXIT_FAILURE);
    }

  // allocate buffer using mmap
  buffer =
    mmap (NULL, BUFFER_SIZE, PROT_READ | PROT_WRITE,
	  MAP_PRIVATE | MAP_ANONYMOUS | MAP_LOCKED, -1, 0);
  if (buffer == MAP_FAILED)
    {
      perror ("mmap()");
      exit (EXIT_FAILURE);
    }

  // receive packets
  while (1)
    {
      read_size =
	recvfrom (sock, buffer, BUFFER_SIZE, 0, (struct sockaddr *) &saddr,
		  &saddr_size);
      if (read_size < 0)
	{
	  perror ("recvfrom()");
	  exit (EXIT_FAILURE);
	}else {
		length += read_size;
		printf("total read %lu",length);
	}


      struct ethhdr *eth_header = (struct ethhdr *) buffer;

      // print source and destination MAC addresses
      //printf("Source MAC: %02X:%02X:%02X:%02X:%02X:%02X\n",
//                              eth_header->h_source[0], eth_header->h_source[1], eth_header->h_source[2],
//                              eth_header->h_source[3], eth_header->h_source[4], eth_header->h_source[5]);
      //printf("Destination MAC: %02X:%02X:%02X:%02X:%02X:%02X\n",
//                              eth_header->h_dest[0], eth_header->h_dest[1], eth_header->h_dest[2],
//                              eth_header->h_dest[3], eth_header->h_dest[4], eth_header->h_dest[5]);

      // parse IP header
      if (ntohs (eth_header->h_proto) == ETH_P_IP)
	{
	  struct iphdr *ip_header =
	    (struct iphdr *) (buffer + sizeof (struct ethhdr));
	  // Print the source IP address
	  // printf("Source IP address: %s\n", inet_ntoa(*(struct in_addr*)&ip_header->saddr));

	  // Print the destination IP address
	  //printf("Destination IP address: %s\n", inet_ntoa(*(struct in_addr*)&ip_header->daddr));

	  // parse TCP or UDP header
	  if (ip_header->protocol == IPPROTO_TCP)
	    {
	      struct tcphdr *tcp_header =
		(struct tcphdr *) (buffer + sizeof (struct ethhdr) +
				   sizeof (struct iphdr));
//                                      printf("Source port: %u\n", ntohs(tcp_header->source));
//                                      printf("Destination port: %u\n", ntohs(tcp_header->dest));
	    }
	  else if (ip_header->protocol == IPPROTO_UDP)
	    {
	      struct udphdr *udp_header =
		(struct udphdr *) (buffer + sizeof (struct ethhdr) +
				   sizeof (struct iphdr));
//                                      printf("Source port: %u\n", ntohs(udp_header->source));
//                                      printf("Destination port: %u\n", ntohs(udp_header->dest));
	    }
	  if (ntohs (eth_header->h_proto) == ETH_P_8021Q)
	    {
	      //struct vlan_tag *vlan_tag = NULL;
	      //vlan_tag = (struct vlan_tag *)(eth_header+1);
	      struct vlan_header *vlan_hdr =
		(struct vlan_header *) (eth_header + 1);

	      __be16 vlan_tci = vlan_hdr->vlan_tci;
	      int vlan_id = ntohs (vlan_tci) & VLAN_VID_MASK;
	      printf ("Received frame with VLAN ID %d\n", vlan_id);

	      //printf("Source MAC: %s\n", ether_ntoa((struct ether_addr *)eth_header->h_source));
	      //printf("Destination MAC: %s\n", ether_ntoa((struct ether_addr *)eth_header->h_dest));
	      //printf("VLAN ID: %d\n", ntohs(vlan_tag->vlan_id));
	    }
	  else
	    {
	      //printf ("Received proto %d\n", ntohs (eth_header->h_proto));
	    }
	}
    }


  if (read_size < 0)
    {

      perror ("recvfrom()");
      exit (EXIT_FAILURE);
    }

  close (sock);
  return 0;


}