/********************************************************/
/* Ethernet driver access via raw socket                */
/*                                                      */
/* Paulo Pedreiras, Out.2005                            */
/*                                                      */
/* RCAI 05/06                                           */
/********************************************************/


/* Includes */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <math.h>
#include <string.h>
#include <sys/time.h>
#include <ctype.h>


#include <signal.h>
#include <sys/ioctl.h>

#include <sys/socket.h>
#include <netinet/in.h>

#include <linux/if.h>
#include <netpacket/packet.h>
#include <net/ethernet.h>     /* the L2 protocols */
#include <asm/types.h>


/* Defines */
#define DEVICE "eth0"
#define ETH_TYPE_FIELD 	0x8FF0
#define D_SIZE 100 /* Data size of messages to send */


/* Global Vars */
int s = 0; // Socket descriptor
struct sockaddr_ll socket_address;

unsigned char src_mac[6];		/*Local host NIC MAC address*/
unsigned char bcast_mac[6] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};	/*Brodacast address - all 1's*/

void * buffer = NULL;

/* Function prototypes */
void sigint(int signum);
int eth_raw_init();


/**************************/
/*       Main             */
/**************************/

int main(int argc, char **argv) 
{

  
  int op_mode;
  int i;

  unsigned char* eth_head;	/* byte pointer to ethenet header*/
  unsigned char* eth_data;	/* byte pointer to ethernet data field*/
  struct ethhdr *eh;            /* structured pointer to ethernet header*/
   

  /* Check input parameters */
  if(argv[1] != NULL) 
    if(argv[1][0] > 'Z')
      op_mode = argv[1][0]-('a'-'A');
  
  if(argc != 2 || (op_mode != 'S' && op_mode != 'R'))
    {
      printf("\n Usage: raw-sr {s,r} ");
      printf("\n     s: send packets");
      printf("\n     r: receive packets");
      printf("\n");
      exit(0);
    }
  
  /* Create socket */
  eth_raw_init();
  
  /* Prepare data structures */
  /* Ethernet frame: Target MAC (6)+ Src MAC(6) + Type (6)+ Data(+Padd)(46..1500) + CRC (4) */
  buffer = (void*)malloc(ETHER_MAX_LEN); /* Buffer for ethernet frame (maximum size)*/
  eth_head = buffer;                     /* eth_head points to beginning of buffer (ethernet header fields) */
  eth_data = buffer + ETH_HLEN;          /* eth_data points to data field of the ethernet frame */
  eh = (struct ethhdr *)eth_head;
  
  
  if(op_mode == 'S'){
    /*Send packets ....*/
    printf("Sending packets...\n");
    while(1) {
      
      /* Build ethernet header*/
      memcpy((void *)eh->h_dest,(void*)bcast_mac, ETH_ALEN);
      memcpy((void *)eh->h_source,(void*)src_mac, ETH_ALEN);
      eh->h_proto = htons(ETH_TYPE_FIELD);
      
      /*Put data ....*/
      for (i = 0; i < D_SIZE; i++) eth_data[i] = 'a'+i%10;
      
      /*Send packet*/
      i = sendto(s, buffer, D_SIZE+ETHER_HDR_LEN, 0, (struct sockaddr*)&socket_address, sizeof(socket_address));
      if (i == -1) {
	perror("sendto():");
	exit(1);
      }
      
      sleep(1); /* Pause 1 second */
      
    }
  }
  else {
    /* op_mode == R -> receive packets */
    while(1){
      
      /*Wait for incoming packet...*/
      i = recvfrom(s, buffer, ETHER_MAX_LEN, 0, NULL, NULL);
      if (i == -1) {
	perror("recvfrom():");
	exit(1);
      }
      
      /* Process packet */
      if(eh->h_proto == ntohs(ETH_TYPE_FIELD)){
	printf("\n Packet received from ");
	for(i=0;i<5;i++)
	  printf(":%02X",eh->h_source[i]);
	
	printf("\n First 20 data bytes):");
	for(i=0;i<20;i++)
	  printf("%c", eth_data[i]);
      }
    }
    
  }
  
  return 0;
  
}


/* Function implementation */

/***************************************/
/* eth_raw_init()                      */
/***************************************/
int eth_raw_init()
{
  
  /* Vars */
  int i;
  struct ifreq ifr;
  int ifindex = 0;			/*Ethernet Interface index*/
  
  /* Open socket */
  s = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
  if (s == -1) {
    perror("socket():");
    exit(1);
  }
  printf("Successfully opened socket: %i\n", s);
  
  /*Get ethernet interface index*/
  strncpy(ifr.ifr_name, DEVICE, IFNAMSIZ);
  if (ioctl(s, SIOCGIFINDEX, &ifr) == -1) {
    perror("SIOCGIFINDEX");
    exit(1);
  }
  ifindex = ifr.ifr_ifindex;
  printf("Successfully got interface index: %i\n", ifindex);
  
  /*retrieve corresponding MAC*/
  if (ioctl(s, SIOCGIFHWADDR, &ifr) == -1) {
    perror("SIOCGIFINDEX");
    exit(1);
  }
  for (i = 0; i < 6; i++) {
    src_mac[i] = ifr.ifr_hwaddr.sa_data[i];
  }
  printf("Host MAC address: %02X:%02X:%02X:%02X:%02X:%02X\n", 
	 src_mac[0],src_mac[1],src_mac[2],src_mac[3],src_mac[4],src_mac[5]);
  
  /*prepare sockaddr_ll*/
  socket_address.sll_family   = PF_PACKET;
  socket_address.sll_protocol = htons(ETH_TYPE_FIELD);
  socket_address.sll_ifindex  = ifindex;
  //socket_address.sll_hatype   = ARPHRD_ETHER;
  socket_address.sll_pkttype  = PACKET_BROADCAST;
  socket_address.sll_halen    = ETH_ALEN;
  socket_address.sll_addr[0]  = bcast_mac[0];
  socket_address.sll_addr[1]  = bcast_mac[1];
  socket_address.sll_addr[2]  = bcast_mac[2];
  socket_address.sll_addr[3]  = bcast_mac[3];
  socket_address.sll_addr[4]  = bcast_mac[4];
  socket_address.sll_addr[5]  = bcast_mac[5];
  socket_address.sll_addr[6]  = 0x00; 
  socket_address.sll_addr[7]  = 0x00;
														
  
  /*establish signal handler*/
  signal(SIGINT, sigint);
  printf("Successfully established signal handler for SIGINT\n");
  
  return 0;
  
}

void sigint(int signum) {
	/*Clean up.......*/

	struct ifreq ifr;
	
        if (s == -1)
	  return; /* No socket has beeen created */
	
	strncpy(ifr.ifr_name, DEVICE, IFNAMSIZ);
	ioctl(s, SIOCGIFFLAGS, &ifr);
	ifr.ifr_flags &= ~IFF_PROMISC;
	ioctl(s, SIOCSIFFLAGS, &ifr);
	close(s);

	free(buffer);
	
	printf("Client terminating....\n");


	exit(0);
}