Problem writing a packet to the network.

[Amith <amith@multitech.co.in>]

hi all,
             i tried  to write a packet (for fun) in ARP format (which 
i build) to the network - i wrote this code below with help looking at 
the man pages for "packet". I could read ARP packets but when i tried to 
write one - the code fails - i get an error message printed by perror 
which says
" Write failed :No such device or address"
Could somebody point out what i have missed out . The arp.h header file 
is mine and have pasted its contents below.
Thank you.
-Amith


#include <sys/socket.h>
#include <features.h>    /* for the glibc version number */
#if __GLIBC__ >= 2 && __GLIBC_MINOR >= 1
#include <netpacket/packet.h>
#include <net/ethernet.h>     /* the L2 protocols */
#else
#include <asm/types.h>
#include <linux/if_packet.h>
#include <linux/if_ether.h>   /* The L2 protocols */
#endif
#include<errno.h>
#include<arp.h> /* My include file */

struct Packet{
  struct Ethernet_Header ether;
  struct Arp_Header      arp;
};


int Int(unsigned char temp)
{
    int x=1;
    int total=0;
    int count = 0;
    while(count < 8)
    {
   total = total + ( (temp & 0x01) * ( (x) ) );      temp  = temp >> 1;
   x = x * 2;
   count++;
    }
return total;
}

void Print_Arp_Packet(struct Packet *pkt);
void Send_Arp_Packet(struct Packet *pkt);


struct Packet *pkt;

unsigned char buffer[1000];
int arp_counter,tcp_counter;

int socket_type = SOCK_RAW;
int protocol;
int len=0;
int packet_socket;

int
main()
{

     protocol = htons(ETH_P_ALL);
     packet_socket = socket(PF_PACKET,  socket_type,  protocol);

     if(packet_socket <= 0)
     {
         perror("could not create socket");
         exit(1);
     }
     printf("\n packet socket created \n");

     while( 1 )
     {
        int count=0;
        printf("========================================= \n");
        len = read(packet_socket,buffer,sizeof(buffer));
        pkt = (struct Packet *)buffer;
                                                                     
if((pkt->ether.type[0] == 0X08) && (pkt->ether.type[1] ==0x06)) /* check 
for ARP Packet */
       {
       printf("ARP :");
       Print_Arp_Packet(pkt);
       Send_Arp_Packet(pkt);
       }
                   }
}
   
    void Print_Arp_Packet(struct Packet *pkt)
{
printf(" MAC Adrres:Dest: %X:%X:%X:%X:%X:%X   
",pkt->ether.dest_addr[0],         pkt->ether.dest_addr[1],     
pkt->ether.dest_addr[2], \
pkt->ether.dest_addr[3], pkt->ether.dest_addr[4], \
pkt->ether.dest_addr[5]);

printf(" MAC Adrres : Src : 
%X:%X:%X:%X:%X:%X\n",pkt->ether.source_addr[0], \
pkt->ether.source_addr[1], pkt->ether.source_addr[2], \
pkt->ether.source_addr[3], pkt->ether.source_addr[4], \
pkt->ether.source_addr[5]);
}     
void Send_Arp_Packet(struct Packet *pkt)
{
struct Packet temp;    pkt->ether.dest_addr[0] = 
pkt->ether.source_addr[0]; /* had set this to 0xFFFFFFFFFFFF initially 
even that                                   
                                                               failed*/
pkt->ether.dest_addr[1] = pkt->ether.source_addr[1];
pkt->ether.dest_addr[2] = pkt->ether.source_addr[2];
pkt->ether.dest_addr[3] = pkt->ether.source_addr[3];
pkt->ether.dest_addr[4] = pkt->ether.source_addr[4];
pkt->ether.dest_addr[5] = pkt->ether.source_addr[5];

  pkt->ether.source_addr[0] = 0x00;
pkt->ether.source_addr[1] = 0x50;
pkt->ether.source_addr[0] = 0xBA;   /* my MAC Address */
pkt->ether.source_addr[0] = 0x88;
pkt->ether.source_addr[0] = 0x15;
pkt->ether.source_addr[0] = 0xF9;

pkt->ether.type[0] = 0x08;               /* Setting it to 0X0806 - > 
arp prot type */
pkt->ether.type[1] = 0x06;
pkt->arp.Opcode[1] = 0x02;

memcpy((void *) &temp, (void *) pkt, sizeof(temp));
len = write(packet_socket,&temp,sizeof(temp));
if(len < 0)
{
    perror("Write failed ");
    exit(0);
}
printf(" Write success len = %d \n",len);
}


/* Write failed : No such device or address */

/* arp.h 's contents */


struct Ethernet_Header {
  unsigned char   dest_addr[6];
  unsigned char source_addr[6];
  unsigned char        type[2];
};

struct Arp_Header {
  unsigned char   Hardware_Type[2];   /* 0x0001 - Ethernet   */
  unsigned char   Protocol_Type[2];   /* 0x0008 - IP */
  unsigned char   Hardware_Size[1];   /* 0X06   - 6 byte ethernet addr */
  unsigned char   Protocol_Size[1];   /* 0x04   - 4 byte ip address */
  unsigned char          Opcode[2];   /* 0x0001  - request */
  unsigned char Sender_MAC_Addr[6];
  unsigned char  Sender_IP_Addr[4];
  unsigned char Target_MAC_Addr[6];
  unsigned char  Target_IP_Addr[4];
};




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