error: ‘struct arphdr’ has no member named ‘ar_sha’

aniruddha.jagdale · 07-05-2015, 11:37 PM

I'm creating my own ARP header with below shown code, however this code ain't working, I get error message as struct arphdr has no member named ar_sha, ar_spa, ar_tha, ar_tpa. I've checked net/if_arp.h, these members are part of struct arphdr. Why i'm unable to use them?? Please assist.

Code:

#include<iostream>
#include<cstdlib>
#include<stdio.h>
#include<string.h>
#include<sys/types.h>
#include<arpa/inet.h>
#include<linux/if_arp.h>
#include<netinet/in.h>
#include<netinet/ether.h>
#include<netinet/arp.h>
#include<net/ethernet.h>
#include<net/if_arp.h>


int main()
{
  int rawsock;
  u_char *pckt;
  int const any=1;
  struct arphdr arp;
  struct sockaddr_in pk;

  arp.ar_hrd=htons(ARPHRD_ETHER);
  arp.ar_pro=htons(ETHERTYPE_IP);
  arp.ar_hln=6;
  arp.ar_pln=4;
  arp.ar_op=htons(ARPOP_REQUEST);
  arp.ar_sha=ether_aton("ss:ss:ss:ss:ss:ss");
  arp.ar_spa=inet_addr("192:168:32:128");
  arp.ar_tha=ether_aton("ff:ff:ff:ff:ff:ff");
  arp.arp_tpa=inet_addr("192.168.32.1"); 

  pckt=(u_char*)malloc(sizeof(arp));

  memcpy(pckt,&arp,sizeof(arp));
 
  pk.sin_family=AF_INET;
  pk.sin_addr.s_addr=arp.arp_spa;

  rawsock=socket(AF_INET,SOCK_RAW,IPPROTO_RAW);

  if(rawsock<0)
    perror("socket() failed:");

  if(setsockopt(rawsock,IPPROTO_IP,IP_HDRINCL,&any,sizeof(any))<0)
    perror("setsockopt() failed:");

  if(sendto(rawsock,pckt,sizeof(arp),0,(struct sockaddr *)&pk,sizeof(pk))<0)
    perror("sendto() failed:");

  return 0;
}

Code:

Output:
error: arphdr has no member named sha
error: arphdr has no member named spa
error: arphdr has no member named tha
error: arphdr has no member named tpa

a4z · 07-06-2015, 12:38 AM

struct arphdr does not have this members
ar_sha, ar_spa, ar_tha, arp_tpa
these are members of struct ether_arp (if_ether.h)

aniruddha.jagdale · 07-06-2015, 12:43 AM

net/if_arp.h says that ar_sha, ar_spa, ar_tha, arp_tpa are members of struct arphdr

1. http://www.scs.stanford.edu/histar/s...e/net/if_arp.h
2. http://unix.superglobalmegacorp.com/....h.html#arphdr

struct arphdr
{
unsigned short int ar_hrd; /* Format of hardware address. */
unsigned short int ar_pro; /* Format of protocol address. */
unsigned char ar_hln; /* Length of hardware address. */
unsigned char ar_pln; /* Length of protocol address. */
unsigned short int ar_op; /* ARP opcode (command). */
#if 0
/* Ethernet looks like this : This bit is variable sized
however... */
unsigned char __ar_sha[ETH_ALEN]; /* Sender hardware address. */
unsigned char __ar_sip[4]; /* Sender IP address. */
unsigned char __ar_tha[ETH_ALEN]; /* Target hardware address. */
unsigned char __ar_tip[4]; /* Target IP address. */
#endif
};

Can you please assist understanding this?

a4z · 07-06-2015, 02:57 AM

#if 0
...
#endif
it the same as commenting the code in between out
so it's comentet out, in both of you headers.

what do you want to write, an arp sniffer?

aniruddha.jagdale · 07-06-2015, 03:07 AM

Yeah.. I took a note of that. Now the question is how to access those members or assign them the values. I don't want to write a sniffer, but a simple code that can inject or send manipulated ARP packet. Besides, why those members are mentioned in struct arphdr if the are to be commented or not to be used?

a4z · 07-06-2015, 03:44 AM

Quote:

Originally Posted by aniruddha.jagdale

Now the question is how to access those members or assign them the values.

you can not access or assign values to something that does not exist

possible you look for struct ether_arp from
http://www.scs.stanford.edu/histar/s...net/if_ether.h
because there are your members