arp 相关

#include <sys/types.h>


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


#include <sys/ioctl.h>
#include <net/if.h>
#include <netinet/if_ether.h> 
#include <net/if_arp.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>


#define DEV_NAME "eth0"
//#define SIOCDARP    0x8953        /* delete ARP table entry    */


//#define SIOCGARP    0x8954        /* get ARP table entry        */


//#define SIOCSARP    0x8955        /* set ARP table entry        */




static int sd;


/* Delete an entry from the ARP cache. */
static int arp_del(char* ip)
{
 struct arpreq arpreq;
 struct sockaddr_in *sin;
 struct in_addr ina;
 int rc;
    
  printf("del arp entry for IP : %s\n", ip);
 
  /*you must add this becasue some system will return "Invlid argument"
    because some argument isn't zero*/
  memset(&arpreq, 0, sizeof(struct arpreq));


  sin = (struct sockaddr_in *) &arpreq.arp_pa;
  memset(sin, 0, sizeof(struct sockaddr_in));
  sin->sin_family = AF_INET;
  ina.s_addr = inet_addr(ip);
  memcpy(&sin->sin_addr, (char *)&ina, sizeof(struct in_addr));
        
  strcpy(arpreq.arp_dev, DEV_NAME);
  rc = ioctl(sd, SIOCDARP, &arpreq);
  if (rc < 0)
    {
      printf("%s\n", "del arp error...");
      return -1;
    }
  else
     printf("%s\n", "del arp success...");
  
  return 0;
}




void get_hw_addr (u_char *buf, char *str) 
{
 int i; 
 unsigned int p[6];
 
 i=sscanf(str, "%x:%x:%x:%x:%x:%x", &p[0],&p[1],&p[2],
                 &p[3],&p[4],&p[5]);        


 if (i != 6)
  {
   printf("%s\n","error parsing MAC");
   exit(1);
  }         
                
  for(i = 0; i<6; i++)
     buf[i] = p[i];
} 


/* Set an entry in the ARP cache. */
static int arp_set(char* ip, char* mac)
{
 struct arpreq arpreq;
 struct sockaddr_in *sin;
 struct in_addr ina;
 int flags;
 int rc;


 printf("set arp entry for IP:%s\tMAC:%s\n", ip, mac);
        
  /*you must add this becasue some system will return "Invlid argument"
    because some argument isn't zero*/
  memset(&arpreq, 0, sizeof(struct arpreq));
  sin = (struct sockaddr_in *) &arpreq.arp_pa;
  memset(sin, 0, sizeof(struct sockaddr_in));
  sin->sin_family = AF_INET;
  ina.s_addr = inet_addr(ip);
  memcpy(&sin->sin_addr, (char *)&ina, sizeof(struct in_addr));
  
  get_hw_addr((unsigned char*)arpreq.arp_ha.sa_data, mac);
  strcpy(arpreq.arp_dev, DEV_NAME);
  
  flags = ATF_PERM | ATF_COM;//note, must set flag, if not,you will get error


  arpreq.arp_flags = flags;
  
  rc = ioctl(sd, SIOCSARP, &arpreq);
  if (rc < 0)
    {
      printf("%s\n", "set arp error...");
      return -1;
    }
  else
     printf("%s\n", "set arp successfully");


  return 0;
}


static int arp_get(char* ip)
{
 struct arpreq arpreq;
 struct sockaddr_in *sin;
 struct in_addr ina;
 unsigned char *hw_addr;
 int rc;


  printf("Find arp entry for IP : %s\n", ip);
        
  /*you must add this becasue some system will return "Invlid argument"
    because some argument isn't zero*/


   memset(&arpreq, 0, sizeof(struct arpreq));


  sin = (struct sockaddr_in *) &arpreq.arp_pa;
  memset(sin, 0, sizeof(struct sockaddr_in));
  sin->sin_family = AF_INET;
  ina.s_addr = inet_addr(ip);
  memcpy(&sin->sin_addr, (char *)&ina, sizeof(struct in_addr));
        
  strcpy(arpreq.arp_dev, DEV_NAME);
  rc = ioctl(sd, SIOCGARP, &arpreq);
  if (rc < 0)
    {
      printf("%s\n", "Entry not available in cache...");
      return -1;
    }
  else
   {
     printf("%s\n", "entry has been successfully retreived");
     hw_addr = (unsigned char *) arpreq.arp_ha.sa_data;


     printf("HWAddr found : %02x:%02x:%02x:%02x:%02x:%02x\n", 
                hw_addr[0], hw_addr[1], hw_addr[2], hw_addr[3], hw_addr[4], hw_addr[5]);
    }
  return 0;
}
    
int main(int argc, char **argv)
{
 sd = socket(AF_INET, SOCK_DGRAM, 0);
 if (sd < 0)
  {
    perror("socket() error\n");
    exit(1);
   }
    
  if(strcmp(argv[1],"add")==0)
      arp_set(argv[2], argv[3]);
  else if(strcmp(argv[1],"del")==0)
      arp_del(argv[2]);
  else if(strcmp(argv[1], "get")==0)    
      arp_get(argv[2]);
 
  close(sd);
  return 0;    
}