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C/C++ Source or Header  |  1999-07-26  |  3.6 KB  |  141 lines
  1. /*
  2.  *  libnet
  3.  *  arp.c - Utility routines for doing ARP resolution.
  4.  *
  5.  */
  6.  
  7. #if (HAVE_CONFIG_H)
  8. #include "../include/config.h"
  9. #endif
  10. #include "../include/libnet.h"
  11.  
  12. #if (RAW_IS_COOKED)
  13. #include <net/if_arp.h>
  14.  
  15. int
  16. libnet_query_arp(u_long ip, char *hwaddr, char *ebuf)
  17. {    
  18.     int fd;
  19.     struct arpreq arpreq;
  20.     struct sockaddr_in *query;
  21.     struct sockaddr *result;
  22.  
  23.     if ((fd=socket(PF_INET, SOCK_DGRAM, 0))==-1)
  24.     {
  25.         sprintf( ebuf, "socket: %s", strerror(errno));
  26.         return -1;
  27.     }
  28.  
  29.     memset(&arpreq, 0, sizeof arpreq);
  30.  
  31.     query=(struct sockaddr_in *)&arpreq.arp_pa;
  32.     result=(struct sockaddr *)&arpreq.arp_ha;
  33.  
  34.     query->sin_family=AF_INET;
  35.     query->sin_addr.s_addr=ip;
  36.     result->sa_family=AF_UNSPEC;
  37.  
  38.     if (ioctl(fd, SIOCGARP, (caddr_t)&arpreq)==-1)
  39.     {
  40.         sprintf( ebuf, "ioctl: %s", strerror(errno));
  41.         close(fd);
  42.         return -1;
  43.     }
  44.     memcpy(hwaddr, (void *)arpreq.arp_ha.sa_data, 6);
  45.  
  46.     close(fd);
  47.     return 0;
  48. }
  49.  
  50. /* Taken from get_mac.c */
  51.  
  52. int
  53. send_arp_request(u_long ip, u_char *device, char *ebuf)
  54. {
  55.     u_char *buf;
  56.     char errbuf[1024];
  57.     struct link_int *linkent;
  58.     struct ether_addr *dev_hwaddr;
  59.     u_long local_ip;
  60.     u_char *enet_dst="\xff\xff\xff\xff\xff\xff";
  61.     int n;
  62.  
  63.     if ((linkent=libnet_open_link_interface(device,errbuf))==NULL)
  64.     {
  65.         sprintf (ebuf,"libnet_open_link_interface: %s",errbuf);
  66.         return -1;
  67.     }
  68.  
  69.     if (libnet_init_packet(ARP_H + ETH_H, &buf) == -1)
  70.     {
  71.         sprintf (ebuf,"libnet_init_packet memory failure");
  72.         return -1;
  73.     }
  74.  
  75.     if ((dev_hwaddr = libnet_get_hwaddr(linkent, device, errbuf))==NULL)
  76.     {
  77.         sprintf(ebuf, "libnet_get_hwaddr: %s\n", errbuf);
  78.         return (-1);
  79.     }
  80.  
  81.     local_ip = htonl(libnet_get_ipaddr(linkent, device, errbuf));
  82.     if (!local_ip)
  83.     {
  84.         sprintf(ebuf, "libnet_get_ipaddr: %s\n", errbuf);
  85.         return (-1);
  86.     }
  87.  
  88.     libnet_build_ethernet(
  89.             enet_dst,               /* broadcast ethernet address */
  90.             dev_hwaddr->ether_addr_octet,    /* source ethernet address */
  91.             ETHERTYPE_ARP,          /* this frame holds an ARP packet */
  92.             NULL,                   /* payload */
  93.             0,                      /* payload size */
  94.             buf);                   /* packet header memory */
  95.  
  96.     libnet_build_arp(
  97.             ARPHRD_ETHER,           /* hardware address type */
  98.             ETHERTYPE_IP,           /* protocol address type */
  99.             ETHER_ADDR_LEN,         /* hardware address length */
  100.             4,                      /* protocol address length */
  101.             ARPOP_REQUEST,          /* packet type - ARP request */
  102.             dev_hwaddr->ether_addr_octet, /* source (local) ethernet address */
  103.             (u_char *)&local_ip,    /* source (local) IP address */
  104.             enet_dst,               /* target's ethernet address (broadcast) */
  105.             (u_char *)&ip,          /* target's IP address */
  106.             NULL,                   /* payload */
  107.             0,                      /* payload size */
  108.             buf + ETH_H);           /* packet header memory */
  109.  
  110.     n = libnet_write_link_layer(linkent, device, buf, ARP_H + ETH_H);
  111.     if (n == -1)
  112.     {
  113.         sprintf(ebuf, "libnet_write_link_layer failed\n");
  114.         return (-1);
  115.     }
  116.     libnet_close_link_interface(linkent);
  117.     libnet_destroy_packet(&buf);
  118.     return 0;
  119. }
  120.  
  121. int
  122. libnet_active_query_arp(u_long ip, char *hwaddr, u_char *device, char *ebuf)
  123. {    
  124.     int tries=3;
  125.  
  126.     while (tries--)
  127.     {
  128.         if (libnet_query_arp(ip,hwaddr,ebuf)!=-1)
  129.             return 0;
  130.  
  131.         send_arp_request(ip,device,ebuf);
  132.  
  133.         sleep(1);
  134.     }
  135.     return -1;
  136. }
  137.  
  138. #endif /* RAW_IS_COOKED */
  139.  
  140. /* EOF */
  141.