rarp.c

   1 /*
   2  * rarp               This file contains an implementation of the command
   3  *              that maintains the kernel's RARP cache.  It is derived
   4  *              from Fred N. van Kempen's arp command.
   5  *
   6  * Version:     $Id: rarp.c,v 1.6 2001/04/08 17:05:05 pb Exp $
   7  *
   8  * Usage:       rarp -d hostname                      Delete entry
   9  *              rarp -s hostname ethernet_address     Add entry
  10  *              rarp -a                               Print entries
  11  *              rarp -f                               Add frop /etc/ethers
  12  *
  13  * Rewritten: Phil Blundell <Philip.Blundell@pobox.com>  1997-08-03
  14  * gettext instead of catgets: Arnaldo Carvalho de Melo <acme@conectiva.com.br> 1998-06-29
  15  * 1998-01-01 Bernd Eckenfels   reorganised usage()
  16  * 2001-04-04 Arnaldo Carvalho de Melo - use setlocale
  17  *
  18  */
  19
  20 #include <sys/types.h>
  21 #include <sys/socket.h>
  22 #include <sys/ioctl.h>
  23 #include <netinet/in.h>
  24 #include <arpa/inet.h>
  25 #include <net/if.h>
  26 #include <net/if_arp.h>
  27 #include <stdlib.h>
  28 #include <stdio.h>
  29 #include <errno.h>
  30 #include <fcntl.h>
  31 #include <netdb.h>
  32 #include <string.h>
  33 #include <unistd.h>
  34 #include <getopt.h>
  35
  36 #define DFLT_HW "ether"
  37
  38 #include "config.h"
  39 #include "intl.h"
  40 #include "net-support.h"
  41 #include "version.h"
  42 #include "pathnames.h"
  43
  44 static char no_rarp_message[] = N_("This kernel does not support RARP.\n");
  45
  46 static char version_string[] = RELEASE "\nrarp 1.03 (2001-04-04)\n";
  47
  48 static struct hwtype *hardware = NULL;
  49
  50 /* Delete an entry from the RARP cache. */
  51 static int rarp_delete(int fd, struct hostent *hp)
  52 {
  53     struct arpreq req;
  54     struct sockaddr_in *si;
  55     unsigned int found = 0;
  56     char **addr;
  57
  58     /* The host can have more than one address, so we loop on them. */
  59     for (addr = hp->h_addr_list; *addr != NULL; addr++) {
  60         memset((char *) &req, 0, sizeof(req));
  61         si = (struct sockaddr_in *) &req.arp_pa;
  62         si->sin_family = hp->h_addrtype;
  63         memcpy((char *) &si->sin_addr, *addr, hp->h_length);
  64
  65         /* Call the kernel. */
  66         if (ioctl(fd, SIOCDRARP, &req) == 0) {
  67             found++;
  68         } else {
  69             switch (errno) {
  70             case ENXIO:
  71                 break;
  72             case ENODEV:
  73                 fputs(_(no_rarp_message), stderr);
  74                 return 1;
  75             default:
  76                 perror("SIOCDRARP");
  77                 return 1;
  78             }
  79         }
  80     }
  81
  82     if (found == 0)
  83         printf(_("no RARP entry for %s.\n"), hp->h_name);
  84     return 0;
  85 }
  86
  87
  88 /* Set an entry in the RARP cache. */
  89 static int rarp_set(int fd, struct hostent *hp, char *hw_addr)
  90 {
  91     struct arpreq req;
  92     struct sockaddr_in *si;
  93     struct sockaddr sap;
  94
  95     if (hardware->input(hw_addr, &sap)) {
  96         fprintf(stderr, _("%s: bad hardware address\n"), hw_addr);
  97         return 1;
  98     }
  99     /* Clear and fill in the request block. */
 100     memset((char *) &req, 0, sizeof(req));
 101     si = (struct sockaddr_in *) &req.arp_pa;
 102     si->sin_family = hp->h_addrtype;
 103     memcpy((char *) &si->sin_addr, hp->h_addr_list[0], hp->h_length);
 104     req.arp_ha.sa_family = hardware->type;
 105     memcpy(req.arp_ha.sa_data, sap.sa_data, hardware->alen);
 106
 107     /* Call the kernel. */
 108     if (ioctl(fd, SIOCSRARP, &req) < 0) {
 109         if (errno == ENODEV)
 110             fputs(_(no_rarp_message), stderr);
 111         else
 112             perror("SIOCSRARP");
 113         return 1;
 114     }
 115     return 0;
 116 }
 117
 118 /* Process an EtherFile */
 119 static int rarp_file(int fd, const char *name)
 120 {
 121     char buff[1024];
 122     char *host, *addr;
 123     int linenr;
 124     FILE *fp;
 125     struct hostent *hp;
 126
 127     if ((fp = fopen(name, "r")) == NULL) {
 128         fprintf(stderr, _("rarp: cannot open file %s:%s.\n"), name, strerror(errno));
 129         return -1;
 130     }
 131     /* Read the lines in the file. */
 132     linenr = 0;
 133     while (fgets(buff, sizeof(buff), fp)) {
 134         ++linenr;
 135         if (buff[0] == '#' || buff[0] == '\0')
 136             continue;
 137         if ((addr = strtok(buff, "\n \t")) == NULL)
 138             continue;
 139         if ((host = strtok(NULL, "\n \t")) == NULL) {
 140             fprintf(stderr, _("rarp: format error at %s:%u\n"), name, linenr);
 141             continue;
 142         }
 143         if ((hp = gethostbyname(host)) == NULL) {
 144             fprintf(stderr, _("rarp: %s: unknown host\n"), host);
 145         }
 146         if (rarp_set(fd, hp, addr) != 0) {
 147             fprintf(stderr, _("rarp: cannot set entry from %s:%u\n"), name, linenr);
 148         }
 149     }
 150
 151     (void) fclose(fp);
 152     return 0;
 153 }
 154
 155 static int display_cache(void)
 156 {
 157     FILE *fd = fopen(_PATH_PROCNET_RARP, "r");
 158     char buffer[256];
 159     if (fd == NULL) {
 160         if (errno == ENOENT)
 161             fputs(_(no_rarp_message), stderr);
 162         else
 163             perror(_PATH_PROCNET_RARP);
 164         return 1;
 165     }
 166     while (feof(fd) == 0) {
 167         if (fgets(buffer, 255, fd))
 168             fputs(buffer, stdout);
 169     }
 170     fclose(fd);
 171     return 0;
 172 }
 173
 174 static void usage(void)
 175 {
 176     fprintf(stderr, _("Usage: rarp -a                               list entries in cache.\n"));
 177     fprintf(stderr, _("       rarp -d <hostname>                    delete entry from cache.\n"));
 178     fprintf(stderr, _("       rarp [<HW>] -s <hostname> <hwaddr>    add entry to cache.\n"));
 179     fprintf(stderr, _("       rarp -f                               add entries from /etc/ethers.\n"));
 180     fprintf(stderr, _("       rarp -V                               display program version.\n\n"));
 181
 182     fprintf(stderr, _("  <HW>=Use '-H <hw>' to specify hardware address type. Default: %s\n"), DFLT_HW);
 183     fprintf(stderr, _("  List of possible hardware types (which support ARP):\n"));
 184     print_hwlist(1); /* 1 = ARPable */
 185     exit(E_USAGE);
 186 }
 187
 188 #define MODE_DISPLAY   1
 189 #define MODE_DELETE    2
 190 #define MODE_SET       3
 191 #define MODE_ETHERS    4
 192
 193 static struct option longopts[] =
 194 {
 195     {"version", 0, NULL, 'V'},
 196     {"verbose", 0, NULL, 'v'},
 197     {"list", 0, NULL, 'a'},
 198     {"set", 0, NULL, 's'},
 199     {"delete", 0, NULL, 'd'},
 200     {"help", 0, NULL, 'h'},
 201     {NULL, 0, NULL, 0}
 202 };
 203
 204 int main(int argc, char **argv)
 205 {
 206     int result = 0, mode = 0, c, nargs = 0, verbose = 0;
 207     char *args[3];
 208     struct hostent *hp;
 209     int fd;
 210
 211 #if I18N
 212     setlocale (LC_ALL, "");
 213     bindtextdomain("net-tools", "/usr/share/locale");
 214     textdomain("net-tools");
 215 #endif
 216
 217     /* Get a default hardware type.  */
 218     hardware = get_hwtype(DFLT_HW);
 219
 220     do {
 221         c = getopt_long(argc, argv, "-ht:aHdsVvf", longopts, NULL);
 222         switch (c) {
 223         case EOF:
 224             break;
 225         case 'h':
 226             usage();
 227         case 'V':
 228             fprintf(stderr, version_string);
 229             exit(E_VERSION);
 230             break;
 231         case 'v':
 232             verbose++;
 233             break;
 234         case 'a':
 235         case 's':
 236         case 'd':
 237             if (mode) {
 238                 fprintf(stderr, _("%s: illegal option mix.\n"), argv[0]);
 239                 usage();
 240             } else {
 241                 mode = (c == 'a' ? MODE_DISPLAY : (c == 'd' ? MODE_DELETE : MODE_SET));
 242             }
 243             break;
 244         case 'f':
 245             mode = MODE_ETHERS;
 246             break;
 247         case 'H':
 248         case 't':
 249             if (optarg) {
 250                 hardware = get_hwtype(optarg);
 251             } else {
 252                 usage();
 253             }
 254             break;
 255         case 1:
 256             if (nargs == 2) {
 257                 usage();
 258                 exit(1);
 259             } else {
 260                 args[nargs++] = optarg;
 261             }
 262             break;
 263         default:
 264             usage();
 265         }
 266     } while (c != EOF);
 267
 268     if (hardware == NULL) {
 269         fprintf(stderr, _("rarp: %s: unknown hardware type.\n"), optarg);
 270         exit(1);
 271     }
 272     switch (mode) {
 273     case 0:
 274         usage();
 275
 276     case MODE_DISPLAY:
 277         if (nargs != (mode - 1)) {
 278             usage();
 279         }
 280         result = display_cache();
 281         break;
 282
 283     case MODE_DELETE:
 284     case MODE_SET:
 285         if (nargs != (mode - 1)) {
 286             usage();
 287         }
 288         if ((hp = gethostbyname(args[0])) == NULL) {
 289             fprintf(stderr, _("rarp: %s: unknown host\n"), args[0]);
 290             exit(1);
 291         }
 292         if (fd = socket(PF_INET, SOCK_DGRAM, 0), fd < 0) {
 293             perror("socket");
 294             exit(1);
 295         }
 296         result = (mode == MODE_DELETE) ? rarp_delete(fd, hp) : rarp_set(fd, hp, args[1]);
 297         close(fd);
 298         break;
 299
 300     case MODE_ETHERS:
 301         if (nargs != 0 && nargs != 1)
 302             usage();
 303         if (fd = socket(PF_INET, SOCK_DGRAM, 0), fd < 0) {
 304             perror("socket");
 305             exit(1);
 306         }
 307         result = rarp_file(fd, nargs ? args[0] : _PATH_ETHERS);
 308         close(fd);
 309
 310     }
 311     exit(result);
 312 }