bin/hostname/hostname.c

   1 /*
   2  * Copyright (c) 1988, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
  30  * @(#)hostname.c       8.1 (Berkeley) 5/31/93
  31  * $FreeBSD: src/bin/hostname/hostname.c,v 1.10.2.1 2001/08/01 02:40:23 obrien Exp $
  32  */
  33
  34 #include <sys/param.h>
  35 #include <sys/ioctl.h>
  36 #include <sys/socket.h>
  37 #include <sys/sysctl.h>
  38 #include <sys/module.h>
  39 #include <sys/linker.h>
  40
  41 #include <net/ethernet.h>
  42 #include <net/if.h>
  43 #include <net/if_var.h>
  44 #include <net/if_dl.h>
  45 #include <net/if_types.h>
  46 #include <net/route.h>
  47 #include <netinet/in.h>
  48
  49 #include <err.h>
  50 #include <stdio.h>
  51 #include <stdlib.h>
  52 #include <string.h>
  53 #include <unistd.h>
  54
  55 #include <netdb.h>
  56 #include <sys/types.h>
  57 #include <arpa/inet.h>
  58
  59 #include <errno.h>
  60
  61 #define HST_IF    (1 << 0)
  62 #define HST_IF_V6 (1 << 1)
  63 #define HST_IF_V4 (1 << 2)
  64
  65
  66
  67 /*
  68  * Expand the compacted form of addresses as returned via the
  69  * configuration read via sysctl().
  70  * Lifted from getifaddrs(3)
  71  */
  72
  73 static void rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
  74 static void usage (void);
  75
  76 #define ROUNDUP(a) \
  77         ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
  78 #define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
  79
  80 static
  81 void
  82 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
  83 {
  84         struct sockaddr *sa;
  85         int i;
  86
  87         memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
  88         for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
  89                 if ((rtinfo->rti_addrs & (1 << i)) == 0)
  90                         continue;
  91                 rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
  92                 ADVANCE(cp, sa);
  93         }
  94 }
  95
  96 int
  97 main(int argc, char **argv)
  98 {
  99         int ch, sflag, rflag, ret, flag6, iflag;
 100         int silen = 0;
 101         char hostname[MAXHOSTNAMELEN];
 102         char *srflag, *siflag;
 103         struct hostent *hst;
 104         struct in_addr ia;
 105         struct in6_addr ia6;
 106
 107         int mib[6];
 108         size_t needed;
 109         char *buf, *next, *p;
 110         int idx;
 111         struct sockaddr_dl *sdl;
 112         struct rt_msghdr *rtm;
 113         struct if_msghdr *ifm;
 114         struct ifa_msghdr *ifam;
 115         struct rt_addrinfo info;
 116         struct sockaddr_in *sai;
 117         struct sockaddr_in6 *sai6;
 118
 119         srflag = NULL;
 120         siflag = NULL;
 121         iflag = sflag = rflag = 0;
 122         flag6 = 0;
 123         hst = NULL;
 124
 125         while ((ch = getopt(argc, argv, "46i:r:s")) != -1) {
 126                 switch (ch) {
 127                 case '4':
 128                         iflag |= HST_IF_V4;
 129                         break;
 130                 case '6':
 131                         iflag |= HST_IF_V6;
 132                         break;
 133                 case 'i':
 134                         siflag = optarg;
 135                         silen = strlen(siflag);
 136                         iflag |= HST_IF;
 137                         break;
 138                 case 'r':
 139                         srflag = optarg;
 140                         rflag = 1;
 141                         break;
 142                 case 's':
 143                         sflag = 1;
 144                         break;
 145                 default:
 146                         usage();
 147                 }
 148         }
 149         argc -= optind;
 150         argv += optind;
 151
 152         if (argc > 1)
 153                 usage();
 154
 155         if (iflag && *argv)
 156                 usage();
 157
 158         if (rflag && *argv)
 159                 usage();
 160
 161         if (rflag && (iflag & HST_IF))
 162                 usage();
 163
 164         if ((iflag & HST_IF_V6) && (iflag & HST_IF_V4))
 165                 usage();
 166
 167         if (!(iflag & HST_IF) && ((iflag & HST_IF_V6)||iflag & HST_IF_V4))
 168                 usage();
 169
 170         if (iflag & HST_IF) {
 171                 mib[0] = CTL_NET;
 172                 mib[1] = PF_ROUTE;
 173                 mib[2] = 0;
 174                 mib[3] = 0;
 175                 mib[4] = NET_RT_IFLIST;
 176                 mib[5] = 0;
 177
 178                 idx = 0;
 179                 needed = 1;
 180
 181                 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
 182                         err(1, "sysctl: iflist-sysctl-estimate");
 183                 if ((buf = malloc(needed)) == NULL)
 184                         err(1, "malloc failed");
 185                 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
 186                         err(1, "sysctl: retrieval of interface table");
 187
 188                 for (next = buf; next < buf + needed; next += rtm->rtm_msglen) {
 189                         rtm = (struct rt_msghdr *)(void *)next;
 190                         if (rtm->rtm_version != RTM_VERSION)
 191                                 continue;
 192                         switch (rtm->rtm_type) {
 193                         case RTM_IFINFO:
 194                                 ifm = (struct if_msghdr *)(void *)rtm;
 195
 196                                 if ((ifm->ifm_addrs & RTA_IFP) == 0)
 197                                         break;
 198                                 sdl = (struct sockaddr_dl *)(ifm + 1);
 199                                 if (silen != sdl->sdl_nlen)
 200                                         break;
 201                                 if (!strncmp(siflag, sdl->sdl_data, silen)) {
 202                                         idx = ifm->ifm_index;
 203                                 }
 204                                 break;
 205                         case RTM_NEWADDR:
 206                                 ifam = (struct ifa_msghdr *)(void *)rtm;
 207
 208                                 if (ifam->ifam_index == idx) {
 209                                         info.rti_addrs = ifam->ifam_addrs;
 210                                         rt_xaddrs((char *)(ifam + 1),
 211                                                 ifam->ifam_msglen + (char *)ifam, &info);
 212                                         sai = (struct sockaddr_in *)info.rti_info[RTAX_IFA];
 213
 214                                         if (iflag & HST_IF_V6) {
 215                                                 if (sai->sin_family == AF_INET6) {
 216                                                         sai6 = (struct sockaddr_in6 *)info.rti_info[RTAX_IFA];
 217                                                         hst = gethostbyaddr(&sai6->sin6_addr,
 218                                                                         sizeof(sai6->sin6_addr),AF_INET6);
 219
 220                                                         if (h_errno == NETDB_SUCCESS) {
 221                                                                 next = buf + needed;
 222                                                                 continue;
 223                                                         }
 224                                                 }
 225                                         } else {
 226                                                 if ((sai->sin_family == AF_INET)) {
 227
 228                                                         hst = gethostbyaddr(&sai->sin_addr,
 229                                                                         sizeof(sai->sin_addr),AF_INET);
 230
 231                                                         if (h_errno == NETDB_SUCCESS) {
 232                                                                 next = buf + needed;
 233                                                                 continue;
 234                                                         }
 235                                                 }
 236                                         }
 237                                 }
 238                                 break;
 239                         } /* switch */
 240                 } /* loop */
 241
 242                 free(buf);
 243
 244                 if (idx == 0)
 245                         errx(1,"interface not found");
 246                 if (hst == NULL)
 247                         errx(1, "ip not found on interface");
 248
 249                 if (h_errno == NETDB_SUCCESS) {
 250                         if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
 251                                 err(1, "sethostname");
 252                 } else if (h_errno == HOST_NOT_FOUND) {
 253                         errx(1,"hostname not found");
 254                 } else {
 255                         herror("gethostbyaddr");
 256                         exit(1);
 257                 }
 258         } else if (rflag) {
 259                 ret = inet_pton(AF_INET, srflag, &ia);
 260                 if (ret != 1) {
 261                         /* check IPV6 */
 262                         ret = inet_pton(AF_INET6, srflag, &ia6);
 263
 264                         if (ret != 1) {
 265                                 errx(1, "invalid ip address");
 266                         }
 267
 268                         flag6 = 1;
 269                 }
 270
 271                 if (flag6 == 1)
 272                         hst = gethostbyaddr(&ia6, sizeof(ia6), AF_INET6);
 273                 else
 274                         hst = gethostbyaddr(&ia, sizeof(ia), AF_INET);
 275                 if (!hst) {
 276                         if (h_errno == HOST_NOT_FOUND)
 277                                 errx(1,"host not found\n");
 278                 }
 279
 280                 if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
 281                         err(1, "sethostname");
 282         } else if (*argv) {
 283                 if (sethostname(*argv, (int)strlen(*argv)))
 284                         err(1, "sethostname");
 285         } else {
 286                 if (gethostname(hostname, (int)sizeof(hostname)))
 287                         err(1, "gethostname");
 288                 if (sflag && (p = strchr(hostname, '.')))
 289                         *p = '\0';
 290                 printf("%s\n", hostname);
 291         }
 292         exit(0);
 293 }
 294
 295 static void
 296 usage(void)
 297 {
 298         fprintf(stderr, "usage: hostname [-s] [name-of-host |"
 299                         " -r ip-address | -i interface [-4 | -6]]\n");
 300         exit(1);
 301 }
 302