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. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  *
  33  * @(#) Copyright (c) 1988, 1993 The Regents of the University of California.  All rights reserved.
  34  * @(#)hostname.c       8.1 (Berkeley) 5/31/93
  35  * $FreeBSD: src/bin/hostname/hostname.c,v 1.10.2.1 2001/08/01 02:40:23 obrien Exp $
  36  * $DragonFly: src/bin/hostname/hostname.c,v 1.13 2005/03/21 16:59:31 liamfoy Exp $
  37  */
  38
  39 #include <sys/param.h>
  40 #include <sys/ioctl.h>
  41 #include <sys/socket.h>
  42 #include <sys/sysctl.h>
  43 #include <sys/module.h>
  44 #include <sys/linker.h>
  45
  46 #include <net/ethernet.h>
  47 #include <net/if.h>
  48 #include <net/if_var.h>
  49 #include <net/if_dl.h>
  50 #include <net/if_types.h>
  51 #include <net/route.h>
  52 #include <netinet/in.h>
  53
  54 #include <err.h>
  55 #include <stdio.h>
  56 #include <stdlib.h>
  57 #include <string.h>
  58 #include <unistd.h>
  59
  60 #include <netdb.h>
  61 #include <sys/types.h>
  62 #include <netinet/in.h>
  63 #include <arpa/inet.h>
  64
  65 #include <errno.h>
  66
  67 #define HST_IF    (1 << 0)
  68 #define HST_IF_V6 (1 << 1)
  69 #define HST_IF_V4 (1 << 2)
  70
  71
  72
  73 /*
  74  * Expand the compacted form of addresses as returned via the
  75  * configuration read via sysctl().
  76  * Lifted from getifaddrs(3)
  77  */
  78
  79 static void rt_xaddrs(caddr_t, caddr_t, struct rt_addrinfo *);
  80 static void usage (void);
  81
  82 #define ROUNDUP(a) \
  83         ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
  84 #define ADVANCE(x, n) (x += ROUNDUP((n)->sa_len))
  85
  86 static
  87 void
  88 rt_xaddrs(caddr_t cp, caddr_t cplim, struct rt_addrinfo *rtinfo)
  89 {
  90         struct sockaddr *sa;
  91         int i;
  92
  93         memset(rtinfo->rti_info, 0, sizeof(rtinfo->rti_info));
  94         for (i = 0; (i < RTAX_MAX) && (cp < cplim); i++) {
  95                 if ((rtinfo->rti_addrs & (1 << i)) == 0)
  96                         continue;
  97                 rtinfo->rti_info[i] = sa = (struct sockaddr *)cp;
  98                 ADVANCE(cp, sa);
  99         }
 100 }
 101
 102 int
 103 main(int argc, char **argv)
 104 {
 105         int ch, sflag, rflag, ret, flag6, iflag;
 106         int silen = 0;
 107         char hostname[MAXHOSTNAMELEN];
 108         char *srflag, *siflag;
 109         struct hostent *hst;
 110         struct in_addr ia;
 111         struct in6_addr ia6;
 112
 113         int mib[6];
 114         size_t needed;
 115         char *buf,*lim,*next,*p;
 116         int idx;
 117         struct sockaddr_dl *sdl;
 118         struct rt_msghdr *rtm;
 119         struct if_msghdr *ifm;
 120         struct ifa_msghdr *ifam;
 121         struct rt_addrinfo info;
 122         struct sockaddr_in *sai;
 123         struct sockaddr_in6 *sai6;
 124
 125         srflag = NULL;
 126         siflag = NULL;
 127         iflag = sflag = rflag = 0;
 128         flag6 = 0;
 129         hst = NULL;
 130
 131         while ((ch = getopt(argc, argv, "46i:r:s")) != -1) {
 132                 switch (ch) {
 133                 case '4':
 134                         iflag |= HST_IF_V4;
 135                         break;
 136                 case '6':
 137                         iflag |= HST_IF_V6;
 138                         break;
 139                 case 'i':
 140                         siflag = optarg;
 141                         silen = strlen(siflag);
 142                         iflag |= HST_IF;
 143                         break;
 144                 case 'r':
 145                         srflag = optarg;
 146                         rflag = 1;
 147                         break;
 148                 case 's':
 149                         sflag = 1;
 150                         break;
 151                 default:
 152                         usage();
 153                 }
 154         }
 155         argc -= optind;
 156         argv += optind;
 157
 158         if (argc > 1)
 159                 usage();
 160
 161         if (iflag && *argv)
 162                 usage();
 163
 164         if (rflag && *argv)
 165                 usage();
 166
 167         if (rflag && (iflag & HST_IF))
 168                 usage();
 169
 170         if ((iflag & HST_IF_V6) && (iflag & HST_IF_V4))
 171                 usage();
 172
 173         if (!(iflag & HST_IF) && ((iflag & HST_IF_V6)||iflag & HST_IF_V4))
 174                 usage();
 175
 176         if (iflag & HST_IF) {
 177                 mib[0] = CTL_NET;
 178                 mib[1] = PF_ROUTE;
 179                 mib[2] = 0;
 180                 mib[3] = 0;
 181                 mib[4] = NET_RT_IFLIST;
 182                 mib[5] = 0;
 183
 184                 idx = 0;
 185                 needed = 1;
 186
 187                 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
 188                         err(1, "sysctl: iflist-sysctl-estimate");
 189                 if ((buf = malloc(needed)) == NULL)
 190                         err(1, "malloc failed");
 191                 if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
 192                         err(1, "sysctl: retrieval of interface table");
 193
 194                 lim = buf + needed;
 195
 196                 for (next = buf; next < buf + needed; next += rtm->rtm_msglen) {
 197                         rtm = (struct rt_msghdr *)(void *)next;
 198                         if (rtm->rtm_version != RTM_VERSION)
 199                                 continue;
 200                         switch (rtm->rtm_type) {
 201                         case RTM_IFINFO:
 202                                 ifm = (struct if_msghdr *)(void *)rtm;
 203
 204                                 if ((ifm->ifm_addrs & RTA_IFP) == 0)
 205                                         break;
 206                                 sdl = (struct sockaddr_dl *)(ifm + 1);
 207                                 if (silen != sdl->sdl_nlen)
 208                                         break;
 209                                 if (!strncmp(siflag, sdl->sdl_data, silen)) {
 210                                         idx = ifm->ifm_index;
 211                                 }
 212                                 break;
 213                         case RTM_NEWADDR:
 214                                 ifam = (struct ifa_msghdr *)(void *)rtm;
 215
 216                                 if (ifam->ifam_index == idx) {
 217                                         info.rti_addrs = ifam->ifam_addrs;
 218                                         rt_xaddrs((char *)(ifam + 1),
 219                                                 ifam->ifam_msglen + (char *)ifam, &info);
 220                                         sai = (struct sockaddr_in *)info.rti_info[RTAX_IFA];
 221
 222                                         if (iflag & HST_IF_V6) {
 223                                                 if (sai->sin_family == AF_INET6) {
 224                                                         sai6 = (struct sockaddr_in6 *)info.rti_info[RTAX_IFA];
 225                                                         hst = gethostbyaddr((const char*)&sai6->sin6_addr,
 226                                                                         sizeof(sai6->sin6_addr),AF_INET6);
 227
 228                                                         if (h_errno == NETDB_SUCCESS) {
 229                                                                 next = buf + needed;
 230                                                                 continue;
 231                                                         }
 232                                                 }
 233                                         } else {
 234                                                 if ((sai->sin_family == AF_INET)) {
 235
 236                                                         hst = gethostbyaddr((const char*)&sai->sin_addr,
 237                                                                         sizeof(sai->sin_addr),AF_INET);
 238
 239                                                         if (h_errno == NETDB_SUCCESS) {
 240                                                                 next = buf + needed;
 241                                                                 continue;
 242                                                         }
 243                                                 }
 244                                         }
 245                                 }
 246                                 break;
 247                         } /* switch */
 248                 } /* loop */
 249
 250                 free(buf);
 251
 252                 if (idx == 0)
 253                         errx(1,"interface not found");
 254                 if (hst == NULL)
 255                         errx(1, "ip not found on interface");
 256
 257                 if (h_errno == NETDB_SUCCESS) {
 258                         if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
 259                                 err(1, "sethostname");
 260                 } else if (h_errno == HOST_NOT_FOUND) {
 261                         errx(1,"hostname not found");
 262                 } else {
 263                         herror("gethostbyaddr");
 264                         exit(1);
 265                 }
 266         } else if (rflag) {
 267                 ret = inet_pton(AF_INET, srflag, &ia);
 268                 if (ret != 1) {
 269                         /* check IPV6 */
 270                         ret = inet_pton(AF_INET6, srflag, &ia6);
 271
 272                         if (ret != 1) {
 273                                 errx(1, "invalid ip address");
 274                         }
 275
 276                         flag6 = 1;
 277                 }
 278
 279                 if (flag6 == 1)
 280                         hst = gethostbyaddr((const char*)&ia6, sizeof(ia6), AF_INET6);
 281                 else
 282                         hst = gethostbyaddr((const char*)&ia, sizeof(ia), AF_INET);
 283                 if (!hst) {
 284                         if (h_errno == HOST_NOT_FOUND)
 285                                 errx(1,"host not found\n");
 286                 }
 287
 288                 if (sethostname(hst->h_name, (int)strlen(hst->h_name)))
 289                         err(1, "sethostname");
 290         } else if (*argv) {
 291                 if (sethostname(*argv, (int)strlen(*argv)))
 292                         err(1, "sethostname");
 293         } else {
 294                 if (gethostname(hostname, (int)sizeof(hostname)))
 295                         err(1, "gethostname");
 296                 if (sflag && (p = strchr(hostname, '.')))
 297                         *p = '\0';
 298                 printf("%s\n", hostname);
 299         }
 300         exit(0);
 301 }
 302
 303 static void
 304 usage(void)
 305 {
 306         fprintf(stderr, "usage: hostname [-s] [name-of-host |"
 307                         " -r ip-address | -i interface [-4 | -6]]\n");
 308         exit(1);
 309 }
 310