usr.sbin/ypserv/common/localhostname.c

   1 /*      $NetBSD: localhostname.c,v 1.8 2002/07/06 21:39:25 wiz Exp $    */
   2
   3 /*-
   4  * Copyright (c) 1996 The NetBSD Foundation, Inc.
   5  * All rights reserved.
   6  *
   7  * This code is derived from software contributed to The NetBSD Foundation
   8  * by Jason R. Thorpe.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  29  * POSSIBILITY OF SUCH DAMAGE.
  30  */
  31
  32 #include <sys/cdefs.h>
  33 #ifndef lint
  34 __RCSID("$NetBSD: localhostname.c,v 1.8 2002/07/06 21:39:25 wiz Exp $");
  35 #endif
  36
  37 #include <sys/param.h>
  38 #include <sys/socket.h>
  39
  40 #include <err.h>
  41 #include <netdb.h>
  42 #include <stdio.h>
  43 #include <string.h>
  44 #include <unistd.h>
  45
  46 #include "protos.h"
  47
  48 void
  49 localhostname(char *buf, size_t buflen)
  50 {
  51         struct addrinfo *res, hints;
  52         char hostname[MAXHOSTNAMELEN + 1];
  53         int error;
  54
  55         if (gethostname(hostname, sizeof(hostname)))
  56                 err(1, "gethostname");
  57         hostname[sizeof(hostname) - 1] = '\0';
  58
  59         memset(buf, 0, buflen);
  60
  61         /*
  62          * If hostname appears to be fully-qualified,
  63          * just return it.
  64          */
  65         if (strchr(hostname, '.')) {
  66                 strlcpy(buf, hostname, buflen);
  67                 return;
  68         }
  69
  70         /*
  71          * Lookup the host.  Return the canonical name.
  72          */
  73         memset(&hints, 0, sizeof(hints));
  74         hints.ai_flags = AI_CANONNAME;
  75         hints.ai_family = PF_UNSPEC;
  76
  77         error = getaddrinfo(hostname, NULL, &hints, &res);
  78         if (error)
  79                 errx(1, "getaddrinfo(%s) failed: %s", hostname,
  80                     gai_strerror(error));
  81         strlcpy(buf, res->ai_canonname, buflen);
  82         freeaddrinfo(res);
  83 }