1 /* $NetBSD: localhostname.c,v 1.9 2008/04/28 20:24:18 martin 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 1.9 2008/04/28 20:24:18 martin 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
localhostname(char * buf,size_t buflen)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 }
84