1 /* $NetBSD: localhostname.c,v 1.6 1998/07/06 07:06:39 mrg 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #ifndef lint 41 __RCSID("$NetBSD: localhostname.c,v 1.6 1998/07/06 07:06:39 mrg Exp $"); 42 #endif 43 44 #include <sys/param.h> 45 #include <err.h> 46 #include <netdb.h> 47 #include <stdio.h> 48 #include <string.h> 49 #include <unistd.h> 50 51 #include "protos.h" 52 53 void 54 localhostname(buf, buflen) 55 char *buf; 56 size_t buflen; 57 { 58 struct hostent *hp; 59 char hostname[MAXHOSTNAMELEN + 1]; 60 int i; 61 62 if (gethostname(hostname, sizeof(hostname))) 63 err(1, "gethostname"); 64 hostname[sizeof(hostname) - 1] = '\0'; 65 66 memset(buf, 0, buflen); 67 68 /* 69 * If hostname appears to be fully-qualified, 70 * just return it. 71 */ 72 if (strchr(hostname, '.')) { 73 snprintf(buf, buflen, "%s", hostname); 74 return; 75 } 76 77 /* 78 * Lookup the host. Return the first name that appears 79 * to be fully-qualified. 80 */ 81 hp = gethostbyname(hostname); 82 if (hp == NULL) 83 errx(1, "gethostbyname(%s) failed", hostname); 84 85 if (strchr(hp->h_name, '.')) { 86 snprintf(buf, buflen, "%s", hp->h_name); 87 return; 88 } 89 90 if (hp->h_aliases != NULL && hp->h_aliases[0] != NULL) { 91 for (i = 0; hp->h_aliases[i] != NULL; i++) { 92 if (strchr(hp->h_aliases[i], '.')) { 93 snprintf(buf, buflen, "%s", hp->h_aliases[i]); 94 return; 95 } 96 } 97 } 98 99 /* 100 * As a last resort, just return hostname. 101 */ 102 snprintf(buf, buflen, "%s", hostname); 103 } 104