1 /* $NetBSD: localhostname.c,v 1.3 1997/07/30 22:55:05 jtc 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/types.h> 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(buf, buflen) 50 char *buf; 51 size_t buflen; 52 { 53 struct hostent *hp; 54 char hostname[MAXHOSTNAMELEN]; 55 int i; 56 57 if (gethostname(hostname, sizeof(hostname))) 58 err(1, "gethostname"); 59 60 memset(buf, 0, buflen); 61 62 /* 63 * If hostname appears to be fully-qualified, 64 * just return it. 65 */ 66 if (strchr(hostname, '.')) { 67 snprintf(buf, buflen, "%s", hostname); 68 return; 69 } 70 71 /* 72 * Lookup the host. Return the first name that appears 73 * to be fully-qualified. 74 */ 75 hp = gethostbyname(hostname); 76 if (hp == NULL) 77 errx(1, "gethostbyname(%s) failed", hostname); 78 79 if (strchr(hp->h_name, '.')) { 80 snprintf(buf, buflen, "%s", hp->h_name); 81 return; 82 } 83 84 if (hp->h_aliases != NULL && hp->h_aliases[0] != NULL) { 85 for (i = 0; hp->h_aliases[i] != NULL; i++) { 86 if (strchr(hp->h_aliases[i], '.')) { 87 snprintf(buf, buflen, "%s", hp->h_aliases[i]); 88 return; 89 } 90 } 91 } 92 93 /* 94 * As a last resort, just return hostname. 95 */ 96 snprintf(buf, buflen, "%s", hostname); 97 } 98