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 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