91 lines
3.0 KiB
C
91 lines
3.0 KiB
C
/* $NetBSD: localhostname.c,v 1.8 2002/07/06 21:39:25 wiz Exp $ */
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/*-
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* Copyright (c) 1996 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__RCSID("$NetBSD: localhostname.c,v 1.8 2002/07/06 21:39:25 wiz Exp $");
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#endif
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#include <sys/param.h>
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#include <sys/socket.h>
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#include <err.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include "protos.h"
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void
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localhostname(char *buf, size_t buflen)
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{
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struct addrinfo *res, hints;
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char hostname[MAXHOSTNAMELEN + 1];
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int error;
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if (gethostname(hostname, sizeof(hostname)))
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err(1, "gethostname");
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hostname[sizeof(hostname) - 1] = '\0';
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memset(buf, 0, buflen);
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/*
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* If hostname appears to be fully-qualified,
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* just return it.
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*/
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if (strchr(hostname, '.')) {
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strlcpy(buf, hostname, buflen);
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return;
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}
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/*
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* Lookup the host. Return the canonical name.
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*/
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memset(&hints, 0, sizeof(hints));
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hints.ai_flags = AI_CANONNAME;
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hints.ai_family = PF_UNSPEC;
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error = getaddrinfo(hostname, NULL, &hints, &res);
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if (error)
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errx(1, "getaddrinfo(%s) failed: %s", hostname,
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gai_strerror(error));
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strlcpy(buf, res->ai_canonname, buflen);
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freeaddrinfo(res);
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}
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