1/*	$NetBSD: gethost.c,v 1.7 2001/06/15 17:26:51 tsutsui Exp $	*/
2
3/*-
4 * Copyright (c) 1985, 1988, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 * -
31 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
32 *
33 * Permission to use, copy, modify, and distribute this software for any
34 * purpose with or without fee is hereby granted, provided that the above
35 * copyright notice and this permission notice appear in all copies, and that
36 * the name of Digital Equipment Corporation not be used in advertising or
37 * publicity pertaining to distribution of the document or software without
38 * specific, written prior permission.
39 *
40 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
41 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
42 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
43 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
44 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
45 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
46 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
47 * SOFTWARE.
48 * -
49 * --Copyright--
50 */
51
52/*
53 * Copied from:  lib/libc/net/gethostnamadr.c
54 * and then gutted, leaving only /etc/hosts support.
55 */
56
57#include <sys/cdefs.h>
58
59#ifdef __weak_alias
60#define gethostbyaddr		_gethostbyaddr
61#define gethostbyname		_gethostbyname
62#endif
63
64#include <sys/param.h>
65#include <sys/socket.h>
66#include <netinet/in.h>
67#include <arpa/inet.h>
68#include <arpa/nameser.h>
69#include <netdb.h>
70#include <resolv.h>
71#include <stdio.h>
72#include <ctype.h>
73#include <errno.h>
74#include <string.h>
75
76#ifdef __weak_alias
77__weak_alias(gethostbyaddr,_gethostbyaddr);
78__weak_alias(gethostbyname,_gethostbyname);
79#endif
80
81#define	MAXALIASES	35
82#define	MAXADDRS	35
83
84static char *h_addr_ptrs[MAXADDRS + 1];
85
86static struct hostent host;
87static char *host_aliases[MAXALIASES];
88static char hostbuf[BUFSIZ+1];
89static struct in_addr host_addr;
90static FILE *hostf = NULL;
91static int stayopen = 0;
92
93void _sethtent __P((int));
94void _endhtent __P((void));
95struct hostent *_gethtent __P((void));
96struct hostent *_gethtbyname __P((const char *));
97struct hostent *_gethtbyaddr __P((const char *, int, int));
98
99
100#if PACKETSZ > 1024
101#define	MAXPACKET	PACKETSZ
102#else
103#define	MAXPACKET	1024
104#endif
105
106extern int h_errno;
107
108struct hostent *
109gethostbyname(name)
110	const char *name;
111{
112	register const char *cp;
113
114	/*
115	 * disallow names consisting only of digits/dots, unless
116	 * they end in a dot.
117	 */
118	if (isdigit(name[0]))
119		for (cp = name;; ++cp) {
120			if (!*cp) {
121				if (*--cp == '.')
122					break;
123				/*
124				 * All-numeric, no dot at the end.
125				 * Fake up a hostent as if we'd actually
126				 * done a lookup.
127				 */
128				if (!inet_aton(name, &host_addr)) {
129					h_errno = HOST_NOT_FOUND;
130					return((struct hostent *) NULL);
131				}
132				host.h_name = (char *)name;
133				host.h_aliases = host_aliases;
134				host_aliases[0] = NULL;
135				host.h_addrtype = AF_INET;
136				host.h_length = sizeof(u_int32_t);
137				h_addr_ptrs[0] = (char *)&host_addr;
138				h_addr_ptrs[1] = NULL;
139				host.h_addr_list = h_addr_ptrs;
140				return (&host);
141			}
142			if (!isdigit(*cp) && *cp != '.')
143				break;
144		}
145
146	/* XXX - Force host table lookup. */
147	return (_gethtbyname(name));
148}
149
150struct hostent *
151gethostbyaddr(addr, len, type)
152	const char *addr;
153	socklen_t len;
154	int type;
155{
156	char qbuf[MAXDNAME];
157
158	if (type != AF_INET)
159		return ((struct hostent *) NULL);
160	(void)sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa",
161		((unsigned)addr[3] & 0xff),
162		((unsigned)addr[2] & 0xff),
163		((unsigned)addr[1] & 0xff),
164		((unsigned)addr[0] & 0xff));
165
166	/* XXX - Force host table lookup. */
167	return (_gethtbyaddr(addr, len, type));
168}
169
170void
171_sethtent(f)
172	int f;
173{
174	if (hostf == NULL)
175		hostf = fopen(_PATH_HOSTS, "r" );
176	else
177		rewind(hostf);
178	stayopen = f;
179}
180
181void
182_endhtent()
183{
184	if (hostf && !stayopen) {
185		(void) fclose(hostf);
186		hostf = NULL;
187	}
188}
189
190struct hostent *
191_gethtent()
192{
193	char *p;
194	register char *cp, **q;
195
196	if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
197		return (NULL);
198again:
199	if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
200		return (NULL);
201	if (*p == '#')
202		goto again;
203	cp = strpbrk(p, "#\n");
204	if (cp == NULL)
205		goto again;
206	*cp = '\0';
207	cp = strpbrk(p, " \t");
208	if (cp == NULL)
209		goto again;
210	*cp++ = '\0';
211	/* THIS STUFF IS INTERNET SPECIFIC */
212	h_addr_ptrs[0] = (char *)&host_addr;
213	h_addr_ptrs[1] = NULL;
214	(void) inet_aton(p, &host_addr);
215	host.h_addr_list = h_addr_ptrs;
216	host.h_length = sizeof(u_int32_t);
217	host.h_addrtype = AF_INET;
218	while (*cp == ' ' || *cp == '\t')
219		cp++;
220	host.h_name = cp;
221	q = host.h_aliases = host_aliases;
222	cp = strpbrk(cp, " \t");
223	if (cp != NULL)
224		*cp++ = '\0';
225	while (cp && *cp) {
226		if (*cp == ' ' || *cp == '\t') {
227			cp++;
228			continue;
229		}
230		if (q < &host_aliases[MAXALIASES - 1])
231			*q++ = cp;
232		cp = strpbrk(cp, " \t");
233		if (cp != NULL)
234			*cp++ = '\0';
235	}
236	*q = NULL;
237	return (&host);
238}
239
240struct hostent *
241_gethtbyname(name)
242	const char *name;
243{
244	register struct hostent *p;
245	register char **cp;
246
247	_sethtent(0);
248	while ((p = _gethtent()) != NULL) {
249		if (strcasecmp(p->h_name, name) == 0)
250			break;
251		for (cp = p->h_aliases; *cp != 0; cp++)
252			if (strcasecmp(*cp, name) == 0)
253				goto found;
254	}
255found:
256	_endhtent();
257	if (p==NULL)
258		h_errno = HOST_NOT_FOUND;
259	return (p);
260}
261
262struct hostent *
263_gethtbyaddr(addr, len, type)
264	const char *addr;
265	int len, type;
266{
267	register struct hostent *p;
268
269	_sethtent(0);
270	while ((p = _gethtent()) != NULL)
271		if (p->h_addrtype == type && !memcmp(p->h_addr, addr, len))
272			break;
273	_endhtent();
274	if (p==NULL)
275		h_errno = HOST_NOT_FOUND;
276	return (p);
277}
278
279