xref: /src/distrib/utils/libhack/gethost.c

/*	$NetBSD: gethost.c,v 1.9 2013/08/20 15:44:17 christos Exp $	*/

/*-
 * Copyright (c) 1985, 1988, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * -
 * Portions Copyright (c) 1993 by Digital Equipment Corporation.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies, and that
 * the name of Digital Equipment Corporation not be used in advertising or
 * publicity pertaining to distribution of the document or software without
 * specific, written prior permission.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 * -
 * --Copyright--
 */

/*
 * Copied from:  lib/libc/net/gethostnamadr.c
 * and then gutted, leaving only /etc/hosts support.
 */

#include <sys/cdefs.h>

#ifdef __weak_alias
#define gethostbyaddr		_gethostbyaddr
#define gethostbyname		_gethostbyname
#endif

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netdb.h>
#include <resolv.h>
#include <stdio.h>
#include <ctype.h>
#include <errno.h>
#include <string.h>

#ifdef __weak_alias
__weak_alias(gethostbyaddr,_gethostbyaddr);
__weak_alias(gethostbyname,_gethostbyname);
#endif

#define	MAXALIASES	35
#define	MAXADDRS	35

static char *h_addr_ptrs[MAXADDRS + 1];

static struct hostent host;
static char *host_aliases[MAXALIASES];
static char hostbuf[BUFSIZ+1];
static struct in_addr host_addr;
static FILE *hostf = NULL;
static int stayopen = 0;

void _sethtent(int);
void _endhtent(void);
struct hostent *_gethtent(void);
struct hostent *_gethtbyname(const char *);
struct hostent *_gethtbyaddr(const void *, socklen_t, int);


#if PACKETSZ > 1024
#define	MAXPACKET	PACKETSZ
#else
#define	MAXPACKET	1024
#endif

extern int h_errno;

struct hostent *
gethostbyname(const char *name)
{
	const char *cp;

	/*
	 * disallow names consisting only of digits/dots, unless
	 * they end in a dot.
	 */
	if (isdigit((unsigned char)name[0]))
		for (cp = name;; ++cp) {
			if (!*cp) {
				if (*--cp == '.')
					break;
				/*
				 * All-numeric, no dot at the end.
				 * Fake up a hostent as if we'd actually
				 * done a lookup.
				 */
				if (!inet_aton(name, &host_addr)) {
					h_errno = HOST_NOT_FOUND;
					return((struct hostent *) NULL);
				}
				host.h_name = (char *)name;
				host.h_aliases = host_aliases;
				host_aliases[0] = NULL;
				host.h_addrtype = AF_INET;
				host.h_length = sizeof(u_int32_t);
				h_addr_ptrs[0] = (char *)&host_addr;
				h_addr_ptrs[1] = NULL;
				host.h_addr_list = h_addr_ptrs;
				return &host;
			}
			if (!isdigit((unsigned char)*cp) && *cp != '.')
				break;
		}

	/* XXX - Force host table lookup. */
	return _gethtbyname(name);
}

struct hostent *
gethostbyaddr(const void *addr, socklen_t len, int type)
{
#if 0
	char qbuf[MAXDNAME];
#endif

	if (type != AF_INET)
		return NULL;
#if 0
	(void)snprintf(qbuf, sizeof(qbuf), "%u.%u.%u.%u.in-addr.arpa",
	    ((unsigned)addr[3] & 0xff), ((unsigned)addr[2] & 0xff),
	    ((unsigned)addr[1] & 0xff), ((unsigned)addr[0] & 0xff));
#endif

	/* XXX - Force host table lookup. */
	return _gethtbyaddr(addr, len, type);
}

void
_sethtent(int f)
{
	if (hostf == NULL)
		hostf = fopen(_PATH_HOSTS, "r" );
	else
		rewind(hostf);
	stayopen = f;
}

void
_endhtent(void)
{
	if (hostf && !stayopen) {
		(void) fclose(hostf);
		hostf = NULL;
	}
}

struct hostent *
_gethtent(void)
{
	char *p;
	char *cp, **q;

	if (hostf == NULL && (hostf = fopen(_PATH_HOSTS, "r" )) == NULL)
		return NULL;
again:
	if ((p = fgets(hostbuf, BUFSIZ, hostf)) == NULL)
		return NULL;
	if (*p == '#')
		goto again;
	cp = strpbrk(p, "#\n");
	if (cp == NULL)
		goto again;
	*cp = '\0';
	cp = strpbrk(p, " \t");
	if (cp == NULL)
		goto again;
	*cp++ = '\0';
	/* THIS STUFF IS INTERNET SPECIFIC */
	h_addr_ptrs[0] = (char *)&host_addr;
	h_addr_ptrs[1] = NULL;
	(void) inet_aton(p, &host_addr);
	host.h_addr_list = h_addr_ptrs;
	host.h_length = sizeof(u_int32_t);
	host.h_addrtype = AF_INET;
	while (*cp == ' ' || *cp == '\t')
		cp++;
	host.h_name = cp;
	q = host.h_aliases = host_aliases;
	cp = strpbrk(cp, " \t");
	if (cp != NULL)
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &host_aliases[MAXALIASES - 1])
			*q++ = cp;
		cp = strpbrk(cp, " \t");
		if (cp != NULL)
			*cp++ = '\0';
	}
	*q = NULL;
	return &host;
}

struct hostent *
_gethtbyname(const char *name)
{
	struct hostent *p;
	char **cp;

	_sethtent(0);
	while ((p = _gethtent()) != NULL) {
		if (strcasecmp(p->h_name, name) == 0)
			break;
		for (cp = p->h_aliases; *cp != 0; cp++)
			if (strcasecmp(*cp, name) == 0)
				goto found;
	}
found:
	_endhtent();
	if (p == NULL)
		h_errno = HOST_NOT_FOUND;
	return p;
}

struct hostent *
_gethtbyaddr(const void *addr, socklen_t len, int type)
{
	struct hostent *p;

	_sethtent(0);
	while ((p = _gethtent()) != NULL)
		if (p->h_addrtype == type && !memcmp(p->h_addr, addr, len))
			break;
	_endhtent();
	if (p == NULL)
		h_errno = HOST_NOT_FOUND;
	return p;
}