glibc/resolv/gethnamaddr.c

/*
 * ++Copyright++ 1985, 1988, 1993
 * -
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 * 	This product includes software developed by the University of
 * 	California, Berkeley and its contributors.
 * 4. 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--
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
static char rcsid[] = "$Id$";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netdb.h>
#include <resolv.h>
#include <ctype.h>
#include <errno.h>
#include <syslog.h>

#include "res_hconf.h"

#ifndef LOG_AUTH
# define LOG_AUTH 0
#endif

#define MULTI_PTRS_ARE_ALIASES 1	/* XXX - experimental */

#if defined(BSD) && (BSD >= 199103) && defined(AF_INET6)
# include <string.h>
#else
# include "../conf/portability.h"
#endif
#if defined(USE_OPTIONS_H)
# include <../conf/options.h>
#endif

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) sprintf x
#endif

#define	MAXALIASES	35
#define	MAXADDRS	35
#define	MAXADDRBUFSIZE	8192

static const char AskedForGot[] =
			  "gethostby*.getanswer: asked for \"%s\", got \"%s\"";

static char *h_addr_ptrs[MAXADDRS + 1];
static struct hostent *gethostbyname_ipv4 __P((const char *));

static struct hostent host;
static char *host_aliases[MAXALIASES];
static char hostbuf[MAXADDRBUFSIZE];
static u_char host_addr[16];	/* IPv4 or IPv6 */
static FILE *hostf = NULL;
static int stayopen = 0;

static void map_v4v6_address __P((const char *src, char *dst));
static void map_v4v6_hostent __P((struct hostent *hp, char **bp, int *len));

#ifdef RESOLVSORT
static void addrsort __P((char **, int));
#endif

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

typedef union {
    HEADER hdr;
    u_char buf[MAXPACKET];
} querybuf;

typedef union {
    int32_t al;
    char ac;
} align;

extern int h_errno;

#ifdef DEBUG
static void
dprintf(msg, num)
	char *msg;
	int num;
{
	if (_res.options & RES_DEBUG) {
		int save = errno;

		printf(msg, num);
		errno = save;
	}
}
#else
# define dprintf(msg, num) /*nada*/
#endif

static struct hostent *
getanswer(answer, anslen, qname, qtype)
	const querybuf *answer;
	int anslen;
	const char *qname;
	int qtype;
{
	register const HEADER *hp;
	register const u_char *cp;
	register int n;
	const u_char *eom;
	char *bp, **ap, **hap;
	int type, class, buflen, ancount, qdcount;
	int haveanswer, had_error;
	int toobig = 0;
	char tbuf[MAXDNAME+1];
	const char *tname;
	int (*name_ok) __P((const char *));

	tname = qname;
	host.h_name = NULL;
	eom = answer->buf + anslen;
	switch (qtype) {
	case T_A:
	case T_AAAA:
		name_ok = res_hnok;
		break;
	case T_PTR:
		name_ok = res_dnok;
		break;
	default:
		return (NULL);	/* XXX should be abort(); */
	}
	/*
	 * find first satisfactory answer
	 */
	hp = &answer->hdr;
	ancount = ntohs(hp->ancount);
	qdcount = ntohs(hp->qdcount);
	bp = hostbuf;
	buflen = sizeof hostbuf;
	cp = answer->buf + HFIXEDSZ;
	if (qdcount != 1) {
		h_errno = NO_RECOVERY;
		return (NULL);
	}
	n = dn_expand(answer->buf, eom, cp, bp, buflen);
	if ((n < 0) || !(*name_ok)(bp)) {
		h_errno = NO_RECOVERY;
		return (NULL);
	}
	cp += n + QFIXEDSZ;
	if (qtype == T_A || qtype == T_AAAA) {
		/* res_send() has already verified that the query name is the
		 * same as the one we sent; this just gets the expanded name
		 * (i.e., with the succeeding search-domain tacked on).
		 */
		n = strlen(bp) + 1;		/* for the \0 */
		host.h_name = bp;
		bp += n;
		buflen -= n;
		/* The qname can be abbreviated, but h_name is now absolute. */
		qname = host.h_name;
	}
	ap = host_aliases;
	*ap = NULL;
	host.h_aliases = host_aliases;
	hap = h_addr_ptrs;
	*hap = NULL;
	host.h_addr_list = h_addr_ptrs;
	haveanswer = 0;
	had_error = 0;
	while (ancount-- > 0 && cp < eom && !had_error) {
		n = dn_expand(answer->buf, eom, cp, bp, buflen);
		if ((n < 0) || !(*name_ok)(bp)) {
			had_error++;
			continue;
		}
		cp += n;			/* name */
		type = _getshort(cp);
 		cp += INT16SZ;			/* type */
		class = _getshort(cp);
 		cp += INT16SZ + INT32SZ;	/* class, TTL */
		n = _getshort(cp);
		cp += INT16SZ;			/* len */
		if (class != C_IN) {
			/* XXX - debug? syslog? */
			cp += n;
			continue;		/* XXX - had_error++ ? */
		}
		if ((qtype == T_A || qtype == T_AAAA) && type == T_CNAME) {
			if (ap >= &host_aliases[MAXALIASES-1])
				continue;
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			if ((n < 0) || !(*name_ok)(tbuf)) {
				had_error++;
				continue;
			}
			cp += n;
			/* Store alias. */
			*ap++ = bp;
			n = strlen(bp) + 1;	/* for the \0 */
			bp += n;
			buflen -= n;
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			if (n > buflen) {
				had_error++;
				continue;
			}
			strcpy(bp, tbuf);
			host.h_name = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		if (qtype == T_PTR && type == T_CNAME) {
			n = dn_expand(answer->buf, eom, cp, tbuf, sizeof tbuf);
			if ((n < 0) || !res_hnok(tbuf)) {
				had_error++;
				continue;
			}
			cp += n;
			/* Get canonical name. */
			n = strlen(tbuf) + 1;	/* for the \0 */
			if (n > buflen) {
				had_error++;
				continue;
			}
			strcpy(bp, tbuf);
			tname = bp;
			bp += n;
			buflen -= n;
			continue;
		}
		if (type != qtype) {
			syslog(LOG_NOTICE|LOG_AUTH,
	       "gethostby*.getanswer: asked for \"%s %s %s\", got type \"%s\"",
			       qname, p_class(C_IN), p_type(qtype),
			       p_type(type));
			cp += n;
			continue;		/* XXX - had_error++ ? */
		}
		switch (type) {
		case T_PTR:
			if (strcasecmp(tname, bp) != 0) {
				syslog(LOG_NOTICE|LOG_AUTH,
				       AskedForGot, qname, bp);
				cp += n;
				continue;	/* XXX - had_error++ ? */
			}
			n = dn_expand(answer->buf, eom, cp, bp, buflen);
			if ((n < 0) || !res_hnok(bp)) {
				had_error++;
				break;
			}
#if MULTI_PTRS_ARE_ALIASES
			cp += n;
			if (!haveanswer)
				host.h_name = bp;
			else if (ap < &host_aliases[MAXALIASES-1])
				*ap++ = bp;
			else
				n = -1;
			if (n != -1) {
				n = strlen(bp) + 1;	/* for the \0 */
				bp += n;
				buflen -= n;
			}
			break;
#else
			host.h_name = bp;
			if (_res.options & RES_USE_INET6) {
				n = strlen(bp) + 1;	/* for the \0 */
				bp += n;
				buflen -= n;
				map_v4v6_hostent(&host, &bp, &buflen);
			}
			h_errno = NETDB_SUCCESS;
			return (&host);
#endif
		case T_A:
		case T_AAAA:
			if (strcasecmp(host.h_name, bp) != 0) {
				syslog(LOG_NOTICE|LOG_AUTH,
				       AskedForGot, host.h_name, bp);
				cp += n;
				continue;	/* XXX - had_error++ ? */
			}
			if (haveanswer) {
				if (n != host.h_length) {
					cp += n;
					continue;
				}
			} else {
				register int nn;

				host.h_name = bp;
				nn = strlen(bp) + 1;	/* for the \0 */
				bp += nn;
				buflen -= nn;
			}

			bp += sizeof(align) - ((u_long)bp % sizeof(align));

			if (bp + n >= &hostbuf[sizeof hostbuf]) {
				dprintf("size (%d) too big\n", n);
				had_error++;
				continue;
			}
			if (hap >= &h_addr_ptrs[MAXADDRS-1]) {
				if (!toobig++)
					dprintf("Too many addresses (%d)\n",
						MAXADDRS);
				cp += n;
				continue;
			}
			bcopy(cp, *hap++ = bp, n);
			bp += n;
			cp += n;
			break;
		default:
			abort();
		}
		if (!had_error)
			haveanswer++;
	}
	if (haveanswer) {
		*ap = NULL;
		*hap = NULL;
# if defined(RESOLVSORT)
		/*
		 * Note: we sort even if host can take only one address
		 * in its return structures - should give it the "best"
		 * address in that case, not some random one
		 */
		if (_res.nsort && haveanswer > 1 && qtype == T_A)
			addrsort(h_addr_ptrs, haveanswer);
# endif /*RESOLVSORT*/
		if (!host.h_name) {
			n = strlen(qname) + 1;	/* for the \0 */
			if (n > buflen)
				goto try_again;
			strcpy(bp, qname);
			host.h_name = bp;
			bp += n;
			buflen -= n;
		}
		if (_res.options & RES_USE_INET6)
			map_v4v6_hostent(&host, &bp, &buflen);
		h_errno = NETDB_SUCCESS;
		return (&host);
	}
 try_again:
	h_errno = TRY_AGAIN;
	return (NULL);
}

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

	if (_res.options & RES_USE_INET6) {
		hp = gethostbyname2(name, AF_INET6);
		if (hp)
			return (hp);
	}
	return (gethostbyname2(name, AF_INET));
}

struct hostent *
gethostbyname2(name, af)
	const char *name;
	int af;
{
	querybuf buf;
	register const char *cp;
	char *bp;
	int i, n, size, type, len;
	extern struct hostent *_gethtbyname2();

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	switch (af) {
	case AF_INET:
		size = INADDRSZ;
		type = T_A;
		break;
	case AF_INET6:
		size = IN6ADDRSZ;
		type = T_AAAA;
		break;
	default:
		h_errno = NETDB_INTERNAL;
		errno = EAFNOSUPPORT;
		return (NULL);
	}

	host.h_addrtype = af;
	host.h_length = size;

	/*
	 * if there aren't any dots, it could be a user-level alias.
	 * this is also done in res_query() since we are not the only
	 * function that looks up host names.
	 */
	if (!strchr(name, '.') && (cp = __hostalias(name)))
		name = cp;

	/*
	 * disallow names consisting only of digits/dots, unless
	 * they end in a dot.
	 */
	if (isdigit(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_pton(af, name, host_addr) <= 0) {
					h_errno = HOST_NOT_FOUND;
					return (NULL);
				}
				strncpy(hostbuf, name, MAXDNAME);
				hostbuf[MAXDNAME] = '\0';
				bp = hostbuf + MAXDNAME;
				len = sizeof hostbuf - MAXDNAME;
				host.h_name = hostbuf;
				host.h_aliases = host_aliases;
				host_aliases[0] = NULL;
				h_addr_ptrs[0] = (char *)host_addr;
				h_addr_ptrs[1] = NULL;
				host.h_addr_list = h_addr_ptrs;
				if (_res.options & RES_USE_INET6)
					map_v4v6_hostent(&host, &bp, &len);
				h_errno = NETDB_SUCCESS;
				return (&host);
			}
			if (!isdigit(*cp) && *cp != '.')
				break;
		}

	h_errno = HOST_NOT_FOUND;
	for (i = 0; i < _res_hconf.num_services; ++i) {
		struct hostent * hp;
		char * cp = (char *) name;

		if (_res_hconf.num_trimdomains > 0) {
			size_t name_len = strlen(name);

			cp = malloc(name_len + 1);
			memcpy(cp, name, name_len + 1);
			_res_hconf_trim_domain(cp);
		}

		hp = NULL;
		switch (_res_hconf.service[i]) {
		      case SERVICE_BIND:
			if ((n = res_search(cp, C_IN, type,
					    buf.buf, sizeof(buf))) < 0)
			{
				dprintf("res_search failed (%d)\n", n);
				break;
			}
			hp = getanswer(&buf, n, cp, type);
			break;

		      case SERVICE_HOSTS:
			hp = _gethtbyname2(cp, af);
			break;
#ifdef HAVE_NYS
		      case SERVICE_NIS:
			hp = _getnishost(cp, "hosts.byname");
			break;
#endif
		      default:
			break;
		}
		if (cp != name)
			free(cp);
		if (hp) {
			if ((_res_hconf.flags & HCONF_FLAG_REORDER)
			    && hp->h_addr_list[0] && hp->h_addr_list[1])
				_res_hconf_reorder_addrs(hp);
			_res_hconf_trim_domains(hp);
			return hp;
		}
	}
	if (h_errno == NETDB_SUCCESS)
		h_errno = HOST_NOT_FOUND;
	return NULL;
}

struct hostent *
gethostbyaddr(addr, len, af)
	const char *addr;	/* XXX should have been def'd as u_char! */
	int len, af;
{
	const u_char *uaddr = (const u_char *)addr;
	static const u_char mapped[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0xff,0xff };
	static const u_char tunnelled[] = { 0,0, 0,0, 0,0, 0,0, 0,0, 0,0 };
	int n, size;
	querybuf buf;
	register struct hostent *hp;
	char qbuf[MAXDNAME+1], *qp;
	register struct hostent *rhp;
	char **haddr;
	u_long old_options;
	char hname2[MAXDNAME+1];
	int i, old_num_trimdomains;
	extern struct hostent *_gethtbyaddr();

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
	if (af == AF_INET6 && len == IN6ADDRSZ &&
	    (!bcmp(uaddr, mapped, sizeof mapped) ||
	     !bcmp(uaddr, tunnelled, sizeof tunnelled))) {
		/* Unmap. */
		addr += sizeof mapped;
		uaddr += sizeof mapped;
		af = AF_INET;
		len = INADDRSZ;
	}
	switch (af) {
	case AF_INET:
		size = INADDRSZ;
		break;
	case AF_INET6:
		size = IN6ADDRSZ;
		break;
	default:
		errno = EAFNOSUPPORT;
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
	if (size != len) {
		errno = EINVAL;
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	h_errno = NETDB_SUCCESS;
	for (i = 0; i < _res_hconf.num_services; ++i) {
		hp = NULL;
		switch (_res_hconf.service[i]) {
		case SERVICE_BIND:
			switch (af) {
			case AF_INET:
				(void) sprintf(qbuf,
					       "%u.%u.%u.%u.in-addr.arpa",
					       (uaddr[3] & 0xff),
					       (uaddr[2] & 0xff),
					       (uaddr[1] & 0xff),
					       (uaddr[0] & 0xff));
				break;
			case AF_INET6:
				qp = qbuf;
				for (n = IN6ADDRSZ - 1; n >= 0; n--) {
					qp += SPRINTF((qp, "%x.%x.",
						       uaddr[n] & 0xf,
						       (uaddr[n] >> 4) & 0xf));
				}
				strcpy(qp, "ip6.int");
				break;
			default:
				abort();
			}
			n = res_query(qbuf, C_IN, T_PTR,
				      (u_char *)buf.buf, sizeof buf.buf);
			if (n < 0) {
				dprintf("res_query failed (%d)\n", n);
				break;
			}
			hp = getanswer(&buf, n, qbuf, T_PTR);
			if (!hp)
				break;	/* h_errno was set by getanswer() */
			if (af == AF_INET
			    && (_res_hconf.flags & HCONF_FLAG_SPOOF)) {
				/*
				 * Turn off search as the name should
				 * be absolute, 'localhost' should be
				 * matched by defnames
				 */
				strncpy(hname2, hp->h_name, MAXDNAME);
				hname2[MAXDNAME] = '\0';
				old_options = _res.options;
				/*
				 * Also turn off domain trimming to prevent it
				 * from causing the name comparison to fail.
				 */
				old_num_trimdomains =
					_res_hconf.num_trimdomains;
				_res.options &= ~RES_DNSRCH;
				_res.options |= RES_DEFNAMES;
				rhp = gethostbyname(hname2);
				_res.options = old_options;
				/* There must be an A record and
				   the names must match.  */
				if (!rhp || strcmp(hname2, rhp->h_name)) {
					syslog(LOG_NOTICE|LOG_AUTH,
					       "gethostbyaddr: No A record for"
					       " %s (verifying [%s])",
					       hname2,
					       inet_ntoa(*((struct in_addr *)
							   addr)));
					h_errno = HOST_NOT_FOUND;
					break;
				}
				for (haddr = rhp->h_addr_list; *haddr; haddr++)
					if (!memcmp(*haddr, addr, INADDRSZ))
						break;
				if (!*haddr) {
					syslog(LOG_NOTICE|LOG_AUTH,
					       "gethostbyaddr: A record of %s"
					       " != PTR record [%s]",
					       hname2,
					       inet_ntoa(*((struct in_addr *)
							   addr)));
					h_errno = HOST_NOT_FOUND;
					break;
				}
			}
			hp->h_addrtype = af;
			hp->h_length = len;
			bcopy(addr, host_addr, len);
			h_addr_ptrs[0] = (char *)host_addr;
			h_addr_ptrs[1] = NULL;
			if (af == AF_INET && (_res.options & RES_USE_INET6)) {
				map_v4v6_address((char*)host_addr,
						 (char*)host_addr);
				hp->h_addrtype = AF_INET6;
				hp->h_length = IN6ADDRSZ;
			}
			h_errno = NETDB_SUCCESS;
			break;

		case SERVICE_HOSTS:
			hp = _gethtbyaddr(addr, len, af);
			break;

#ifdef HAVE_NYS
		case SERVICE_NIS:
			if (af == AF_INET) {
				sprintf(qbuf, "%u.%u.%u.%u",
					(unsigned)addr[0] & 0xff,
					(unsigned)addr[1] & 0xff,
					(unsigned)addr[2] & 0xff,
					(unsigned)addr[3] & 0xff);
				hp = _getnishost(qbuf, "hosts.byaddr");
			}
			break;
#endif

		default:
			break;
		}
		if (hp) {
			_res_hconf_trim_domains(hp);
			return hp;
		}
	}
	if (h_errno == NETDB_SUCCESS)
		h_errno = HOST_NOT_FOUND;
	return NULL;
}

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

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

struct hostent *
_gethtent()
{
	char *p;
	register char *cp, **q;
	int af, len;

	if (!hostf && !(hostf = fopen(_PATH_HOSTS, "r" ))) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}
 again:
	if (!(p = fgets(hostbuf, sizeof hostbuf, hostf))) {
		h_errno = HOST_NOT_FOUND;
		return (NULL);
	}
	if (*p == '#')
		goto again;
	if (!(cp = strpbrk(p, "#\n")))
		goto again;
	*cp = '\0';
	if (!(cp = strpbrk(p, " \t")))
		goto again;
	*cp++ = '\0';
	if ((_res.options & RES_USE_INET6) &&
	    inet_pton(AF_INET6, p, host_addr) > 0) {
		af = AF_INET6;
		len = IN6ADDRSZ;
	} else if (inet_pton(AF_INET, p, host_addr) > 0) {
		if (_res.options & RES_USE_INET6) {
			map_v4v6_address((char*)host_addr, (char*)host_addr);
			af = AF_INET6;
			len = IN6ADDRSZ;
		} else {
			af = AF_INET;
			len = INADDRSZ;
		}
	} else {
		goto again;
	}
	h_addr_ptrs[0] = (char *)host_addr;
	h_addr_ptrs[1] = NULL;
	host.h_addr_list = h_addr_ptrs;
	host.h_length = len;
	host.h_addrtype = af;
	while (*cp == ' ' || *cp == '\t')
		cp++;
	host.h_name = cp;
	q = host.h_aliases = host_aliases;
	if (cp = strpbrk(cp, " \t"))
		*cp++ = '\0';
	while (cp && *cp) {
		if (*cp == ' ' || *cp == '\t') {
			cp++;
			continue;
		}
		if (q < &host_aliases[MAXALIASES - 1])
			*q++ = cp;
		if (cp = strpbrk(cp, " \t"))
			*cp++ = '\0';
	}
	*q = NULL;
	if (_res.options & RES_USE_INET6) {
		char *bp = hostbuf;
		int buflen = sizeof hostbuf;

		map_v4v6_hostent(&host, &bp, &buflen);
	}
	h_errno = NETDB_SUCCESS;
	return (&host);
}

struct hstorage {
	char	*name;				/* canonical name */
	char **	alp;				/* address list pointer */
	char *	abp;				/* address buffer pointer */
	char *	addr_list[MAXADDRS + 1];	/* address list storage */
	char	addr_buf[MAXADDRBUFSIZE];	/* addresses storage */
};

static void
append_addr (struct hstorage * hs, struct hostent *p)
{
	if (hs->alp < hs->addr_list + MAXADDRS
	    && hs->abp + p->h_length < hs->addr_buf + MAXADDRBUFSIZE)
	{
		hs->alp[0] = hs->abp;
		hs->alp[1] = 0;
		memcpy(hs->abp, p->h_addr_list[0], p->h_length);
		hs->abp += p->h_length;
		++hs->alp;
	}
}

/*
 * Lookup IP address and aliases for host NAME.  If multiaddress mode
 * is enabled, the entire /etc/hosts file is searched and the union of
 * all addresses found for NAME is returned (this may be slow with
 * large /etc/hosts files, but is convenient for smallish sites that
 * don't want to go through the complexity of running named locally).
 * If multiaddress mode is enabled, the address returned in
 * h_addr_list[0] is one that is on the same net as one of the host's
 * local addresses (if such an address exists).  For compatibility
 * with the BIND version of gethostbyname(), the alias field is empty
 * unless the name being looked up is an alias itself.  In the latter
 * case, the name field contains the canonical name and the alias
 * field the name that is being looked up.  A difference from the BIND
 * version is that this is true even if the alias applies only to one
 * of the interfaces on the target host.o
 */
struct hostent *
_gethtbyname(name)
	const char *name;
{
	extern struct hostent *_gethtbyname2();
	struct hostent *hp;

	if (_res.options & RES_USE_INET6) {
		hp = _gethtbyname2(name, AF_INET6);
		if (hp)
			return (hp);
	}
	return (_gethtbyname2(name, AF_INET));
}

struct hostent *
_gethtbyname2(name, af)
	const char *name;
	int af;
{
	register struct hostent *p;
	register char **cp;

	_sethtent(0);

	if (_res_hconf.flags & HCONF_FLAG_MULTI) {
		/*
		 * More statics; not pretty, but it would require
		 * interface changes to make these functions
		 * reentrant.
		 */
		static char *aliases[2] = {0};
		static struct hstorage self = {0}, target = {0};
		static size_t self_name_size = 0; /* Allocated in self.name. */
		static struct hostent ht;
		int found;

		if (aliases[0])
			free (aliases[0]);	/* Malloced in a prev call.  */
		aliases[0] = aliases[1] = 0;

		/* Get current host name in a large enough buffer.  */
		do {
			   errno = 0;

			   if (self.name)
			   {
				   self_name_size += self_name_size;
				   self.name =
					   realloc (self.name, self_name_size);
			   } else {
				   self_name_size = 128; /* Initial guess */
				   self.name = malloc (self_name_size);
			   }

			   if (! self.name)
			   {
				   errno = ENOMEM;
				   return 0;
			   }
		   } while ((gethostname(self.name, self_name_size) == 0
			     && !memchr (self.name, '\0', self_name_size))
			    || errno == ENAMETOOLONG);
		
		if (errno)
			/* gethostname failed, abort.  */
		{
			free (self.name);
			self.name = 0;
		}

		self.alp = self.addr_list;
		self.abp = self.addr_buf;

		if (target.name)
			free (target.name);
		target.name = strdup (name);

		target.alp = target.addr_list;
		target.abp = target.addr_buf;

		_sethtent(0);
		while ((p = _gethtent()) != 0) {
			found = 1;

			if (p->h_addrtype != af)
				continue;
			if (strcasecmp(p->h_name, name) != 0) {
				found = 0;
				for (cp = p->h_aliases; *cp; ++cp)
					if (strcasecmp(*cp, name) == 0) {
						found = 1;
						if (!aliases[0]) {
							aliases[0] =
							  target.name;
							target.name =
							  strdup (p->h_name);
						}
						break;
					}
			}
			if (found) {
				/* they better be all the same type and length! */
				ht.h_addrtype = p->h_addrtype;
				ht.h_length = p->h_length;
				append_addr(&target, p);
				/*
				 * If the current hostentry is for the target host, we don't
				 * check for the local host name.  This nicely optimizes the
				 * case where NAME is a local name since address ordering
				 * doesn't matter in that case.
				 */
				continue;
			}
			found = 1;
			if (strcasecmp(p->h_name, self.name) != 0) {
				found = 0;
				for (cp = p->h_aliases; *cp; ++cp)
					if (strcasecmp(*cp, self.name) == 0) {
						found = 1;
						break;
					}
			}
			if (found) {
				append_addr(&self, p);
			}
		}
		_endhtent();

		if (target.alp == target.addr_list)
			return NULL;		/* found nothing */

		ht.h_aliases   = aliases;
		ht.h_name      = target.name;
		ht.h_addr_list = target.addr_list;
		/*
		 * XXX (davidm) Isn't this subsumed by REORDER???
		 *
		 * Finding the `best' address is necessarily address
		 * specific.  For now, we do IPv4 addresses only.
		 */
		if (af == AF_INET) {
			u_int32_t a1, a2, diff, mindiff = ~0;
			int i, j, bestaddr = 0;

			for (i = 0; self.addr_list[i]; ++i) {
				for (j = 0; target.addr_list[j]; ++j) {
					memcpy(&a1, self.addr_list[i], 4);
					memcpy(&a2, target.addr_list[j], 4);
					a1 = ntohl(a1);
					a2 = ntohl(a2);
					diff = a1 ^ a2;
					if (diff < mindiff) {
						bestaddr = j;
						mindiff = diff;
					}
				}
			}
			if (bestaddr > 0) {
				char * tmp;

				tmp = target.addr_list[0];
				target.addr_list[0] = target.addr_list[bestaddr];
				target.addr_list[bestaddr] = tmp;
			}
		} else if (af == AF_INET6) {
			/* XXX To do!!! */
		}
		ht.h_addr_list = target.addr_list;
		return &ht;
	} else {
		_sethtent(0);
		while (p = _gethtent()) {
			if (p->h_addrtype != af)
				continue;
			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();
	return (p);
}

struct hostent *
_gethtbyaddr(addr, len, af)
	const char *addr;
	int len, af;
{
	register struct hostent *p;

	_sethtent(0);
	while (p = _gethtent())
		if (p->h_addrtype == af && !bcmp(p->h_addr, addr, len))
			break;
	_endhtent();
	return (p);
}

static void
map_v4v6_address(src, dst)
	const char *src;
	char *dst;
{
	u_char *p = (u_char *)dst;
	char tmp[INADDRSZ];
	int i;

	/* Stash a temporary copy so our caller can update in place. */
	bcopy(src, tmp, INADDRSZ);
	/* Mark this ipv6 addr as a mapped ipv4. */
	for (i = 0; i < 10; i++)
		*p++ = 0x00;
	*p++ = 0xff;
	*p++ = 0xff;
	/* Retrieve the saved copy and we're done. */
	bcopy(tmp, (void*)p, INADDRSZ);
}

static void
map_v4v6_hostent(hp, bpp, lenp)
	struct hostent *hp;
	char **bpp;
	int *lenp;
{
	char **ap;

	if (hp->h_addrtype != AF_INET || hp->h_length != INADDRSZ)
		return;
	hp->h_addrtype = AF_INET6;
	hp->h_length = IN6ADDRSZ;
	for (ap = hp->h_addr_list; *ap; ap++) {
		int i = sizeof(align) - ((u_long)*bpp % sizeof(align));

		if (*lenp < (i + IN6ADDRSZ)) {
			/* Out of memory.  Truncate address list here.  XXX */
			*ap = NULL;
			return;
		}
		*bpp += i;
		*lenp -= i;
		map_v4v6_address(*ap, *bpp);
		*ap = *bpp;
		*bpp += IN6ADDRSZ;
		*lenp -= IN6ADDRSZ;
	}
}

#ifdef RESOLVSORT
static void
addrsort(ap, num)
	char **ap;
	int num;
{
	int i, j;
	char **p;
	short aval[MAXADDRS];
	int needsort = 0;

	p = ap;
	for (i = 0; i < num; i++, p++) {
	    for (j = 0 ; (unsigned)j < _res.nsort; j++)
		if (_res.sort_list[j].addr.s_addr ==
		    (((struct in_addr *)(*p))->s_addr & _res.sort_list[j].mask))
			break;
	    aval[i] = j;
	    if (needsort == 0 && i > 0 && j < aval[i-1])
		needsort = i;
	}
	if (!needsort)
	    return;

	while (needsort < num) {
	    for (j = needsort - 1; j >= 0; j--) {
		if (aval[j] > aval[j+1]) {
		    char *hp;

		    i = aval[j];
		    aval[j] = aval[j+1];
		    aval[j+1] = i;

		    hp = ap[j];
		    ap[j] = ap[j+1];
		    ap[j+1] = hp;

		} else
		    break;
	    }
	    needsort++;
	}
}
#endif

#if defined(BSD43_BSD43_NFS) || defined(sun)
/* some libc's out there are bound internally to these names (UMIPS) */
void
ht_sethostent(stayopen)
	int stayopen;
{
	_sethtent(stayopen);
}

void
ht_endhostent()
{
	_endhtent();
}

struct hostent *
ht_gethostbyname(name)
	char *name;
{
	return (_gethtbyname(name));
}

struct hostent *
ht_gethostbyaddr(addr, len, af)
	const char *addr;
	int len, af;
{
	return (_gethtbyaddr(addr, len, af));
}

struct hostent *
gethostent()
{
	struct hostent * hp;
	int i;

	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
		h_errno = NETDB_INTERNAL;
		return (NULL);
	}

	/*
	 * This doesn't look quite right.  Shouldn't we read one
	 * service until it returns 0, then move on to the next
	 * service?  If so, it requires adding some state and
	 * initializing that state in sethostent().
	 * (davidm@azstarnet.com)
	 */
	for (i = 0; i < _res_hconf.num_services; ++i) {
		hp = NULL;
		switch (_res_hconf.service[i]) {
		      case SERVICE_HOSTS:
			hp = _gethtent ();
			break;

#ifdef HAVE_NYS
		      case SERVICE_NIS:
			hp = _getnishost (NULL, "hosts.byname");
			break;
#endif

		      case SERVICE_BIND:
		      default:
			break;
		}
		if (hp) {
			if ((_res_hconf.flags & HCONF_FLAG_REORDER)
			    && hp->h_addr_list[0] && hp->h_addr_list[1])
				_res_hconf_reorder_addrs (hp);
			return hp;
		}
	}
	h_errno = HOST_NOT_FOUND;
	return NULL;
}

void
dns_service()
{
	return;
}

#undef dn_skipname
dn_skipname(comp_dn, eom)
	const u_char *comp_dn, *eom;
{
	return (__dn_skipname(comp_dn, eom));
}
#endif /*old-style libc with yp junk in it*/