text: /*-
   * Copyright (c) 1985, 1988, 1993
   *	The Regents of the University of California.  All rights reserved.
   *
   * Portions copyright (c) 1999, 2000
   * Intel Corporation.
   * 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, Intel Corporation, and its contributors.
   *
   * 4. Neither the name of University, Intel Corporation, or their respective
   *    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, INTEL CORPORATION 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,
   * INTEL CORPORATION 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--
   */
  /* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
   *	Dep. Matematica Universidade de Coimbra, Portugal, Europe
   *
   * 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.
   */
  
  #if defined(LIBC_SCCS) && !defined(lint)
  static char sccsid[] = "@(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93";
  static char rcsid[] = "$Id: getnetbydns.c,v 1.1.1.1 2003/11/19 01:51:27 kyu3 Exp $";
  #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 <netdb.h>
  #include <resolv.h>
  #include <ctype.h>
  #include <errno.h>
  #include <string.h>
  #include <unistd.h>
  #ifdef _ORG_FREEBSD_
  #include <syslog.h>
  #endif
  
  #include "res_config.h"
  #include "Socklib_internals.h"
  
  extern int h_errno;
  
  #define BYADDR 0
  #define BYNAME 1
  #define	MAXALIASES	35
  
  #if PACKETSZ > 1024
  #define	MAXPACKET	PACKETSZ
  #else
  #define	MAXPACKET	1024
  #endif
  
  typedef union {
  	HEADER	hdr;
  	u_char	buf[MAXPACKET];
  } querybuf;
  
  typedef union {
  	long	al;
  	char	ac;
  } align;
  
  static struct netent *
  getnetanswer(querybuf *answer, int anslen, int net_i)
  {
  
  	register HEADER *hp;
  	register u_char *cp;
  	register int n;
  	u_char *eom;
  	int type, class, buflen, ancount, qdcount, haveanswer, i, nchar;
  	char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];
  	char *in, *st, *pauxt, *bp, **ap;
  	char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
  static	struct netent net_entry;
  static	char *net_aliases[MAXALIASES], netbuf[PACKETSZ];
  
  	/*
  	 * find first satisfactory answer
  	 *
  	 *      answer --> +------------+  ( MESSAGE )
  	 *		   |   Header   |
  	 *		   +------------+
  	 *		   |  Question  | the question for the name server
  	 *		   +------------+
  	 *		   |   Answer   | RRs answering the question
  	 *		   +------------+
  	 *		   | Authority  | RRs pointing toward an authority
  	 *		   | Additional | RRs holding additional information
  	 *		   +------------+
  	 */
  	eom = answer->buf + anslen;
  	hp = &answer->hdr;
  	ancount = ntohs(hp->ancount); /* #/records in the answer section */
  	qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
  	bp = netbuf;
  	buflen = sizeof(netbuf);
  	cp = answer->buf + HFIXEDSZ;
  	if (!qdcount) {
  		if (hp->aa)
  			h_errno = HOST_NOT_FOUND;
  		else
  			h_errno = TRY_AGAIN;
  		return (NULL);
  	}
  	while (qdcount-- > 0)
  		cp += __dn_skipname(cp, eom) + QFIXEDSZ;
  	ap = net_aliases;
  	*ap = NULL;
  	net_entry.n_aliases = net_aliases;
  	haveanswer = 0;
  	while (--ancount >= 0 && cp < eom) {
  		n = dn_expand(answer->buf, eom, cp, bp, buflen);
  		if ((n < 0) || !res_dnok(bp))
  			break;
  		cp += n;
  		ans[0] = '\0';
  		(void)strncpy(&ans[0], bp, sizeof(ans) - 1);
  		ans[sizeof(ans) - 1] = '\0';
  		GETSHORT(type, cp);
  		GETSHORT(class, cp);
  		cp += INT32SZ;		/* TTL */
  		GETSHORT(n, cp);
  		if (class == C_IN && type == T_PTR) {
  			n = dn_expand(answer->buf, eom, cp, bp, buflen);
  			if ((n < 0) || !res_hnok(bp)) {
  				cp += n;
  				return (NULL);
  			}
  			cp += n;
  			*ap++ = bp;
  			bp += strlen(bp) + 1;
  			net_entry.n_addrtype =
  				(class == C_IN) ? AF_INET : AF_UNSPEC;
  			haveanswer++;
  		}
  	}
  	if (haveanswer) {
  		*ap = NULL;
  		switch (net_i) {
  		case BYADDR:
  			net_entry.n_name = *net_entry.n_aliases;
  			net_entry.n_net = 0L;
  			break;
  		case BYNAME:
  			in = *net_entry.n_aliases;
  			net_entry.n_name = &ans[0];
  			aux2[0] = '\0';
  			for (i = 0; i < 4; i++) {
  				for (st = in, nchar = 0;
  				     *st != '.';
  				     st++, nchar++)
  					;
  				if (nchar != 1 || *in != '0' || flag) {
  					flag = 1;
  					(void)strncpy(paux1,
  						      (i==0) ? in : in-1,
  						      (i==0) ?nchar : nchar+1);
  					paux1[(i==0) ? nchar : nchar+1] = '\0';
  					pauxt = paux2;
  					paux2 = strcat(paux1, paux2);
  					paux1 = pauxt;
  				}
  				in = ++st;
  			}
  			net_entry.n_net = inet_network(paux2);
  			break;
  		}
  		net_entry.n_aliases++;
  		return (&net_entry);
  	}
  	h_errno = TRY_AGAIN;
  	return (NULL);
  }
  
  struct netent *
  _getnetbydnsaddr(register unsigned long net, register int net_type)
  {
  	unsigned int netbr[4];
  	int nn, anslen;
  	querybuf buf;
  	char qbuf[MAXDNAME];
  	unsigned long net2;
  	struct netent *net_entry;
  
  	if (net_type != AF_INET)
  		return (NULL);
  
  	for (nn = 4, net2 = net; net2; net2 >>= 8)
  		netbr[--nn] = net2 & 0xff;
  	switch (nn) {
  	case 3: 	/* Class A */
  		sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
  		break;
  	case 2: 	/* Class B */
  		sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
  		break;
  	case 1: 	/* Class C */
  		sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
  		    netbr[1]);
  		break;
  	case 0: 	/* Class D - E */
  		sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
  		    netbr[1], netbr[0]);
  		break;
  	}
  	anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
  	if (anslen < 0) {
  #ifdef DEBUG
  		if (_res.options & RES_DEBUG)
  			printf("res_query failed\n");
  #endif
  		return (NULL);
  	}
  	net_entry = getnetanswer(&buf, anslen, BYADDR);
  	if (net_entry) {
  		unsigned u_net = net;	/* maybe net should be unsigned ? */
  
  		/* Strip trailing zeros */
  		while ((u_net & 0xff) == 0 && u_net != 0)
  			u_net >>= 8;
  		net_entry->n_net = u_net;
  		return (net_entry);
  	}
  	return (NULL);
  }
  
  struct netent *
  _getnetbydnsname(register const char *net)
  {
  	int anslen;
  	querybuf buf;
  	char qbuf[MAXDNAME];
  
  	if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
  		h_errno = NETDB_INTERNAL;
  		return (NULL);
  	}
  	strncpy(qbuf, net, sizeof(qbuf) - 1);
  	qbuf[sizeof(qbuf) - 1] = '\0';
  	anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
  	if (anslen < 0) {
  #ifdef DEBUG
  		if (_res.options & RES_DEBUG)
  			printf("res_query failed\n");
  #endif
  		return (NULL);
  	}
  	return getnetanswer(&buf, anslen, BYNAME);
  }
  
  void
  _setnetdnsent(int stayopen)
  {
  	if (stayopen)
  		_res.options |= RES_STAYOPEN | RES_USEVC;
  }
  
  void
  _endnetdnsent()
  {
  	_res.options &= ~(RES_STAYOPEN | RES_USEVC);
  	res_close();
  }
  