text: /*-
   * 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.
   * 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--
   *
   * @(#)gethostnamadr.c	8.1 (Berkeley) 6/4/93
   * $FreeBSD: src/lib/libc/net/getnetbydns.c,v 1.34 2007/01/09 00:28:02 imp Exp $
   */
  /* 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.
   */
  
  #include <sys/param.h>
  #include <sys/socket.h>
  #include <netinet/in.h>
  #include <arpa/inet.h>
  #include <arpa/nameser.h>
  
  #include <errno.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <netdb.h>
  #include <resolv.h>
  #include <ctype.h>
  #include <string.h>
  #include <unistd.h>
  #include <syslog.h>
  #include <stdarg.h>
  #include <nsswitch.h>
  
  #include "netdb_private.h"
  #include "res_config.h"
  
  #define BYADDR 0
  #define BYNAME 1
  
  #define MAXPACKET	(64*1024)
  
  typedef union {
  	HEADER	hdr;
  	u_char	buf[MAXPACKET];
  } querybuf;
  
  typedef union {
  	long	al;
  	char	ac;
  } align;
  
  /*
   * Reverse the order of first four dotted entries of in.
   * Out must contain space for at least strlen(in) characters.
   * The result does not include any leading 0s of in.
   */
  static void
  ipreverse(char *in, char *out)
  {
  	char *pos[4];
  	int len[4];
  	char *p, *start;
  	int i = 0;
  	int leading = 1;
  
  	/* Fill-in element positions and lengths: pos[], len[]. */
  	start = p = in;
  	for (;;) {
  		if (*p == '.' || *p == '\0') {
  			/* Leading 0? */
  			if (leading && p - start == 1 && *start == '0')
  				len[i] = 0;
  			else {
  				len[i] = p - start;
  				leading = 0;
  			}
  			pos[i] = start;
  			start = p + 1;
  			i++;
  		}
  		if (i == 4)
  			break;
  		if (*p == 0) {
  			for (; i < 4; i++) {
  				pos[i] = p;
  				len[i] = 0;
  			}
  			break;
  		}
  		p++;
  	}
  
  	/* Copy the entries in reverse order */
  	p = out;
  	leading = 1;
  	for (i = 3; i >= 0; i--) {
  		memcpy(p, pos[i], len[i]);
  		if (len[i])
  			leading = 0;
  		p += len[i];
  		/* Need a . separator? */
  		if (!leading && i > 0 && len[i - 1])
  			*p++ = '.';
  	}
  	*p = '\0';
  }
  
  static int
  getnetanswer(querybuf *answer, int anslen, int net_i, struct netent *ne,
  	     struct netent_data *ned, res_state statp)
  {
  
  	HEADER *hp;
  	u_char *cp;
  	int n;
  	u_char *eom;
  	int type, class, ancount, qdcount, haveanswer;
  	char aux[MAXHOSTNAMELEN];
  	char ans[MAXHOSTNAMELEN];
  	char *in, *bp, *ep, **ap;
  
  	/*
  	 * 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 = ned->netbuf;
  	ep = ned->netbuf + sizeof(ned->netbuf);
  	cp = answer->buf + HFIXEDSZ;
  	if (!qdcount) {
  		if (hp->aa)
  			RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
  		else
  			RES_SET_H_ERRNO(statp, TRY_AGAIN);
  		return (-1);
  	}
  	while (qdcount-- > 0)
  		cp += __dn_skipname(cp, eom) + QFIXEDSZ;
  	ap = ned->net_aliases;
  	*ap = NULL;
  	ne->n_aliases = ned->net_aliases;
  	haveanswer = 0;
  	while (--ancount >= 0 && cp < eom) {
  		n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
  		if ((n < 0) || !res_dnok(bp))
  			break;
  		cp += n;
  		ans[0] = '\0';
  		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, ep - bp);
  			if ((n < 0) || !res_hnok(bp)) {
  				cp += n;
  				return (-1);
  			}
  			cp += n;
  			*ap++ = bp;
  			n = strlen(bp) + 1;
  			bp += n;
  			ne->n_addrtype = (class == C_IN) ? AF_INET : AF_UNSPEC;
  			haveanswer++;
  		}
  	}
  	if (haveanswer) {
  		*ap = NULL;
  		switch (net_i) {
  		case BYADDR:
  			ne->n_name = *ne->n_aliases;
  			ne->n_net = 0L;
  			break;
  		case BYNAME:
  			in = *ne->n_aliases;
  			n = strlen(ans) + 1;
  			if (ep - bp < n) {
  				RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  				errno = ENOBUFS;
  				return (-1);
  			}
  			strlcpy(bp, ans, ep - bp);
  			ne->n_name = bp;
  			if (strlen(in) + 1 > sizeof(aux)) {
  				RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  				errno = ENOBUFS;
  				return (-1);
  			}
  			ipreverse(in, aux);
  			ne->n_net = inet_network(aux);
  			break;
  		}
  		ne->n_aliases++;
  		return (0);
  	}
  	RES_SET_H_ERRNO(statp, TRY_AGAIN);
  	return (-1);
  }
  
  int
  _dns_getnetbyaddr(void *rval, void *cb_data __unused, va_list ap)
  {
  	uint32_t net;
  	int net_type;
  	char *buffer;
  	size_t buflen;
  	int *errnop, *h_errnop;
  	struct netent *nptr, ne;
  	struct netent_data *ned;
  	unsigned int netbr[4];
  	int nn, anslen, error;
  	querybuf *buf;
  	char qbuf[MAXDNAME];
  	uint32_t net2;
  	res_state statp;
  
  	net = va_arg(ap, uint32_t);
  	net_type = va_arg(ap, int);
  	nptr = va_arg(ap, struct netent *);
  	buffer = va_arg(ap, char *);
  	buflen = va_arg(ap, size_t);
  	errnop = va_arg(ap, int *);
  	h_errnop = va_arg(ap, int *);
  
  	statp = __res_state();
  	if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  
  	if ((ned = __netent_data_init()) == NULL) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  
  	*((struct netent **)rval) = NULL;
  
  	if (net_type != AF_INET) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  
  	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;
  	}
  	if ((buf = malloc(sizeof(*buf))) == NULL) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_NOTFOUND);
  	}
  	anslen = res_nquery(statp, qbuf, C_IN, T_PTR, (u_char *)buf,
  	    sizeof(*buf));
  	if (anslen < 0) {
  		free(buf);
  #ifdef DEBUG
  		if (statp->options & RES_DEBUG)
  			printf("res_nsearch failed\n");
  #endif
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	} else if (anslen > sizeof(*buf)) {
  		free(buf);
  #ifdef DEBUG
  		if (statp->options & RES_DEBUG)
  			printf("res_nsearch static buffer too small\n");
  #endif
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  	error = getnetanswer(buf, anslen, BYADDR, &ne, ned, statp);
  	free(buf);
  	if (error == 0) {
  		/* Strip trailing zeros */
  		while ((net & 0xff) == 0 && net != 0)
  			net >>= 8;
  		ne.n_net = net;
  		if (__copy_netent(&ne, nptr, buffer, buflen) != 0) {
  			*h_errnop = statp->res_h_errno;
  			return (NS_NOTFOUND);
  		}
  		*((struct netent **)rval) = nptr;
  		return (NS_SUCCESS);
  	}
  	*h_errnop = statp->res_h_errno;
  	return (NS_NOTFOUND);
  }
  
  int
  _dns_getnetbyname(void *rval, void *cb_data __unused, va_list ap)
  {
  	const char *net;
  	char *buffer;
  	size_t buflen;
  	int *errnop, *h_errnop;
  	struct netent *nptr, ne;
  	struct netent_data *ned;
  	int anslen, error;
  	querybuf *buf;
  	char qbuf[MAXDNAME];
  	res_state statp;
  
  	net = va_arg(ap, const char *);
  	nptr = va_arg(ap, struct netent *);
  	buffer = va_arg(ap, char *);
  	buflen = va_arg(ap, size_t);
  	errnop = va_arg(ap, int *);
  	h_errnop = va_arg(ap, int *);
  
  	statp = __res_state();
  	if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  	if ((ned = __netent_data_init()) == NULL) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_UNAVAIL);
  	}
  	if ((buf = malloc(sizeof(*buf))) == NULL) {
  		RES_SET_H_ERRNO(statp, NETDB_INTERNAL);
  		*h_errnop = statp->res_h_errno;
  		return (NS_NOTFOUND);
  	}
  
  	*((struct netent **)rval) = NULL;
  
  	strncpy(qbuf, net, sizeof(qbuf) - 1);
  	qbuf[sizeof(qbuf) - 1] = '\0';
  	anslen = res_nsearch(statp, qbuf, C_IN, T_PTR, (u_char *)buf,
  	    sizeof(*buf));
  	if (anslen < 0) {
  		free(buf);
  #ifdef DEBUG
  		if (statp->options & RES_DEBUG)
  			printf("res_nsearch failed\n");
  #endif
  		return (NS_UNAVAIL);
  	} else if (anslen > sizeof(*buf)) {
  		free(buf);
  #ifdef DEBUG
  		if (statp->options & RES_DEBUG)
  			printf("res_search static buffer too small\n");
  #endif
  		return (NS_UNAVAIL);
  	}
  	error = getnetanswer(buf, anslen, BYNAME, &ne, ned, statp);
  	free(buf);
  	if (error != 0) {
  		*h_errnop = statp->res_h_errno;
  		return (NS_NOTFOUND);
  	}
  	if (__copy_netent(&ne, nptr, buffer, buflen) != 0) {
  		*h_errnop = statp->res_h_errno;
  		return (NS_NOTFOUND);
  	}
  	*((struct netent **)rval) = nptr;
  	return (NS_SUCCESS);
  }
  
  void
  _setnetdnsent(int stayopen)
  {
  	res_state statp;
  
  	statp = __res_state();
  	if ((statp->options & RES_INIT) == 0 && res_ninit(statp) == -1)
  		return;
  	if (stayopen)
  		statp->options |= RES_STAYOPEN | RES_USEVC;
  }
  
  void
  _endnetdnsent(void)
  {
  	res_state statp;
  
  	statp = __res_state();
  	statp->options &= ~(RES_STAYOPEN | RES_USEVC);
  	res_nclose(statp);
  }
  