/*

 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")

 * Copyright (c) 1996,1999 by Internet Software Consortium.

 *

 * 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.

 *

 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES

 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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.

 */

/* Import. */

#include <sys/types.h>

#include <netinet/in.h>

#include <arpa/nameser.h>

#include <errno.h>

#include <resolv.h>

#include <string.h>

/* Forward. */

static void	setsection(ns_msg *msg, ns_sect sect);

/* Macros. */

#define RETERR(err) do { __set_errno (err); return (-1); } while (0)

/* Public. */

/* These need to be in the same order as the nres.h:ns_flag enum. */

const struct _ns_flagdata _ns_flagdata[16] = {

	{ 0x8000, 15 },		/*%< qr. */

	{ 0x7800, 11 },		/*%< opcode. */

	{ 0x0400, 10 },		/*%< aa. */

	{ 0x0200, 9 },		/*%< tc. */

	{ 0x0100, 8 },		/*%< rd. */

	{ 0x0080, 7 },		/*%< ra. */

	{ 0x0040, 6 },		/*%< z. */

	{ 0x0020, 5 },		/*%< ad. */

	{ 0x0010, 4 },		/*%< cd. */

	{ 0x000f, 0 },		/*%< rcode. */

	{ 0x0000, 0 },		/*%< expansion (1/6). */

	{ 0x0000, 0 },		/*%< expansion (2/6). */

	{ 0x0000, 0 },		/*%< expansion (3/6). */

	{ 0x0000, 0 },		/*%< expansion (4/6). */

	{ 0x0000, 0 },		/*%< expansion (5/6). */

	{ 0x0000, 0 },		/*%< expansion (6/6). */

};

#undef ns_msg_getflag

int ns_msg_getflag(ns_msg handle, int flag) {

	return(((handle)._flags & _ns_flagdata[flag].mask) >> _ns_flagdata[flag].shift);

}

int

ns_skiprr(const u_char *ptr, const u_char *eom, ns_sect section, int count) {

	const u_char *optr = ptr;

	for ((void)NULL; count > 0; count--) {

		int b, rdlength;

		b = dn_skipname(ptr, eom);

		if (b < 0)

			RETERR(EMSGSIZE);

		ptr += b/*Name*/ + NS_INT16SZ/*Type*/ + NS_INT16SZ/*Class*/;

		if (section != ns_s_qd) {

			if (ptr + NS_INT32SZ + NS_INT16SZ > eom)

				RETERR(EMSGSIZE);

			ptr += NS_INT32SZ/*TTL*/;

			NS_GET16(rdlength, ptr);

			ptr += rdlength/*RData*/;

		}

	}

	if (ptr > eom)

		RETERR(EMSGSIZE);

	return (ptr - optr);

}

libresolv_hidden_def (ns_skiprr)

int

ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {

	const u_char *eom = msg + msglen;

	int i;

	memset(handle, 0x5e, sizeof *handle);

	handle->_msg = msg;

	handle->_eom = eom;

	if (msg + NS_INT16SZ > eom)

		RETERR(EMSGSIZE);

	NS_GET16(handle->_id, msg);

	if (msg + NS_INT16SZ > eom)

		RETERR(EMSGSIZE);

	NS_GET16(handle->_flags, msg);

	for (i = 0; i < ns_s_max; i++) {

		if (msg + NS_INT16SZ > eom)

			RETERR(EMSGSIZE);

		NS_GET16(handle->_counts[i], msg);

	}

	for (i = 0; i < ns_s_max; i++)

		if (handle->_counts[i] == 0)

			handle->_sections[i] = NULL;

		else {

			int b = ns_skiprr(msg, eom, (ns_sect)i,

					  handle->_counts[i]);

			if (b < 0)

				return (-1);

			handle->_sections[i] = msg;

			msg += b;

		}

	if (msg != eom)

		RETERR(EMSGSIZE);

	setsection(handle, ns_s_max);

	return (0);

}

libresolv_hidden_def (ns_initparse)

int

ns_parserr(ns_msg *handle, ns_sect section, int rrnum, ns_rr *rr) {

	int b;

	int tmp;

	/* Make section right. */

	tmp = section;

	if (tmp < 0 || section >= ns_s_max)

		RETERR(ENODEV);

	if (section != handle->_sect)

		setsection(handle, section);

	/* Make rrnum right. */

	if (rrnum == -1)

		rrnum = handle->_rrnum;

	if (rrnum < 0 || rrnum >= handle->_counts[(int)section])

		RETERR(ENODEV);

	if (rrnum < handle->_rrnum)

		setsection(handle, section);

	if (rrnum > handle->_rrnum) {

		b = ns_skiprr(handle->_msg_ptr, handle->_eom, section,

			      rrnum - handle->_rrnum);

		if (b < 0)

			return (-1);

		handle->_msg_ptr += b;

		handle->_rrnum = rrnum;

	}

	/* Do the parse. */

	b = dn_expand(handle->_msg, handle->_eom,

		      handle->_msg_ptr, rr->name, NS_MAXDNAME);

	if (b < 0)

		return (-1);

	handle->_msg_ptr += b;

	if (handle->_msg_ptr + NS_INT16SZ + NS_INT16SZ > handle->_eom)

		RETERR(EMSGSIZE);

	NS_GET16(rr->type, handle->_msg_ptr);

	NS_GET16(rr->rr_class, handle->_msg_ptr);

	if (section == ns_s_qd) {

		rr->ttl = 0;

		rr->rdlength = 0;

		rr->rdata = NULL;

	} else {

		if (handle->_msg_ptr + NS_INT32SZ + NS_INT16SZ > handle->_eom)

			RETERR(EMSGSIZE);

		NS_GET32(rr->ttl, handle->_msg_ptr);

		NS_GET16(rr->rdlength, handle->_msg_ptr);

		if (handle->_msg_ptr + rr->rdlength > handle->_eom)

			RETERR(EMSGSIZE);

		rr->rdata = handle->_msg_ptr;

		handle->_msg_ptr += rr->rdlength;

	}

	if (++handle->_rrnum > handle->_counts[(int)section])

		setsection(handle, (ns_sect)((int)section + 1));

	/* All done. */

	return (0);

}

libresolv_hidden_def (ns_parserr)

/* Private. */

static void

setsection(ns_msg *msg, ns_sect sect) {

	msg->_sect = sect;

	if (sect == ns_s_max) {

		msg->_rrnum = -1;

		msg->_msg_ptr = NULL;

	} else {

		msg->_rrnum = 0;

		msg->_msg_ptr = msg->_sections[(int)sect];

	}

}

/*! \file */