/*      $NetBSD: ns_parse.c,v 1.9 2012/03/13 21:13:39 christos Exp $    */

/*
 * 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.
 */

#include <sys/cdefs.h>
#ifndef lint
#ifdef notdef
static const char rcsid[] = "Id: ns_parse.c,v 1.10 2009/01/23 19:59:16 each Exp";
#else
//__RCSID("$NetBSD: ns_parse.c,v 1.9 2012/03/13 21:13:39 christos Exp $");
#endif
#endif

/* Import. */

#include "port_before.h"

#include <sys/types.h>

#include <netinet/in.h>
#include <arpa/nameser.h>

#include <assert.h>
#include <errno.h>
#include <resolv.h>
#include <string.h>

#include "port_after.h"

/* Forward. */

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

/* Macros. */

#if !defined(SOLARIS2) || defined(__COVERITY__)
#define RETERR(err) do { errno = (err); return (-1); } while (/*NOTREACHED*//*CONSTCOND*/0)
#else
#define RETERR(err) \
        do { errno = (err); if (errno == errno) return (-1); } while (0)
#endif

#define PARSE_FMT_PRESO 0       /* Parse using presentation-format names */
#define PARSE_FMT_WIRE 1        /* Parse using network-format names */

/* Public. */

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

int ns_msg_getflag(ns_msg handle, int flag) {
        return((u_int32_t)((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 (; 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);
        assert(INT_MIN <= (ptr - optr) && (ptr - optr) <= INT_MAX);
        return (int)(ptr - optr);
}

int
ns_initparse(const u_char *msg, int msglen, ns_msg *handle) {
        const u_char *eom = msg + msglen;
        int i;

        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);
}

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);
}

extern int
ns_name_unpack2(const u_char *msg, const u_char *eom, const u_char *src,
                u_char *dst, size_t dstsiz, size_t *dstlen);

/*
 * This is identical to the above but uses network-format (uncompressed) names.
 */
int
ns_parserr2(ns_msg *handle, ns_sect section, int rrnum, ns_rr2 *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 = ns_name_unpack2(handle->_msg, handle->_eom, handle->_msg_ptr,
                            rr->nname, NS_MAXNNAME, &rr->nnamel);
        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);
}

/* 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 */