__ns_initparse.c

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/*
 * 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM 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.
 */

#ifndef lint
static const char rcsid[] = "$Id: ns_parse.c,v 1.3.2.1 2003/06/27 03:51:42 marka Exp $";
#endif

/* Import. */

/* #include "port_before.h" */
#include "config.h"

#include <sys/types.h>

#include <netinet/in.h>
#include "arpa_nameser.h"

#include <errno.h>
/* #include <resolv.h> */
#ifdef HAVE_STRING_H
# include <string.h>       /* strstr / strdup */
#else
# ifdef HAVE_STRINGS_H
#  include <strings.h>       /* strstr / strdup */
# endif
#endif


/* #include "port_after.h" */

/* Forward. */

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

/* Macros. */

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

/* 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_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);
}

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);
}

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

        /* Make section right. */
        if ((tmp = section) < 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);
}

/* 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];
        }
}

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