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/*
* Copyright (c) 1985 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.
* 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 and its contributors.
* 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.
*/
#ifndef lint
/*static char sccsid[] = "from: @(#)skip.c 5.12 (Berkeley) 3/21/91";*/
static char rcsid[] = "$Id: skip.c,v 1.1 1995/10/18 08:47:55 deraadt Exp $";
#endif /* not lint */
/*
*******************************************************************************
*
* skip.c --
*
* Routines to skip over portions of a query buffer.
*
* Note: this file has been submitted for inclusion in
* BIND resolver library. When this has been done, this file
* is no longer necessary (assuming there haven't been any
* changes).
*
* Adapted from 4.3BSD BIND res_debug.c
*
*******************************************************************************
*/
#include <sys/param.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <stdio.h>
char *res_skip_rr();
/*
*******************************************************************************
*
* res_skip --
*
* Skip the contents of a query.
*
* Interpretation of numFieldsToSkip argument:
* res_skip returns pointer to:
* 1 -> start of question records.
* 2 -> start of authoritative answer records.
* 3 -> start of additional records.
* 4 -> first byte after end of additional records.
*
* Results:
* (address) - success operation.
* NULL - a resource record had an incorrect format.
*
*******************************************************************************
*/
char *
res_skip(msg, numFieldsToSkip, eom)
char *msg;
int numFieldsToSkip;
char *eom;
{
register char *cp;
register HEADER *hp;
register int tmp;
register int n;
/*
* Skip the header fields.
*/
hp = (HEADER *)msg;
cp = msg + sizeof(HEADER);
/*
* skip question records.
*/
if (n = ntohs(hp->qdcount) ) {
while (--n >= 0 && cp < eom) {
tmp = dn_skipname((u_char *)cp, (u_char *)eom);
if (tmp == -1) return(NULL);
cp += tmp;
cp += sizeof(u_short); /* type */
cp += sizeof(u_short); /* class */
}
}
if (--numFieldsToSkip <= 0) return(cp);
/*
* skip authoritative answer records
*/
if (n = ntohs(hp->ancount)) {
while (--n >= 0 && cp < eom) {
cp = res_skip_rr(cp, eom);
if (cp == NULL) return(NULL);
}
}
if (--numFieldsToSkip == 0) return(cp);
/*
* skip name server records
*/
if (n = ntohs(hp->nscount)) {
while (--n >= 0 && cp < eom) {
cp = res_skip_rr(cp, eom);
if (cp == NULL) return(NULL);
}
}
if (--numFieldsToSkip == 0) return(cp);
/*
* skip additional records
*/
if (n = ntohs(hp->arcount)) {
while (--n >= 0 && cp < eom) {
cp = res_skip_rr(cp, eom);
if (cp == NULL) return(NULL);
}
}
return(cp);
}
/*
*******************************************************************************
*
* res_skip_rr --
*
* Skip over resource record fields.
*
* Results:
* (address) - success operation.
* NULL - a resource record had an incorrect format.
*******************************************************************************
*/
char *
res_skip_rr(cp, eom)
char *cp;
char *eom;
{
int tmp;
int dlen;
if ((tmp = dn_skipname((u_char *)cp, (u_char *)eom)) == -1)
return (NULL); /* compression error */
cp += tmp;
if ((cp + RRFIXEDSZ) > eom)
return (NULL);
cp += sizeof(u_short); /* type */
cp += sizeof(u_short); /* class */
cp += sizeof(u_long); /* ttl */
dlen = _getshort(cp);
cp += sizeof(u_short); /* dlen */
cp += dlen;
if (cp > eom)
return (NULL);
return (cp);
}
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