220 lines
6.3 KiB
C
220 lines
6.3 KiB
C
/*
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* Copyright (c) 1985, 1989
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* Portions Copyright (c) 1993 by Digital Equipment Corporation.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies, and that
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* the name of Digital Equipment Corporation not be used in advertising or
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* publicity pertaining to distribution of the document or software without
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* specific, written prior permission.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
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* WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT
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* CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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#ifndef lint
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static const char sccsid[] = "@(#)skip.c 5.12 (Berkeley) 3/21/91";
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static const char rcsid[] = "$Id: skip.c,v 8.7 2001/06/20 12:30:35 marka Exp $";
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#endif /* not lint */
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/*
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*******************************************************************************
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*
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* skip.c --
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*
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* Routines to skip over portions of a query buffer.
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*
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* Note: this file has been submitted for inclusion in
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* BIND resolver library. When this has been done, this file
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* is no longer necessary (assuming there haven't been any
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* changes).
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*
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* Adapted from 4.3BSD BIND res_debug.c
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*
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*******************************************************************************
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*/
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#include "port_before.h"
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#include <sys/param.h>
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <resolv.h>
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#include <stdio.h>
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#include "port_after.h"
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#include "res.h"
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static unsigned char *res_skip_rr(unsigned char *cp, unsigned char *eom);
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/*
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*******************************************************************************
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*
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* res_skip --
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*
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* Skip the contents of a query.
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*
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* Interpretation of numFieldsToSkip argument:
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* res_skip returns pointer to:
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* 1 -> start of question records.
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* 2 -> start of authoritative answer records.
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* 3 -> start of additional records.
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* 4 -> first byte after end of additional records.
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*
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* Results:
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* (address) - success operation.
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* NULL - a resource record had an incorrect format.
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*
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*******************************************************************************
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*/
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unsigned char *
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res_skip(msg, numFieldsToSkip, eom)
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unsigned char *msg;
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int numFieldsToSkip;
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unsigned char *eom;
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{
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register unsigned char *cp;
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register HEADER *hp;
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register int tmp;
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register int n;
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/*
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* Skip the header fields.
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*/
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hp = (HEADER *)msg;
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cp = msg + HFIXEDSZ;
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/*
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* skip question records.
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*/
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n = ntohs(hp->qdcount);
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if (n > 0) {
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while (--n >= 0 && cp < eom) {
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tmp = dn_skipname(cp, eom);
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if (tmp == -1) return(NULL);
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cp += tmp;
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cp += INT16SZ; /* type */
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cp += INT16SZ; /* class */
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}
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}
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if (--numFieldsToSkip <= 0) return(cp);
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/*
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* skip authoritative answer records
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*/
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n = ntohs(hp->ancount);
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if (n > 0) {
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while (--n >= 0 && cp < eom) {
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cp = res_skip_rr(cp, eom);
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if (cp == NULL) return(NULL);
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}
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}
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if (--numFieldsToSkip == 0) return(cp);
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/*
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* skip name server records
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*/
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n = ntohs(hp->nscount);
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if (n > 0) {
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while (--n >= 0 && cp < eom) {
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cp = res_skip_rr(cp, eom);
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if (cp == NULL) return(NULL);
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}
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}
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if (--numFieldsToSkip == 0) return(cp);
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/*
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* skip additional records
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*/
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n = ntohs(hp->arcount);
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if (n > 0) {
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while (--n >= 0 && cp < eom) {
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cp = res_skip_rr(cp, eom);
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if (cp == NULL) return(NULL);
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}
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}
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return(cp);
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}
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/*
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*******************************************************************************
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*
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* res_skip_rr --
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*
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* Skip over resource record fields.
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*
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* Results:
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* (address) - success operation.
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* NULL - a resource record had an incorrect format.
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*******************************************************************************
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*/
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static unsigned char *
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res_skip_rr(cp, eom)
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unsigned char *cp;
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unsigned char *eom;
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{
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int tmp;
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int dlen;
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if ((tmp = dn_skipname(cp, eom)) == -1)
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return (NULL); /* compression error */
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cp += tmp;
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if ((cp + RRFIXEDSZ) > eom)
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return (NULL);
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cp += INT16SZ; /* type */
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cp += INT16SZ; /* class */
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cp += INT32SZ; /* ttl */
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dlen = ns_get16(cp);
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cp += INT16SZ; /* dlen */
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cp += dlen;
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if (cp > eom)
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return (NULL);
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return (cp);
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}
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