/* $OpenBSD: skip.c,v 1.2 1997/03/12 10:42:50 downsj Exp $ */ /* * ++Copyright++ 1985, 1989 * - * Copyright (c) 1985, 1989 * The 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. * - * Portions Copyright (c) 1993 by Digital Equipment Corporation. * * 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, and that * the name of Digital Equipment Corporation not be used in advertising or * publicity pertaining to distribution of the document or software without * specific, written prior permission. * * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT * CORPORATION 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. * - * --Copyright-- */ #ifndef lint #if 0 static char sccsid[] = "@(#)skip.c 5.12 (Berkeley) 3/21/91"; static char rcsid[] = "$From: skip.c,v 8.1 1994/12/15 06:24:31 vixie Exp $"; #else static char rcsid[] = "$OpenBSD: skip.c,v 1.2 1997/03/12 10:42:50 downsj Exp $"; #endif #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 #include #include #include #include #include "conf/portability.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 + HFIXEDSZ; /* * 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 += INT16SZ; /* type */ cp += INT16SZ; /* 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 += INT16SZ; /* type */ cp += INT16SZ; /* class */ cp += INT32SZ; /* ttl */ dlen = _getshort((u_char*)cp); cp += INT16SZ; /* dlen */ cp += dlen; if (cp > eom) return (NULL); return (cp); }