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Annotation of 43BSDTahoe/etc/named/tools/nslookup/skip.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1985 Regents of the University of California.
        !             3:  * All rights reserved.
        !             4:  *
        !             5:  * Redistribution and use in source and binary forms are permitted
        !             6:  * provided that this notice is preserved and that due credit is given
        !             7:  * to the University of California at Berkeley. The name of the University
        !             8:  * may not be used to endorse or promote products derived from this
        !             9:  * software without specific prior written permission. This software
        !            10:  * is provided ``as is'' without express or implied warranty.
        !            11:  */
        !            12: 
        !            13: #ifndef lint
        !            14: static char sccsid[] = "@(#)skip.c     5.4 (Berkeley) 2/17/88";
        !            15: #endif /* not lint */
        !            16: 
        !            17: /*
        !            18:  *******************************************************************************
        !            19:  *
        !            20:  *  skip.c --
        !            21:  *
        !            22:  *     Routines to skip over portions of a query buffer.
        !            23:  *
        !            24:  *     Note: this file has been submitted for inclusion in
        !            25:  *     BIND resolver library. When this has been done, this file
        !            26:  *     is no longer necessary (assuming there haven't been any
        !            27:  *     changes).
        !            28:  *
        !            29:  *     Adapted from 4.3BSD BIND res_debug.c
        !            30:  *
        !            31:  *******************************************************************************
        !            32:  */
        !            33: 
        !            34: #include <sys/types.h>
        !            35: #include <netinet/in.h>
        !            36: #include <stdio.h>
        !            37: #include <arpa/nameser.h>
        !            38: 
        !            39: char *res_skip_rr();
        !            40: 
        !            41: 
        !            42: /*
        !            43:  *******************************************************************************
        !            44:  *
        !            45:  *  res_skip --
        !            46:  *
        !            47:  *     Skip the contents of a query.
        !            48:  *
        !            49:  *     Interpretation of numFieldsToSkip argument:
        !            50:  *            res_skip returns pointer to:
        !            51:  *     1 ->  start of question records.
        !            52:  *     2 ->  start of authoritative answer records.
        !            53:  *     3 ->  start of additional records.
        !            54:  *     4 ->  first byte after end of additional records.
        !            55:  *
        !            56:  *   Results:
        !            57:  *     (address)       - success operation.
        !            58:  *     NULL            - a resource record had an incorrect format.
        !            59:  *
        !            60:  *******************************************************************************
        !            61:  */
        !            62: 
        !            63: char *
        !            64: res_skip(msg, numFieldsToSkip, eom)
        !            65:        char *msg;
        !            66:        int numFieldsToSkip;
        !            67:        char *eom;
        !            68: {
        !            69:        register char *cp;
        !            70:        register HEADER *hp;
        !            71:        register int tmp;
        !            72:        register int n;
        !            73: 
        !            74:        /*
        !            75:         * Skip the header fields.
        !            76:         */
        !            77:        hp = (HEADER *)msg;
        !            78:        cp = msg + sizeof(HEADER);
        !            79: 
        !            80:        /*
        !            81:         * skip question records.
        !            82:         */
        !            83:        if (n = ntohs(hp->qdcount) ) {
        !            84:                while (--n >= 0) {
        !            85:                        tmp = dn_skipname(cp, eom);
        !            86:                        if (tmp == -1) return(NULL);
        !            87:                        cp += tmp;
        !            88:                        cp += sizeof(u_short);  /* type         */
        !            89:                        cp += sizeof(u_short);  /* class        */
        !            90:                }
        !            91:        }
        !            92:        if (--numFieldsToSkip <= 0) return(cp);
        !            93: 
        !            94:        /*
        !            95:         * skip authoritative answer records
        !            96:         */
        !            97:        if (n = ntohs(hp->ancount)) {
        !            98:                while (--n >= 0) {
        !            99:                        cp = res_skip_rr(cp, eom);
        !           100:                        if (cp == NULL) return(NULL);
        !           101:                }
        !           102:        }
        !           103:        if (--numFieldsToSkip == 0) return(cp);
        !           104: 
        !           105:        /*
        !           106:         * skip name server records
        !           107:         */
        !           108:        if (n = ntohs(hp->nscount)) {
        !           109:                while (--n >= 0) {
        !           110:                        cp = res_skip_rr(cp, eom);
        !           111:                        if (cp == NULL) return(NULL);
        !           112:                }
        !           113:        }
        !           114:        if (--numFieldsToSkip == 0) return(cp);
        !           115: 
        !           116:        /*
        !           117:         * skip additional records
        !           118:         */
        !           119:        if (n = ntohs(hp->arcount)) {
        !           120:                while (--n >= 0) {
        !           121:                        cp = res_skip_rr(cp, eom);
        !           122:                        if (cp == NULL) return(NULL);
        !           123:                }
        !           124:        }
        !           125: 
        !           126:        return(cp);
        !           127: }
        !           128: 
        !           129: 
        !           130: /*
        !           131:  *******************************************************************************
        !           132:  *
        !           133:  *  res_skip_rr --
        !           134:  *
        !           135:  *     Skip over resource record fields.
        !           136:  *
        !           137:  *   Results:
        !           138:  *     (address)       - success operation.
        !           139:  *     NULL            - a resource record had an incorrect format.
        !           140:  *******************************************************************************
        !           141:  */
        !           142: 
        !           143: char *
        !           144: res_skip_rr(cp, eom)
        !           145:        char *cp;
        !           146:        char *eom;
        !           147: {
        !           148:        int tmp;
        !           149:        int dlen;
        !           150: 
        !           151:        if ((tmp = dn_skipname(cp, eom)) == -1)
        !           152:                return (NULL);                  /* compression error */
        !           153:        cp += tmp;
        !           154:        cp += sizeof(u_short);  /*      type    */
        !           155:        cp += sizeof(u_short);  /*      class   */
        !           156:        cp += sizeof(u_long);   /*      ttl     */
        !           157:        dlen = _getshort(cp);
        !           158:        cp += sizeof(u_short);  /*      dlen    */
        !           159:        cp += dlen;
        !           160:        return (cp);
        !           161: }

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