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soa.c revision 1.2 
      1 /*	$NetBSD: soa.c,v 1.2 2018/08/12 13:02:35 christos Exp $	*/
      2 
      3 /*
      4  * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
      5  *
      6  * This Source Code Form is subject to the terms of the Mozilla Public
      7  * License, v. 2.0. If a copy of the MPL was not distributed with this
      8  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
      9  *
     10  * See the COPYRIGHT file distributed with this work for additional
     11  * information regarding copyright ownership.
     12  */
     13 
     14 
     15 /*! \file */
     16 
     17 #include <config.h>
     18 #include <string.h>
     19 
     20 #include <isc/buffer.h>
     21 #include <isc/util.h>
     22 
     23 #include <dns/rdata.h>
     24 #include <dns/rdatastruct.h>
     25 #include <dns/soa.h>
     26 
     27 static inline isc_uint32_t
     28 decode_uint32(unsigned char *p) {
     29 	return ((p[0] << 24) +
     30 		(p[1] << 16) +
     31 		(p[2] <<  8) +
     32 		(p[3] <<  0));
     33 }
     34 
     35 static inline void
     36 encode_uint32(isc_uint32_t val, unsigned char *p) {
     37 	p[0] = (isc_uint8_t)(val >> 24);
     38 	p[1] = (isc_uint8_t)(val >> 16);
     39 	p[2] = (isc_uint8_t)(val >>  8);
     40 	p[3] = (isc_uint8_t)(val >>  0);
     41 }
     42 
     43 static isc_uint32_t
     44 soa_get(dns_rdata_t *rdata, int offset) {
     45 	INSIST(rdata->type == dns_rdatatype_soa);
     46 	/*
     47 	 * Locate the field within the SOA RDATA based
     48 	 * on its position relative to the end of the data.
     49 	 *
     50 	 * This is a bit of a kludge, but the alternative approach of
     51 	 * using dns_rdata_tostruct() and dns_rdata_fromstruct() would
     52 	 * involve a lot of unnecessary work (like building domain
     53 	 * names and allocating temporary memory) when all we really
     54 	 * want to do is to get 32 bits of fixed-sized data.
     55 	 */
     56 	INSIST(rdata->length >= 20);
     57 	INSIST(offset >= 0 && offset <= 16);
     58 	return (decode_uint32(rdata->data + rdata->length - 20 + offset));
     59 }
     60 
     61 isc_result_t
     62 dns_soa_buildrdata(const dns_name_t *origin, const dns_name_t *contact,
     63 		   dns_rdataclass_t rdclass,
     64 		   isc_uint32_t serial, isc_uint32_t refresh,
     65 		   isc_uint32_t retry, isc_uint32_t expire,
     66 		   isc_uint32_t minimum, unsigned char *buffer,
     67 		   dns_rdata_t *rdata) {
     68 	dns_rdata_soa_t soa;
     69 	isc_buffer_t rdatabuf;
     70 
     71 	REQUIRE(origin != NULL);
     72 	REQUIRE(contact != NULL);
     73 
     74 	memset(buffer, 0, DNS_SOA_BUFFERSIZE);
     75 	isc_buffer_init(&rdatabuf, buffer, DNS_SOA_BUFFERSIZE);
     76 
     77 	soa.common.rdtype = dns_rdatatype_soa;
     78 	soa.common.rdclass = rdclass;
     79 	soa.mctx = NULL;
     80 	soa.serial = serial;
     81 	soa.refresh = refresh;
     82 	soa.retry = retry;
     83 	soa.expire = expire;
     84 	soa.minimum = minimum;
     85 	dns_name_init(&soa.origin, NULL);
     86 	dns_name_clone(origin, &soa.origin);
     87 	dns_name_init(&soa.contact, NULL);
     88 	dns_name_clone(contact, &soa.contact);
     89 
     90 	return (dns_rdata_fromstruct(rdata, rdclass, dns_rdatatype_soa,
     91 				      &soa, &rdatabuf));
     92 }
     93 
     94 isc_uint32_t
     95 dns_soa_getserial(dns_rdata_t *rdata) {
     96 	return soa_get(rdata, 0);
     97 }
     98 isc_uint32_t
     99 dns_soa_getrefresh(dns_rdata_t *rdata) {
    100 	return soa_get(rdata, 4);
    101 }
    102 isc_uint32_t
    103 dns_soa_getretry(dns_rdata_t *rdata) {
    104 	return soa_get(rdata, 8);
    105 }
    106 isc_uint32_t
    107 dns_soa_getexpire(dns_rdata_t *rdata) {
    108 	return soa_get(rdata, 12);
    109 }
    110 isc_uint32_t
    111 dns_soa_getminimum(dns_rdata_t *rdata) {
    112 	return soa_get(rdata, 16);
    113 }
    114 
    115 static void
    116 soa_set(dns_rdata_t *rdata, isc_uint32_t val, int offset) {
    117 	INSIST(rdata->type == dns_rdatatype_soa);
    118 	INSIST(rdata->length >= 20);
    119 	INSIST(offset >= 0 && offset <= 16);
    120 	encode_uint32(val, rdata->data + rdata->length - 20 + offset);
    121 }
    122 
    123 void
    124 dns_soa_setserial(isc_uint32_t val, dns_rdata_t *rdata) {
    125 	soa_set(rdata, val, 0);
    126 }
    127 void
    128 dns_soa_setrefresh(isc_uint32_t val, dns_rdata_t *rdata) {
    129 	soa_set(rdata, val, 4);
    130 }
    131 void
    132 dns_soa_setretry(isc_uint32_t val, dns_rdata_t *rdata) {
    133 	soa_set(rdata, val, 8);
    134 }
    135 void
    136 dns_soa_setexpire(isc_uint32_t val, dns_rdata_t *rdata) {
    137 	soa_set(rdata, val, 12);
    138 }
    139 void
    140 dns_soa_setminimum(isc_uint32_t val, dns_rdata_t *rdata) {
    141 	soa_set(rdata, val, 16);
    142 }
    143