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soa.c revision 1.4 
      1 /*	$NetBSD: soa.c,v 1.4 2020/05/24 19:46:23 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 /*! \file */
     15 
     16 #include <inttypes.h>
     17 #include <string.h>
     18 
     19 #include <isc/buffer.h>
     20 #include <isc/util.h>
     21 
     22 #include <dns/rdata.h>
     23 #include <dns/rdatastruct.h>
     24 #include <dns/soa.h>
     25 
     26 static inline uint32_t
     27 decode_uint32(unsigned char *p) {
     28 	return ((p[0] << 24) + (p[1] << 16) + (p[2] << 8) + (p[3] << 0));
     29 }
     30 
     31 static inline void
     32 encode_uint32(uint32_t val, unsigned char *p) {
     33 	p[0] = (uint8_t)(val >> 24);
     34 	p[1] = (uint8_t)(val >> 16);
     35 	p[2] = (uint8_t)(val >> 8);
     36 	p[3] = (uint8_t)(val >> 0);
     37 }
     38 
     39 static uint32_t
     40 soa_get(dns_rdata_t *rdata, int offset) {
     41 	INSIST(rdata->type == dns_rdatatype_soa);
     42 	/*
     43 	 * Locate the field within the SOA RDATA based
     44 	 * on its position relative to the end of the data.
     45 	 *
     46 	 * This is a bit of a kludge, but the alternative approach of
     47 	 * using dns_rdata_tostruct() and dns_rdata_fromstruct() would
     48 	 * involve a lot of unnecessary work (like building domain
     49 	 * names and allocating temporary memory) when all we really
     50 	 * want to do is to get 32 bits of fixed-sized data.
     51 	 */
     52 	INSIST(rdata->length >= 20);
     53 	INSIST(offset >= 0 && offset <= 16);
     54 	return (decode_uint32(rdata->data + rdata->length - 20 + offset));
     55 }
     56 
     57 isc_result_t
     58 dns_soa_buildrdata(const dns_name_t *origin, const dns_name_t *contact,
     59 		   dns_rdataclass_t rdclass, uint32_t serial, uint32_t refresh,
     60 		   uint32_t retry, uint32_t expire, uint32_t minimum,
     61 		   unsigned char *buffer, dns_rdata_t *rdata) {
     62 	dns_rdata_soa_t soa;
     63 	isc_buffer_t rdatabuf;
     64 
     65 	REQUIRE(origin != NULL);
     66 	REQUIRE(contact != NULL);
     67 
     68 	memset(buffer, 0, DNS_SOA_BUFFERSIZE);
     69 	isc_buffer_init(&rdatabuf, buffer, DNS_SOA_BUFFERSIZE);
     70 
     71 	soa.common.rdtype = dns_rdatatype_soa;
     72 	soa.common.rdclass = rdclass;
     73 	soa.mctx = NULL;
     74 	soa.serial = serial;
     75 	soa.refresh = refresh;
     76 	soa.retry = retry;
     77 	soa.expire = expire;
     78 	soa.minimum = minimum;
     79 	dns_name_init(&soa.origin, NULL);
     80 	dns_name_clone(origin, &soa.origin);
     81 	dns_name_init(&soa.contact, NULL);
     82 	dns_name_clone(contact, &soa.contact);
     83 
     84 	return (dns_rdata_fromstruct(rdata, rdclass, dns_rdatatype_soa, &soa,
     85 				     &rdatabuf));
     86 }
     87 
     88 uint32_t
     89 dns_soa_getserial(dns_rdata_t *rdata) {
     90 	return (soa_get(rdata, 0));
     91 }
     92 uint32_t
     93 dns_soa_getrefresh(dns_rdata_t *rdata) {
     94 	return (soa_get(rdata, 4));
     95 }
     96 uint32_t
     97 dns_soa_getretry(dns_rdata_t *rdata) {
     98 	return (soa_get(rdata, 8));
     99 }
    100 uint32_t
    101 dns_soa_getexpire(dns_rdata_t *rdata) {
    102 	return (soa_get(rdata, 12));
    103 }
    104 uint32_t
    105 dns_soa_getminimum(dns_rdata_t *rdata) {
    106 	return (soa_get(rdata, 16));
    107 }
    108 
    109 static void
    110 soa_set(dns_rdata_t *rdata, uint32_t val, int offset) {
    111 	INSIST(rdata->type == dns_rdatatype_soa);
    112 	INSIST(rdata->length >= 20);
    113 	INSIST(offset >= 0 && offset <= 16);
    114 	encode_uint32(val, rdata->data + rdata->length - 20 + offset);
    115 }
    116 
    117 void
    118 dns_soa_setserial(uint32_t val, dns_rdata_t *rdata) {
    119 	soa_set(rdata, val, 0);
    120 }
    121 void
    122 dns_soa_setrefresh(uint32_t val, dns_rdata_t *rdata) {
    123 	soa_set(rdata, val, 4);
    124 }
    125 void
    126 dns_soa_setretry(uint32_t val, dns_rdata_t *rdata) {
    127 	soa_set(rdata, val, 8);
    128 }
    129 void
    130 dns_soa_setexpire(uint32_t val, dns_rdata_t *rdata) {
    131 	soa_set(rdata, val, 12);
    132 }
    133 void
    134 dns_soa_setminimum(uint32_t val, dns_rdata_t *rdata) {
    135 	soa_set(rdata, val, 16);
    136 }
    137