soa.c

Go to the documentation of this file.

/*
 * Copyright (C) 2004, 2005, 2007, 2009  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 2000, 2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or 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.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC 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.
 */

/* $Id: soa.c,v 1.12 2009/09/10 02:18:40 each Exp $ */

/*! \file */

#include <config.h>
#include <string.h>

#include <isc/buffer.h>
#include <isc/util.h>

#include <dns/rdata.h>
#include <dns/rdatastruct.h>
#include <dns/soa.h>

static inline isc_uint32_t
decode_uint32(unsigned char *p) {
        return ((p[0] << 24) +
                (p[1] << 16) +
                (p[2] <<  8) +
                (p[3] <<  0));
}

static inline void
encode_uint32(isc_uint32_t val, unsigned char *p) {
        p[0] = (isc_uint8_t)(val >> 24);
        p[1] = (isc_uint8_t)(val >> 16);
        p[2] = (isc_uint8_t)(val >>  8);
        p[3] = (isc_uint8_t)(val >>  0);
}

static isc_uint32_t
soa_get(dns_rdata_t *rdata, int offset) {
        INSIST(rdata->type == dns_rdatatype_soa);
        /*
         * Locate the field within the SOA RDATA based
         * on its position relative to the end of the data.
         *
         * This is a bit of a kludge, but the alternative approach of
         * using dns_rdata_tostruct() and dns_rdata_fromstruct() would
         * involve a lot of unnecessary work (like building domain
         * names and allocating temporary memory) when all we really
         * want to do is to get 32 bits of fixed-sized data.
         */
        INSIST(rdata->length >= 20);
        INSIST(offset >= 0 && offset <= 16);
        return (decode_uint32(rdata->data + rdata->length - 20 + offset));
}

isc_result_t
dns_soa_buildrdata(dns_name_t *origin, dns_name_t *contact,
                   dns_rdataclass_t rdclass,
                   isc_uint32_t serial, isc_uint32_t refresh,
                   isc_uint32_t retry, isc_uint32_t expire,
                   isc_uint32_t minimum, unsigned char *buffer,
                   dns_rdata_t *rdata) {
        dns_rdata_soa_t soa;
        isc_buffer_t rdatabuf;

        REQUIRE(origin != NULL);
        REQUIRE(contact != NULL);

        memset(buffer, 0, DNS_SOA_BUFFERSIZE);
        isc_buffer_init(&rdatabuf, buffer, DNS_SOA_BUFFERSIZE);

        soa.common.rdtype = dns_rdatatype_soa;
        soa.common.rdclass = rdclass;
        soa.mctx = NULL;
        soa.serial = serial;
        soa.refresh = refresh;
        soa.retry = retry;
        soa.expire = expire;
        soa.minimum = minimum;
        dns_name_init(&soa.origin, NULL);
        dns_name_clone(origin, &soa.origin);
        dns_name_init(&soa.contact, NULL);
        dns_name_clone(contact, &soa.contact);

        return (dns_rdata_fromstruct(rdata, rdclass, dns_rdatatype_soa,
                                      &soa, &rdatabuf));
}

isc_uint32_t
dns_soa_getserial(dns_rdata_t *rdata) {
        return soa_get(rdata, 0);
}
isc_uint32_t
dns_soa_getrefresh(dns_rdata_t *rdata) {
        return soa_get(rdata, 4);
}
isc_uint32_t
dns_soa_getretry(dns_rdata_t *rdata) {
        return soa_get(rdata, 8);
}
isc_uint32_t
dns_soa_getexpire(dns_rdata_t *rdata) {
        return soa_get(rdata, 12);
}
isc_uint32_t
dns_soa_getminimum(dns_rdata_t *rdata) {
        return soa_get(rdata, 16);
}

static void
soa_set(dns_rdata_t *rdata, isc_uint32_t val, int offset) {
        INSIST(rdata->type == dns_rdatatype_soa);
        INSIST(rdata->length >= 20);
        INSIST(offset >= 0 && offset <= 16);
        encode_uint32(val, rdata->data + rdata->length - 20 + offset);
}

void
dns_soa_setserial(isc_uint32_t val, dns_rdata_t *rdata) {
        soa_set(rdata, val, 0);
}
void
dns_soa_setrefresh(isc_uint32_t val, dns_rdata_t *rdata) {
        soa_set(rdata, val, 4);
}
void
dns_soa_setretry(isc_uint32_t val, dns_rdata_t *rdata) {
        soa_set(rdata, val, 8);
}
void
dns_soa_setexpire(isc_uint32_t val, dns_rdata_t *rdata) {
        soa_set(rdata, val, 12);
}
void
dns_soa_setminimum(isc_uint32_t val, dns_rdata_t *rdata) {
        soa_set(rdata, val, 16);
}

---