nsec.c revision 70e5a7403f0e0a3bd292b8287c5fed5772c15270
/*
* Copyright (C) 2004, 2005, 2007 Internet Systems Consortium, Inc. ("ISC")
* Copyright (C) 1999-2001, 2003 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: nsec.c,v 1.9 2007/06/19 23:47:16 tbox Exp $ */
/*! \file */
#include <config.h>
#include <isc/string.h>
#include <isc/util.h>
#include <dns/db.h>
#include <dns/nsec.h>
#include <dns/rdata.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/rdatasetiter.h>
#include <dns/rdatastruct.h>
#include <dns/result.h>
#define RETERR(x) do { \
result = (x); \
if (result != ISC_R_SUCCESS) \
goto failure; \
} while (0)
static void
set_bit(unsigned char *array, unsigned int index, unsigned int bit) {
unsigned int shift, mask;
shift = 7 - (index % 8);
mask = 1 << shift;
if (bit != 0)
array[index / 8] |= mask;
else
array[index / 8] &= (~mask & 0xFF);
}
static unsigned int
bit_isset(unsigned char *array, unsigned int index) {
unsigned int byte, shift, mask;
byte = array[index / 8];
shift = 7 - (index % 8);
mask = 1 << shift;
return ((byte & mask) != 0);
}
isc_result_t
dns_nsec_buildrdata(dns_db_t *db, dns_dbversion_t *version,
dns_dbnode_t *node, dns_name_t *target,
unsigned char *buffer, dns_rdata_t *rdata)
{
isc_result_t result;
dns_rdataset_t rdataset;
isc_region_t r;
unsigned int i, window;
int octet;
unsigned char *nsec_bits, *bm;
unsigned int max_type;
dns_rdatasetiter_t *rdsiter;
memset(buffer, 0, DNS_NSEC_BUFFERSIZE);
dns_name_toregion(target, &r);
memcpy(buffer, r.base, r.length);
r.base = buffer;
/*
* Use the end of the space for a raw bitmap leaving enough
* space for the window identifiers and length octets.
*/
bm = r.base + r.length + 512;
nsec_bits = r.base + r.length;
set_bit(bm, dns_rdatatype_nsec, 1);
max_type = dns_rdatatype_nsec;
dns_rdataset_init(&rdataset);
rdsiter = NULL;
result = dns_db_allrdatasets(db, node, version, 0, &rdsiter);
if (result != ISC_R_SUCCESS)
return (result);
for (result = dns_rdatasetiter_first(rdsiter);
result == ISC_R_SUCCESS;
result = dns_rdatasetiter_next(rdsiter))
{
dns_rdatasetiter_current(rdsiter, &rdataset);
if (rdataset.type != dns_rdatatype_nsec) {
if (rdataset.type > max_type)
max_type = rdataset.type;
set_bit(bm, rdataset.type, 1);
}
dns_rdataset_disassociate(&rdataset);
}
/*
* At zone cuts, deny the existence of glue in the parent zone.
*/
if (bit_isset(bm, dns_rdatatype_ns) &&
! bit_isset(bm, dns_rdatatype_soa)) {
for (i = 0; i <= max_type; i++) {
if (bit_isset(bm, i) &&
! dns_rdatatype_iszonecutauth((dns_rdatatype_t)i))
set_bit(bm, i, 0);
}
}
dns_rdatasetiter_destroy(&rdsiter);
if (result != ISC_R_NOMORE)
return (result);
for (window = 0; window < 256; window++) {
if (window * 256 > max_type)
break;
for (octet = 31; octet >= 0; octet--)
if (bm[window * 32 + octet] != 0)
break;
if (octet < 0)
continue;
nsec_bits[0] = window;
nsec_bits[1] = octet + 1;
/*
* Note: potential overlapping move.
*/
memmove(&nsec_bits[2], &bm[window * 32], octet + 1);
nsec_bits += 3 + octet;
}
r.length = nsec_bits - r.base;
INSIST(r.length <= DNS_NSEC_BUFFERSIZE);
dns_rdata_fromregion(rdata,
dns_db_class(db),
dns_rdatatype_nsec,
&r);
return (ISC_R_SUCCESS);
}
isc_result_t
dns_nsec_build(dns_db_t *db, dns_dbversion_t *version, dns_dbnode_t *node,
dns_name_t *target, dns_ttl_t ttl)
{
isc_result_t result;
dns_rdata_t rdata = DNS_RDATA_INIT;
unsigned char data[DNS_NSEC_BUFFERSIZE];
dns_rdatalist_t rdatalist;
dns_rdataset_t rdataset;
dns_rdataset_init(&rdataset);
dns_rdata_init(&rdata);
RETERR(dns_nsec_buildrdata(db, version, node, target, data, &rdata));
rdatalist.rdclass = dns_db_class(db);
rdatalist.type = dns_rdatatype_nsec;
rdatalist.covers = 0;
rdatalist.ttl = ttl;
ISC_LIST_INIT(rdatalist.rdata);
ISC_LIST_APPEND(rdatalist.rdata, &rdata, link);
RETERR(dns_rdatalist_tordataset(&rdatalist, &rdataset));
result = dns_db_addrdataset(db, node, version, 0, &rdataset,
0, NULL);
if (result == DNS_R_UNCHANGED)
result = ISC_R_SUCCESS;
RETERR(result);
failure:
if (dns_rdataset_isassociated(&rdataset))
dns_rdataset_disassociate(&rdataset);
return (result);
}
isc_boolean_t
dns_nsec_typepresent(dns_rdata_t *nsec, dns_rdatatype_t type) {
dns_rdata_nsec_t nsecstruct;
isc_result_t result;
isc_boolean_t present;
unsigned int i, len, window;
REQUIRE(nsec != NULL);
REQUIRE(nsec->type == dns_rdatatype_nsec);
/* This should never fail */
result = dns_rdata_tostruct(nsec, &nsecstruct, NULL);
INSIST(result == ISC_R_SUCCESS);
present = ISC_FALSE;
for (i = 0; i < nsecstruct.len; i += len) {
INSIST(i + 2 <= nsecstruct.len);
window = nsecstruct.typebits[i];
len = nsecstruct.typebits[i + 1];
INSIST(len > 0 && len <= 32);
i += 2;
INSIST(i + len <= nsecstruct.len);
if (window * 256 > type)
break;
if ((window + 1) * 256 <= type)
continue;
if (type < (window * 256) + len * 8)
present = ISC_TF(bit_isset(&nsecstruct.typebits[i],
type % 256));
break;
}
dns_rdata_freestruct(&nsec);
return (present);
}