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// Copyright (C) 2012-2020 Internet Systems Consortium, Inc. ("ISC")
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
#include <config.h>
#include <dns/zone_checker.h>
#include <dns/name.h>
#include <dns/rdataclass.h>
#include <dns/rrclass.h>
#include <dns/rrtype.h>
#include <dns/rrset.h>
#include <dns/rrset_collection_base.h>
#include <boost/lexical_cast.hpp>
#include <functional>
#include <string>
using boost::lexical_cast;
using std::string;
namespace ph = std::placeholders;
namespace isc {
namespace dns {
namespace {
std::string
zoneText(const Name& zone_name, const RRClass& zone_class) {
return (zone_name.toText(true) + "/" + zone_class.toText());
}
void
checkSOA(const Name& zone_name, const RRClass& zone_class,
const RRsetCollectionBase& zone_rrsets,
ZoneCheckerCallbacks& callback) {
ConstRRsetPtr rrset =
zone_rrsets.find(zone_name, zone_class, RRType::SOA());
size_t count = 0;
if (rrset) {
for (RdataIteratorPtr rit = rrset->getRdataIterator();
!rit->isLast();
rit->next(), ++count) {
if (dynamic_cast<const rdata::generic::SOA*>(&rit->getCurrent()) ==
NULL) {
isc_throw(Unexpected, "Zone checker found bad RDATA in SOA");
}
}
if (count == 0) {
// this should be an implementation bug, not an operational error.
isc_throw(Unexpected, "Zone checker found an empty SOA RRset");
}
}
if (count != 1) {
callback.error("zone " + zoneText(zone_name, zone_class) + ": has " +
lexical_cast<string>(count) + " SOA records");
}
}
// Check if a target name is beyond zone cut, either due to delegation or
// DNAME. Note that DNAME works on the origin but not on the name itself,
// while delegation works on the name itself (but the NS at the origin is not
// delegation).
ConstRRsetPtr
findZoneCut(const Name& zone_name, const RRClass& zone_class,
const RRsetCollectionBase& zone_rrsets, const Name& target_name) {
const unsigned int origin_count = zone_name.getLabelCount();
const unsigned int target_count = target_name.getLabelCount();
assert(origin_count <= target_count);
for (unsigned int l = origin_count; l <= target_count; ++l) {
const Name& mid_name = (l == target_count) ? target_name :
target_name.split(target_count - l);
ConstRRsetPtr found;
if (l != origin_count &&
(found = zone_rrsets.find(mid_name, zone_class, RRType::NS())) !=
NULL) {
return (found);
}
if (l != target_count &&
(found = zone_rrsets.find(mid_name, zone_class, RRType::DNAME()))
!= NULL) {
return (found);
}
}
return (ConstRRsetPtr());
}
// Check if each "in-zone" NS name has an address record, identifying some
// error cases.
void
checkNSNames(const Name& zone_name, const RRClass& zone_class,
const RRsetCollectionBase& zone_rrsets,
ConstRRsetPtr ns_rrset, ZoneCheckerCallbacks& callbacks) {
if (ns_rrset->getRdataCount() == 0) {
// this should be an implementation bug, not an operational error.
isc_throw(Unexpected, "Zone checker found an empty NS RRset");
}
for (RdataIteratorPtr rit = ns_rrset->getRdataIterator();
!rit->isLast();
rit->next()) {
const rdata::generic::NS* ns_data =
dynamic_cast<const rdata::generic::NS*>(&rit->getCurrent());
if (ns_data == NULL) {
isc_throw(Unexpected, "Zone checker found bad RDATA in NS");
}
const Name& ns_name = ns_data->getNSName();
const NameComparisonResult::NameRelation reln =
ns_name.compare(zone_name).getRelation();
if (reln != NameComparisonResult::EQUAL &&
reln != NameComparisonResult::SUBDOMAIN) {
continue; // not in the zone. we can ignore it.
}
// Check if there's a zone cut between the origin and the NS name.
ConstRRsetPtr cut_rrset = findZoneCut(zone_name, zone_class,
zone_rrsets, ns_name);
if (cut_rrset) {
if (cut_rrset->getType() == RRType::NS()) {
continue; // delegation; making the NS name "out of zone".
} else if (cut_rrset->getType() == RRType::DNAME()) {
callbacks.error("zone " + zoneText(zone_name, zone_class) +
": NS '" + ns_name.toText(true) + "' is " +
"below a DNAME '" +
cut_rrset->getName().toText(true) +
"' (illegal per RFC6672)");
continue;
} else {
assert(false);
}
}
if (zone_rrsets.find(ns_name, zone_class, RRType::CNAME()) != NULL) {
callbacks.error("zone " + zoneText(zone_name, zone_class) +
": NS '" + ns_name.toText(true) + "' is a CNAME " +
"(illegal per RFC2181)");
continue;
}
if (zone_rrsets.find(ns_name, zone_class, RRType::A()) == NULL &&
zone_rrsets.find(ns_name, zone_class, RRType::AAAA()) == NULL) {
callbacks.warn("zone " + zoneText(zone_name, zone_class) +
": NS has no address records (A or AAAA)");
}
}
}
void
checkNS(const Name& zone_name, const RRClass& zone_class,
const RRsetCollectionBase& zone_rrsets,
ZoneCheckerCallbacks& callbacks) {
ConstRRsetPtr rrset =
zone_rrsets.find(zone_name, zone_class, RRType::NS());
if (rrset == NULL) {
callbacks.error("zone " + zoneText(zone_name, zone_class) +
": has no NS records");
return;
}
checkNSNames(zone_name, zone_class, zone_rrsets, rrset, callbacks);
}
// The following is a simple wrapper of checker callback so checkZone()
// can also remember any critical errors.
void
errorWrapper(const string& reason, const ZoneCheckerCallbacks* callbacks,
bool* had_error) {
*had_error = true;
callbacks->error(reason);
}
}
bool
checkZone(const Name& zone_name, const RRClass& zone_class,
const RRsetCollectionBase& zone_rrsets,
const ZoneCheckerCallbacks& callbacks) {
bool had_error = false;
ZoneCheckerCallbacks my_callbacks(
std::bind(errorWrapper, ph::_1, &callbacks, &had_error),
std::bind(&ZoneCheckerCallbacks::warn, &callbacks, ph::_1));
checkSOA(zone_name, zone_class, zone_rrsets, my_callbacks);
checkNS(zone_name, zone_class, zone_rrsets, my_callbacks);
return (!had_error);
}
} // end namespace dns
} // end namespace isc
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