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// Copyright (C) 2010-2015 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 <stdint.h>
#include <cassert>
#include <boost/lexical_cast.hpp>
#include <exceptions/exceptions.h>
#include <dns/edns.h>
#include <dns/exceptions.h>
#include <dns/message.h>
#include <dns/messagerenderer.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rrclass.h>
#include <dns/rrttl.h>
#include <dns/rrtype.h>
using namespace std;
using boost::lexical_cast;
using namespace isc::dns::rdata;
using namespace isc::util;
namespace isc {
namespace dns {
namespace {
// This diagram shows the wire-format representation of the TTL field of
// OPT RR and its relationship with implementation specific parameters.
//
// 0 7 15 31
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// | EXTENDED-RCODE| VERSION |D| Z |
// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// <= VERSION_SHIFT (16 bits)
// <= EXTRCODE_SHIFT (24 bits)
//EXTFLAG_DO:0 0 0 ....................... 0 1 0 0 0 0.....................0
//VER_MASK: 0 0 0 ........0 1 1 1 1 1 1 1 1 0 0 ..........................0
const unsigned int VERSION_SHIFT = 16;
const unsigned int EXTRCODE_SHIFT = 24;
const uint32_t VERSION_MASK = 0x00ff0000;
const uint32_t EXTFLAG_DO = 0x00008000;
}
EDNS::EDNS(const uint8_t version) :
version_(version),
udp_size_(Message::DEFAULT_MAX_UDPSIZE),
dnssec_aware_(false)
{
if (version_ > SUPPORTED_VERSION) {
isc_throw(isc::InvalidParameter,
"failed to construct EDNS: unsupported version: " <<
static_cast<unsigned int>(version_));
}
}
EDNS::EDNS(const Name& name, const RRClass& rrclass, const RRType& rrtype,
const RRTTL& ttl, const Rdata&) :
version_((ttl.getValue() & VERSION_MASK) >> VERSION_SHIFT)
{
if (rrtype != RRType::OPT()) {
isc_throw(isc::InvalidParameter,
"EDNS is being created with incompatible RR type: "
<< rrtype);
}
if (version_ > EDNS::SUPPORTED_VERSION) {
isc_throw(DNSMessageBADVERS, "unsupported EDNS version: " <<
static_cast<unsigned int>(version_));
}
if (name != Name::ROOT_NAME()) {
isc_throw(DNSMessageFORMERR, "invalid owner name for EDNS OPT RR: " <<
name);
}
dnssec_aware_ = ((ttl.getValue() & EXTFLAG_DO) != 0);
udp_size_ = rrclass.getCode();
}
string
EDNS::toText() const {
string ret = "; EDNS: version: ";
ret += lexical_cast<string>(static_cast<int>(getVersion()));
ret += ", flags:";
if (getDNSSECAwareness()) {
ret += " do";
}
ret += "; udp: " + lexical_cast<string>(getUDPSize()) + "\n";
return (ret);
}
namespace {
/// Helper function to define unified implementation for the public versions
/// of toWire().
template <typename Output>
int
toWireCommon(Output& output, const uint8_t version,
const uint16_t udp_size, const bool dnssec_aware,
const uint8_t extended_rcode)
{
// Render EDNS OPT RR
uint32_t extrcode_flags = extended_rcode << EXTRCODE_SHIFT;
extrcode_flags |= (version << VERSION_SHIFT) & VERSION_MASK;
if (dnssec_aware) {
extrcode_flags |= EXTFLAG_DO;
}
// Construct an RRset corresponding to the EDNS.
// We don't support any options for now, so the OPT RR can be empty.
RRsetPtr edns_rrset(new RRset(Name::ROOT_NAME(), RRClass(udp_size),
RRType::OPT(), RRTTL(extrcode_flags)));
edns_rrset->addRdata(ConstRdataPtr(new generic::OPT()));
edns_rrset->toWire(output);
return (1);
}
}
unsigned int
EDNS::toWire(AbstractMessageRenderer& renderer,
const uint8_t extended_rcode) const
{
// If adding the OPT RR would exceed the size limit, don't do it.
// 11 = len(".") + type(2byte) + class(2byte) + TTL(4byte) + RDLEN(2byte)
// (RDATA is empty in this simple implementation)
if (renderer.getLength() + 11 > renderer.getLengthLimit()) {
return (0);
}
return (toWireCommon(renderer, version_, udp_size_, dnssec_aware_,
extended_rcode));
}
unsigned int
EDNS::toWire(isc::util::OutputBuffer& buffer,
const uint8_t extended_rcode) const
{
return (toWireCommon(buffer, version_, udp_size_, dnssec_aware_,
extended_rcode));
}
EDNS*
createEDNSFromRR(const Name& name, const RRClass& rrclass,
const RRType& rrtype, const RRTTL& ttl,
const Rdata& rdata,
uint8_t& extended_rcode)
{
// Create a new EDNS object first for exception guarantee.
EDNS* edns = new EDNS(name, rrclass, rrtype, ttl, rdata);
// At this point we can update extended_rcode safely.
extended_rcode = ttl.getValue() >> EXTRCODE_SHIFT;
return (edns);
}
ostream&
operator<<(std::ostream& os, const EDNS& edns) {
os << edns.toText();
return (os);
}
} // end of namespace dns
} // end of namespace isc
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