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// Copyright (C) 2011 Internet Systems Consortium, Inc. ("ISC")
//
// 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.
#include <sys/time.h>
#include <stdint.h>
#include <cassert> // for the tentative verifyTentative()
#include <vector>
#include <boost/lexical_cast.hpp>
#include <boost/shared_ptr.hpp>
#include <exceptions/exceptions.h>
#include <util/buffer.h>
#include <dns/rdataclass.h>
#include <dns/rrclass.h>
#include <dns/tsig.h>
#include <dns/tsigerror.h>
#include <dns/tsigkey.h>
#include <cryptolink/cryptolink.h>
#include <cryptolink/crypto_hmac.h>
using namespace std;
using namespace isc::util;
using namespace isc::cryptolink;
using namespace isc::dns::rdata;
namespace isc {
namespace dns {
// Borrowed from dnssectime.cc. This trick should be unified somewhere.
namespace tsig {
namespace detail {
int64_t (*gettimeFunction)() = NULL;
}
}
namespace {
int64_t
gettimeofdayWrapper() {
using namespace tsig::detail;
if (gettimeFunction != NULL) {
return (gettimeFunction());
}
struct timeval now;
gettimeofday(&now, NULL);
return (static_cast<int64_t>(now.tv_sec));
}
}
namespace {
typedef boost::shared_ptr<HMAC> HMACPtr;
struct TSIGContext::TSIGContextImpl {
TSIGContextImpl(const TSIGKey& key) :
state_(INIT), key_(key), error_(Rcode::NOERROR()),
previous_timesigned_(0)
{}
State state_;
TSIGKey key_;
vector<uint8_t> previous_digest_;
TSIGError error_;
uint64_t previous_timesigned_; // only meaningful for response with BADTIME
};
}
const RRClass&
TSIGRecord::getClass() {
return (RRClass::ANY());
}
TSIGContext::TSIGContext(const TSIGKey& key) : impl_(new TSIGContextImpl(key))
{
}
TSIGContext::~TSIGContext() {
delete impl_;
}
TSIGContext::State
TSIGContext::getState() const {
return (impl_->state_);
}
TSIGError
TSIGContext::getError() const {
return (impl_->error_);
}
ConstTSIGRecordPtr
TSIGContext::sign(const uint16_t qid, const void* const data,
const size_t data_len)
{
TSIGError error(TSIGError::NOERROR());
const uint64_t now = (gettimeofdayWrapper() & 0x0000ffffffffffffULL);
// For responses adjust the error code.
if (impl_->state_ == CHECKED) {
error = impl_->error_;
}
// For errors related to key or MAC, return an unsigned response as
// specified in Section 4.3 of RFC2845.
if (error == TSIGError::BAD_SIG() || error == TSIGError::BAD_KEY()) {
impl_->previous_digest_.clear();
impl_->state_ = SIGNED;
ConstTSIGRecordPtr tsig(new TSIGRecord(
any::TSIG(impl_->key_.getAlgorithmName(),
now, DEFAULT_FUDGE, NULL, 0,
qid, error.getCode(), 0, NULL)));
return (tsig);
}
OutputBuffer variables(0);
HMACPtr hmac(CryptoLink::getCryptoLink().createHMAC(
impl_->key_.getSecret(),
impl_->key_.getSecretLength(),
impl_->key_.getCryptoAlgorithm()),
deleteHMAC);
// If the context has previous MAC (either the Request MAC or its own
// previous MAC), digest it.
if (impl_->state_ != INIT) {
const uint16_t previous_digest_len(impl_->previous_digest_.size());
variables.writeUint16(previous_digest_len);
if (previous_digest_len != 0) {
variables.writeData(&impl_->previous_digest_[0],
previous_digest_len);
}
hmac->update(variables.getData(), variables.getLength());
}
// Digest the message (without TSIG)
hmac->update(data, data_len);
//
// Digest TSIG variables. If state_ is SIGNED we skip digesting them
// except for time related variables (RFC2845 4.4).
//
variables.clear();
if (impl_->state_ != SIGNED) {
impl_->key_.getKeyName().toWire(variables);
TSIGRecord::getClass().toWire(variables);
variables.writeUint32(TSIGRecord::TSIG_TTL);
impl_->key_.getAlgorithmName().toWire(variables);
}
const uint64_t time_signed = (error == TSIGError::BAD_TIME()) ?
impl_->previous_timesigned_ : now;
variables.writeUint16(time_signed >> 32);
variables.writeUint32(time_signed & 0xffffffff);
variables.writeUint16(DEFAULT_FUDGE);
hmac->update(variables.getData(), variables.getLength());
variables.clear();
if (impl_->state_ != SIGNED) {
variables.writeUint16(error.getCode());
// For BADTIME error, digest 6 bytes of other data.
// (6 bytes = size of time signed value)
variables.writeUint16((error == TSIGError::BAD_TIME()) ? 6 : 0);
hmac->update(variables.getData(), variables.getLength());
variables.clear();
if (error == TSIGError::BAD_TIME()) {
variables.writeUint16(now >> 32);
variables.writeUint32(now & 0xffffffff);
hmac->update(variables.getData(), variables.getLength());
}
}
const uint16_t otherlen = variables.getLength();
// Get the final digest, update internal state, then finish.
impl_->previous_digest_ = hmac->sign();
impl_->state_ = SIGNED;
ConstTSIGRecordPtr tsig(new TSIGRecord(
any::TSIG(impl_->key_.getAlgorithmName(),
time_signed, DEFAULT_FUDGE,
impl_->previous_digest_.size(),
&impl_->previous_digest_[0],
qid, error.getCode(), otherlen,
otherlen == 0 ?
NULL : variables.getData())));
return (tsig);
}
void
TSIGContext::verifyTentative(ConstTSIGRecordPtr tsig, TSIGError error) {
const any::TSIG tsig_rdata = tsig->getRdata();
impl_->error_ = error;
if (error == TSIGError::BAD_TIME()) {
impl_->previous_timesigned_ = tsig_rdata.getTimeSigned();
}
// For simplicity we assume non empty digests.
assert(tsig_rdata.getMACSize() != 0);
impl_->previous_digest_.assign(
static_cast<const uint8_t*>(tsig_rdata.getMAC()),
static_cast<const uint8_t*>(tsig_rdata.getMAC()) +
tsig_rdata.getMACSize());
impl_->state_ = CHECKED;
}
namespace {
const char* const tsigerror_text[] = {
"BADSIG",
"BADKEY",
"BADTIME"
};
}
TSIGError::TSIGError(Rcode rcode) : code_(rcode.getCode()) {
if (code_ > MAX_RCODE_FOR_TSIGERROR) {
isc_throw(OutOfRange, "Invalid RCODE for TSIG Error: " << rcode);
}
}
string
TSIGError::toText() const {
if (code_ <= MAX_RCODE_FOR_TSIGERROR) {
return (Rcode(code_).toText());
} else if (code_ <= BAD_TIME_CODE) {
return (tsigerror_text[code_ - (MAX_RCODE_FOR_TSIGERROR + 1)]);
} else {
return (boost::lexical_cast<string>(code_));
}
}
} // namespace dns
} // namespace isc
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