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/*
*
* Copyright (c) 2020 Project CHIP Authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* @file
* This file implements the ExchangeContext class.
*
*/
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
#ifndef __STDC_LIMIT_MACROS
#define __STDC_LIMIT_MACROS
#endif
#include <inttypes.h>
#include <stdint.h>
#include <stdlib.h>
#include <lib/core/CHIPCore.h>
#include <lib/core/CHIPEncoding.h>
#include <lib/core/CHIPKeyIds.h>
#include <lib/support/Defer.h>
#include <lib/support/TypeTraits.h>
#include <lib/support/logging/CHIPLogging.h>
#include <messaging/ApplicationExchangeDispatch.h>
#include <messaging/EphemeralExchangeDispatch.h>
#include <messaging/ExchangeContext.h>
#include <messaging/ExchangeMgr.h>
#include <platform/LockTracker.h>
#include <protocols/Protocols.h>
#include <protocols/secure_channel/Constants.h>
#if CONFIG_DEVICE_LAYER
#include <platform/CHIPDeviceLayer.h>
#endif
using namespace chip::Encoding;
using namespace chip::Inet;
using namespace chip::System;
namespace chip {
namespace Messaging {
static void DefaultOnMessageReceived(ExchangeContext * ec, Protocols::Id protocolId, uint8_t msgType, uint32_t messageCounter,
PacketBufferHandle && payload)
{
ChipLogError(ExchangeManager,
"Dropping unexpected message of type " ChipLogFormatMessageType " with protocolId " ChipLogFormatProtocolId
" and MessageCounter:" ChipLogFormatMessageCounter " on exchange " ChipLogFormatExchange,
msgType, ChipLogValueProtocolId(protocolId), messageCounter, ChipLogValueExchange(ec));
}
bool ExchangeContext::IsInitiator() const
{
return mFlags.Has(Flags::kFlagInitiator);
}
bool ExchangeContext::IsResponseExpected() const
{
return mFlags.Has(Flags::kFlagResponseExpected);
}
void ExchangeContext::SetResponseExpected(bool inResponseExpected)
{
mFlags.Set(Flags::kFlagResponseExpected, inResponseExpected);
}
void ExchangeContext::UseSuggestedResponseTimeout(Timeout applicationProcessingTimeout)
{
SetResponseTimeout(mSession->ComputeRoundTripTimeout(applicationProcessingTimeout));
}
void ExchangeContext::SetResponseTimeout(Timeout timeout)
{
mResponseTimeout = timeout;
}
#if CONFIG_DEVICE_LAYER && CHIP_DEVICE_CONFIG_ENABLE_SED
void ExchangeContext::UpdateSEDIntervalMode()
{
if (!HasSessionHandle())
{
// After the session has been deleted, no further communication can occur on the exchange,
// so withdraw a SED active mode request.
UpdateSEDIntervalMode(false);
return;
}
Transport::PeerAddress address;
switch (GetSessionHandle()->GetSessionType())
{
case Transport::Session::SessionType::kSecure:
address = GetSessionHandle()->AsSecureSession()->GetPeerAddress();
break;
case Transport::Session::SessionType::kUnauthenticated:
address = GetSessionHandle()->AsUnauthenticatedSession()->GetPeerAddress();
break;
default:
return;
}
VerifyOrReturn(address.GetTransportType() != Transport::Type::kBle);
UpdateSEDIntervalMode(IsResponseExpected() || IsSendExpected() || IsMessageNotAcked());
}
void ExchangeContext::UpdateSEDIntervalMode(bool activeMode)
{
if (activeMode != IsRequestingActiveMode())
{
SetRequestingActiveMode(activeMode);
DeviceLayer::ConnectivityMgr().RequestSEDActiveMode(activeMode, true);
}
}
#endif
CHIP_ERROR ExchangeContext::SendMessage(Protocols::Id protocolId, uint8_t msgType, PacketBufferHandle && msgBuf,
const SendFlags & sendFlags)
{
// This is the first point all outgoing messages funnel through. Ensure
// that our message sends are all synchronized correctly.
assertChipStackLockedByCurrentThread();
bool isStandaloneAck =
(protocolId == Protocols::SecureChannel::Id) && msgType == to_underlying(Protocols::SecureChannel::MsgType::StandaloneAck);
VerifyOrReturnError(mExchangeMgr != nullptr, CHIP_ERROR_INTERNAL);
VerifyOrReturnError(mSession, CHIP_ERROR_CONNECTION_ABORTED);
// Don't let method get called on a freed object.
VerifyOrDie(mExchangeMgr != nullptr && GetReferenceCount() > 0);
// we hold the exchange context here in case the entity that
// originally generated it tries to close it as a result of
// an error arising below. at the end, we have to close it.
ExchangeHandle ref(*this);
// If session requires MRP, NoAutoRequestAck send flag is not specified and is not a group exchange context, request reliable
// transmission.
bool reliableTransmissionRequested =
GetSessionHandle()->RequireMRP() && !sendFlags.Has(SendMessageFlags::kNoAutoRequestAck) && !IsGroupExchangeContext();
bool startedResponseTimer = false;
// If a response message is expected...
if (sendFlags.Has(SendMessageFlags::kExpectResponse) && !IsGroupExchangeContext())
{
// Only one 'response expected' message can be outstanding at a time.
if (IsResponseExpected())
{
// TODO: add a test for this case.
return CHIP_ERROR_INCORRECT_STATE;
}
SetResponseExpected(true);
// Arm the response timer if a timeout has been specified.
if (mResponseTimeout > System::Clock::kZero)
{
CHIP_ERROR err = StartResponseTimer();
if (err != CHIP_NO_ERROR)
{
SetResponseExpected(false);
return err;
}
startedResponseTimer = true;
}
}
{
// ExchangeContext for group are supposed to always be Initiator
if (IsGroupExchangeContext() && !IsInitiator())
{
return CHIP_ERROR_INTERNAL;
}
//
// It is possible that we might have evicted a session as a side-effect of processing an inbound message on this exchange.
// We cannot proceed any further sending a message since we don't have an attached session, so let's error out.
//
// This should not happen to well-behaved logic attempting to sending messages on exchanges, so let's print out a warning
// to ensure it alerts someone to fixing their logic...
//
if (!mSession)
{
ChipLogError(ExchangeManager,
"WARNING: We shouldn't be sending a message on an exchange that has no attached session...");
return CHIP_ERROR_MISSING_SECURE_SESSION;
}
CHIP_ERROR err;
#if CONFIG_BUILD_FOR_HOST_UNIT_TEST
if (mInjectedFailures.Has(InjectedFailureType::kFailOnSend))
{
err = CHIP_ERROR_SENDING_BLOCKED;
}
else
{
#endif
err = mDispatch.SendMessage(GetExchangeMgr()->GetSessionManager(), mSession.Get().Value(), mExchangeId, IsInitiator(),
GetReliableMessageContext(), reliableTransmissionRequested, protocolId, msgType,
std::move(msgBuf));
#if CONFIG_BUILD_FOR_HOST_UNIT_TEST
}
#endif
// We should only cancel the response timer if the ExchangeContext fails to send the message that starts the response timer.
if (err != CHIP_NO_ERROR && startedResponseTimer)
{
CancelResponseTimer();
SetResponseExpected(false);
}
// Standalone acks are not application-level message sends.
if (!isStandaloneAck && err == CHIP_NO_ERROR)
{
//
// Once we've sent the message successfully, we can clear out the WillSendMessage flag.
//
mFlags.Clear(Flags::kFlagWillSendMessage);
MessageHandled();
}
return err;
}
}
void ExchangeContext::DoClose(bool clearRetransTable)
{
if (mFlags.Has(Flags::kFlagClosed))
{
return;
}
mFlags.Set(Flags::kFlagClosed);
// Clear protocol callbacks
if (mDelegate != nullptr)
{
mDelegate->OnExchangeClosing(this);
}
mDelegate = nullptr;
// Closure of an exchange context is based on ref counting. The Protocol, when it calls DoClose(), indicates that
// it is done with the exchange context and the message layer sets all callbacks to NULL and does not send anything
// received on the exchange context up to higher layers. At this point, the message layer needs to handle the
// remaining work to be done on that exchange, (e.g. send all pending acks) before truly cleaning it up.
FlushAcks();
// In case the protocol wants a harder release of the EC right away, such as calling Abort(), exchange
// needs to clear the MRP retransmission table immediately.
if (clearRetransTable)
{
mExchangeMgr->GetReliableMessageMgr()->ClearRetransTable(this);
}
if (IsResponseExpected())
{
// Cancel the response timer.
CancelResponseTimer();
}
}
/**
* Gracefully close an exchange context. This call decrements the
* reference count and releases the exchange when the reference
* count goes to zero.
*
*/
void ExchangeContext::Close()
{
VerifyOrDie(mExchangeMgr != nullptr && GetReferenceCount() > 0);
#if defined(CHIP_EXCHANGE_CONTEXT_DETAIL_LOGGING)
ChipLogDetail(ExchangeManager, "ec - close[" ChipLogFormatExchange "], %s", ChipLogValueExchange(this), __func__);
#endif
DoClose(false);
Release();
}
/**
* Abort the Exchange context immediately and release all
* references to it.
*
*/
void ExchangeContext::Abort()
{
VerifyOrDie(mExchangeMgr != nullptr && GetReferenceCount() > 0);
#if defined(CHIP_EXCHANGE_CONTEXT_DETAIL_LOGGING)
ChipLogDetail(ExchangeManager, "ec - abort[" ChipLogFormatExchange "], %s", ChipLogValueExchange(this), __func__);
#endif
DoClose(true);
Release();
}
void ExchangeContextDeletor::Release(ExchangeContext * ec)
{
ec->mExchangeMgr->ReleaseContext(ec);
}
ExchangeContext::ExchangeContext(ExchangeManager * em, uint16_t ExchangeId, const SessionHandle & session, bool Initiator,
ExchangeDelegate * delegate, bool isEphemeralExchange) :
mDispatch(GetMessageDispatch(isEphemeralExchange, delegate)),
mSession(*this)
{
VerifyOrDie(mExchangeMgr == nullptr);
mExchangeMgr = em;
mExchangeId = ExchangeId;
mSession.Grab(session);
mFlags.Set(Flags::kFlagInitiator, Initiator);
mFlags.Set(Flags::kFlagEphemeralExchange, isEphemeralExchange);
mDelegate = delegate;
//
// If we're an initiator and we just created this exchange, we obviously did so to send a message. Let's go ahead and
// set the flag on this to correctly mark it as so.
//
// This only applies to non-ephemeral exchanges. Ephemeral exchanges do not have an intention of sending out a message
// since they're created expressly for the purposes of sending out a standalone ACK when the message could not be handled
// through normal means.
//
if (Initiator && !isEphemeralExchange)
{
WillSendMessage();
}
SetAckPending(false);
// Do not request Ack for multicast
SetAutoRequestAck(!session->IsGroupSession());
#if defined(CHIP_EXCHANGE_CONTEXT_DETAIL_LOGGING)
ChipLogDetail(ExchangeManager, "ec++ id: " ChipLogFormatExchange, ChipLogValueExchange(this));
#endif
SYSTEM_STATS_INCREMENT(chip::System::Stats::kExchangeMgr_NumContexts);
}
ExchangeContext::~ExchangeContext()
{
VerifyOrDie(mExchangeMgr != nullptr && GetReferenceCount() == 0);
//
// Ensure that DoClose has been called by the time we get here. If not, we have a leak somewhere.
//
VerifyOrDie(mFlags.Has(Flags::kFlagClosed));
#if CONFIG_DEVICE_LAYER && CHIP_DEVICE_CONFIG_ENABLE_SED
// Make sure that the exchange withdraws the request for Sleepy End Device active mode.
UpdateSEDIntervalMode(false);
#endif
// Ideally, in this scenario, the retransmit table should
// be clear of any outstanding messages for this context and
// the boolean parameter passed to DoClose() should not matter.
DoClose(false);
mExchangeMgr = nullptr;
#if defined(CHIP_EXCHANGE_CONTEXT_DETAIL_LOGGING)
ChipLogDetail(ExchangeManager, "ec-- id: " ChipLogFormatExchange, ChipLogValueExchange(this));
#endif
SYSTEM_STATS_DECREMENT(chip::System::Stats::kExchangeMgr_NumContexts);
}
bool ExchangeContext::MatchExchange(const SessionHandle & session, const PacketHeader & packetHeader,
const PayloadHeader & payloadHeader)
{
// A given message is part of a particular exchange if...
return
// The exchange identifier of the message matches the exchange identifier of the context.
(mExchangeId == payloadHeader.GetExchangeID())
// AND The Session associated with the incoming message matches the Session associated with the exchange.
&& (mSession.Contains(session))
// TODO: This check should be already implied by the equality of session check,
// It should be removed after we have implemented the temporary node id for PASE and CASE sessions
&& (IsEncryptionRequired() == packetHeader.IsEncrypted())
// AND The message was sent by an initiator and the exchange context is a responder (IsInitiator==false)
// OR The message was sent by a responder and the exchange context is an initiator (IsInitiator==true) (for the broadcast
// case, the initiator is ill defined)
&& (payloadHeader.IsInitiator() != IsInitiator());
}
void ExchangeContext::OnSessionReleased()
{
if (ShouldIgnoreSessionRelease())
{
return;
}
if (mFlags.Has(Flags::kFlagClosed))
{
// Exchange is already being closed. It may occur when closing an exchange after sending
// RemoveFabric response which triggers removal of all sessions for the given fabric.
mExchangeMgr->GetReliableMessageMgr()->ClearRetransTable(this);
return;
}
// Hold a ref to ourselves so we can make calls into our delegate that might
// decrease our refcount without worrying about use-after-free.
ExchangeHandle ref(*this);
//
// If a send is not expected (either because we're waiting for a response OR
// we're in the middle of processing a OnMessageReceived call), we can go ahead
// and notify our delegate and abort the exchange since we still own the ref.
//
if (!IsSendExpected())
{
if (IsResponseExpected())
{
// If we're waiting on a response, we now know it's never going to show up
// and we should notify our delegate accordingly.
CancelResponseTimer();
// We want to Abort, not just Close, so that RMP bits are cleared, so
// don't let NotifyResponseTimeout close us.
NotifyResponseTimeout(/* aCloseIfNeeded = */ false);
}
Abort();
}
else
{
DoClose(true /* clearRetransTable */);
}
}
CHIP_ERROR ExchangeContext::StartResponseTimer()
{
System::Layer * lSystemLayer = mExchangeMgr->GetSessionManager()->SystemLayer();
if (lSystemLayer == nullptr)
{
// this is an assertion error, which shall never happen
return CHIP_ERROR_INTERNAL;
}
return lSystemLayer->StartTimer(mResponseTimeout, HandleResponseTimeout, this);
}
void ExchangeContext::CancelResponseTimer()
{
System::Layer * lSystemLayer = mExchangeMgr->GetSessionManager()->SystemLayer();
if (lSystemLayer == nullptr)
{
// this is an assertion error, which shall never happen
return;
}
lSystemLayer->CancelTimer(HandleResponseTimeout, this);
}
void ExchangeContext::HandleResponseTimeout(System::Layer * aSystemLayer, void * aAppState)
{
ExchangeContext * ec = reinterpret_cast<ExchangeContext *>(aAppState);
if (ec == nullptr)
return;
ec->NotifyResponseTimeout(/* aCloseIfNeeded = */ true);
}
void ExchangeContext::NotifyResponseTimeout(bool aCloseIfNeeded)
{
SetResponseExpected(false);
// Hold a ref to ourselves so we can make calls into our delegate that might
// decrease our refcount (e.g. by expiring out session) without worrying
// about use-after-free.
ExchangeHandle ref(*this);
// mSession might be null if this timeout is due to the session being
// evicted.
if (mSession)
{
if (mSession->IsSecureSession() && mSession->AsSecureSession()->IsCASESession())
{
mSession->AsSecureSession()->MarkAsDefunct();
}
mSession->DispatchSessionEvent(&SessionDelegate::OnSessionHang);
}
ExchangeDelegate * delegate = GetDelegate();
// Call the user's timeout handler.
if (delegate != nullptr)
{
delegate->OnResponseTimeout(this);
}
if (aCloseIfNeeded)
{
MessageHandled();
}
}
CHIP_ERROR ExchangeContext::HandleMessage(uint32_t messageCounter, const PayloadHeader & payloadHeader, MessageFlags msgFlags,
PacketBufferHandle && msgBuf)
{
// We hold a reference to the ExchangeContext here to
// guard against Close() calls(decrementing the reference
// count) by the protocol before the CHIP Exchange
// layer has completed its work on the ExchangeContext.
ExchangeHandle ref(*this);
bool isStandaloneAck = payloadHeader.HasMessageType(Protocols::SecureChannel::MsgType::StandaloneAck);
bool isDuplicate = msgFlags.Has(MessageFlagValues::kDuplicateMessage);
auto deferred = MakeDefer([&]() {
// Duplicates and standalone acks are not application-level messages, so they should generally not lead to any state
// changes. The one exception to that is that if we have a null mDelegate then our lifetime is not application-defined,
// since we don't interact with the application at that point. That can happen when we are already closed (in which case
// MessageHandled is a no-op) or if we were just created to send a standalone ack for this incoming message, in which case
// we should treat it as an app-level message for purposes of our state.
if ((isStandaloneAck || isDuplicate) && mDelegate != nullptr)
{
return;
}
MessageHandled();
});
if (mDispatch.IsReliableTransmissionAllowed() && !IsGroupExchangeContext())
{
if (!msgFlags.Has(MessageFlagValues::kDuplicateMessage) && payloadHeader.IsAckMsg() &&
payloadHeader.GetAckMessageCounter().HasValue())
{
HandleRcvdAck(payloadHeader.GetAckMessageCounter().Value());
}
if (payloadHeader.NeedsAck())
{
// An acknowledgment needs to be sent back to the peer for this message on this exchange,
HandleNeedsAck(messageCounter, msgFlags);
}
}
if (IsAckPending() && !mDelegate)
{
// The incoming message wants an ack, but we have no delegate, so
// there's not going to be a response to piggyback on. Just flush the
// ack out right now.
ReturnErrorOnFailure(FlushAcks());
}
// The SecureChannel::StandaloneAck message type is only used for MRP; do not pass such messages to the application layer.
if (isStandaloneAck)
{
return CHIP_NO_ERROR;
}
// Since the message is duplicate, let's not forward it up the stack
if (isDuplicate)
{
return CHIP_NO_ERROR;
}
if (IsEphemeralExchange())
{
// The EphemeralExchange has done its job, since StandaloneAck is sent in previous FlushAcks() call.
return CHIP_NO_ERROR;
}
if (IsMessageNotAcked())
{
// The only way we can get here is a spec violation on the other side:
// we sent a message that needs an ack, and the other side responded
// with a message that does not contain an ack for the message we sent.
// Just drop this message; if we delivered it to our delegate it might
// try to send another message-needing-an-ack in response, which would
// violate our internal invariants.
ChipLogError(ExchangeManager, "Dropping message without piggyback ack when we are waiting for an ack.");
return CHIP_ERROR_INCORRECT_STATE;
}
if (IsResponseExpected())
{
// Since we got the response, cancel the response timer.
CancelResponseTimer();
// If the context was expecting a response to a previously sent message, this message
// is implicitly that response.
SetResponseExpected(false);
}
// Don't send messages on to our delegate if our dispatch does not allow
// those messages.
if (mDelegate != nullptr && mDispatch.MessagePermitted(payloadHeader.GetProtocolID(), payloadHeader.GetMessageType()))
{
return mDelegate->OnMessageReceived(this, payloadHeader, std::move(msgBuf));
}
DefaultOnMessageReceived(this, payloadHeader.GetProtocolID(), payloadHeader.GetMessageType(), messageCounter,
std::move(msgBuf));
return CHIP_NO_ERROR;
}
void ExchangeContext::MessageHandled()
{
#if CONFIG_DEVICE_LAYER && CHIP_DEVICE_CONFIG_ENABLE_SED
UpdateSEDIntervalMode();
#endif
if (mFlags.Has(Flags::kFlagClosed) || IsResponseExpected() || IsSendExpected())
{
return;
}
Close();
}
ExchangeMessageDispatch & ExchangeContext::GetMessageDispatch(bool isEphemeralExchange, ExchangeDelegate * delegate)
{
if (isEphemeralExchange)
return EphemeralExchangeDispatch::Instance();
if (delegate != nullptr)
return delegate->GetMessageDispatch();
return ApplicationExchangeDispatch::Instance();
}
void ExchangeContext::AbortAllOtherCommunicationOnFabric()
{
if (!mSession || !mSession->IsSecureSession())
{
ChipLogError(ExchangeManager, "AbortAllOtherCommunicationOnFabric called when we don't have a PASE/CASE session");
return;
}
// Save our session so it does not actually go away.
Optional<SessionHandle> session = mSession.Get();
SetIgnoreSessionRelease(true);
GetExchangeMgr()->GetSessionManager()->ExpireAllSessionsForFabric(mSession->GetFabricIndex());
mSession.GrabExpiredSession(session.Value());
SetIgnoreSessionRelease(false);
}
void ExchangeContext::ExchangeSessionHolder::GrabExpiredSession(const SessionHandle & session)
{
VerifyOrDie(session->AsSecureSession()->IsPendingEviction());
GrabUnchecked(session);
}
} // namespace Messaging
} // namespace chip