[Group] Move group session check to ExchangeContext

src/app/WriteClient.cpp

@@ -244,28 +244,28 @@ CHIP_ERROR WriteClient::SendWriteRequest(SessionHandle session, System::Clock::T
     // Create a new exchange context.
     mpExchangeCtx = mpExchangeMgr->NewContext(session, this);
     VerifyOrExit(mpExchangeCtx != nullptr, err = CHIP_ERROR_NO_MEMORY);
-    if (session.IsGroupSession())
-    {
-        // Exchange will be closed by WriteClientHandle::SendWriteRequest for group messages
-        err = mpExchangeCtx->SendMessage(Protocols::InteractionModel::MsgType::WriteRequest, std::move(packet),
-                                         Messaging::SendFlags(Messaging::SendMessageFlags::kNoAutoRequestAck));
-    }
-    else
-    {
-        mpExchangeCtx->SetResponseTimeout(timeout);
 
-        err = mpExchangeCtx->SendMessage(Protocols::InteractionModel::MsgType::WriteRequest, std::move(packet),
-                                         Messaging::SendFlags(Messaging::SendMessageFlags::kExpectResponse));
-        SuccessOrExit(err);
-        MoveToState(State::AwaitingResponse);
-    }
+    mpExchangeCtx->SetResponseTimeout(timeout);
+
+    // kExpectResponse is ignored by ExchangeContext in case of groupcast
+    err = mpExchangeCtx->SendMessage(Protocols::InteractionModel::MsgType::WriteRequest, std::move(packet),
+                                     Messaging::SendFlags(Messaging::SendMessageFlags::kExpectResponse));
+    SuccessOrExit(err);
+
+    MoveToState(State::AwaitingResponse);
 
 exit:
     if (err != CHIP_NO_ERROR)
     {
         ClearExistingExchangeContext();
     }
 
+    if (session.IsGroupSession())
+    {
+        // Always shutdown on Group communication
+        Shutdown();
+    }
+
     return err;
 }
 
@@ -361,7 +361,7 @@ CHIP_ERROR WriteClientHandle::SendWriteRequest(SessionHandle session, System::Cl
 
     // Transferring ownership of the underlying WriteClient to the IM layer. IM will manage its lifetime.
     // For groupcast writes, there is no transfer of ownership since the interaction is done upon transmission of the action
-    if (err == CHIP_NO_ERROR && !session.IsGroupSession())
+    if (err == CHIP_NO_ERROR)
     {
         // Release the WriteClient without closing it.
         mpWriteClient = nullptr;

src/messaging/ExchangeContext.cpp

@@ -129,11 +129,13 @@ CHIP_ERROR ExchangeContext::SendMessage(Protocols::Id protocolId, uint8_t msgTyp
     const Transport::PeerAddress * peerAddress = GetSessionHandle().GetPeerAddress(mExchangeMgr->GetSessionManager());
     // Treat unknown peer address as "not UDP", because we have no idea whether
     // it's safe to do MRP there.
-    bool isUDPTransport                = peerAddress && peerAddress->GetTransportType() == Transport::Type::kUdp;
+    bool isUDPTransport = peerAddress && peerAddress->GetTransportType() == Transport::Type::kUdp;
+
+    // this check is ignored by the ExchangeMsgDispatch if !AutoRequestAck()
     bool reliableTransmissionRequested = isUDPTransport && !sendFlags.Has(SendMessageFlags::kNoAutoRequestAck);
 
     // If a response message is expected...
-    if (sendFlags.Has(SendMessageFlags::kExpectResponse))
+    if (sendFlags.Has(SendMessageFlags::kExpectResponse) && !IsGroupExchangeContext())
     {
         // Only one 'response expected' message can be outstanding at a time.
         if (IsResponseExpected())

src/messaging/ExchangeContext.h

@@ -76,6 +76,8 @@ class DLL_EXPORT ExchangeContext : public ReliableMessageContext, public Referen
 
     bool IsEncryptionRequired() const { return mDispatch->IsEncryptionRequired(); }
 
+    bool IsGroupExchangeContext() const { return (mSession.HasValue() && mSession.Value().IsGroupSession()); }
+
     /**
      *  Send a CHIP message on this exchange.
      *