Start on the implementation of the Python side.

Also add the transfer obtained context to the C++ methods relating to expecting transfers.

src/controller/python/chip/ChipDeviceCtrl.py

@@ -1343,6 +1343,40 @@ def WriteGroupAttribute(
         # An empty list is the expected return for sending group write attribute.
         return []
 
+    async def PrepareToReceiveBdxData(self):
+        '''
+        Sets up the system to expect a node to initiate a BDX transfer. The transfer will send data here.
+
+        Returns:
+            - a BdxTransfer with the init message from the transfer.
+        Raises:
+            - ? on error
+        '''
+        self.CheckIsActive()
+
+        eventLoop = asyncio.get_running_loop()
+        future = eventLoop.create_future()
+
+        res = await Bdx.PrepareToReceiveBdxData(future)
+        res.raise_on_error()
+        return await future
+
+    async def PrepareToSendBdxData(self, data: bytes): # TODO: Type of `data`.
+        '''
+        Sets up the system to expect a node to initiate a BDX transfer. The transfer will send data to the node.
+
+        Raises:
+            - ? on error
+        '''
+        self.CheckIsActive()
+
+        eventLoop = asyncio.get_running_loop()
+        future = eventLoop.create_future()
+
+        res = await Bdx.PrepareToSendBdxData(future, data)
+        res.raise_on_error()
+        return await future
+
     def _parseAttributePathTuple(self, pathTuple: typing.Union[
         None,  # Empty tuple, all wildcard
         typing.Tuple[int],  # Endpoint

src/controller/python/chip/bdx/Bdx.py

@@ -28,23 +28,46 @@
 
 
 @_OnTransferObtainedCallbackFunct
-def _OnTransferObtainedCallback(closure, result: PyChipError, bdxTransfer, transferControlFlags: int, maxBlockSize: int,
+def _OnTransferObtainedCallback(future: Future, result: PyChipError, bdxTransfer, transferControlFlags: int, maxBlockSize: int,
                                 startOffset: int, length: int, fileDesignator, fileDesignatorLength: int, metadata,
                                 metadataLength: int):
-    # TODO: Call the closure with the rest of the parameters.
-    pass
+    if result is CHIP_NO_ERROR:
+        transfer = BdxTransfer()
+        # TODO: Set the parameters of the transfer.
+        future.set_result(transfer)
+    else:
+        future.set_exception(result.to_exception())
 
 
 @_OnDataReceivedCallbackFunct
-def _OnDataReceivedCallback(closure, dataBuffer, bufferLength: int):
-    # TODO: Call the closure with the data.
+def _OnDataReceivedCallback(context, dataBuffer, bufferLength: int):
+    # TODO: Call the context with the data.
     pass
 
 
 @_OnTransferCompletedCallbackFunct
-def _OnTransferCompletedCallback(closure, result: PyChipError):
-    # TODO: Call the closure.
-    pass
+def _OnTransferCompletedCallback(future: Future, result: PyChipError):
+    future.set_result(result)
+
+
+async def PrepareToReceiveBdxData(future: Future):
+    handle = chip.native.GetLibraryHandle()
+
+    # TODO: Do I need to increment a reference to the future? (using ctypes.pythonapi.Py_IncRef(ctypes.py_object(future)))
+    return await builtins.chipStack.CallAsync(
+        lambda: handle.pychip_Bdx_ExpectBdxTransfer(future)
+    )
+
+
+async def PrepareToSendBdxData(future: Future, data): # TODO: Type of data?
+    handle = chip.native.GetLibraryHandle()
+
+    # TODO: Store data somewhere.
+
+    # TODO: Do I need to increment a reference to the future? (using ctypes.pythonapi.Py_IncRef(ctypes.py_object(future)))
+    return await builtins.chipStack.CallAsync(
+        lambda: handle.pychip_Bdx_ExpectBdxTransfer(future)
+    )
 
 
 def Init():

src/controller/python/chip/bdx/bdx.cpp

@@ -62,6 +62,16 @@ class TransferMap
         return &*result;
     }
 
+    TransferData * TransferDataForTransferObtainedContext(PyObject transferObtainedContext)
+    {
+        std::vector<TransferData>::iterator result = std::find(mTransfers.begin(), mTransfers.end(),
+                                                               [transferObtainedContext](const TransferData& data) {
+                                                                   return data.OnTransferObtainedContext == transferObtainedContext;
+                                                               });
+        VerifyOrReturnValue(result != mTransfers.end(), nullptr);
+        return &*result;
+    }
+
     // This returns the next transfer data that has no associated BdxTransfer.
     TransferData * NextUnassociatedTransferData()
     {
@@ -80,10 +90,7 @@ class TransferMap
 
     void RemoveTransferData(TransferData * transferData)
     {
-        std::vector<TransferData>::iterator result = std::find(mTransfers.begin(), mTransfers.end(),
-                                                               [transferData](const TransferData& data) {
-                                                                   return &data == transferData;
-                                                               });
+        std::vector<TransferData>::iterator result = std::find(mTransfers.begin(), mTransfers.end(), *transferData);
         VerifyOrReturn(result != mTransfers.end());
         mTransfers.erase(result);
     }
@@ -100,7 +107,7 @@ class TransferDelegate : public bdx::BdxTransfer::Delegate
 
     virtual void InitMessageReceived(bdx::BdxTransfer * transfer, bdx::TransferSession::TransferInitData init_data)
     {
-        TransferData * transferData = mTransfers->CreateUnassociatedTransferData();
+        TransferData * transferData = mTransfers->NextUnassociatedTransferData();
         if (gOnTransferObtainedCallback && transferData)
         {
             transferData->Transfer = transfer;
@@ -165,14 +172,20 @@ void pychip_Bdx_InitCallbacks(OnTransferObtainedCallback onTransferObtainedCallb
     OnTransferCompletedCallback gOnTransferCompletedCallback = onTransferCompletedCallback;
 }
 
-PyChipError pychip_Bdx_ExpectBdxTransfer()
+PyChipError pychip_Bdx_ExpectBdxTransfer(PyObject transferObtainedContext)
 {
+    TransferData * transferData = gTransfers.CreateUnassociatedTransferData();
+    VerifyOrReturnValue(transferData != nullptr, ToPyChipError(CHIP_ERROR_NO_MEMORY));
+    transferData->OnTransferObtainedContext = transferObtainedContext;
     gBdxTransferManager.ExpectATransfer();
 }
 
-PyChipError pychip_Bdx_StopExpectingBdxTransfer()
+PyChipError pychip_Bdx_StopExpectingBdxTransfer(PyObject transferObtainedContext)
 {
+    TransferData * transferData = gTransfers.TransferDataForTransferObtainedContext(transferObtainedContext);
+    VerifyOrReturnValue(transferData != nullptr, ToPyChipError(CHIP_ERROR_NOT_FOUND));
     gBdxTransferManager.StopExpectingATransfer();
+    gTransfers.RemoveTransferData(transferData);
 }
 
 PyChipError pychip_Bdx_AcceptSendTransfer(chip::bdx::BdxTransfer * transfer, PyObject dataReceivedContext,