src/darwin/Framework/CHIP/MTRDiagnosticLogsDownloader.mm - third_party/github/project-chip/connectedhomeip - Git at Google

 /**
  *
  *    Copyright (c) 2024 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.
  */

 #import "MTRDiagnosticLogsDownloader.h"

 #include <protocols/bdx/BdxTransferServerDelegate.h>

 #import "MTRDeviceControllerFactory_Internal.h"
 #import "MTRDeviceController_Internal.h"
 #import "MTRError_Internal.h"
 #import "MTRLogging_Internal.h"
 #import "NSDataSpanConversion.h"
 #import "NSStringSpanConversion.h"

 #import "zap-generated/MTRClusters.h"

 typedef void (^AbortHandler)(NSError * error);

 static NSString * const kErrorInitDiagnosticLogsDownloader = @"Init failure while initializing Diagnostic Logs bridge.";
 static NSString * const kEndUserSupport = @"EndUserSupport";
 static NSString * const kNetworkDiagnostics = @"NetworkDiagnostics";
 static NSString * const kCrash = @"Crash";

 constexpr uint8_t kDiagnosticLogsEndPoint = 0;

 class DiagnosticLogsDownloaderBridge;

 NS_ASSUME_NONNULL_BEGIN

 @interface Download : NSObject
 @property (nonatomic) NSString * fileDesignator;
 @property (nonatomic) NSNumber * fabricIndex;
 @property (nonatomic) NSNumber * nodeID;
 @property (nonatomic) NSURL * fileURL;
 @property (nonatomic) NSFileHandle * fileHandle;
 @property (nonatomic) AbortHandler abortHandler;
 @property (nonatomic) MTRStatusCompletion finalize;

 - (instancetype)initWithType:(MTRDiagnosticLogType)type
                  fabricIndex:(NSNumber *)fabricIndex
                       nodeID:(NSNumber *)nodeID
                        queue:(dispatch_queue_t)queue
                   completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
                         done:(void (^)(Download * finishedDownload))done;

 - (void)writeToFile:(NSData *)data error:(out NSError **)error;

 - (BOOL)matches:(NSString *)fileDesignator
     fabricIndex:(NSNumber *)fabricIndex
          nodeID:(NSNumber *)nodeID;

 - (void)checkInteractionModelResponse:(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable)response error:(NSError * _Nullable)error;

 - (void)success;
 - (void)failure:(NSError * _Nullable)error;
 @end

 @interface Downloads : NSObject
 @property (nonatomic, strong) NSMutableArray<Download *> * downloads;

 - (Download * _Nullable)get:(NSString *)fileDesignator
                 fabricIndex:(NSNumber *)fabricIndex
                      nodeID:(NSNumber *)nodeID;

 - (Download * _Nullable)add:(MTRDiagnosticLogType)type
                 fabricIndex:(NSNumber *)fabricIndex
                      nodeID:(NSNumber *)nodeID
                       queue:(dispatch_queue_t)queue
                  completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
                        done:(void (^)(Download * finishedDownload))done;
 @end

 @interface MTRDiagnosticLogsDownloader ()
 @property (readonly) DiagnosticLogsDownloaderBridge * bridge;
 @property (nonatomic, strong) Downloads * downloads;

 /**
  * Notify the delegate when a BDX Session starts for some logs.
  *
  * If completion is passed a non-nil error, that will be converted into
  * an error response to the BDX initiatior. Otherwise a success response will be sent.
  */
 - (void)handleBDXTransferSessionBeginForFileDesignator:(NSString *)fileDesignator
                                            fabricIndex:(NSNumber *)fabricIndex
                                                 nodeID:(NSNumber *)nodeID
                                             completion:(MTRStatusCompletion)completion
                                           abortHandler:(AbortHandler)abortHandler;

 /**
  * Notify the delegate when some data is received on the BDX Session.
  *
  * If completion is passed a non-nil error, that will be converted into
  * an error response to the sender. Otherwise a success response will be sent.
  */
 - (void)handleBDXTransferSessionDataForFileDesignator:(NSString *)fileDesignator
                                           fabricIndex:(NSNumber *)fabricIndex
                                                nodeID:(NSNumber *)nodeID
                                                  data:(NSData *)data
                                            completion:(MTRStatusCompletion)completion;

 /**
  * Notify the delegate when a BDX Session ends for some logs.
  */
 - (void)handleBDXTransferSessionEndForFileDesignator:(NSString *)fileDesignator
                                          fabricIndex:(NSNumber *)fabricIndex
                                               nodeID:(NSNumber *)nodeID
                                                error:(NSError * _Nullable)error;

 @end

 NS_ASSUME_NONNULL_END

 class DiagnosticLogsDownloaderBridge : public chip::bdx::BDXTransferServerDelegate {
 public:
     DiagnosticLogsDownloaderBridge(MTRDiagnosticLogsDownloader * delegate);
     ~DiagnosticLogsDownloaderBridge();

     /////////// BDXTransferServerDelegate Interface /////////
     CHIP_ERROR OnTransferBegin(chip::bdx::BDXTransferProxy * transfer) override;
     CHIP_ERROR OnTransferEnd(chip::bdx::BDXTransferProxy * transfer, CHIP_ERROR error) override;
     CHIP_ERROR OnTransferData(chip::bdx::BDXTransferProxy * transfer, const chip::ByteSpan & data) override;

     CHIP_ERROR StartBDXTransferTimeout(Download * download, uint16_t timeoutInSeconds);
     void CancelBDXTransferTimeout(Download * download);

 private:
     static void OnTransferTimeout(chip::System::Layer * layer, void * context);
     MTRDiagnosticLogsDownloader * __weak mDelegate;
 };

 @implementation Download
 - (instancetype)initWithType:(MTRDiagnosticLogType)type
                  fabricIndex:(NSNumber *)fabricIndex
                       nodeID:(NSNumber *)nodeID
                        queue:(dispatch_queue_t)queue
                   completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
                         done:(void (^)(Download * finishedDownload))done;
 {
     self = [super init];
     if (self) {
         auto * fileDesignator = [self _toFileDesignatorString:type nodeID:nodeID];
         auto * fileURL = [self _toFileURL:type nodeID:nodeID];

         __weak typeof(self) weakSelf = self;
         auto bdxTransferDone = ^(NSError * bdxError) {
             dispatch_async(queue, ^{
                 Download * strongSelf = weakSelf;
                 if (strongSelf) {
                     // If a fileHandle exists, it means that the BDX session has been initiated and a file has
                     // been created to host the data of the session. So even if there is an error there may be some
                     // data in the logs that the caller may find useful. For this reason, fileURL is passed in even
                     // when there is an error but fileHandle is not nil.
                     completion(strongSelf->_fileHandle ? fileURL : nil, bdxError);
                     [strongSelf deleteFile];

                     done(strongSelf);
                 }
             });
         };

         _fileDesignator = fileDesignator;
         _fabricIndex = fabricIndex;
         _nodeID = nodeID;
         _fileURL = fileURL;
         _fileHandle = nil;
         _finalize = bdxTransferDone;
     }
     return self;
 }

 - (void)checkInteractionModelResponse:(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable)response error:(NSError * _Nullable)error
 {
     VerifyOrReturn(nil == error, [self failure:error]);

     auto status = response.status;

     VerifyOrReturn(![status isEqual:@(MTRDiagnosticLogsStatusBusy)], [self failure:[MTRError errorForCHIPErrorCode:CHIP_ERROR_BUSY]]);
     VerifyOrReturn(![status isEqual:@(MTRDiagnosticLogsStatusDenied)], [self failure:[MTRError errorForCHIPErrorCode:CHIP_ERROR_ACCESS_DENIED]]);

     // If the whole log content fits into the response LogContent field or if there is no log, forward it to the caller
     // and stop here.
     if ([status isEqual:@(MTRDiagnosticLogsStatusExhausted)] || [status isEqual:@(MTRDiagnosticLogsStatusNoLogs)]) {
         NSError * writeError = nil;
         [self writeToFile:response.logContent error:&writeError];
         VerifyOrReturn(nil == writeError, [self failure:writeError]);

         [self success];
         return;
     };

     // The file is going to be transferred over BDX. Everything past this point will be handled in bdxTransferDone.
 }

 - (void)createFile:(NSError **)error
 {
     VerifyOrReturn(nil == _fileHandle);

     auto * fileManager = [NSFileManager defaultManager];
     [fileManager URLForDirectory:NSItemReplacementDirectory
                         inDomain:NSUserDomainMask
                appropriateForURL:_fileURL
                           create:YES
                            error:error];
     VerifyOrReturn(nil == *error);

     BOOL success = [fileManager createFileAtPath:[_fileURL path] contents:nil attributes:nil];
     VerifyOrReturn(success, *error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL]);

     auto * fileHandle = [NSFileHandle fileHandleForWritingToURL:_fileURL error:error];
     VerifyOrReturn(nil == *error);

     _fileHandle = fileHandle;
 }

 - (void)deleteFile
 {
     VerifyOrReturn(nil != _fileHandle);

     NSError * error = nil;
     [[NSFileManager defaultManager] removeItemAtPath:[_fileURL path] error:&error];
     if (nil != error) {
         // There is an error but there is really not much we can do at that point besides logging it.
         MTR_LOG_ERROR("Error trying to delete the log file: %@. Error: %@", _fileURL, error);
     }
 }

 - (void)writeToFile:(NSData *)data error:(out NSError **)error
 {
     [self createFile:error];
     [_fileHandle seekToEndOfFile];
     [_fileHandle writeData:data error:error];
 }

 - (BOOL)matches:(NSString *)fileDesignator
     fabricIndex:(NSNumber *)fabricIndex
          nodeID:(NSNumber *)nodeID
 {
     return [_fileDesignator isEqualToString:fileDesignator] && [_fabricIndex isEqualToNumber:fabricIndex] && [_nodeID isEqualToNumber:nodeID];
 }

 - (void)failure:(NSError * _Nullable)error
 {
     _finalize(error);
 }

 - (void)success
 {
     _finalize(nil);
 }

 - (NSURL *)_toFileURL:(MTRDiagnosticLogType)type nodeID:(NSNumber *)nodeID
 {
     auto * dateFormatter = [[NSDateFormatter alloc] init];
     dateFormatter.dateFormat = @"yyyy-MM-dd_HH:mm:ss.SSSZZZ";
     auto * timeString = [dateFormatter stringFromDate:NSDate.now];
     auto * nodeIDString = [self _toNodeIDString:nodeID];
     auto * typeString = [self _toTypeString:type];
     auto * filename = [NSString stringWithFormat:@"%@_%@_%@", timeString, nodeIDString, typeString];
     return [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:filename] isDirectory:YES];
 }

 - (NSString *)_toFileDesignatorString:(MTRDiagnosticLogType)type nodeID:(NSNumber *)nodeID
 {
     auto * nodeIDString = [self _toNodeIDString:nodeID];
     auto * typeString = [self _toTypeString:type];
     auto * fileDesignator = [NSString stringWithFormat:@"bdx://%@/%@", nodeIDString, typeString];
     auto substringIndex = MIN(chip::bdx::DiagnosticLogs::kMaxFileDesignatorLen, [fileDesignator length]);
     return [fileDesignator substringToIndex:substringIndex];
 }

 - (NSString *)_toNodeIDString:(NSNumber *)nodeID
 {
     return [NSString stringWithFormat:@"%016llX", nodeID.unsignedLongLongValue];
 }

 - (NSString *)_toTypeString:(MTRDiagnosticLogType)type
 {
     switch (type) {
     case MTRDiagnosticLogTypeEndUserSupport:
         return kEndUserSupport;
     case MTRDiagnosticLogTypeNetworkDiagnostics:
         return kNetworkDiagnostics;
     case MTRDiagnosticLogTypeCrash:
         return kCrash;
     default:
         // This should never happen.
         chipDie();
     }
 }

 @end

 @implementation Downloads
 - (instancetype)init
 {
     if (self = [super init]) {
         _downloads = [[NSMutableArray alloc] init];
     }
     return self;
 }

 - (void)dealloc
 {
     auto error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL];
     for (Download * download in _downloads) {
         [download failure:error];
     }
     _downloads = nil;
 }

 - (Download * _Nullable)get:(NSString *)fileDesignator fabricIndex:(NSNumber *)fabricIndex nodeID:(NSNumber *)nodeID
 {
     for (Download * download in _downloads) {
         if ([download matches:fileDesignator fabricIndex:fabricIndex nodeID:nodeID]) {
             return download;
         }
     }

     return nil;
 }

 - (Download * _Nullable)add:(MTRDiagnosticLogType)type
                 fabricIndex:(NSNumber *)fabricIndex
                      nodeID:(NSNumber *)nodeID
                       queue:(dispatch_queue_t)queue
                  completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
                        done:(void (^)(Download * finishedDownload))done
 {
     assertChipStackLockedByCurrentThread();

     auto download = [[Download alloc] initWithType:type fabricIndex:fabricIndex nodeID:nodeID queue:queue completion:completion done:done];
     VerifyOrReturnValue(nil != download, nil);

     [_downloads addObject:download];
     return download;
 }

 - (void)remove:(Download *)download
 {
     assertChipStackLockedByCurrentThread();

     [_downloads removeObject:download];
 }
 @end

 @implementation MTRDiagnosticLogsDownloader
 - (instancetype)init
 {
     assertChipStackLockedByCurrentThread();

     if (self = [super init]) {
         _downloads = [[Downloads alloc] init];
         _bridge = new DiagnosticLogsDownloaderBridge(self);
         if (_bridge == nullptr) {
             MTR_LOG_ERROR("Error: %@", kErrorInitDiagnosticLogsDownloader);
             return nil;
         }
     }
     return self;
 }

 - (void)dealloc
 {
     if (_bridge) {
         delete _bridge;
         _bridge = nil;
     }
     _downloads = nil;
 }

 - (chip::bdx::BDXTransferServerDelegate *)getBridge
 {
     return _bridge;
 }

 - (void)downloadLogFromNodeWithID:(NSNumber *)nodeID
                        controller:(MTRDeviceController *)controller
                              type:(MTRDiagnosticLogType)type
                           timeout:(NSTimeInterval)timeout
                             queue:(dispatch_queue_t)queue
                        completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion;
 {
     assertChipStackLockedByCurrentThread();

     uint16_t timeoutInSeconds = 0;
     if (timeout <= 0) {
         timeoutInSeconds = 0;
     } else if (timeout > UINT16_MAX) {
         MTR_LOG_INFO("Warning: timeout is too large. It will be truncated to UINT16_MAX.");
         timeoutInSeconds = UINT16_MAX;
     } else {
         timeoutInSeconds = static_cast<uint16_t>(timeout);
     }

     // This block is always called when a download is finished.
     auto done = ^(Download * finishedDownload) {
         [controller asyncDispatchToMatterQueue:^() {
             [self->_downloads remove:finishedDownload];

             if (timeoutInSeconds > 0) {
                 self->_bridge->CancelBDXTransferTimeout(finishedDownload);
             }
         } errorHandler:nil];
     };

     auto fabricIndex = @(controller.fabricIndex);
     auto download = [_downloads add:type fabricIndex:fabricIndex nodeID:nodeID queue:queue completion:completion done:done];
     VerifyOrReturn(nil != download,
         dispatch_async(queue, ^{ completion(nil, [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL]); }));

     auto interactionModelDone = ^(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable response, NSError * _Nullable error) {
         [download checkInteractionModelResponse:response error:error];
     };

     auto * device = [controller deviceForNodeID:nodeID];
     auto * cluster = [[MTRClusterDiagnosticLogs alloc] initWithDevice:device endpointID:@(kDiagnosticLogsEndPoint) queue:queue];

     auto * params = [[MTRDiagnosticLogsClusterRetrieveLogsRequestParams alloc] init];
     params.intent = @(type);
     params.requestedProtocol = @(MTRDiagnosticLogsTransferProtocolBDX);
     params.transferFileDesignator = download.fileDesignator;

     [cluster retrieveLogsRequestWithParams:params expectedValues:nil expectedValueInterval:nil completion:interactionModelDone];

     if (timeoutInSeconds > 0) {
         auto err = _bridge->StartBDXTransferTimeout(download, timeoutInSeconds);
         VerifyOrReturn(CHIP_NO_ERROR == err, [download failure:[MTRError errorForCHIPErrorCode:err]]);
     }
 }

 - (void)handleBDXTransferSessionBeginForFileDesignator:(NSString *)fileDesignator
                                            fabricIndex:(NSNumber *)fabricIndex
                                                 nodeID:(NSNumber *)nodeID
                                             completion:(MTRStatusCompletion)completion
                                           abortHandler:(AbortHandler)abortHandler;
 {
     assertChipStackLockedByCurrentThread();
     MTR_LOG_DEFAULT("BDX Transfer Session Begin: %@", fileDesignator);

     auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
     VerifyOrReturn(nil != download, completion([MTRError errorForCHIPErrorCode:CHIP_ERROR_NOT_FOUND]));

     download.abortHandler = abortHandler;
     completion(nil);
 }

 - (void)handleBDXTransferSessionDataForFileDesignator:(NSString *)fileDesignator
                                           fabricIndex:(NSNumber *)fabricIndex
                                                nodeID:(NSNumber *)nodeID
                                                  data:(NSData *)data
                                            completion:(MTRStatusCompletion)completion
 {
     assertChipStackLockedByCurrentThread();
     MTR_LOG_DEFAULT("BDX Transfer Session Data: %@: %@", fileDesignator, data);

     auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
     VerifyOrReturn(nil != download, completion([MTRError errorForCHIPErrorCode:CHIP_ERROR_NOT_FOUND]));

     NSError * error = nil;
     [download writeToFile:data error:&error];
     VerifyOrReturn(nil != error, completion(error));

     completion(nil);
 }

 - (void)handleBDXTransferSessionEndForFileDesignator:(NSString *)fileDesignator
                                          fabricIndex:(NSNumber *)fabricIndex
                                               nodeID:(NSNumber *)nodeID
                                                error:(NSError * _Nullable)error
 {
     assertChipStackLockedByCurrentThread();
     MTR_LOG_DEFAULT("BDX Transfer Session End: %@: %@", fileDesignator, error);

     auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
     VerifyOrReturn(nil != download);

     VerifyOrReturn(nil == error, [download failure:error]);
     [download success];
 }
 @end

 DiagnosticLogsDownloaderBridge::DiagnosticLogsDownloaderBridge(MTRDiagnosticLogsDownloader * delegate)
 {
     mDelegate = delegate;
 }

 DiagnosticLogsDownloaderBridge::~DiagnosticLogsDownloaderBridge()
 {
     mDelegate = nil;
 }

 CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferBegin(chip::bdx::BDXTransferProxy * transfer)
 {
     VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

     auto fileDesignatorSpan = transfer->GetFileDesignator();
     auto fileDesignator = AsString(fileDesignatorSpan);
     VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

     auto * fabricIndex = @(transfer->GetFabricIndex());
     auto * nodeId = @(transfer->GetPeerNodeId());

     auto completionHandler = ^(NSError * _Nullable error) {
         assertChipStackLockedByCurrentThread();

         if (error != nil) {
             auto err = [MTRError errorToCHIPErrorCode:error];
             transfer->Reject(err);
         } else {
             transfer->Accept();
         }
     };

     auto abortHandler = ^(NSError * error) {
         assertChipStackLockedByCurrentThread();
         auto err = [MTRError errorToCHIPErrorCode:error];
         transfer->Reject(err);
     };

     [mDelegate handleBDXTransferSessionBeginForFileDesignator:fileDesignator
                                                   fabricIndex:fabricIndex
                                                        nodeID:nodeId
                                                    completion:completionHandler
                                                  abortHandler:abortHandler];
     return CHIP_NO_ERROR;
 }

 CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferEnd(chip::bdx::BDXTransferProxy * transfer, CHIP_ERROR error)
 {
     VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

     auto fileDesignatorSpan = transfer->GetFileDesignator();
     auto fileDesignator = AsString(fileDesignatorSpan);
     VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

     NSError * mtrError = nil;
     if (CHIP_NO_ERROR != error) {
         mtrError = [MTRError errorForCHIPErrorCode:error];
     }

     auto * fabricIndex = @(transfer->GetFabricIndex());
     auto * nodeId = @(transfer->GetPeerNodeId());
     [mDelegate handleBDXTransferSessionEndForFileDesignator:fileDesignator
                                                 fabricIndex:fabricIndex
                                                      nodeID:nodeId
                                                       error:mtrError];
     return CHIP_NO_ERROR;
 }

 CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferData(chip::bdx::BDXTransferProxy * transfer, const chip::ByteSpan & dataSpan)
 {
     VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

     auto fileDesignatorSpan = transfer->GetFileDesignator();
     auto fileDesignator = AsString(fileDesignatorSpan);
     VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

     auto * fabricIndex = @(transfer->GetFabricIndex());
     auto * nodeId = @(transfer->GetPeerNodeId());

     auto data = AsData(dataSpan);
     VerifyOrReturnError(nil != data, CHIP_ERROR_INCORRECT_STATE);

     auto completionHandler = ^(NSError * _Nullable error) {
         assertChipStackLockedByCurrentThread();

         if (error != nil) {
             auto err = [MTRError errorToCHIPErrorCode:error];
             transfer->Reject(err);
         } else {
             transfer->Continue();
         }
     };

     [mDelegate handleBDXTransferSessionDataForFileDesignator:fileDesignator
                                                  fabricIndex:fabricIndex
                                                       nodeID:nodeId
                                                         data:data
                                                   completion:completionHandler];
     return CHIP_NO_ERROR;
 }

 CHIP_ERROR DiagnosticLogsDownloaderBridge::StartBDXTransferTimeout(Download * download, uint16_t timeoutInSeconds)
 {
     assertChipStackLockedByCurrentThread();
     return chip::DeviceLayer::SystemLayer().StartTimer(chip::System::Clock::Seconds16(timeoutInSeconds), OnTransferTimeout, (__bridge void *) download);
 }

 void DiagnosticLogsDownloaderBridge::CancelBDXTransferTimeout(Download * download)
 {
     assertChipStackLockedByCurrentThread();
     chip::DeviceLayer::SystemLayer().CancelTimer(OnTransferTimeout, (__bridge void *) download);
 }

 void DiagnosticLogsDownloaderBridge::OnTransferTimeout(chip::System::Layer * layer, void * context)
 {
     assertChipStackLockedByCurrentThread();

     auto * download = (__bridge Download *) context;
     VerifyOrReturn(nil != download);

     // If there is no abortHandler, it means that the BDX transfer has not started.
     // When a BDX transfer has started we need to abort the transfer and we would error out
     // at next poll. We would end up calling OnTransferEnd and eventually [download failure:error].
     // But if the transfer has not started we would stop right now.
     auto error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_TIMEOUT];
     if (download.abortHandler == nil) {
         [download failure:error];
     } else {
         download.abortHandler(error);
     }
 }
	/**
	*
	* Copyright (c) 2024 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.
	*/

	#import "MTRDiagnosticLogsDownloader.h"

	#include <protocols/bdx/BdxTransferServerDelegate.h>

	#import "MTRDeviceControllerFactory_Internal.h"
	#import "MTRDeviceController_Internal.h"
	#import "MTRError_Internal.h"
	#import "MTRLogging_Internal.h"
	#import "NSDataSpanConversion.h"
	#import "NSStringSpanConversion.h"

	#import "zap-generated/MTRClusters.h"

	typedef void (^AbortHandler)(NSError * error);

	static NSString * const kErrorInitDiagnosticLogsDownloader = @"Init failure while initializing Diagnostic Logs bridge.";
	static NSString * const kEndUserSupport = @"EndUserSupport";
	static NSString * const kNetworkDiagnostics = @"NetworkDiagnostics";
	static NSString * const kCrash = @"Crash";

	constexpr uint8_t kDiagnosticLogsEndPoint = 0;

	class DiagnosticLogsDownloaderBridge;

	NS_ASSUME_NONNULL_BEGIN

	@interface Download : NSObject
	@property (nonatomic) NSString * fileDesignator;
	@property (nonatomic) NSNumber * fabricIndex;
	@property (nonatomic) NSNumber * nodeID;
	@property (nonatomic) NSURL * fileURL;
	@property (nonatomic) NSFileHandle * fileHandle;
	@property (nonatomic) AbortHandler abortHandler;
	@property (nonatomic) MTRStatusCompletion finalize;

	- (instancetype)initWithType:(MTRDiagnosticLogType)type
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	queue:(dispatch_queue_t)queue
	completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
	done:(void (^)(Download * finishedDownload))done;

	- (void)writeToFile:(NSData )data error:(out NSError *)error;

	- (BOOL)matches:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID;

	- (void)checkInteractionModelResponse:(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable)response error:(NSError * _Nullable)error;

	- (void)success;
	- (void)failure:(NSError * _Nullable)error;
	@end

	@interface Downloads : NSObject
	@property (nonatomic, strong) NSMutableArray<Download > downloads;

	- (Download * _Nullable)get:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID;

	- (Download * _Nullable)add:(MTRDiagnosticLogType)type
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	queue:(dispatch_queue_t)queue
	completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
	done:(void (^)(Download * finishedDownload))done;
	@end

	@interface MTRDiagnosticLogsDownloader ()
	@property (readonly) DiagnosticLogsDownloaderBridge * bridge;
	@property (nonatomic, strong) Downloads * downloads;

	/**
	* Notify the delegate when a BDX Session starts for some logs.
	*
	* If completion is passed a non-nil error, that will be converted into
	* an error response to the BDX initiatior. Otherwise a success response will be sent.
	*/
	- (void)handleBDXTransferSessionBeginForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	completion:(MTRStatusCompletion)completion
	abortHandler:(AbortHandler)abortHandler;

	/**
	* Notify the delegate when some data is received on the BDX Session.
	*
	* If completion is passed a non-nil error, that will be converted into
	* an error response to the sender. Otherwise a success response will be sent.
	*/
	- (void)handleBDXTransferSessionDataForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	data:(NSData *)data
	completion:(MTRStatusCompletion)completion;

	/**
	* Notify the delegate when a BDX Session ends for some logs.
	*/
	- (void)handleBDXTransferSessionEndForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	error:(NSError * _Nullable)error;

	@end

	NS_ASSUME_NONNULL_END

	class DiagnosticLogsDownloaderBridge : public chip::bdx::BDXTransferServerDelegate {
	public:
	DiagnosticLogsDownloaderBridge(MTRDiagnosticLogsDownloader * delegate);
	~DiagnosticLogsDownloaderBridge();

	/////////// BDXTransferServerDelegate Interface /////////
	CHIP_ERROR OnTransferBegin(chip::bdx::BDXTransferProxy * transfer) override;
	CHIP_ERROR OnTransferEnd(chip::bdx::BDXTransferProxy * transfer, CHIP_ERROR error) override;
	CHIP_ERROR OnTransferData(chip::bdx::BDXTransferProxy * transfer, const chip::ByteSpan & data) override;

	CHIP_ERROR StartBDXTransferTimeout(Download * download, uint16_t timeoutInSeconds);
	void CancelBDXTransferTimeout(Download * download);

	private:
	static void OnTransferTimeout(chip::System::Layer * layer, void * context);
	MTRDiagnosticLogsDownloader * __weak mDelegate;
	};

	@implementation Download
	- (instancetype)initWithType:(MTRDiagnosticLogType)type
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	queue:(dispatch_queue_t)queue
	completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
	done:(void (^)(Download * finishedDownload))done;
	{
	self = [super init];
	if (self) {
	auto * fileDesignator = [self _toFileDesignatorString:type nodeID:nodeID];
	auto * fileURL = [self _toFileURL:type nodeID:nodeID];

	__weak typeof(self) weakSelf = self;
	auto bdxTransferDone = ^(NSError * bdxError) {
	dispatch_async(queue, ^{
	Download * strongSelf = weakSelf;
	if (strongSelf) {
	// If a fileHandle exists, it means that the BDX session has been initiated and a file has
	// been created to host the data of the session. So even if there is an error there may be some
	// data in the logs that the caller may find useful. For this reason, fileURL is passed in even
	// when there is an error but fileHandle is not nil.
	completion(strongSelf->_fileHandle ? fileURL : nil, bdxError);
	[strongSelf deleteFile];

	done(strongSelf);
	}
	});
	};

	_fileDesignator = fileDesignator;
	_fabricIndex = fabricIndex;
	_nodeID = nodeID;
	_fileURL = fileURL;
	_fileHandle = nil;
	_finalize = bdxTransferDone;
	}
	return self;
	}

	- (void)checkInteractionModelResponse:(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable)response error:(NSError * _Nullable)error
	{
	VerifyOrReturn(nil == error, [self failure:error]);

	auto status = response.status;

	VerifyOrReturn(![status isEqual:@(MTRDiagnosticLogsStatusBusy)], [self failure:[MTRError errorForCHIPErrorCode:CHIP_ERROR_BUSY]]);
	VerifyOrReturn(![status isEqual:@(MTRDiagnosticLogsStatusDenied)], [self failure:[MTRError errorForCHIPErrorCode:CHIP_ERROR_ACCESS_DENIED]]);

	// If the whole log content fits into the response LogContent field or if there is no log, forward it to the caller
	// and stop here.
	if ([status isEqual:@(MTRDiagnosticLogsStatusExhausted)] \|\| [status isEqual:@(MTRDiagnosticLogsStatusNoLogs)]) {
	NSError * writeError = nil;
	[self writeToFile:response.logContent error:&writeError];
	VerifyOrReturn(nil == writeError, [self failure:writeError]);

	[self success];
	return;
	};

	// The file is going to be transferred over BDX. Everything past this point will be handled in bdxTransferDone.
	}

	- (void)createFile:(NSError **)error
	{
	VerifyOrReturn(nil == _fileHandle);

	auto * fileManager = [NSFileManager defaultManager];
	[fileManager URLForDirectory:NSItemReplacementDirectory
	inDomain:NSUserDomainMask
	appropriateForURL:_fileURL
	create:YES
	error:error];
	VerifyOrReturn(nil == *error);

	BOOL success = [fileManager createFileAtPath:[_fileURL path] contents:nil attributes:nil];
	VerifyOrReturn(success, *error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL]);

	auto * fileHandle = [NSFileHandle fileHandleForWritingToURL:_fileURL error:error];
	VerifyOrReturn(nil == *error);

	_fileHandle = fileHandle;
	}

	- (void)deleteFile
	{
	VerifyOrReturn(nil != _fileHandle);

	NSError * error = nil;
	[[NSFileManager defaultManager] removeItemAtPath:[_fileURL path] error:&error];
	if (nil != error) {
	// There is an error but there is really not much we can do at that point besides logging it.
	MTR_LOG_ERROR("Error trying to delete the log file: %@. Error: %@", _fileURL, error);
	}
	}

	- (void)writeToFile:(NSData )data error:(out NSError *)error
	{
	[self createFile:error];
	[_fileHandle seekToEndOfFile];
	[_fileHandle writeData:data error:error];
	}

	- (BOOL)matches:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	{
	return [_fileDesignator isEqualToString:fileDesignator] && [_fabricIndex isEqualToNumber:fabricIndex] && [_nodeID isEqualToNumber:nodeID];
	}

	- (void)failure:(NSError * _Nullable)error
	{
	_finalize(error);
	}

	- (void)success
	{
	_finalize(nil);
	}

	- (NSURL )_toFileURL:(MTRDiagnosticLogType)type nodeID:(NSNumber )nodeID
	{
	auto * dateFormatter = [[NSDateFormatter alloc] init];
	dateFormatter.dateFormat = @"yyyy-MM-dd_HH:mm:ss.SSSZZZ";
	auto * timeString = [dateFormatter stringFromDate:NSDate.now];
	auto * nodeIDString = [self _toNodeIDString:nodeID];
	auto * typeString = [self _toTypeString:type];
	auto * filename = [NSString stringWithFormat:@"%@_%@_%@", timeString, nodeIDString, typeString];
	return [NSURL fileURLWithPath:[NSTemporaryDirectory() stringByAppendingPathComponent:filename] isDirectory:YES];
	}

	- (NSString )_toFileDesignatorString:(MTRDiagnosticLogType)type nodeID:(NSNumber )nodeID
	{
	auto * nodeIDString = [self _toNodeIDString:nodeID];
	auto * typeString = [self _toTypeString:type];
	auto * fileDesignator = [NSString stringWithFormat:@"bdx://%@/%@", nodeIDString, typeString];
	auto substringIndex = MIN(chip::bdx::DiagnosticLogs::kMaxFileDesignatorLen, [fileDesignator length]);
	return [fileDesignator substringToIndex:substringIndex];
	}

	- (NSString )_toNodeIDString:(NSNumber )nodeID
	{
	return [NSString stringWithFormat:@"%016llX", nodeID.unsignedLongLongValue];
	}

	- (NSString *)_toTypeString:(MTRDiagnosticLogType)type
	{
	switch (type) {
	case MTRDiagnosticLogTypeEndUserSupport:
	return kEndUserSupport;
	case MTRDiagnosticLogTypeNetworkDiagnostics:
	return kNetworkDiagnostics;
	case MTRDiagnosticLogTypeCrash:
	return kCrash;
	default:
	// This should never happen.
	chipDie();
	}
	}

	@end

	@implementation Downloads
	- (instancetype)init
	{
	if (self = [super init]) {
	_downloads = [[NSMutableArray alloc] init];
	}
	return self;
	}

	- (void)dealloc
	{
	auto error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL];
	for (Download * download in _downloads) {
	[download failure:error];
	}
	_downloads = nil;
	}

	- (Download * _Nullable)get:(NSString )fileDesignator fabricIndex:(NSNumber )fabricIndex nodeID:(NSNumber *)nodeID
	{
	for (Download * download in _downloads) {
	if ([download matches:fileDesignator fabricIndex:fabricIndex nodeID:nodeID]) {
	return download;
	}
	}

	return nil;
	}

	- (Download * _Nullable)add:(MTRDiagnosticLogType)type
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	queue:(dispatch_queue_t)queue
	completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion
	done:(void (^)(Download * finishedDownload))done
	{
	assertChipStackLockedByCurrentThread();

	auto download = [[Download alloc] initWithType:type fabricIndex:fabricIndex nodeID:nodeID queue:queue completion:completion done:done];
	VerifyOrReturnValue(nil != download, nil);

	[_downloads addObject:download];
	return download;
	}

	- (void)remove:(Download *)download
	{
	assertChipStackLockedByCurrentThread();

	[_downloads removeObject:download];
	}
	@end

	@implementation MTRDiagnosticLogsDownloader
	- (instancetype)init
	{
	assertChipStackLockedByCurrentThread();

	if (self = [super init]) {
	_downloads = [[Downloads alloc] init];
	_bridge = new DiagnosticLogsDownloaderBridge(self);
	if (_bridge == nullptr) {
	MTR_LOG_ERROR("Error: %@", kErrorInitDiagnosticLogsDownloader);
	return nil;
	}
	}
	return self;
	}

	- (void)dealloc
	{
	if (_bridge) {
	delete _bridge;
	_bridge = nil;
	}
	_downloads = nil;
	}

	- (chip::bdx::BDXTransferServerDelegate *)getBridge
	{
	return _bridge;
	}

	- (void)downloadLogFromNodeWithID:(NSNumber *)nodeID
	controller:(MTRDeviceController *)controller
	type:(MTRDiagnosticLogType)type
	timeout:(NSTimeInterval)timeout
	queue:(dispatch_queue_t)queue
	completion:(void (^)(NSURL * _Nullable url, NSError * _Nullable error))completion;
	{
	assertChipStackLockedByCurrentThread();

	uint16_t timeoutInSeconds = 0;
	if (timeout <= 0) {
	timeoutInSeconds = 0;
	} else if (timeout > UINT16_MAX) {
	MTR_LOG_INFO("Warning: timeout is too large. It will be truncated to UINT16_MAX.");
	timeoutInSeconds = UINT16_MAX;
	} else {
	timeoutInSeconds = static_cast<uint16_t>(timeout);
	}

	// This block is always called when a download is finished.
	auto done = ^(Download * finishedDownload) {
	[controller asyncDispatchToMatterQueue:^() {
	[self->_downloads remove:finishedDownload];

	if (timeoutInSeconds > 0) {
	self->_bridge->CancelBDXTransferTimeout(finishedDownload);
	}
	} errorHandler:nil];
	};

	auto fabricIndex = @(controller.fabricIndex);
	auto download = [_downloads add:type fabricIndex:fabricIndex nodeID:nodeID queue:queue completion:completion done:done];
	VerifyOrReturn(nil != download,
	dispatch_async(queue, ^{ completion(nil, [MTRError errorForCHIPErrorCode:CHIP_ERROR_INTERNAL]); }));

	auto interactionModelDone = ^(MTRDiagnosticLogsClusterRetrieveLogsResponseParams * _Nullable response, NSError * _Nullable error) {
	[download checkInteractionModelResponse:response error:error];
	};

	auto * device = [controller deviceForNodeID:nodeID];
	auto * cluster = [[MTRClusterDiagnosticLogs alloc] initWithDevice:device endpointID:@(kDiagnosticLogsEndPoint) queue:queue];

	auto * params = [[MTRDiagnosticLogsClusterRetrieveLogsRequestParams alloc] init];
	params.intent = @(type);
	params.requestedProtocol = @(MTRDiagnosticLogsTransferProtocolBDX);
	params.transferFileDesignator = download.fileDesignator;

	[cluster retrieveLogsRequestWithParams:params expectedValues:nil expectedValueInterval:nil completion:interactionModelDone];

	if (timeoutInSeconds > 0) {
	auto err = _bridge->StartBDXTransferTimeout(download, timeoutInSeconds);
	VerifyOrReturn(CHIP_NO_ERROR == err, [download failure:[MTRError errorForCHIPErrorCode:err]]);
	}
	}

	- (void)handleBDXTransferSessionBeginForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	completion:(MTRStatusCompletion)completion
	abortHandler:(AbortHandler)abortHandler;
	{
	assertChipStackLockedByCurrentThread();
	MTR_LOG_DEFAULT("BDX Transfer Session Begin: %@", fileDesignator);

	auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
	VerifyOrReturn(nil != download, completion([MTRError errorForCHIPErrorCode:CHIP_ERROR_NOT_FOUND]));

	download.abortHandler = abortHandler;
	completion(nil);
	}

	- (void)handleBDXTransferSessionDataForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	data:(NSData *)data
	completion:(MTRStatusCompletion)completion
	{
	assertChipStackLockedByCurrentThread();
	MTR_LOG_DEFAULT("BDX Transfer Session Data: %@: %@", fileDesignator, data);

	auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
	VerifyOrReturn(nil != download, completion([MTRError errorForCHIPErrorCode:CHIP_ERROR_NOT_FOUND]));

	NSError * error = nil;
	[download writeToFile:data error:&error];
	VerifyOrReturn(nil != error, completion(error));

	completion(nil);
	}

	- (void)handleBDXTransferSessionEndForFileDesignator:(NSString *)fileDesignator
	fabricIndex:(NSNumber *)fabricIndex
	nodeID:(NSNumber *)nodeID
	error:(NSError * _Nullable)error
	{
	assertChipStackLockedByCurrentThread();
	MTR_LOG_DEFAULT("BDX Transfer Session End: %@: %@", fileDesignator, error);

	auto * download = [_downloads get:fileDesignator fabricIndex:fabricIndex nodeID:nodeID];
	VerifyOrReturn(nil != download);

	VerifyOrReturn(nil == error, [download failure:error]);
	[download success];
	}
	@end

	DiagnosticLogsDownloaderBridge::DiagnosticLogsDownloaderBridge(MTRDiagnosticLogsDownloader * delegate)
	{
	mDelegate = delegate;
	}

	DiagnosticLogsDownloaderBridge::~DiagnosticLogsDownloaderBridge()
	{
	mDelegate = nil;
	}

	CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferBegin(chip::bdx::BDXTransferProxy * transfer)
	{
	VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

	auto fileDesignatorSpan = transfer->GetFileDesignator();
	auto fileDesignator = AsString(fileDesignatorSpan);
	VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

	auto * fabricIndex = @(transfer->GetFabricIndex());
	auto * nodeId = @(transfer->GetPeerNodeId());

	auto completionHandler = ^(NSError * _Nullable error) {
	assertChipStackLockedByCurrentThread();

	if (error != nil) {
	auto err = [MTRError errorToCHIPErrorCode:error];
	transfer->Reject(err);
	} else {
	transfer->Accept();
	}
	};

	auto abortHandler = ^(NSError * error) {
	assertChipStackLockedByCurrentThread();
	auto err = [MTRError errorToCHIPErrorCode:error];
	transfer->Reject(err);
	};

	[mDelegate handleBDXTransferSessionBeginForFileDesignator:fileDesignator
	fabricIndex:fabricIndex
	nodeID:nodeId
	completion:completionHandler
	abortHandler:abortHandler];
	return CHIP_NO_ERROR;
	}

	CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferEnd(chip::bdx::BDXTransferProxy * transfer, CHIP_ERROR error)
	{
	VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

	auto fileDesignatorSpan = transfer->GetFileDesignator();
	auto fileDesignator = AsString(fileDesignatorSpan);
	VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

	NSError * mtrError = nil;
	if (CHIP_NO_ERROR != error) {
	mtrError = [MTRError errorForCHIPErrorCode:error];
	}

	auto * fabricIndex = @(transfer->GetFabricIndex());
	auto * nodeId = @(transfer->GetPeerNodeId());
	[mDelegate handleBDXTransferSessionEndForFileDesignator:fileDesignator
	fabricIndex:fabricIndex
	nodeID:nodeId
	error:mtrError];
	return CHIP_NO_ERROR;
	}

	CHIP_ERROR DiagnosticLogsDownloaderBridge::OnTransferData(chip::bdx::BDXTransferProxy * transfer, const chip::ByteSpan & dataSpan)
	{
	VerifyOrReturnError(nil != mDelegate, CHIP_ERROR_INCORRECT_STATE);

	auto fileDesignatorSpan = transfer->GetFileDesignator();
	auto fileDesignator = AsString(fileDesignatorSpan);
	VerifyOrReturnError(nil != fileDesignator, CHIP_ERROR_INCORRECT_STATE);

	auto * fabricIndex = @(transfer->GetFabricIndex());
	auto * nodeId = @(transfer->GetPeerNodeId());

	auto data = AsData(dataSpan);
	VerifyOrReturnError(nil != data, CHIP_ERROR_INCORRECT_STATE);

	auto completionHandler = ^(NSError * _Nullable error) {
	assertChipStackLockedByCurrentThread();

	if (error != nil) {
	auto err = [MTRError errorToCHIPErrorCode:error];
	transfer->Reject(err);
	} else {
	transfer->Continue();
	}
	};

	[mDelegate handleBDXTransferSessionDataForFileDesignator:fileDesignator
	fabricIndex:fabricIndex
	nodeID:nodeId
	data:data
	completion:completionHandler];
	return CHIP_NO_ERROR;
	}

	CHIP_ERROR DiagnosticLogsDownloaderBridge::StartBDXTransferTimeout(Download * download, uint16_t timeoutInSeconds)
	{
	assertChipStackLockedByCurrentThread();
	return chip::DeviceLayer::SystemLayer().StartTimer(chip::System::Clock::Seconds16(timeoutInSeconds), OnTransferTimeout, (__bridge void *) download);
	}

	void DiagnosticLogsDownloaderBridge::CancelBDXTransferTimeout(Download * download)
	{
	assertChipStackLockedByCurrentThread();
	chip::DeviceLayer::SystemLayer().CancelTimer(OnTransferTimeout, (__bridge void *) download);
	}

	void DiagnosticLogsDownloaderBridge::OnTransferTimeout(chip::System::Layer * layer, void * context)
	{
	assertChipStackLockedByCurrentThread();

	auto * download = (__bridge Download *) context;
	VerifyOrReturn(nil != download);

	// If there is no abortHandler, it means that the BDX transfer has not started.
	// When a BDX transfer has started we need to abort the transfer and we would error out
	// at next poll. We would end up calling OnTransferEnd and eventually [download failure:error].
	// But if the transfer has not started we would stop right now.
	auto error = [MTRError errorForCHIPErrorCode:CHIP_ERROR_TIMEOUT];
	if (download.abortHandler == nil) {
	[download failure:error];
	} else {
	download.abortHandler(error);
	}
	}