DfuInstallation.Start() Exception thrown on .Net MAUI

[MouratidisA]

Describe the bug

I tried to implement the DFU on a .NET MAUI application, but it seems that when I create the DfuInstallation object and call the Start() function the process throws an Exception with a message:
Exception of type 'Foundation.You_Should_Not_Call_base_In_This_Method' was thrown.

To Reproduce

Steps to reproduce the behavior:

1. Create a MAUI project
2. Install the Laerdal.Dfu 1.27.8 NuGet package
3. Create a method to download or retrieve your firmware update file
4. Scan for the desired device to DFU
5. Create the DfuInstallation object and call Start()

To download the firmware File:

public async Task<bool> DownloadFirmwareFile()
{ 
    //Retrieve firmware file in bytes 
    byte[] fileBytes = await HttpClientService.Instance.GetByteArrayAsync(Constants.GetFirmwareUpdate);

    //Create the file inside LocalApplicationData
    string outputFilePath = Path.Combine(System.Environment.GetFolderPath(System.Environment.SpecialFolder.Personal), "app_dfu_package.zip");

    File.WriteAllBytes(outputFilePath, fileBytes);

    //Check if the file exists and update the SelectedFirmwareFile
    var exists = File.Exists(outputFilePath);
    if (!exists)
    {
        Instance.SelectedFirmwareFile = null;                            
        return false;
    }
    else
    {
        Instance.SelectedFirmwareFile = new FileInfo(outputFilePath);
        return true;
    }
}

To launch the update process:

var deviceId = $"{Instance.SelectedDevice?.Id.ToString()}";
var filePath = $"{Instance.SelectedFirmwareFile?.FullName.ToString()}";

var fileExists = File.Exists(filePath);
Debug.WriteLine($"File path exists: {fileExists}");

var output = new DfuInstallation(deviceId, filePath);

output.DfuErrorReceived += DfuInstallationOnErrorOccured;
output.DfuStateChanged += DfuInstallationOnStateChanged;
output.DfuProgressChanged += DfuInstallationOnProgressChanged;

output.Start();

FileUrl value: /var/mobile/Containers/Data/Application/537D36A3-7D6D-4A0F-B78A-8A03F85CEFEF/Documents/app_dfu_package.zip

Expected behavior

Start and complete the DFU process with the BLE device.

Exception information
Source: Laerdal.Dfu.Bindings.iOS
Message: Exception of type 'Foundation.You_Should_Not_Call_base_In_This_Method' was thrown.
StackTrace:
at Laerdal.Dfu.Bindings.iOS.DFUFirmware..ctor(NSUrl urlToZipFile, NSError& error)
at Laerdal.Dfu.DfuServiceInitiatorDelegate..ctor(DfuInstallation dfuInstallation)
at Laerdal.Dfu.DfuInstallation.Start(DfuConfiguration configuration)
at ProjectName.ViewModels.FirmwareUpdatePopUpViewModel.GetDfuInstallation() in /Users/username/ProjectName/ProjectName/ViewModels/FirmwareUpdatePopUpViewModel.cs: line 264

line 264 has the command Start command

Environment:

• OS: macOS 13.5.2 (22G91)
• IDE: Visual Studio for Mac 17.6.4 (build 472)
• NuGet package Laerdal.Dfu version 1.27.8
• Tested target device: iPhone 11 with iOS 17.1

Additional context

I've tried to recreate the exception on Android 12, but the debugger gets disconnected when reaches the start command.
(I am using wireless debug, due to maui issues #16274.

Is there an active example on MAUI I can follow?

[ISSPRO-Eng]

What BLE Nuget are you using? @MouratidisA

[MouratidisA]

@ISSPRO-Eng I am using this NuGet package Plugin.BLE version 3.0.0.

[ISSPRO-Eng]

Okay. I am currently porting over a DFU application from Xamarin. Forms to MAUI, so I can help out once I get there. Do you have a public repo of the DFU app you have currently? No worries if you don't @MouratidisA

[framinosona]

Hi guys, I'm sorry I have very little time to contribute here. I have heard that one of our team has experienced that too. Not sure what the fix for it should be though.

If one of you finds a fix, and has the time, I'd love to approve a PR on this 👍👍

[MouratidisA]

Hey @framinosona , I'm not very experienced with NuGet package development, but I'm willing to give it a shot and assist with this issue. I've noticed there might be problems related to the new NSUrl(FileUrl, false) line in the Laerdal.Dfu/Laerdal.Dfu/iOS/DfuInstallation.cs file, specifically on line 26. Could you please look into this?

[ISSPRO-Eng]

@MouratidisA Did you have a working Xamarin.Forms version of the DFU Process? I could share that with you if that would help as well. Also, I am unable to set the File URL as it is protected in the updated nuget. Any idea how to get around this?

public FileInfo SelectedFirmwareFile
{
get => GetValue();
set
{
if (SetValue(value))
{
DfuInstallationConfigurationPageViewModel.Instance.DfuInstallation.FileUrl = value?.FullName;
}
}
}

[MouratidisA]

@ISSPRO-Eng You can use my DownloadFirmwareFile() from the description of the issue. I was using a property on my view model class and then when I had to execute the DFU I had to create a new DfuInstallation object (using the ctor you can pass the filePath and the device Id values).

[ISSPRO-Eng]

at Laerdal.Dfu.Bindings.iOS.DFUFirmware..ctor(NSUrl urlToZipFile, NSError& error)
at Laerdal.Dfu.DfuServiceInitiatorDelegate..ctor(DfuInstallation dfuInstallation)
at Laerdal.Dfu.DfuInstallation.Start(DfuConfiguration configuration)
at MauiAttributeProgrammer.ViewModels.DFUPageViewModel.Start() in /Users/isspro/Documents/GitHub/MauiAttributeProgrammer/MauiAttributeProgrammer/ViewModels/DFUPageViewModel.cs:line 31

@MouratidisA Same error here now... guess it is time to start trying to modify the nuget.

[ISSPRO-Eng]

@MouratidisA Have you tried on an Android device or only iOS?

[juniorsaraviao]

I'm getting the same error using Net MAUI v8 on iOS.
Also, when I try to upgrade a firmware on Android I got the following error (issue):

PostForegroundServiceNotificationException: Bad notification for startForeground

[ISSPRO-Eng]

@juniorsaraviao Jumping back onto this project. Any luck with either iOS or Android? I of not need notifications or even to configure anything. Just need to select device and firmware file and send over. Everything else can be default for the time being.

[juniorsaraviao]

@ISSPRO-Eng I'm still getting issues on iOS, but there's a workaround to avoid Bad notification for startForeground on Android using (full implementation here):

DfuConfiguration() { DisableNotification = true };

[schneifa]

Going back to the original topic of this issue (the iOS error), the exception

at Laerdal.Dfu.Bindings.iOS.DFUFirmware..ctor(NSUrl urlToZipFile, NSError& error)
at Laerdal.Dfu.DfuServiceInitiatorDelegate..ctor(DfuInstallation dfuInstallation)
at Laerdal.Dfu.DfuInstallation.Start(DfuConfiguration configuration)
at MauiAttributeProgrammer.ViewModels.DFUPageViewModel.Start() in /Users/isspro/Documents/GitHub/MauiAttributeProgrammer/MauiAttributeProgrammer/ViewModels/DFUPageViewModel.cs:line 31

seems to occur in the SetInitiator()-Method of the iOS specific DfuInstallation.cs in line 26:

Firmware = new Laerdal.Dfu.iOS.DFUFrmware(new NSUrl(FileUrl, false), out NSError error);

As someone mentioned in another issue, nordic seems to have switched from NSUrl to Url type in their library implementation.
Unfortunately, I know very little about library binding development or iOS specific development, but could changing this line to

Firmware = new Laerdal.Dfu.iOS.DFUFrmware(new Url(FileUrl, false), out NSError error);

and accordingly changing the DFUFirmware interface in ApiDefinition.cs of ObjC and Sharpie from NSUrl to Url fix this issue?
Can someone with a little more knowledge of the package look into this and maybe try?

[WanftMoon]

For those interested, the issue is in the native bindings: dotnet/maui#29