I'm writing a C++ application that is run as Windows Service (Win XP, Vista, 7, 8, servers).
My apllication uses third-patry library that maps local folder to the drive and this drive should be available in user mode (for all users). The problem occurs when user has some network share mapped to the local drive and third-party library doesn't recognize that specified drive letter as already in use.
The question is how to determine (from service application) if required drive letter is definitely available?
I'm using
GetLogicalDrives
QueryDosDevice
to determine logical devices. I've tried
WNetGetConnection
WNetGetUniversalName
to retrieve information about network share, but those functions doesn't return anything for required drive letter despite the fact that there were shares mapped to the specified drive letters.
My guess is that problem is in priveledges. Since my application run as service it can't get information about shares mapped in user mode (which seems very strange to me).
So the final question is - how to detect if specified drive letter is not used for mapping network share by any user?
The problem is in fact that there may be a difference with shares that a user can hold and shares that an admin can hold.
There is a flag in the registry that controls this:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System
EnableLinkedConnections = 1 (DWord)
Here is also a MSDN-KB article that explains this. Using EnableLinkedConnections set to 1 should fix this. Usually it is set to 1.
Background: When the UAC was invented this change was one side effect.
Related
Link to the bug report on 'Feedback Hub'
An audio endpoint device, from here on referred to as 'endpoint', is a physical or virtual audio output or input device.
With the Windows 10 April Update 1803 the long overdue 'App volume and device preferences' have been introduced. These settings allow more control over audio stream management as it is now possible to set different endpoints for different applications, no matter whether that particular application comes with an endpoint selection or not.
However, there is an issue where the audio of a program, whose endpoint is non-default, is streamed through the default endpoint (or not at all) after it has been closed and launched again, although the endpoint is displayed correctly in the settings:
As far as I know the issue can be recreated on a Windows 10 machine (version 1803 or higher) with any virtual or physical endpoint and an affected program. I used 'VLC Media Player' in this example (disregarding the fact that it comes with an endpoint selection) as it is well known and widely accessible, which should make it easier to recreate the issue.
What I'm searching for...
... is a programmatically solution to switch between endpoints, which ideally can be launched in form of a script to set the correct endpoint with an application launch.
For my purpose it would be enough to have to adjust the device instance path manually, as the device would be always the same, but I'm not going to complain about a solution which retrieves the device instance path from the registry, too.
Defined endpoints and the device instance path of the device they are using can be retrieved from the subkeys of the key HKEY_USERS\# YOUR SID #\Software\Microsoft\Multimedia\Audio\DefaultEndpoint. I don't know how windows generates the name of the subkeys or where they can be found. If I had to take a wild guess, I'd say these are Application IDs (feel free to correct me if I'm wrong).
The device instance path itself can be found in the Device Manager (under 'Audio inputs and outputs' double click the desired device, navigate to the tab 'Details' and select 'Device instance path' from the 'Property' drop-down menu).
Additionally the entry about Audio Endpoint Devices and Stream Management in the Microsoft Docs might be helpful, but that is way above my head.
A possible but impractical workaround...
... would be, to manually set another endpoint for the application and switch back to desired endpoint at every launch of said application (as shown above).
But not just takes this at least 10 seconds at each and every launch, you might even forget to do this as the audio might just get streamed through the default endpoint *¹.
The alternative to the latter is, that no audio will be streamed at all *² or in some cases it actually works *³.
*¹ e.g.: VLC Media Player, Tom Clancy's Rainbow Six Siege (although the audio will be streamed correctly during the splash screens)
*² e.g.: Call of Duty 4: Modern Warfare, Call of Duty: Modern Warfare 2, Call of Duty: Modern Warfare 3
*³ e.g.: Window Media Player, Microsoft Edge, Firefox
Observations
VLC Media Player comes with an endpoint selection, but so does TeamSpeak 3 and, unlike VLC, it skips the Windows settings completely.
Call of Duty not streaming any audio most likely is connected to the engine as I didn't encounter any other application doing something similar.
Windows Media Player, Microsoft Edge and Firefox are the only programs (I tested so far) which work fine. They have no endpoint selection (I'd know of) and will use the correct endpoint after closing and launching it again. It should be noted, however, that Firefox and Microsoft Edge will show multiple instances in the "App volume and device preferences" when adjusting the endpoint.
Disclaimer
I already tried two 3rd party softwares: 'Audio Router', which didn't work at all and 'CheVolume', which doesn't solve the issue and constantly crashes while doing so.
This question is based on one I asked over at Super User (here), where I didn't get an answer I was able to work with due to my lack of knowledge regarding actual programming (I'm only somewhat familiar with Batch and PowerShell). I'm well aware that neither Stack Overflow nor Super User are script writing services, however, the issue is not being fixed with the Windows 10 October Update 1809 and I see this as a problem which is affecting not just me and with that would be helpful for multiple people after me. Feel free to write a comment or propose an edit if you see this differently.
I'm also not sure whether the tags 'audio-streaming' and 'endpoint' should be used in this context, please propose an edit if they shouldn't or you can think of any better.
Edit - 05/11/18
Using the 3rd party software 'EarTrumpet' I was able to overcome the issue with the 'Call of Duty' games (no audio at all after restarting), however, 'VLC Media Player' would not restart after I assigned a non-default endpoint with 'EarTrumpet' until I closed 'EarTrumpet' again and the issue with 'Tom Clancy's Rainbow Six Siege' remains the same.
Edit - 18/01/19
Added link to a bug report I created on the 'Feedback Hub' 2 month ago.
Edit - 20/01/19
After doing some testing again it should be noted that having 'EarTrumpet' run in the background will keep a non-default endpoint for 'VLC Media Player' across restarts, however, 'VLC Media Player' will only (reliably) restart when the non-default endpoint was set in the 'App volume and device preferences'.
I do not have any solution regarding a programming language to handle such events.
But I can recommend EarTrumpet app to handle this change more quickly https://www.theverge.com/2018/6/13/17457778/eartrumpet-windows-10-audio-app
(Windows store: https://www.microsoft.com/en-us/p/eartrumpet/9nblggh516xp?ranMID=24542&ranEAID=nOD%2FrLJHOac&ranSiteID=nOD_rLJHOac-hUn6PgKuMKwQLdrzRqnPTA&epi=nOD_rLJHOac-hUn6PgKuMKwQLdrzRqnPTA&irgwc=1&OCID=AID681541_aff_7593_1243925&tduid=%28ir__qwqlg6jd0jba3y9hpnbvikaite2xk6kuyv9udtr100%29%287593%29%281243925%29%28nOD_rLJHOac-hUn6PgKuMKwQLdrzRqnPTA%29%28%29&irclickid=_qwqlg6jd0jba3y9hpnbvikaite2xk6kuyv9udtr100&activetab=pivot:overviewtab )
I will update the answer if I find a easy way to script/program a change of output on each app.
I searched a bunch and am either not using the right key words or have a unique problem as I haven't found anything specific to what I'm seeing.
I've inherited a project at work, written in C++ and using WindowsAPI, that is supposed to identify USB drives that are currently connected to the machine, display those drives with manufacturer, model and serial number. This is all stored in the registry. Currently the program accesses the desired registry by:
RegOpenKeyEx(HKEY_LOCAL_MACHINE, TEXT("SYSTEM\\CurrentControlSet\\Control\\DeviceClasses\\{53f56307-b6bf-11d0-94f2-00a0c91efb8b}"), 0, KEY_READ, &hKey)
Then using a combination of calls to RegQueryInfoKey and RegEnumKeyEx evaluates the key
/#/Control/Linked for each entry, if Linked equals 1 the drive is connected.
This works just fine in Windows 7, the problem I'm having is porting the program to Windows 8.1 It simply doesn't return any USB drives even when they're visible in File Explorer.
Running regedit and comparing Windows 7 and 8.1 what I'm noticing is that in win8.1 when I expand the registries nowhere do I see the Control key when I expand registries, all I get is the # with no value set.
So the question is, am I missing something or did Microsoft make some changes in this regard when moving to Win8.1. If it turns out I can no longer use this registry for this purpose does anyone have a suggestion as to how I may go about doing it?
Thanks is advance for the help.
I doubt reading from that registry key has ever been officially supported and so the fact that it's changed isn't that surprising.
One way you can do this is to use GetLogicalDriveStrings to get a list of drives in your system, and then test if each device is a USB drive using DeviceIoControl with the IOCTL_STORAGE_QUERY_PROPERTY command. This will fill out a STORAGE_DEVICE_DESCRIPTOR structure and the BusType member will be BusTypeUsb for USB devices.
Here is the situation:
I have a RESTful web service which when queried returns a list of virtual files (file-name, size, last modified, creation date and an id). It is also possible to get the binary content data of any file using its id from the same web service.
What I want to do:
I want to write a piece of C++ code which convinces the operating system (Windows XP, vista or 7) that there exists a mapped network drive (for ex: Z) such that when the user types (Z:\) in windows explorer the list of virtual files (which is returned from the web service) is displayed. Also when double clicking on a file icon in the explorer view, the piece of C++ code should retrieve the binary data form the web service and present it to the OS as the legitimate file content.
In other words, the user (and the OS for that matter) shouldn't be able to tell the difference between Z and any other ordinary drive.
Any ideas?
What you need is called "userspace file system". You can create one, for example, on top of Dokan library.
http://pages.cs.wisc.edu/~driscoll/fuse-nt.pdf
A couple more listed on wikipedia
Our Callback File System is what you are looking for.
Callback File System lets you map generic data (such as the ones retrieved from the remote web service) to the drive letter.
For a requirement to generate per-PC license keys, I need some code which will return a stable and (near) unique key on any PC. It doesn't have to be guaranteed unique, but close. It does need to be reasonably stable though, so that a given PC always generates the same result unless the hardware is substantially changed.
This is for a Windows application, using wxWidgets but a Win32 or other option is fine.
I was thinking about MAC address but what about laptops which can routinely disable the network card in power-saving mode? I came across GetCurrentHwProfile but it doesn't quite look like what I want?
One idea I had a while back for this is to use CryptProtectData as a way to identify a machine. Behind-the-scenes in that API, Microsoft has done what you're looking for. I never tested it though and I'm curious if it's actually viable.
Basically you would encode a constant magic value with CryptProtectData with CRYPTPROTECT_LOCAL_MACHINE, and the result is your machine ID.
I would just go with the MAC address method; when the wireless / LAN cards are turned off they still show up in Network Connections. You should therefore still be able to get the MAC.
Consider this: Any time you'd be able to contact your webserver or whatever you're cataloging these IDs with, the user is going to have to have some form of network card available.
Oh, and you might be able to use CPU serial number of the customer's computer supports it.
I think there no really easy and unique method so far discovered here.
GetVolumeInformation retrieves not even close to unique ID.....
To use any hardware serial is problematic because manufactures are not committed to supported it always and especially to keep it globally unique
GetCurrentHwProfile retrieves GUID but it's value affected by minor! hardware changes...
Using Product Key ... will bring U to deal with the stolen software - there lot of pirate installations over the globe.
Creation of own GUID and preserving it under registry (in any place) will not prevent duplication by cloning of image ....
etc...
From my perspective of view the best way is combine:
Volume ID + MAC's list + Machine SID + Machine Name. And obviously manage license policy on the server side ;0)
Regards
Mickel.
If you want something a bit harder to spoof than whatever the machine itself can tell you, you'll probably need to provide a USB dongle dedicated for this purpose (not just a flash drive).
For a pretty brain dead test I am using the ProductID code of the OS and the computer name - both extracted from the registry. Not really secure, but its all pretend security anyway.
edit
To answer John's question about what keys I am reading:
SOFTWARE\Microsoft\Windows NT\CurrentVersion\ProductID
SYSTEM\CurrentControlset\Control\ComputerName\ComputerName\ComputerName
How about using the serial number of the harddisk where windows is installed?
The function GetVolumeInformation() will give you such serial number.
To access the ID assigned by the harddisk vendor instead of the ID assigned by Windows, you can use the Win32_PhysicalMedia Class.
To determine the drive where windows is installed, you could expand the variable %windir" by using the function ExpandEnvironmentStrings()
Another option, if your architecture allows, is to use UuidCreate() to generate a random GUID at installation time and save it permanently in the registry. This GUID can then be used as the ID as long as the registry remains. A new registry database is generally considered as a new installation.
A third option is to have a well-known server assigning the IDs. Upon starting up, the software could look up for the ID in the registry and if not found, would contact the server and supply it with its MAC address, hostname, harddisk serial number, Machine SID and any number of indentifyable information (keys).
The server then determines if the client is already registered or not based on the information given. The server could have a relaxed policy and for example only require most of the keys for a match, so that the mechanism would work even in the event of a complete wipe out of the registry and if part (but not all) of the hardware was replaced.
How about using the serial number of a CPU. I remember Microsoft used to provide an api for this that would run the necessary assembler code and give you back all sorts of info about the CPU including serial number. Not sure if it'd work with AMD chips or not, I think it was intel specific.
Surely CPU Id is secure and static enough!!
I would like to restrict people using my application to one Computer, so I was thinking about IP's.. but people in some countries get new IP's after they reboot their Internet.. so I need something better to identify the users, like some value that doesn't change until the user performs a format.
Thanks
The MAC address of e.g. an ethernet interface typically doesn't change even across formats (only if the user changes ethernet interface card). Don't worry, nothing to do with Apple Macs, MAC stands for Media Access Control;-).
You will probably need some registration process, so you could tell the user that you will connect to get some update, and in that process send the serial number of the application and the mac address. If the serial number has already been registered then return an error to the user.
Ideally you should perhaps download some needed dll that is tied to a specific serial number and perhaps mac address, so that if the user copies the dll to a different program it will require more work to get it to work.
It depends on how much you want to inconvenience the user as to the best approach, I believe.
Where I specified dll could be any assembly, jar file, etc, that the language in question uses for running the application.