Our program has a piece of code that calculates the list of computers on our local network. It uses the Windows Networking API (WNetOpenEnum/WNetEnumResource) to unwind the network. For many years, the resulting list was identical to the one that can be seen in Windows Explorer under the "Network" entry. However, recently we have noticed that the same code returns an empty list. During debugging I found that WNetOpenEnum returns error 1231 (ERROR_NETWORK_UNREACHABLE) when it is called for the "Microsoft Windows Network" under the root node.
I have to mention, though I'm pretty sure it has nothing to do with the matter, that the network unwinding is done multithreaded, to avoid possible delays in the main GUI thread. Each time a node of type RESOURCEUSAGE_CONTAINER is encountered, a new worker thread is launched. The thread function calls the following procedure:
DWORD WINAPI EnumNetwork(NETRESOURCE_M* lpNR)
{
const int BUF_SIZE = 16384; // 16K is a good size.
HANDLE hEnum;
DWORD Result;
// Call the WNetOpenEnum function to begin the enumeration.
Result = ::WNetOpenEnum(RESOURCE_GLOBALNET, // all network
RESOURCETYPE_ANY, // all resource types
0, // enumerate all
(LPNETRESOURCE)lpNR,// parent resource
&hEnum); // enumeration handle
if (Result != NO_ERROR) // -> for "Microsoft Windows Network" Result = 1231
return Result;
std::vector<std::wstring> SrvList;
// Allocate buffer for enumeration.
LPNETRESOURCE lpEnumNR = (LPNETRESOURCE)new char[BUF_SIZE];
if (lpEnumNR == 0)
Result = ERROR_OUTOFMEMORY;
else
{
while (1)
{
::ZeroMemory(lpEnumNR, BUF_SIZE); // Initialize the buffer.
DWORD NumEntries = -1; // Enumerate all entries.
DWORD BufSize = BUF_SIZE;
// Call WNetEnumResource to continue the enumeration.
Result = ::WNetEnumResource(hEnum, // enumeration handle
&NumEntries,// number of entries to enumerate
lpEnumNR, // array of resources to return
&BufSize); // buffer size
if (Result == NO_ERROR)
{
// If the call succeeds, loop through the array.
for (unsigned i = 0; i < NumEntries; ++i)
{
if (lpEnumNR[i].dwDisplayType == RESOURCEDISPLAYTYPE_SERVER)
{
// Collect servers.
LPCWSTR SrvName = lpEnumNR[i].lpRemoteName;
if (PathHelpers::IsFullPath(SrvName))
SrvList.push_back(SrvName);
}
else if ((lpEnumNR[i].dwUsage & RESOURCEUSAGE_CONTAINER) &&
lpEnumNR[i].lpRemoteName != 0)
{
TCHAR PathBuf[1024] = {0};
if (lpNR && lpNR->Path)
{
_tcscpy(PathBuf, lpNR->Path);
::PathAddBackslash(PathBuf);
}
_tcscat(PathBuf, lpEnumNR[i].lpRemoteName);
if (RegisterServer(PathBuf))
{
// Start new thread for recursive enumeration.
NETRESOURCE_M* lpChildNR = DeepCopyNR(&lpEnumNR[i], PathBuf);
ExploreNetwork(lpChildNR); // -> this starts a worker thread
}
else
{
GetLogger().LogMessage(
_T("Cycles found while unwinding network: %s"), PathBuf);
}
}
}
}
else
{
if (Result == ERROR_NO_MORE_ITEMS)
Result = NO_ERROR;
break;
}
} // end while
delete [] (char*)lpEnumNR;
} // end if
::WNetCloseEnum(hEnum);
if (!SrvList.empty())
NotifyServerAdded(SrvList);
return Result;
}
where NETRESOURCE_M is the structure
struct NETRESOURCE_M
{
NETRESOURCE NR;
LPTSTR Path;
};
Trying to figure out what could have caused such a sudden change in behavior, I found in Google that a few years ago Microsoft disabled the SMB1 protocol, which could affect Network Discovery. However, I can't believe they could have damaged their own API without saying a word in the documentation.
EDIT: At the same time, Windows Explorer has a bunch of computers under its "Network" node. In the network settings, the network type is "Domain", and the network discovery is ON. Services "Function Discovery Provider Host" and "Function Discovery Resources Publication" are running. Windows OS build is 19042.685.
Edit 2: The Sysinternals' "ShareEnum" tool also fails with the error: "No domains or workgroups where found on your network". Because of this, and also because some time ago our company moved all of its computers to a different network, I got the feeling that the problem is in the network configuration. Such as though the network is declared as "Domain", the computers were not enrolled to this domain. I do not understand much in that, but something like this.
I was recently asked if our existing signing code will work with a European Qualified Digital Certificate in place of the RSA signing certificate we normally use. As far as I can tell it should, but I haven't found anything that actually confirms this theory.
Short of figuring out how to acquire a qualified certificate and actually testing it, I'm not sure how to answer this question definitively. Anybody happen to have experience with this?
The code in question is shown below. It's a Windows-based C++ application that is using Microsoft's Cryptographic API for signing.
int SignData(
const std::string &data, // Data to be signed
const char *containerName, // Name of key container to use
std::string &signature) // Returns the signature
{
HCRYPTPROV hProv = NULL;
HCRYPTHASH hHash = NULL;
HCRYPTKEY hKey = NULL;
DWORD dwLength;
int status = 0;
// Attempt to open the key container as a LocalMachine key.
if (CryptAcquireContext(
&hProv,
containerName,
NULL,
PROV_RSA_FULL,
CRYPT_MACHINE_KEYSET | CRYPT_SILENT))
{
// Create a SHA-1 hash context.
if (CryptCreateHash(hProv, CALG_SHA1, 0, 0, &hHash))
{
// Calculate hash of the buffer.
if (CryptHashData(hHash, (const BYTE *)data.data(), (DWORD)data.size(), 0))
{
// Determine the size of the signature and allocate memory.
if (CryptSignHash(hHash, AT_SIGNATURE, 0, 0, NULL, &dwLength))
{
signature.resize(dwLength);
// Sign the hash object.
if (!CryptSignHash(hHash, AT_SIGNATURE, 0, 0, (BYTE*)&signature[0], &dwLength))
status = HandleCryptError("CryptSignHash failed");
}
else
status = HandleCryptError("CryptSignHash failed");
}
else
status = HandleCryptError("CryptHashData failed");
}
else
status = HandleCryptError("CryptCreateHash failed");
}
else
status = HandleCryptError("CryptAcquireContext failed");
return status;
}
The above code is using the default Microsoft software cryptographic provider which doesn't meet the requirements of eIDAS.
If you replace the default Microsoft provider by an eIDAS compliant provider in the above code then this approach of performing signature is OK. Under the hood, the compliant CSP will take care of non-repudiation requirement of the key usage, for example by displaying a PIN popup or if the key is stored remotely in a server by sending a 2FA notification to the key owner.
I am converting a project to a UWP App, and thus have been following guidelines outlined in the MSDN post here. The existing project heavily relies on CreateFile() to communicate with connected devices.
There are many posts in SO that show us how to get a CreateFile()-accepted device path using SetupAPI's SetupDiGetDeviceInterfaceDetail() Is there an alternative way to do this using the PnP Configuration Manager API? Or an alternative, user-mode way at all?
I had some hope when I saw this example in Windows Driver Samples github, but quickly became dismayed when I saw that the function they used in the sample is ironically not intended for developer use, as noted in this MSDN page.
function GetDevicePath in general correct and can be used as is. about difference between CM_*(..) and CM_*_Ex(.., HMACHINE hMachine) - the CM_*(..) simply call CM_*_Ex(.., NULL) - so for local computer versions with and without _Ex suffix the same.
about concrete GetDevicePath code - call CM_Get_Device_Interface_List_Size and than CM_Get_Device_Interface_List only once not 100% correct - because between this two calls new device with this interface can be arrived to system and buffer size returned by CM_Get_Device_Interface_List_Size can be already not enough for CM_Get_Device_Interface_List. of course possibility of this very low, and you can ignore this. but i prefer make code maximum theoretical correct and call this in loop, until we not receive error other than CR_BUFFER_SMALL. also need understand that CM_Get_Device_Interface_List return multiple, NULL-terminated Unicode strings - so we need iterate here. in [example] always used only first returned symbolic link name of an interface instance. but it can be more than 1 or at all - 0 (empty). so better name function - GetDevicePaths - note s at the end. i be use code like this:
ULONG GetDevicePaths(LPGUID InterfaceClassGuid, PWSTR* pbuf)
{
CONFIGRET err;
ULONG len = 1024;//first try with some reasonable buffer size, without call *_List_SizeW
for(PWSTR buf;;)
{
if (!(buf = (PWSTR)LocalAlloc(0, len * sizeof(WCHAR))))
{
return ERROR_NO_SYSTEM_RESOURCES;
}
switch (err = CM_Get_Device_Interface_ListW(InterfaceClassGuid, 0, buf, len, CM_GET_DEVICE_INTERFACE_LIST_PRESENT))
{
case CR_BUFFER_SMALL:
err = CM_Get_Device_Interface_List_SizeW(&len, InterfaceClassGuid, 0, CM_GET_DEVICE_INTERFACE_LIST_PRESENT);
default:
LocalFree(buf);
if (err)
{
return CM_MapCrToWin32Err(err, ERROR_UNIDENTIFIED_ERROR);
}
continue;
case CR_SUCCESS:
*pbuf = buf;
return NOERROR;
}
}
}
and usage example:
void example()
{
PWSTR buf, sz;
if (NOERROR == GetDevicePaths((GUID*)&GUID_DEVINTERFACE_VOLUME, &buf))
{
sz = buf;
while (*sz)
{
DbgPrint("%S\n", sz);
HANDLE hFile = CreateFile(sz, FILE_GENERIC_READ, FILE_SHARE_VALID_FLAGS, 0, OPEN_EXISTING, 0, 0);
if (hFile != INVALID_HANDLE_VALUE)
{
// do something
CloseHandle(hFile);
}
sz += 1 + wcslen(sz);
}
LocalFree(buf);
}
}
so we must not simply use in returned DevicePathS (sz) only first string, but iterate it
while (*sz)
{
// use sz
sz += 1 + wcslen(sz);
}
I got a valid Device Path to a USB Hub Device, and used it successfully to get various device descriptors by sending some IOCTLs, by using the function I posted in my own answer to another question
I'm reporting the same function below:
This function returns a list of NULL-terminated Device Paths (that's what we get from CM_Get_Device_Interface_List())
You need to pass it the DEVINST, and the wanted interface GUID.
Since both the DEVINST and interface GUID are specified, it is highly likely that CM_Get_Device_Interface_List() will return a single Device Path for that interface, but technically you should be prepared to get more than one result.
It is responsibility of the caller to delete[] the returned list if the function returns successfully (return code 0)
int GetDevInstInterfaces(DEVINST dev, LPGUID interfaceGUID, wchar_t**outIfaces, ULONG* outIfacesLen)
{
CONFIGRET cres;
if (!outIfaces)
return -1;
if (!outIfacesLen)
return -2;
// Get System Device ID
WCHAR sysDeviceID[256];
cres = CM_Get_Device_ID(dev, sysDeviceID, sizeof(sysDeviceID) / sizeof(sysDeviceID[0]), 0);
if (cres != CR_SUCCESS)
return -11;
// Get list size
ULONG ifaceListSize = 0;
cres = CM_Get_Device_Interface_List_Size(&ifaceListSize, interfaceGUID, sysDeviceID, CM_GET_DEVICE_INTERFACE_LIST_PRESENT);
if (cres != CR_SUCCESS)
return -12;
// Allocate memory for the list
wchar_t* ifaceList = new wchar_t[ifaceListSize];
// Populate the list
cres = CM_Get_Device_Interface_List(interfaceGUID, sysDeviceID, ifaceList, ifaceListSize, CM_GET_DEVICE_INTERFACE_LIST_PRESENT);
if (cres != CR_SUCCESS) {
delete[] ifaceList;
return -13;
}
// Return list
*outIfaces = ifaceList;
*outIfacesLen = ifaceListSize;
return 0;
}
Please note that, as RbMm already said in his answer, you may get a CR_BUFFER_SMALL error from the last CM_Get_Device_Interface_List() call, since the device list may have been changed in the time between the CM_Get_Device_Interface_List_Size() and CM_Get_Device_Interface_List() calls.
I have a point of sale application that uses Serial Communication ports (RS-232) to communicate with a scale for weighing products. I am now working on being able to support USB devices directly rather than using a Virtual Serial Communication port as they have an annoying tendency to move around.
What we have found is that while Windows 7 seems to automatically create the Virtual Serial Communication port, other versions of Windows such as POS Ready 7 may not. We suspect this is due to a specific .inf file with Windows 7 that is missing from POS Ready 7. Can someone confirm that?
I have a USB sample application that works intermittently. I am having a problem with the USB level communication with the ReadFile() Windows API function. I am using CreateFile() specifying the USB device path to obtain an I/O handle followed by using WriteFile() and ReadFile() to communicate with the scale. The ReadFile() is not providing data in some cases.
Background Information
The particular scale I am using, Brecknell 67xx bench scale, worked with using Virtual Serial Communication port directly out of the box with the point of sale application. I connected the scale to my Windows 7 PC with a USB cable and Windows automatically installed the drivers to create a Virtual Serial port, COM4 in my case. I then configured the application to talk to the scale through COM4 and everything worked fine.
The protocol for using the scale is to send a two byte command, "W\r" (capital letter W followed by a carriage return character) to the scale and to then read a 16 byte response which contains the current weight as well as status information about scale mechanics such as In Motion.
The sample USB application that I am learning from will work successfully providing a weight. Then it will stop working properly with the behavior of the ReadFile() returning zero bytes read. Once it stops working it will continue failing to provide data from the ReadFile() even if I unplug and replug the USB cable or restart my PC.
A previous version of the learning application was hanging on the ReadFile() and when a Break All was done with Visual Studio, a pause followed by a message indicating a deadlock would be displayed. However since I started using SetCommTimeouts() with a 5000 millisecond timeout value in ReadTotalTimeoutConstant I see a consistent 5 second pause before the ReadFile() returns with zero bytes read.
The strange thing is that if I then use the application which opens the Virtual Serial Communication port, COM4, that application works fine and the scale reports the weight of items.
I can then return to the sample application that uses direct USB rather than the Virtual Serial Communication port and it will work fine reporting weights.
However if I then unplug the USB cable connecting scale with PC, which powers off the scale as well, then plug the USB cable back in, the sample application no longer functions correctly and once again I see the pause with timeout.
Then I try using the original point of sale application that depends on Serial Communication ports using the Virtual Serial port, COM4, and that application weighs items just fine.
And when I then retry my sample application, it also will report item weights.
My Questions.
If a USB device creates a Virtual Serial Communications port when it is plugged in then is it required to only use the Virtual Serial port by specifying the communications port, COM4 in my case, in the CreateFile() call?
How is it possible to have direct USB serial communication by using CreateFile() with the USB device path if the device causes Windows to generate a Virtual Communication port?
Is there some way of specifying that any version of Windows is to automatically create a Virtual Serial Communications port for the device when it is plugged in?
Source Code of the Sample USB Application
The source code from my sample USB Windows Console application using Visual Studio 2005 is as follows with the main being at the bottom and much of this being the class for finding a particular USB device and then allowing ReadFile() and WriteFile():
// usb_test_cons.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <windows.h>
#include <setupapi.h>
#include <initguid.h>
#include <stdio.h>
// This is the GUID for the USB device class.
// It is defined in the include file Usbiodef.h of the Microsoft Windows Driver Kit.
// See also https://msdn.microsoft.com/en-us/library/windows/hardware/ff545972(v=vs.85).aspx which
// provides basic documentation on this GUID.
DEFINE_GUID(GUID_DEVINTERFACE_USB_DEVICE, 0xA5DCBF10L, 0x6530, 0x11D2, 0x90, 0x1F, 0x00, 0xC0, 0x4F, 0xB9, 0x51, 0xED);
// (A5DCBF10-6530-11D2-901F-00C04FB951ED)
// Following are standard defines to be used with all of the
// devices that are use through the UIE interface.
#define UIE_DEVICE_ERROR (-11) /* error when accessing the device */
#define UIE_DEVICE_NOT_PROVIDE (-12) /* device is not provided */
#define UIE_DEVICE_ERROR_RANGE (-13) /* range error */
#define UIE_DEVICE_ERROR_COM (-14) /* communication error */
#define UIE_DEVICE_TIMEOUT (-15) /* communication error */
#define UIE_DEVICE_SPECIFIC (-20) /* device specific errors start here */
#define UIE_SCALE_ETX 0x03 /* ETX character */
#define UIE_SCALE_IN_MOTION 0x01 /* scale in motion */
#define UIE_SCALE_ZERO 0x02 /* zero weight */
#define UIE_SCALE_UNDER 0x01 /* under capacity */
#define UIE_SCALE_OVER 0x02 /* over capacity */
#define UIE_SCALE_ERROR UIE_DEVICE_ERROR /* error */
#define UIE_SCALE_NOT_PROVIDE UIE_DEVICE_NOT_PROVIDE /* not provide */
#define UIE_SCALE_TIMEOUT UIE_DEVICE_TIMEOUT /* time out when reading from scale */
#define UIE_SCALE_MOTION (UIE_DEVICE_SPECIFIC-1) /* motion */
#define UIE_SCALE_UNDER_CAPACITY (UIE_DEVICE_SPECIFIC-2) /* under capacity */
#define UIE_SCALE_OVER_CAPACITY (UIE_DEVICE_SPECIFIC-3) /* over capacity */
#define UIE_SCALE_DATAFORMAT (UIE_DEVICE_SPECIFIC-4) /* Data read from scale incorrect format in UieScaleAnalysis() */
#define UIE_SCALE_DATAUNITS (UIE_DEVICE_SPECIFIC-5) /* Units read from scale incorrect in UieScaleAnalysis() */
static SHORT UieScaleStatus(char *puchBuffer, DWORD sLength)
{
UCHAR uchByte;
switch (sLength) {
case 16:
// The scale message is a weight message with a status section.
// Move the buffer pointer to where the status section should begin.
// A status only message has the same format as the status section of a weight message.
puchBuffer += 10;
case 6:
// The scale message may be a status only message if there is a problem with the scale.
// A status only message is 6 characters with the letter S as the second character.
if (*(puchBuffer + 0) != '\n' ||
*(puchBuffer + 1) != 'S' ||
*(puchBuffer + 4) != '\r' ||
*(puchBuffer + 5) != UIE_SCALE_ETX) {
return (UIE_SCALE_DATAFORMAT); /* exit ... */
}
break;
default:
return (UIE_SCALE_DATAFORMAT); /* exit ... */
break;
}
/* --- check status of low byte --- */
uchByte = *(puchBuffer + 3) - (UCHAR)0x30;
if (uchByte & UIE_SCALE_UNDER) {
return (UIE_SCALE_UNDER_CAPACITY);
} else if (uchByte & UIE_SCALE_OVER) {
return (UIE_SCALE_OVER_CAPACITY);
}
/* --- check status of high byte --- */
uchByte = *(puchBuffer + 2) - (UCHAR)0x30;
if (uchByte & UIE_SCALE_IN_MOTION) {
return (UIE_SCALE_MOTION);
} else if (uchByte & UIE_SCALE_ZERO) {
return (0);
} else {
return (TRUE);
}
}
class UsbSerialDevice
{
public:
UsbSerialDevice();
~UsbSerialDevice();
int CreateEndPoint (wchar_t *wszVendorId);
int CloseEndPoint ();
int ReadStream (void *bString, size_t nBytes);
int WriteStream (void *bString, size_t nBytes);
DWORD m_dwError; // GetLastError() for last action
DWORD m_dwErrorWrite; // GetLastError() for last write
DWORD m_dwErrorRead; // GetLastError() for last read
DWORD m_dwBytesWritten;
DWORD m_dwBytesRead;
private:
HANDLE m_hFile;
DWORD m_dwStatError;
COMMTIMEOUTS m_timeOut;
COMSTAT m_statOut;
};
UsbSerialDevice::UsbSerialDevice() :
m_dwError(0),
m_dwErrorWrite(0),
m_dwErrorRead(0),
m_dwBytesWritten(0),
m_dwBytesRead(0),
m_hFile(NULL)
{
}
UsbSerialDevice::~UsbSerialDevice()
{
CloseHandle (m_hFile);
}
int UsbSerialDevice::WriteStream(void *bString, size_t nBytes)
{
BOOL bWrite = FALSE;
if (m_hFile) {
m_dwError = m_dwErrorWrite = 0;
m_dwBytesWritten = 0;
ClearCommError (m_hFile, &m_dwStatError, &m_statOut);
bWrite = WriteFile (m_hFile, bString, nBytes, &m_dwBytesWritten, NULL);
m_dwError = m_dwErrorWrite = GetLastError();
return 0;
}
return -1;
}
int UsbSerialDevice::ReadStream(void *bString, size_t nBytes)
{
BOOL bRead = FALSE;
if (m_hFile) {
m_dwError = m_dwErrorRead = 0;
m_dwBytesRead = 0;
ClearCommError (m_hFile, &m_dwStatError, &m_statOut);
bRead = ReadFile (m_hFile, bString, nBytes, &m_dwBytesRead, NULL);
m_dwError = m_dwErrorRead = GetLastError();
return 0;
}
return -1;
}
int UsbSerialDevice::CreateEndPoint (wchar_t *wszVendorId)
{
HDEVINFO hDevInfo;
m_dwError = ERROR_INVALID_HANDLE;
// We will try to get device information set for all USB devices that have a
// device interface and are currently present on the system (plugged in).
hDevInfo = SetupDiGetClassDevs(&GUID_DEVINTERFACE_USB_DEVICE, NULL, 0, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT);
if (hDevInfo != INVALID_HANDLE_VALUE)
{
DWORD dwMemberIdx;
BOOL bContinue = TRUE;
SP_DEVICE_INTERFACE_DATA DevIntfData;
// Prepare to enumerate all device interfaces for the device information
// set that we retrieved with SetupDiGetClassDevs(..)
DevIntfData.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
dwMemberIdx = 0;
// Next, we will keep calling this SetupDiEnumDeviceInterfaces(..) until this
// function causes GetLastError() to return ERROR_NO_MORE_ITEMS. With each
// call the dwMemberIdx value needs to be incremented to retrieve the next
// device interface information.
for (BOOL bContinue = TRUE; bContinue; ) {
PSP_DEVICE_INTERFACE_DETAIL_DATA DevIntfDetailData;
SP_DEVINFO_DATA DevData;
DWORD dwSize;
dwMemberIdx++;
SetupDiEnumDeviceInterfaces(hDevInfo, NULL, &GUID_DEVINTERFACE_USB_DEVICE, dwMemberIdx, &DevIntfData);
if (GetLastError() == ERROR_NO_MORE_ITEMS) break;
// As a last step we will need to get some more details for each
// of device interface information we are able to retrieve. This
// device interface detail gives us the information we need to identify
// the device (VID/PID), and decide if it's useful to us. It will also
// provide a DEVINFO_DATA structure which we can use to know the serial
// port name for a virtual com port.
DevData.cbSize = sizeof(DevData);
// Get the required buffer size. Call SetupDiGetDeviceInterfaceDetail with
// a NULL DevIntfDetailData pointer, a DevIntfDetailDataSize
// of zero, and a valid RequiredSize variable. In response to such a call,
// this function returns the required buffer size at dwSize.
SetupDiGetDeviceInterfaceDetail(hDevInfo, &DevIntfData, NULL, 0, &dwSize, NULL);
// Allocate memory for the DeviceInterfaceDetail struct. Don't forget to
// deallocate it later!
DevIntfDetailData = (PSP_DEVICE_INTERFACE_DETAIL_DATA) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, dwSize);
DevIntfDetailData->cbSize = sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA);
if (SetupDiGetDeviceInterfaceDetail(hDevInfo, &DevIntfData, DevIntfDetailData, dwSize, &dwSize, &DevData))
{
// Finally we can start checking if we've found a useable device,
// by inspecting the DevIntfDetailData->DevicePath variable.
//
// The DevicePath looks something like this for a Brecknell 67xx Series Serial Scale
// \\?\usb#vid_1a86&pid_7523#6&28eaabda&0&2#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
//
// The VID for a particular vendor will be the same for a particular vendor's equipment.
// The PID is variable for each device of the vendor.
//
// As you can see it contains the VID/PID for the device, so we can check
// for the right VID/PID with string handling routines.
// See https://github.com/Microsoft/Windows-driver-samples/blob/master/usb/usbview/vndrlist.h
if (wcsstr (DevIntfDetailData->DevicePath, wszVendorId)) {
m_dwError = 0;
m_hFile = CreateFile (DevIntfDetailData->DevicePath, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
if (m_hFile == INVALID_HANDLE_VALUE) {
m_dwError = GetLastError();
} else {
GetCommTimeouts (m_hFile, &m_timeOut);
m_timeOut.ReadIntervalTimeout = 0;
m_timeOut.ReadTotalTimeoutMultiplier = 0;
m_timeOut.ReadTotalTimeoutConstant = 5000;
SetCommTimeouts (m_hFile, &m_timeOut);
m_dwError = GetLastError();
}
bContinue = FALSE; // found the vendor so stop processing after freeing the heap.
}
}
HeapFree(GetProcessHeap(), 0, DevIntfDetailData);
}
SetupDiDestroyDeviceInfoList(hDevInfo);
}
return 0;
}
int _tmain(int argc, _TCHAR* argv[])
{
UsbSerialDevice myDev;
myDev.CreateEndPoint (L"vid_1a86&pid_7523");
switch (myDev.m_dwError) {
case 0:
// no error so just ignore.
break;
case ERROR_ACCESS_DENIED:
wprintf (_T(" CreateFile() failed. GetLastError() = %d\n ERROR_ACCESS_DENIED: Access is denied.\n Is it already in use?\n"), myDev.m_dwError);
break;
case ERROR_GEN_FAILURE:
wprintf (_T(" CreateFile() failed. GetLastError() = %d\n ERROR_GEN_FAILURE: A device attached to the system is not functioning.\n Is it an HID?\n"), myDev.m_dwError);
break;
case ERROR_INVALID_HANDLE:
wprintf (_T(" CreateFile() failed. GetLastError() = %d\n ERROR_INVALID_HANDLE: The handle is invalid.\n CreateFile() failed?\n"), myDev.m_dwError);
break;
default:
wprintf (_T(" CreateFile() failed. GetLastError() = %d\n"), myDev.m_dwError);
break;
}
if (myDev.m_dwError == 0) {
char reqWeight[] = "W\r";
char resWeight[256] = {0};
myDev.WriteStream (reqWeight, strlen (reqWeight));
wprintf (_T(" Sent request now get response.\n"));
Sleep (50);
myDev.ReadStream (resWeight, 16);
wprintf (_T(" Got response.\n"));
if (resWeight[0] != '\n' || resWeight[9] != '\r') {
wprintf (_T(" Unexpected format of response.\n"));
}
short sRet = UieScaleStatus (resWeight, myDev.m_dwBytesRead);
resWeight[9] = 0; // terminate the weight string so that we can write it out.
wprintf (_T(" ScaleStatus = %d, Response from device - \"%S\"\n"), sRet, resWeight + 1);
}
return 0;
}
Additional Information Developed
Overview of INF Files from Microsoft MSDN https://msdn.microsoft.com/en-us/windows/hardware/drivers/install/overview-of-inf-files
Stackoverflow Do I need to write my own host side USB driver for a CDC device
Stackoverflow how to get vendor id and product id of a plugged usb device on windows
Is it possible to “transplant” drivers between machines? has a link to a document Debugging USB Device Installation on Windows and this posting Remove Windows Device Class in Registry has a bit more info.
USB serial driver (Usbser.sys) from Microsoft.
USB device class drivers included in Windows from Microsoft.
The communication of the PC that runs windows (USB host) and the scale (USB device) obeys the USB protocol. If you install libusb for windows you can get similar informations as the PC gets from the USB device, when using lsusb -v. It is possible for a USB device to implement more than one USB class.
If the USB device creates a Virtual COM port it for sure implements the CDC ACM class (Communication Device Class Abstract Control Model) beside this it can also implement other USB classes like Mass Storage class,...
Direct communication with USB device depends also on what device classes it implements and its interfaces and endpoints. If the USB device implements a CDC ACM (Virtual COM) you use the specific RS-232 commands (i.e. https://www.commfront.com/pages/3-easy-steps-to-understand-and-control-your-rs232-devices or send a hexadecimal 'D' to a multimeter to receive the measured value) if it implements the Mass Storage class you normally use bulk transfers
To change the mode of the USB device you use control transfers (see USB in a nutshell)
In this link is how Win determines which driver to load after determining the USB class of the device https://msdn.microsoft.com/en-us/library/windows/hardware/ff538820%28v=vs.85%29.aspx
(https://msdn.microsoft.com/en-us/library/windows/hardware/jj649944%28v=vs.85%29.aspx)
i do not know how Brecknell implemented the CDC ACM device class that is the Virtual COM however normally any Win version that supports USB should be able to load a driver for a CDC ACM device class (Virtual COM) so you are correct this seems to be a problem of the .inf driver file or the driver loading mechanism (maybe a problem of the Brecknell CDC ACM implementation but i do not think so)
Then, if Win loads a working driver the normal way is what you did: use CreateFile() with the COM that is assigned to the USB device.
The strange thing is that if I then use the application which opens the Virtual Serial Communication port, COM4, that application works fine and the scale reports the weight of items. <- this is not strange, strange is that some Win versions do not recognize a CDC USB device .
The standard driver for CDC devices seems to be USBser.sys (https://msdn.microsoft.com/de-de/library/windows/hardware/dn707976%28v=vs.85%29.aspx)
If you search 'windows does not recognize CDC device' you get results
If a USB device creates a Virtual Serial Communications port when it is plugged in then is it required to only use the Virtual Serial port by specifying the communications port, COM4 in my case, in the CreateFile() call? Yes, if a USB device implements a virtual COM it is the easiest way to use this COM to communicate with this device
See also http://www.beyondlogic.org/usbnutshell/usb1.shtml USB in a nutshell
standard USB: device descriptor (class) -> interface -> (configuration) -> endpoint
Testing with a modified USB Serial sample application indicates that when a USB device that creates a Virtual Serial Communications port is unplugged the Virtual Serial Port created is torn down and disappears from the port listing in Device Manager app of Control Panel.
When the device, a USB scale in this case, is plugged in and turned on the Virtual Serial Communications port reappears in Device Manager. However when the Virtual Serial Communications port is created, it is created with default serial port settings (baud rate, parity, etc.) and these may not be the same as for your actual device.
In summary it appears that the Virtual Serial Communications port settings apply regardless of whether the port is opened as a COM port or if the USB device path name is used with the CreateFile().
I am still investigating the Virtual Serial Port not automatically being created when using POS Ready 7 and will update this answer once I know more. However preliminary comparison between Windows 7 and POS Ready 7 is showing that a file that specifies usbser.sys, mdmcpq.inf, that is on my Windows 7 PC is not on the POS Ready 7 terminal in the folder C:\Windows\inf.
See The INF File for a write up on the .inf file structure and the various sections. It is a bit old however it seems to cover the basics in a readable manner.
I modified the function CreateEndPoint() in the question to the following along with a change to the class and the constructor to create a set of default communication port settings for my scale.
The class and the constructor now contain a set of defaults for the communication port settings (9600 baud, 7 data bits, one stop bit, even parity for the scale) and look like:
class UsbSerialDevice
{
public:
UsbSerialDevice();
UsbSerialDevice(DWORD BaudRate, BYTE ByteSize = 8, BYTE Parity = NOPARITY, BYTE StopBits = ONESTOPBIT);
~UsbSerialDevice();
int CreateEndPoint (wchar_t *wszVendorId);
int SetCommPortSettings (DWORD BaudRate, BYTE ByteSize = 8, BYTE Parity = NOPARITY, BYTE StopBits = ONESTOPBIT);
int CloseEndPoint ();
int ReadStream (void *bString, size_t nBytes);
int WriteStream (void *bString, size_t nBytes);
int UpdateSettingsProxy (void);
DWORD m_dwError; // GetLastError() for last action
DWORD m_dwErrorWrite; // GetLastError() for last write
DWORD m_dwErrorRead; // GetLastError() for last read
DWORD m_dwErrorCommState;
DWORD m_dwErrorCommTimeouts;
DWORD m_dwBytesWritten;
DWORD m_dwBytesRead;
COMMTIMEOUTS m_timeOut; // last result from GetCommTimeouts(), updated by UpdateSettingsProxy()
COMSTAT m_statOut; // last result from ClearCommError()
DCB m_commSet; // last result from GetCommState(), updated by UpdateSettingsProxy()
private:
HANDLE m_hFile;
DWORD m_dwStatError;
DCB m_commSetDefault; // the defaults used as standard
wchar_t m_portName[24]; // contains portname if defined for device in form \\.\\COMnn
};
UsbSerialDevice::UsbSerialDevice() :
m_dwError(0),
m_dwErrorWrite(0),
m_dwErrorRead(0),
m_dwBytesWritten(0),
m_dwBytesRead(0),
m_hFile(NULL)
{
// initialize our COM port settings and allow people to change with
memset (&m_commSetDefault, 0, sizeof(m_commSetDefault));
m_commSetDefault.DCBlength = sizeof(m_commSetDefault);
m_commSetDefault.BaudRate = CBR_9600;
m_commSetDefault.ByteSize = 7;
m_commSetDefault.Parity = EVENPARITY;
m_commSetDefault.StopBits = ONESTOPBIT;
m_commSet.fDtrControl = DTR_CONTROL_DISABLE;
m_portName[0] = 0;
}
The function CreateEndPoint() is modified so that after doing the CreateFile() to open the USB device using the pathname of the USB Device, it will now also set the communication port parameters.
An additional experimental change to the method was to check if a communications port name was also created and if so to generate the proper COM port specification to be used with CreateFile(). I plan to split out the CreateEndPoint() method into two methods, one to do a look up of the USB device and a second to actually do the open as I continue my investigation.
The format for the COM port specifier for CreateFile() for COM ports greater than COM9 appear to need the \\.\ as a prefix. See HOWTO: Specify Serial Ports Larger than COM9 from Microsoft Support.
The new version of CreateEndPoint() looks like:
int UsbSerialDevice::CreateEndPoint (wchar_t *wszVendorId)
{
HDEVINFO hDevInfo;
m_dwError = ERROR_INVALID_HANDLE;
// We will try to get device information set for all USB devices that have a
// device interface and are currently present on the system (plugged in).
hDevInfo = SetupDiGetClassDevs(&GUID_DEVINTERFACE_USB_DEVICE, NULL, 0, DIGCF_DEVICEINTERFACE | DIGCF_PRESENT);
if (hDevInfo != INVALID_HANDLE_VALUE)
{
DWORD dwMemberIdx;
BOOL bContinue = TRUE;
SP_DEVICE_INTERFACE_DATA DevIntfData;
// Prepare to enumerate all device interfaces for the device information
// set that we retrieved with SetupDiGetClassDevs(..)
DevIntfData.cbSize = sizeof(SP_DEVICE_INTERFACE_DATA);
dwMemberIdx = 0;
// Next, we will keep calling this SetupDiEnumDeviceInterfaces(..) until this
// function causes GetLastError() to return ERROR_NO_MORE_ITEMS. With each
// call the dwMemberIdx value needs to be incremented to retrieve the next
// device interface information.
for (BOOL bContinue = TRUE; bContinue; ) {
PSP_DEVICE_INTERFACE_DETAIL_DATA DevIntfDetailData;
SP_DEVINFO_DATA DevData;
DWORD dwSize;
dwMemberIdx++;
SetupDiEnumDeviceInterfaces(hDevInfo, NULL, &GUID_DEVINTERFACE_USB_DEVICE, dwMemberIdx, &DevIntfData);
if (GetLastError() == ERROR_NO_MORE_ITEMS) break;
// As a last step we will need to get some more details for each
// of device interface information we are able to retrieve. This
// device interface detail gives us the information we need to identify
// the device (VID/PID), and decide if it's useful to us. It will also
// provide a DEVINFO_DATA structure which we can use to know the serial
// port name for a virtual com port.
DevData.cbSize = sizeof(DevData);
// Get the required buffer size. Call SetupDiGetDeviceInterfaceDetail with
// a NULL DevIntfDetailData pointer, a DevIntfDetailDataSize
// of zero, and a valid RequiredSize variable. In response to such a call,
// this function returns the required buffer size at dwSize.
SetupDiGetDeviceInterfaceDetail(hDevInfo, &DevIntfData, NULL, 0, &dwSize, NULL);
// Allocate memory for the DeviceInterfaceDetail struct. Don't forget to
// deallocate it later!
DevIntfDetailData = (PSP_DEVICE_INTERFACE_DETAIL_DATA) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, dwSize);
DevIntfDetailData->cbSize = sizeof(SP_DEVICE_INTERFACE_DETAIL_DATA);
if (SetupDiGetDeviceInterfaceDetail(hDevInfo, &DevIntfData, DevIntfDetailData, dwSize, &dwSize, &DevData))
{
// Finally we can start checking if we've found a useable device,
// by inspecting the DevIntfDetailData->DevicePath variable.
//
// The DevicePath looks something like this for a Brecknell 67xx Series Serial Scale
// \\?\usb#vid_1a86&pid_7523#6&28eaabda&0&2#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
//
// The VID for a particular vendor will be the same for a particular vendor's equipment.
// The PID is variable for each device of the vendor.
//
// As you can see it contains the VID/PID for the device, so we can check
// for the right VID/PID with string handling routines.
// See https://github.com/Microsoft/Windows-driver-samples/blob/master/usb/usbview/vndrlist.h
if (wcsstr (DevIntfDetailData->DevicePath, wszVendorId)) {
HKEY hKey;
m_dwError = 0;
// To find out the serial port for our scale device,
// we'll need to check the registry:
hKey = SetupDiOpenDevRegKey(hDevInfo, &DevData, DICS_FLAG_GLOBAL, 0, DIREG_DEV, KEY_READ);
if (hKey != INVALID_HANDLE_VALUE) {
DWORD dwSize = 0, dwType = 0;
wchar_t lpData[16] = {0};
dwType = REG_SZ;
dwSize = sizeof(lpData);
LONG queryStat = RegQueryValueEx(hKey, _T("PortName"), NULL, &dwType, (LPBYTE)&lpData[0], &dwSize);
RegCloseKey(hKey);
if (queryStat == ERROR_SUCCESS) {
wcscpy (m_portName, L"\\\\.\\");
wcsncat (m_portName, lpData, dwSize / sizeof(wchar_t));
}
} else {
m_dwError = GetLastError();
}
m_hFile = CreateFile (DevIntfDetailData->DevicePath, GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, 0, 0);
if (m_hFile == INVALID_HANDLE_VALUE) {
m_dwError = GetLastError();
} else {
m_dwError = 0;
GetCommState (m_hFile, &m_commSet);
m_commSet = m_commSetDefault;
SetCommState (m_hFile, &m_commSet);
m_dwErrorCommState = GetLastError();
GetCommState (m_hFile, &m_commSet);
GetCommTimeouts (m_hFile, &m_timeOut);
m_timeOut.ReadIntervalTimeout = 0;
m_timeOut.ReadTotalTimeoutMultiplier = 0;
m_timeOut.ReadTotalTimeoutConstant = 5000;
SetCommTimeouts (m_hFile, &m_timeOut);
GetCommTimeouts (m_hFile, &m_timeOut);
m_dwErrorCommTimeouts = GetLastError();
}
bContinue = FALSE; // found the vendor so stop processing after freeing the heap.
}
}
HeapFree(GetProcessHeap(), 0, DevIntfDetailData);
}
SetupDiDestroyDeviceInfoList(hDevInfo);
}
return 0;
}
POS Ready 7 Investigation
Looking back on the Windows 7 PC which seems to work fine with the scale, we looked in the driver details for the Virtual Serial Communications port using Device Manager from the Control Panel. The driver details indicated that the driver being used was CH341S64.SYS provided by www.winchiphead.com and the Property "Inf name" has a value of oem50.inf. I found a forum post http://doityourselfchristmas.com/forums/showthread.php?14690-CH340-USB-RS232-Driver which provides a link to a driver download at http://www.winchiphead.com/download/CH341/CH341SER.ZIP however another version available from http://www.wch.cn/download/CH341SER_ZIP.html may be more up to date.
Putting the downloaded zip file, CH341SER.ZIP from the later on to the POS Ready 7 terminal, I unzipped the contents and ran SETUP.EXE in the folder CH341SER (there were two folders in the zip file and the one called INSTALL seemed for device development) which displayed a dialog and allowed me to install the CH341SER.INF. Once the install completed, when I plugged in the USB scale, the device was recognized and a Virtual Serial Communications port was created and my test application worked.
I did find some documentation however it was all in Chinese. Google Translate provided a readable version of the USB device documentation. It looks like there is additional work to be done for device management when the scale may be unplugged/replugged while in use.
One other strange thing is that the scale is now using a different COM port name, COM5 rather than COM4. Looking in the Advanced Settings it appears that COM4 is "In Use" though not showing in the list of ports. Further experiments indicates that the COM port name used for the scale device depends on which of the two front panel USB ports are plugged into. I had originally plugged into the left one and today, plugged into the right USB port with the result of the Virtual Serial Communications port being created with a new COM port name.
However since we are using the USB path in the CreateFile(), no change was needed in the USB sample test application.
Further testing with POS Ready 7 using three USB to Serial converter cables showed that different vendor's cables had the same vendor id and product code in the USB path. The USB path also changed depending on which USB port a cable was plugged into. In some cases only the last digit in the path name differed. An interesting experiment would be if a USB hub is connected to a USB port and then USB connections are made to the hub what does the path name look like then?
You are confusing two issues, and it's probably not viable for us to tell them apart.
I say this because you link ReadFile problems to the device name. However, ReadFile works on a HANDLE. The function which takes a name and converts it into a HANDLE is called CreateFile. That means ReadFile doesn't even know on what name it's operating.
This misunderstanding also explains a few other behaviors. For instance, when you unplug the device, the HANDLE becomes invalid, and it stays invalid. Replugging the device may restore the name, but not the HANDLE.
i writing a program that lists Windows network shared objects, using WNet functions. i noticed that, on some reason, WNetEnumResource function retrieve just my local shares, although the explorer sees much more objects. what could be causing this?
here's code:
dwResult = WNetOpenEnum(RESOURCE_GLOBALNET, RESOURCETYPE_ANY,
RESOURCEUSAGE_CONNECTABLE | RESOURCEUSAGE_CONTAINER, lpnr, &hEnum);
................
dwResultEnum = WNetEnumResource(hEnum, &cEntries, lpnrLocal, &cbBuffer);
that's what i got:
Microsoft Terminal Services network
Microsoft Windows Network network
WORKGROUP domain
\\MOSKKM server
\\MOSKKM\HP LaserJet 3055 PCL5 share
\\MOSKKM\share share
\\MOSKKM\soft share
\\MOSKKM\tunnel share
Web Client Network network
my system is Win7, i use an administrator account, and no antiviruses or firewalls running. and also on bridged VirtualBox VM hosted on the same machine it works correct (however, for a long time). what's might be wrong? maybe there are some other ways to solve this problem, not using WNet functions?
and also: WNetEnumResource gives up shared objects sorted by alphabet. i can't imagine any approach how to parallelize this process. any ideas?
I think you need to write recursive function to enumerate the network resources,
To enumerate all network resources, an application can begin the enumeration by calling WNetOpenEnum with the lpNetResource parameter set to NULL, and then use the returned handle to call WNetEnumResource to enumerate resources. If one of the resources in the NETRESOURCE array returned by the WNetEnumResource function is a container resource, you can call WNetOpenEnum to open the resource for further enumeration. (MSDN: WNetOpenEnum)
int EnumNetRes(NETRESOURCE *lpNetRes)
{
DWORD dwResult;
DWORD dwCount = -1;
DWORD dwSize = sizeof(NETRESOURCE)*MAX_NET_RESOURCES;
HANDLE hEnum;
dwResult = WNetOpenEnum(RESOURCE_GLOBALNET, RESOURCETYPE_ANY,
RESOURCEUSAGE_CONNECTABLE | RESOURCEUSAGE_CONTAINER, lpNetRes, &hEnum);
if(dwResult != NO_ERROR)
{
cerr << "WNetOpenEnum failed, error: " << dwResult << endl;
//...
return 1;
}
NETRESOURCE NetResources[MAX_NET_RESOURCES]; // #define MAX_NET_RESOURCES 1024
dwResult = WNetEnumResource(hEnum, &dwCount, NetResource, dwSize);
if(dwResult != NO_ERROR)
{
//...
return 1;
}
for( int i=0; i<dwCount; i++){
//...
// retrieve of information about resource
//...
if(NetResources[i].dwUsage & RESOURCEUSAGE_CONTAINER)
EnumNetRes(&NetResources[i]);
}
}