WNetOpenEnum returns ERROR_NETWORK_UNREACHABLE for the "Microsoft Windows Network" node - c++

Question

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.