This might be a final fix for GitHub issue #173 and possibly others: ACTIVELY detect borked port status on Windows and if any "cable unplugged" or other wacky states are detected whack the adapter (close and reopen). Tested adding a whole bunch of windows networks, removing, adding more, etc. and it seems to work very well!

osdep/WindowsEthernetTap.cpp

@@ -92,9 +92,6 @@ static const WindowsEthernetTapEnv WINENV;
 // Only create or delete devices one at a time
 static Mutex _systemTapInitLock;
 
-// Incrementing this causes everyone currently open to close and reopen
-static volatile int _systemTapResetStatus = 0;
-
 } // anonymous namespace
 
 WindowsEthernetTap::WindowsEthernetTap(
@@ -268,12 +265,6 @@ WindowsEthernetTap::WindowsEthernetTap(
 				}
 			} else break; // no more keys or error occurred
 		}
-
-		// When we create a new tap device from scratch, existing taps for
-		// some reason go into 'unplugged' state. This can be fixed by
-		// closing and re-opening them. Incrementing this causes all
-		// existing tap threads to do this.
-		++_systemTapResetStatus;
 	}
 
 	if (_netCfgInstanceId.length() > 0) {
@@ -299,7 +290,6 @@ WindowsEthernetTap::WindowsEthernetTap(
 		throw std::runtime_error("unable to find or create tap adapter");
 	}
 
-	// Convert device GUID junk... blech... is there an easier way to do this?
 	{
 		char nobraces[128];
 		const char *nbtmp1 = _netCfgInstanceId.c_str();
@@ -573,36 +563,23 @@ void WindowsEthernetTap::scanMulticastGroups(std::vector<MulticastGroup> &added,
 void WindowsEthernetTap::threadMain()
 	throw()
 {
-	char tapPath[256];
+	char tapReadBuf[ZT_IF_MTU + 32];
-	OVERLAPPED tapOvlRead,tapOvlWrite;
+	char tapPath[128];
 	HANDLE wait4[3];
-	char *tapReadBuf = (char *)0;
+	OVERLAPPED tapOvlRead,tapOvlWrite;
-
-	/* No idea why I did this. I did it a long time ago and there was only a
-	 * a snarky comment. But I'd never do crap like this without a reason, so
-	 * I am leaving it alone with a more descriptive snarky comment. */
-	while (!tapReadBuf) {
-		tapReadBuf = (char *)::malloc(ZT_IF_MTU + 32);
-		if (!tapReadBuf)
-			Sleep(1000);
-	}
 
 	Utils::snprintf(tapPath,sizeof(tapPath),"\\\\.\\Global\\%s.tap",_netCfgInstanceId.c_str());
-	int prevTapResetStatus = _systemTapResetStatus;
+
-	bool throwOneAway = true; // Restart once on startup, because Windows.
+	try {
-	bool powerCycle = true; // If true, "power cycle" the device, because Windows.
 		while (_run) {
-		if (powerCycle) {
-			_disableTapDevice();
-			Sleep(500);
 			_enableTapDevice();
 			Sleep(500);
-		}
 
 			_tap = CreateFileA(tapPath,GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_ATTRIBUTE_SYSTEM|FILE_FLAG_OVERLAPPED,NULL);
 			if (_tap == INVALID_HANDLE_VALUE) {
-			fprintf(stderr,"Error opening %s -- retrying.\r\n",tapPath);
+				_disableTapDevice();
-			powerCycle = true;
+				_enableTapDevice();
+				Sleep(1000);
 				continue;
 			}
 
@@ -612,8 +589,8 @@ void WindowsEthernetTap::threadMain()
 				DeviceIoControl(_tap,TAP_WIN_IOCTL_SET_MEDIA_STATUS,&tmpi,sizeof(tmpi),&tmpi,sizeof(tmpi),&bytesReturned,NULL);
 			}
 
-		{
 #ifdef ZT_WINDOWS_CREATE_FAKE_DEFAULT_ROUTE
+			{
 				/* This inserts a fake default route and a fake ARP entry, forcing
 				 * Windows to detect this as a "real" network and apply proper
 				 * firewall rules.
@@ -688,8 +665,8 @@ void WindowsEthernetTap::threadMain()
 						Sleep(500);
 					else break;
 				}
-#endif
 			}
+#endif
 
 			memset(&tapOvlRead,0,sizeof(tapOvlRead));
 			tapOvlRead.hEvent = CreateEvent(NULL,TRUE,FALSE,NULL);
@@ -702,17 +679,39 @@ void WindowsEthernetTap::threadMain()
 
 			ReadFile(_tap,tapReadBuf,sizeof(tapReadBuf),NULL,&tapOvlRead);
 			bool writeInProgress = false;
+			ULONGLONG timeOfLastBorkCheck = GetTickCount64();
 			while (_run) {
-			if ((prevTapResetStatus != _systemTapResetStatus)||(throwOneAway)) {
+				DWORD waitResult = WaitForMultipleObjectsEx(writeInProgress ? 3 : 2,wait4,FALSE,2500,TRUE);
-				powerCycle = throwOneAway;
-				throwOneAway = false;
-				prevTapResetStatus = _systemTapResetStatus;
-				break; // this will cause us to close and reopen the tap
-			}
-			DWORD r = WaitForMultipleObjectsEx(writeInProgress ? 3 : 2,wait4,FALSE,2500,TRUE);
 				if (!_run) break; // will also break outer while(_run)
 
-			if ((r == WAIT_TIMEOUT)||(r == WAIT_FAILED))
+				// Check for issues with adapter and close/reopen if any are detected. This
+				// check fixes a while boatload of Windows adapter 'coma' issues after
+				// sleep/wake and when adapters are added/removed. Basically if the tap
+				// device is borked, whack it.
+				{
+					ULONGLONG tc = GetTickCount64();
+					if ((tc - timeOfLastBorkCheck) >= 2500) {
+						timeOfLastBorkCheck = tc;
+						MIB_IF_TABLE2 *ift = NULL;
+						if ((GetIfTable2(&ift) == NO_ERROR)&&(ift)) {
+							bool isBorked = false;
+							for(ULONG r=0;r<ift->NumEntries;++r) {
+								if (ift->Table[r].InterfaceLuid.Value == _deviceLuid.Value) {
+									if ((ift->Table[r].InterfaceAndOperStatusFlags.NotMediaConnected)||(ift->Table[r].MediaConnectState == MediaConnectStateDisconnected))
+										isBorked = true;
+									break;
+								}
+							}
+							FreeMibTable(ift);
+							if (isBorked) {
+								// Close and reopen tap device if there's an issue (outer loop)
+								break;
+							}
+						}
+					}
+				}
+
+				if ((waitResult == WAIT_TIMEOUT)||(waitResult == WAIT_FAILED))
 					continue;
 
 				if (HasOverlappedIoCompleted(&tapOvlRead)) {
@@ -756,8 +755,7 @@ void WindowsEthernetTap::threadMain()
 
 			// We will restart and re-open the tap unless _run == false
 		}
-
+	} catch ( ... ) {} // catch unexpected exceptions -- this should not happen but would prevent program crash or other weird issues since threads should not throw
-	::free(tapReadBuf);
 }
 
 void WindowsEthernetTap::destroyAllPersistentTapDevices(const char *pathToHelpers)

osdep/WindowsEthernetTap.hpp

@@ -98,8 +98,8 @@ private:
 
 	GUID _deviceGuid;
 	NET_LUID _deviceLuid;
-	std::string _netCfgInstanceId; // NetCfgInstanceId, a GUID
+	std::string _netCfgInstanceId;
-	std::string _deviceInstanceId; // DeviceInstanceID, another kind of "instance ID"
+	std::string _deviceInstanceId;
 
 	std::vector<MulticastGroup> _multicastGroups;