static HANDLE device_handle = INVALID_HANDLE_VALUE;
static io_t device_read_io;
static OVERLAPPED device_read_overlapped;
+static OVERLAPPED device_write_overlapped;
static vpn_packet_t device_read_packet;
+static vpn_packet_t device_write_packet;
char *device = NULL;
char *iface = NULL;
static char *device_info = NULL;
get_config_string(lookup_config(config_tree, "Device"), &device);
get_config_string(lookup_config(config_tree, "Interface"), &iface);
+ if(device && iface)
+ logger(DEBUG_ALWAYS, LOG_WARNING, "Warning: both Device and Interface specified, results may not be as expected");
+
/* Open registry and look for network adapters */
if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, NETWORK_CONNECTIONS_KEY, 0, KEY_READ, &key)) {
}
for (i = 0; ; i++) {
- len = sizeof adapterid;
+ len = sizeof(adapterid);
if(RegEnumKeyEx(key, i, adapterid, &len, 0, 0, 0, NULL))
break;
/* Find out more about this adapter */
- snprintf(regpath, sizeof regpath, "%s\\%s\\Connection", NETWORK_CONNECTIONS_KEY, adapterid);
+ snprintf(regpath, sizeof(regpath), "%s\\%s\\Connection", NETWORK_CONNECTIONS_KEY, adapterid);
if(RegOpenKeyEx(HKEY_LOCAL_MACHINE, regpath, 0, KEY_READ, &key2))
continue;
- len = sizeof adaptername;
+ len = sizeof(adaptername);
err = RegQueryValueEx(key2, "Name", 0, 0, (LPBYTE)adaptername, &len);
RegCloseKey(key2);
continue;
}
- snprintf(tapname, sizeof tapname, USERMODEDEVICEDIR "%s" TAPSUFFIX, adapterid);
+ snprintf(tapname, sizeof(tapname), USERMODEDEVICEDIR "%s" TAPSUFFIX, adapterid);
device_handle = CreateFile(tapname, GENERIC_WRITE | GENERIC_READ, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED, 0);
if(device_handle != INVALID_HANDLE_VALUE) {
found = true;
/* Try to open the corresponding tap device */
if(device_handle == INVALID_HANDLE_VALUE) {
- snprintf(tapname, sizeof tapname, USERMODEDEVICEDIR "%s" TAPSUFFIX, device);
+ snprintf(tapname, sizeof(tapname), USERMODEDEVICEDIR "%s" TAPSUFFIX, device);
device_handle = CreateFile(tapname, GENERIC_WRITE | GENERIC_READ, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_SYSTEM | FILE_FLAG_OVERLAPPED, 0);
}
{
ULONG info[3] = {0};
DWORD len;
- if(!DeviceIoControl(device_handle, TAP_IOCTL_GET_VERSION, &info, sizeof info, &info, sizeof info, &len, NULL))
+ if(!DeviceIoControl(device_handle, TAP_IOCTL_GET_VERSION, &info, sizeof(info), &info, sizeof info, &len, NULL))
logger(DEBUG_ALWAYS, LOG_WARNING, "Could not get version information from Windows tap device %s (%s): %s", device, iface, winerror(GetLastError()));
else {
logger(DEBUG_ALWAYS, LOG_INFO, "TAP-Windows driver version: %lu.%lu%s", info[0], info[1], info[2] ? " (DEBUG)" : "");
/* Get MAC address from tap device */
- if(!DeviceIoControl(device_handle, TAP_IOCTL_GET_MAC, mymac.x, sizeof mymac.x, mymac.x, sizeof mymac.x, &len, 0)) {
+ if(!DeviceIoControl(device_handle, TAP_IOCTL_GET_MAC, mymac.x, sizeof(mymac.x), mymac.x, sizeof mymac.x, &len, 0)) {
logger(DEBUG_ALWAYS, LOG_ERR, "Could not get MAC address from Windows tap device %s (%s): %s", device, iface, winerror(GetLastError()));
return false;
}
logger(DEBUG_ALWAYS, LOG_INFO, "%s (%s) is a %s", device, iface, device_info);
+ device_read_overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+ device_write_overlapped.hEvent = CreateEvent(NULL, TRUE, FALSE, NULL);
+
return true;
}
ULONG status = 1;
DWORD len;
- DeviceIoControl(device_handle, TAP_IOCTL_SET_MEDIA_STATUS, &status, sizeof status, &status, sizeof status, &len, NULL);
+ DeviceIoControl(device_handle, TAP_IOCTL_SET_MEDIA_STATUS, &status, sizeof(status), &status, sizeof status, &len, NULL);
+
+ /* We don't use the write event directly, but GetOverlappedResult() does, internally. */
- io_add_event(&device_read_io, device_handle_read, NULL, CreateEvent(NULL, TRUE, FALSE, NULL));
- device_read_overlapped.hEvent = device_read_io.event;
+ io_add_event(&device_read_io, device_handle_read, NULL, device_read_overlapped.hEvent);
device_issue_read();
}
logger(DEBUG_ALWAYS, LOG_INFO, "Disabling %s", device_info);
io_del(&device_read_io);
- CancelIo(device_handle);
- CloseHandle(device_read_overlapped.hEvent);
ULONG status = 0;
DWORD len;
- DeviceIoControl(device_handle, TAP_IOCTL_SET_MEDIA_STATUS, &status, sizeof status, &status, sizeof status, &len, NULL);
+ DeviceIoControl(device_handle, TAP_IOCTL_SET_MEDIA_STATUS, &status, sizeof(status), &status, sizeof status, &len, NULL);
+
+ /* Note that we don't try to cancel ongoing I/O here - we just stop listening.
+ This is because some TAP-Win32 drivers don't seem to handle cancellation very well,
+ especially when combined with other events such as the computer going to sleep - cases
+ were observed where the GetOverlappedResult() would just block indefinitely and never
+ return in that case. */
}
static void close_device(void) {
+ CancelIo(device_handle);
+
+ /* According to MSDN, CancelIo() does not necessarily wait for the operation to complete.
+ To prevent race conditions, make sure the operation is complete
+ before we close the event it's referencing. */
+
+ DWORD len;
+ if(!GetOverlappedResult(device_handle, &device_read_overlapped, &len, TRUE) && GetLastError() != ERROR_OPERATION_ABORTED)
+ logger(DEBUG_ALWAYS, LOG_ERR, "Could not wait for %s %s read to cancel: %s", device_info, device, winerror(GetLastError()));
+ if(device_write_packet.len > 0 && !GetOverlappedResult(device_handle, &device_write_overlapped, &len, TRUE) && GetLastError() != ERROR_OPERATION_ABORTED)
+ logger(DEBUG_ALWAYS, LOG_ERR, "Could not wait for %s %s write to cancel: %s", device_info, device, winerror(GetLastError()));
+ device_write_packet.len = 0;
+
+ CloseHandle(device_read_overlapped.hEvent);
+ CloseHandle(device_write_overlapped.hEvent);
+
CloseHandle(device_handle); device_handle = INVALID_HANDLE_VALUE;
free(device); device = NULL;
static bool write_packet(vpn_packet_t *packet) {
DWORD outlen;
- OVERLAPPED overlapped = {0};
logger(DEBUG_TRAFFIC, LOG_DEBUG, "Writing packet of %d bytes to %s",
packet->len, device_info);
- if(!WriteFile(device_handle, DATA(packet), packet->len, &outlen, &overlapped)) {
+ if(device_write_packet.len > 0) {
+ /* Make sure the previous write operation is finished before we start the next one;
+ otherwise we end up with multiple write ops referencing the same OVERLAPPED structure,
+ which according to MSDN is a no-no. */
+
+ if(!GetOverlappedResult(device_handle, &device_write_overlapped, &outlen, FALSE)) {
+ int log_level = (GetLastError() == ERROR_IO_INCOMPLETE) ? DEBUG_TRAFFIC : DEBUG_ALWAYS;
+ logger(log_level, LOG_ERR, "Error while checking previous write to %s %s: %s", device_info, device, winerror(GetLastError()));
+ return false;
+ }
+ }
+
+ /* Copy the packet, since the write operation might still be ongoing after we return. */
+
+ memcpy(&device_write_packet, packet, sizeof(*packet));
+
+ if(WriteFile(device_handle, DATA(&device_write_packet), device_write_packet.len, &outlen, &device_write_overlapped))
+ device_write_packet.len = 0;
+ else if (GetLastError() != ERROR_IO_PENDING) {
logger(DEBUG_ALWAYS, LOG_ERR, "Error while writing to %s %s: %s", device_info, device, winerror(GetLastError()));
return false;
}