Merge b4b1b56fff into 25b102ac34

- Updated `handleHidRPCKeyboardInput` to return errors directly instead of keys down state.
- Refactored `rpcKeyboardReport` and `rpcKeypressReport` to return errors instead of states.
- Introduced a queue for managing key down state updates in the `Session` struct to prevent input handling stalls.
- Adjusted the `UpdateKeysDown` method to handle state changes more efficiently.
- Removed unnecessary logging and commented-out code for clarity.

go.mod

@@ -12,6 +12,7 @@ require (
 	github.com/gin-contrib/logger v1.2.6
 	github.com/gin-gonic/gin v1.10.1
 	github.com/go-co-op/gocron/v2 v2.16.5
+	github.com/google/flatbuffers v25.2.10+incompatible
 	github.com/google/uuid v1.6.0
 	github.com/guregu/null/v6 v6.0.0
 	github.com/gwatts/rootcerts v0.0.0-20250901182336-dc5ae18bd79f
@@ -23,6 +24,7 @@ require (
 	github.com/prometheus/common v0.66.0
 	github.com/prometheus/procfs v0.17.0
 	github.com/psanford/httpreadat v0.1.0
+	github.com/rs/xid v1.6.0
 	github.com/rs/zerolog v1.34.0
 	github.com/sourcegraph/tf-dag v0.2.2-0.20250131204052-3e8ff1477b4f
 	github.com/stretchr/testify v1.11.1

go.sum

@@ -53,6 +53,8 @@ github.com/go-playground/validator/v10 v10.26.0/go.mod h1:I5QpIEbmr8On7W0TktmJAu
 github.com/goccy/go-json v0.10.5 h1:Fq85nIqj+gXn/S5ahsiTlK3TmC85qgirsdTP/+DeaC4=
 github.com/goccy/go-json v0.10.5/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
+github.com/google/flatbuffers v25.2.10+incompatible h1:F3vclr7C3HpB1k9mxCGRMXq6FdUalZ6H/pNX4FP1v0Q=
+github.com/google/flatbuffers v25.2.10+incompatible/go.mod h1:1AeVuKshWv4vARoZatz6mlQ0JxURH0Kv5+zNeJKJCa8=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
 github.com/google/gofuzz v1.0.0/go.mod h1:dBl0BpW6vV/+mYPU4Po3pmUjxk6FQPldtuIdl/M65Eg=
@@ -152,6 +154,7 @@ github.com/robfig/cron/v3 v3.0.1 h1:WdRxkvbJztn8LMz/QEvLN5sBU+xKpSqwwUO1Pjr4qDs=
 github.com/robfig/cron/v3 v3.0.1/go.mod h1:eQICP3HwyT7UooqI/z+Ov+PtYAWygg1TEWWzGIFLtro=
 github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
 github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
+github.com/rs/xid v1.6.0 h1:fV591PaemRlL6JfRxGDEPl69wICngIQ3shQtzfy2gxU=
 github.com/rs/xid v1.6.0/go.mod h1:7XoLgs4eV+QndskICGsho+ADou8ySMSjJKDIan90Nz0=
 github.com/rs/zerolog v1.34.0 h1:k43nTLIwcTVQAncfCw4KZ2VY6ukYoZaBPNOE8txlOeY=
 github.com/rs/zerolog v1.34.0/go.mod h1:bJsvje4Z08ROH4Nhs5iH600c3IkWhwp44iRc54W6wYQ=

hidrpc.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/jetkvm/kvm/internal/hidrpc"
 	"github.com/jetkvm/kvm/internal/usbgadget"
+	"github.com/rs/zerolog"
 )
 
 func handleHidRPCMessage(message hidrpc.Message, session *Session) {
@@ -24,11 +25,9 @@ func handleHidRPCMessage(message hidrpc.Message, session *Session) {
 		}
 		session.hidRPCAvailable = true
 	case hidrpc.TypeKeypressReport, hidrpc.TypeKeyboardReport:
-		keysDownState, err := handleHidRPCKeyboardInput(message)
-		if keysDownState != nil {
-			session.reportHidRPCKeysDownState(*keysDownState)
-		}
-		rpcErr = err
+		rpcErr = handleHidRPCKeyboardInput(message)
+	case hidrpc.TypeKeypressKeepAliveReport:
+		gadget.DelayAutoRelease()
 	case hidrpc.TypePointerReport:
 		pointerReport, err := message.PointerReport()
 		if err != nil {
@@ -52,8 +51,13 @@ func handleHidRPCMessage(message hidrpc.Message, session *Session) {
 	}
 }
 
-func onHidMessage(data []byte, session *Session) {
-	scopedLogger := hidRPCLogger.With().Bytes("data", data).Logger()
+func onHidMessage(msg hidQueueMessage, session *Session) {
+	data := msg.Data
+
+	scopedLogger := hidRPCLogger.With().
+		Str("channel", msg.channel).
+		Bytes("data", data).
+		Logger()
 	scopedLogger.Debug().Msg("HID RPC message received")
 
 	if len(data) < 1 {
@@ -68,7 +72,9 @@ func onHidMessage(data []byte, session *Session) {
 		return
 	}
 
-	scopedLogger = scopedLogger.With().Str("descr", message.String()).Logger()
+	if scopedLogger.GetLevel() <= zerolog.DebugLevel {
+		scopedLogger = scopedLogger.With().Str("descr", message.String()).Logger()
+	}
 
 	t := time.Now()
 
@@ -85,27 +91,25 @@ func onHidMessage(data []byte, session *Session) {
 	}
 }
 
-func handleHidRPCKeyboardInput(message hidrpc.Message) (*usbgadget.KeysDownState, error) {
+func handleHidRPCKeyboardInput(message hidrpc.Message) error {
 	switch message.Type() {
 	case hidrpc.TypeKeypressReport:
 		keypressReport, err := message.KeypressReport()
 		if err != nil {
 			logger.Warn().Err(err).Msg("failed to get keypress report")
-			return nil, err
+			return err
 		}
-		keysDownState, rpcError := rpcKeypressReport(keypressReport.Key, keypressReport.Press)
-		return &keysDownState, rpcError
+		return rpcKeypressReport(keypressReport.Key, keypressReport.Press)
 	case hidrpc.TypeKeyboardReport:
 		keyboardReport, err := message.KeyboardReport()
 		if err != nil {
 			logger.Warn().Err(err).Msg("failed to get keyboard report")
-			return nil, err
+			return err
 		}
-		keysDownState, rpcError := rpcKeyboardReport(keyboardReport.Modifier, keyboardReport.Keys)
-		return &keysDownState, rpcError
+		return rpcKeyboardReport(keyboardReport.Modifier, keyboardReport.Keys)
 	}
 
-	return nil, fmt.Errorf("unknown HID RPC message type: %d", message.Type())
+	return fmt.Errorf("unknown HID RPC message type: %d", message.Type())
 }
 
 func reportHidRPC(params any, session *Session) {
@@ -115,7 +119,10 @@ func reportHidRPC(params any, session *Session) {
 	}
 
 	if !session.hidRPCAvailable || session.HidChannel == nil {
-		logger.Warn().Msg("HID RPC is not available, skipping reportHidRPC")
+		logger.Warn().
+			Bool("hidRPCAvailable", session.hidRPCAvailable).
+			Bool("HidChannel", session.HidChannel != nil).
+			Msg("HID RPC is not available, skipping reportHidRPC")
 		return
 	}
 
@@ -156,7 +163,9 @@ func (s *Session) reportHidRPCKeyboardLedState(state usbgadget.KeyboardState) {
 
 func (s *Session) reportHidRPCKeysDownState(state usbgadget.KeysDownState) {
 	if !s.hidRPCAvailable {
+		usbLogger.Debug().Interface("state", state).Msg("reporting keys down state")
 		writeJSONRPCEvent("keysDownState", state, s)
 	}
+	usbLogger.Debug().Interface("state", state).Msg("reporting keys down state, calling reportHidRPC")
 	reportHidRPC(state, s)
 }

internal/hidrpc/hidrpc.go

@@ -10,14 +10,15 @@ import (
 type MessageType byte
 
 const (
-	TypeHandshake        MessageType = 0x01
-	TypeKeyboardReport   MessageType = 0x02
-	TypePointerReport    MessageType = 0x03
-	TypeWheelReport      MessageType = 0x04
-	TypeKeypressReport   MessageType = 0x05
-	TypeMouseReport      MessageType = 0x06
-	TypeKeyboardLedState MessageType = 0x32
-	TypeKeydownState     MessageType = 0x33
+	TypeHandshake               MessageType = 0x01
+	TypeKeyboardReport          MessageType = 0x02
+	TypePointerReport           MessageType = 0x03
+	TypeWheelReport             MessageType = 0x04
+	TypeKeypressReport          MessageType = 0x05
+	TypeKeypressKeepAliveReport MessageType = 0x09
+	TypeMouseReport             MessageType = 0x06
+	TypeKeyboardLedState        MessageType = 0x32
+	TypeKeydownState            MessageType = 0x33
 )
 
 const (

internal/hidrpc/message.go

@@ -43,6 +43,8 @@ func (m *Message) String() string {
 			return fmt.Sprintf("MouseReport{Malformed: %v}", m.d)
 		}
 		return fmt.Sprintf("MouseReport{DX: %d, DY: %d, Button: %d}", m.d[0], m.d[1], m.d[2])
+	case TypeKeypressKeepAliveReport:
+		return "KeypressKeepAliveReport"
 	default:
 		return fmt.Sprintf("Unknown{Type: %d, Data: %v}", m.t, m.d)
 	}

internal/usbgadget/hid_keyboard.go

@@ -5,7 +5,11 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"sync"
 	"time"
+
+	"github.com/rs/xid"
+	"github.com/rs/zerolog"
 )
 
 var keyboardConfig = gadgetConfigItem{
@@ -22,6 +26,11 @@ var keyboardConfig = gadgetConfigItem{
 	reportDesc: keyboardReportDesc,
 }
 
+// macOS default: 15 * 15 = 225ms https://discussions.apple.com/thread/1316947?sortBy=rank
+// Linux default: 250ms https://man.archlinux.org/man/kbdrate.8.en
+// Windows default: 1s `HKEY_CURRENT_USER\Control Panel\Accessibility\Keyboard Response\AutoRepeatDelay`
+const autoReleaseKeyboardInterval = time.Millisecond * 225
+
 // Source: https://www.kernel.org/doc/Documentation/usb/gadget_hid.txt
 var keyboardReportDesc = []byte{
 	0x05, 0x01, /* USAGE_PAGE (Generic Desktop)	          */
@@ -145,32 +154,82 @@ func (u *UsbGadget) GetKeysDownState() KeysDownState {
 	return u.keysDownState
 }
 
-func (u *UsbGadget) updateKeyDownState(state KeysDownState) {
-	u.log.Trace().Interface("old", u.keysDownState).Interface("new", state).Msg("acquiring keyboardStateLock for updateKeyDownState")
+func (u *UsbGadget) SetOnKeysDownChange(f func(state KeysDownState)) {
+	u.onKeysDownChange = &f
+}
 
-	// this is intentional to unlock keyboard state lock before onKeysDownChange callback
-	{
-		u.keyboardStateLock.Lock()
-		defer u.keyboardStateLock.Unlock()
+func (u *UsbGadget) scheduleAutoRelease(key byte) {
+	u.kbdAutoReleaseLock.Lock()
+	defer unlockWithLog(&u.kbdAutoReleaseLock, u.log, "autoRelease scheduled")
 
-		if u.keysDownState.Modifier == state.Modifier &&
-			bytes.Equal(u.keysDownState.Keys, state.Keys) {
-			return // No change in key down state
-		}
-
-		u.log.Trace().Interface("old", u.keysDownState).Interface("new", state).Msg("keysDownState updated")
-		u.keysDownState = state
+	if u.kbdAutoReleaseTimers[key] != nil {
+		u.kbdAutoReleaseTimers[key].Stop()
 	}
 
-	if u.onKeysDownChange != nil {
-		u.log.Trace().Interface("state", state).Msg("calling onKeysDownChange")
-		(*u.onKeysDownChange)(state)
-		u.log.Trace().Interface("state", state).Msg("onKeysDownChange called")
+	u.kbdAutoReleaseTimers[key] = time.AfterFunc(autoReleaseKeyboardInterval, func() {
+		u.performAutoRelease(key)
+	})
+}
+
+func (u *UsbGadget) cancelAutoRelease(key byte) {
+	u.kbdAutoReleaseLock.Lock()
+	defer unlockWithLog(&u.kbdAutoReleaseLock, u.log, "autoRelease cancelled")
+
+	if timer := u.kbdAutoReleaseTimers[key]; timer != nil {
+		timer.Stop()
+		u.kbdAutoReleaseTimers[key] = nil
+		delete(u.kbdAutoReleaseTimers, key)
 	}
 }
 
-func (u *UsbGadget) SetOnKeysDownChange(f func(state KeysDownState)) {
-	u.onKeysDownChange = &f
+func (u *UsbGadget) DelayAutoRelease() {
+	u.kbdAutoReleaseLock.Lock()
+	defer unlockWithLog(&u.kbdAutoReleaseLock, u.log, "autoRelease delayed")
+
+	if u.kbdAutoReleaseTimers == nil {
+		return
+	}
+
+	for _, timer := range u.kbdAutoReleaseTimers {
+		if timer != nil {
+			timer.Reset(autoReleaseKeyboardInterval)
+		}
+	}
+}
+
+func (u *UsbGadget) performAutoRelease(key byte) {
+	u.kbdAutoReleaseLock.Lock()
+
+	if u.kbdAutoReleaseTimers[key] == nil {
+		u.log.Warn().Uint8("key", key).Msg("autoRelease timer not found")
+		u.kbdAutoReleaseLock.Unlock()
+		return
+	}
+
+	u.kbdAutoReleaseTimers[key].Stop()
+	u.kbdAutoReleaseTimers[key] = nil
+	delete(u.kbdAutoReleaseTimers, key)
+	u.kbdAutoReleaseLock.Unlock()
+
+	// Skip if already released
+	state := u.GetKeysDownState()
+	alreadyReleased := true
+
+	for i := range state.Keys {
+		if state.Keys[i] == key {
+			alreadyReleased = false
+			break
+		}
+	}
+
+	if alreadyReleased {
+		return
+	}
+
+	_, err := u.keypressReport(key, false)
+	if err != nil {
+		u.log.Warn().Uint8("key", key).Msg("failed to release key")
+	}
 }
 
 func (u *UsbGadget) listenKeyboardEvents() {
@@ -242,7 +301,11 @@ func (u *UsbGadget) OpenKeyboardHidFile() error {
 	return u.openKeyboardHidFile()
 }
 
+var keyboardWriteHidFileLock sync.Mutex
+
 func (u *UsbGadget) keyboardWriteHidFile(modifier byte, keys []byte) error {
+	keyboardWriteHidFileLock.Lock()
+	defer keyboardWriteHidFileLock.Unlock()
 	if err := u.openKeyboardHidFile(); err != nil {
 		return err
 	}
@@ -266,17 +329,29 @@ func (u *UsbGadget) UpdateKeysDown(modifier byte, keys []byte) KeysDownState {
 		}
 	}
 
-	downState := KeysDownState{
+	state := KeysDownState{
 		Modifier: modifier,
 		Keys:     []byte(keys[:]),
 	}
-	u.updateKeyDownState(downState)
-	return downState
+
+	u.keyboardStateLock.Lock()
+
+	if u.keysDownState.Modifier == state.Modifier &&
+		bytes.Equal(u.keysDownState.Keys, state.Keys) {
+		u.keyboardStateLock.Unlock()
+		return state // No change in key down state
+	}
+
+	u.keysDownState = state
+	u.keyboardStateLock.Unlock()
+
+	if u.onKeysDownChange != nil {
+		(*u.onKeysDownChange)(state) // this enques to the outgoing hidrpc queue via usb.go → currentSession.enqueueKeysDownState(...)
+	}
+	return state
 }
 
-func (u *UsbGadget) KeyboardReport(modifier byte, keys []byte) (KeysDownState, error) {
-	u.keyboardLock.Lock()
-	defer u.keyboardLock.Unlock()
+func (u *UsbGadget) KeyboardReport(modifier byte, keys []byte) error {
 	defer u.resetUserInputTime()
 
 	if len(keys) > hidKeyBufferSize {
@@ -291,7 +366,8 @@ func (u *UsbGadget) KeyboardReport(modifier byte, keys []byte) (KeysDownState, e
 		u.log.Warn().Uint8("modifier", modifier).Uints8("keys", keys).Msg("Could not write keyboard report to hidg0")
 	}
 
-	return u.UpdateKeysDown(modifier, keys), err
+	u.UpdateKeysDown(modifier, keys)
+	return err
 }
 
 const (
@@ -331,17 +407,23 @@ var KeyCodeToMaskMap = map[byte]byte{
 	RightSuper:   ModifierMaskRightSuper,
 }
 
-func (u *UsbGadget) KeypressReport(key byte, press bool) (KeysDownState, error) {
-	u.keyboardLock.Lock()
-	defer u.keyboardLock.Unlock()
+func (u *UsbGadget) keypressReport(key byte, press bool) (KeysDownState, error) {
 	defer u.resetUserInputTime()
 
+	l := u.log.With().Uint8("key", key).Bool("press", press).Logger()
+	if l.GetLevel() <= zerolog.DebugLevel {
+		requestID := xid.New()
+		l = l.With().Str("requestID", requestID.String()).Logger()
+	}
+
 	// IMPORTANT: This code parallels the logic in the kernel's hid-gadget driver
 	// for handling key presses and releases. It ensures that the USB gadget
 	// behaves similarly to a real USB HID keyboard. This logic is paralleled
 	// in the client/browser-side code in useKeyboard.ts so make sure to keep
 	// them in sync.
-	var state = u.keysDownState
+	var state = u.GetKeysDownState()
+	l.Trace().Interface("state", state).Msg("got keys down state")
+
 	modifier := state.Modifier
 	keys := append([]byte(nil), state.Keys...)
 
@@ -381,22 +463,36 @@ func (u *UsbGadget) KeypressReport(key byte, press bool) (KeysDownState, error)
 		// If we reach here it means we didn't find an empty slot or the key in the buffer
 		if overrun {
 			if press {
-				u.log.Error().Uint8("key", key).Msg("keyboard buffer overflow, key not added")
+				l.Error().Msg("keyboard buffer overflow, key not added")
 				// Fill all key slots with ErrorRollOver (0x01) to indicate overflow
 				for i := range keys {
 					keys[i] = hidErrorRollOver
 				}
 			} else {
 				// If we are releasing a key, and we didn't find it in a slot, who cares?
-				u.log.Warn().Uint8("key", key).Msg("key not found in buffer, nothing to release")
+				l.Warn().Msg("key not found in buffer, nothing to release")
 			}
 		}
 	}
 
 	err := u.keyboardWriteHidFile(modifier, keys)
-	if err != nil {
-		u.log.Warn().Uint8("modifier", modifier).Uints8("keys", keys).Msg("Could not write keypress report to hidg0")
-	}
-
 	return u.UpdateKeysDown(modifier, keys), err
 }
+
+func (u *UsbGadget) KeypressReport(key byte, press bool) error {
+	state, err := u.keypressReport(key, press)
+	if err != nil {
+		u.log.Warn().Uint8("key", key).Bool("press", press).Msg("failed to report key")
+	}
+	isRolledOver := state.Keys[0] == hidErrorRollOver
+
+	if isRolledOver {
+		u.cancelAutoRelease(key)
+	} else if press {
+		u.scheduleAutoRelease(key)
+	} else {
+		u.cancelAutoRelease(key)
+	}
+
+	return err
+}

internal/usbgadget/usbgadget.go

@@ -68,6 +68,9 @@ type UsbGadget struct {
 	keyboardState byte          // keyboard latched state (NumLock, CapsLock, ScrollLock, Compose, Kana)
 	keysDownState KeysDownState // keyboard dynamic state (modifier keys and pressed keys)
 
+	kbdAutoReleaseLock   sync.Mutex
+	kbdAutoReleaseTimers map[byte]*time.Timer
+
 	keyboardStateLock   sync.Mutex
 	keyboardStateCtx    context.Context
 	keyboardStateCancel context.CancelFunc
@@ -118,23 +121,24 @@ func newUsbGadget(name string, configMap map[string]gadgetConfigItem, enabledDev
 	keyboardCtx, keyboardCancel := context.WithCancel(context.Background())
 
 	g := &UsbGadget{
-		name:                name,
-		kvmGadgetPath:       path.Join(gadgetPath, name),
-		configC1Path:        path.Join(gadgetPath, name, "configs/c.1"),
-		configMap:           configMap,
-		customConfig:        *config,
-		configLock:          sync.Mutex{},
-		keyboardLock:        sync.Mutex{},
-		absMouseLock:        sync.Mutex{},
-		relMouseLock:        sync.Mutex{},
-		txLock:              sync.Mutex{},
-		keyboardStateCtx:    keyboardCtx,
-		keyboardStateCancel: keyboardCancel,
-		keyboardState:       0,
-		keysDownState:       KeysDownState{Modifier: 0, Keys: []byte{0, 0, 0, 0, 0, 0}}, // must be initialized to hidKeyBufferSize (6) zero bytes
-		enabledDevices:      *enabledDevices,
-		lastUserInput:       time.Now(),
-		log:                 logger,
+		name:                 name,
+		kvmGadgetPath:        path.Join(gadgetPath, name),
+		configC1Path:         path.Join(gadgetPath, name, "configs/c.1"),
+		configMap:            configMap,
+		customConfig:         *config,
+		configLock:           sync.Mutex{},
+		keyboardLock:         sync.Mutex{},
+		absMouseLock:         sync.Mutex{},
+		relMouseLock:         sync.Mutex{},
+		txLock:               sync.Mutex{},
+		keyboardStateCtx:     keyboardCtx,
+		keyboardStateCancel:  keyboardCancel,
+		keyboardState:        0,
+		keysDownState:        KeysDownState{Modifier: 0, Keys: []byte{0, 0, 0, 0, 0, 0}}, // must be initialized to hidKeyBufferSize (6) zero bytes
+		kbdAutoReleaseTimers: make(map[byte]*time.Timer),
+		enabledDevices:       *enabledDevices,
+		lastUserInput:        time.Now(),
+		log:                  logger,
 
 		strictMode: config.strictMode,
 
@@ -149,3 +153,35 @@ func newUsbGadget(name string, configMap map[string]gadgetConfigItem, enabledDev
 
 	return g
 }
+
+// Close cleans up resources used by the USB gadget
+func (u *UsbGadget) Close() error {
+	// Cancel keyboard state context
+	if u.keyboardStateCancel != nil {
+		u.keyboardStateCancel()
+	}
+
+	// Stop auto-release timer
+	u.kbdAutoReleaseLock.Lock()
+	for _, timer := range u.kbdAutoReleaseTimers {
+		timer.Stop()
+	}
+	u.kbdAutoReleaseTimers = make(map[byte]*time.Timer)
+	u.kbdAutoReleaseLock.Unlock()
+
+	// Close HID files
+	if u.keyboardHidFile != nil {
+		u.keyboardHidFile.Close()
+		u.keyboardHidFile = nil
+	}
+	if u.absMouseHidFile != nil {
+		u.absMouseHidFile.Close()
+		u.absMouseHidFile = nil
+	}
+	if u.relMouseHidFile != nil {
+		u.relMouseHidFile.Close()
+		u.relMouseHidFile = nil
+	}
+
+	return nil
+}

internal/usbgadget/utils.go

@@ -9,6 +9,7 @@ import (
 	"path/filepath"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/rs/zerolog"
@@ -120,6 +121,12 @@ func (u *UsbGadget) writeWithTimeout(file *os.File, data []byte) (n int, err err
 		return
 	}
 
+	u.log.Trace().
+		Str("file", file.Name()).
+		Bytes("data", data).
+		Err(err).
+		Msg("write failed")
+
 	if errors.Is(err, os.ErrDeadlineExceeded) {
 		u.logWithSuppression(
 			fmt.Sprintf("writeWithTimeout_%s", file.Name()),
@@ -164,3 +171,8 @@ func (u *UsbGadget) resetLogSuppressionCounter(counterName string) {
 		u.logSuppressionCounter[counterName] = 0
 	}
 }
+
+func unlockWithLog(lock *sync.Mutex, logger *zerolog.Logger, msg string, args ...any) {
+	logger.Trace().Msgf(msg, args...)
+	lock.Unlock()
+}

internal/utils/ssh.go

@@ -20,6 +20,8 @@ var ValidSSHKeyTypes = []string{
 	ssh.KeyAlgoECDSA256,
 	ssh.KeyAlgoECDSA384,
 	ssh.KeyAlgoECDSA521,
+	ssh.KeyAlgoSKED25519,
+	ssh.KeyAlgoSKECDSA256,
 }
 
 // ValidateSSHKey validates authorized_keys file content

internal/utils/ssh_test.go

@@ -27,6 +27,16 @@ func TestValidateSSHKey(t *testing.T) {
 			sshKey:      "ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBAlTkxIo4mXBR+gEX0Q74BpYX4bFFHoX+8Uz7tsob8HvsnMvsEE+BW9h9XrbWX4/4ppL/o6sHbvsqNr9HcyKfdc= test@example.com",
 			expectError: false,
 		},
+		{
+			name:        "valid SK-backed ED25519 key",
+			sshKey:      "sk-ssh-ed25519@openssh.com AAAAGnNrLXNzaC1lZDI1NTE5QG9wZW5zc2guY29tAAAAIHHSRVC3qISk/mOorf24au6esimA9Uu1/BkEnVKJ+4bFAAAABHNzaDo= test@example.com",
+			expectError: false,
+		},
+		{
+			name:        "valid SK-backed ECDSA key",
+			sshKey:      "sk-ecdsa-sha2-nistp256@openssh.com AAAAInNrLWVjZHNhLXNoYTItbmlzdHAyNTZAb3BlbnNzaC5jb20AAAAIbmlzdHAyNTYAAABBBL/CFBZksvs+gJODMB9StxnkY6xRKH73npOzJBVb0UEGCPTAhDrvzW1PE5X5GDYXmZw1s7c/nS+GH0LF0OFCpwAAAAAEc3NoOg== test@example.com",
+			expectError: false,
+		},
 		{
 			name:        "multiple valid keys",
 			sshKey:      "ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDiYUb9Fy2vlPfO+HwubnshimpVrWPoePyvyN+jPC5gWqZSycjMy6Is2vFVn7oQc72bkY0wZalspT5wUOwKtltSoLpL7vcqGL9zHVw4yjYXtPGIRd3zLpU9wdngevnepPQWTX3LvZTZfmOsrGoMDKIG+Lbmiq/STMuWYecIqMp7tUKRGS8vfAmpu6MsrN9/4UTcdWWXYWJQQn+2nCyMz28jYlWRsKtqFK6owrdZWt8WQnPN+9Upcf2ByQje+0NLnpNrnh+yd2ocuVW9wQYKAZXy7IaTfEJwd5m34sLwkqlZTaBBcmWJU+3RfpYXE763cf3rUoPIGQ8eUEBJ8IdM4vhp test@example.com\nssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIBSbM8wuD5ab0nHsXaYOqaD3GLLUwmDzSk79Xi/N+H2j test@example.com",
@@ -131,6 +141,8 @@ func TestValidSSHKeyTypes(t *testing.T) {
 		"ecdsa-sha2-nistp256",
 		"ecdsa-sha2-nistp384",
 		"ecdsa-sha2-nistp521",
+		"sk-ecdsa-sha2-nistp256@openssh.com",
+		"sk-ssh-ed25519@openssh.com",
 	}
 
 	if len(ValidSSHKeyTypes) != len(expectedTypes) {

jsonrpc.go

@@ -1066,9 +1066,7 @@ var rpcHandlers = map[string]RPCHandler{
 	"getNetworkSettings":     {Func: rpcGetNetworkSettings},
 	"setNetworkSettings":     {Func: rpcSetNetworkSettings, Params: []string{"settings"}},
 	"renewDHCPLease":         {Func: rpcRenewDHCPLease},
-	"keyboardReport":         {Func: rpcKeyboardReport, Params: []string{"modifier", "keys"}},
 	"getKeyboardLedState":    {Func: rpcGetKeyboardLedState},
-	"keypressReport":         {Func: rpcKeypressReport, Params: []string{"key", "press"}},
 	"getKeyDownState":        {Func: rpcGetKeysDownState},
 	"absMouseReport":         {Func: rpcAbsMouseReport, Params: []string{"x", "y", "buttons"}},
 	"relMouseReport":         {Func: rpcRelMouseReport, Params: []string{"dx", "dy", "buttons"}},

ui/src/components/WebRTCVideo.tsx

@@ -190,7 +190,7 @@ export default function WebRTCVideo() {
     if (!isFullscreenEnabled || !videoElm.current) return;
 
     // per https://wicg.github.io/keyboard-lock/#system-key-press-handler
-    // If keyboard lock is activated after fullscreen is already in effect, then the user my 
+    // If keyboard lock is activated after fullscreen is already in effect, then the user my
     // see multiple messages about how to exit fullscreen. For this reason, we recommend that
     // developers call lock() before they enter fullscreen:
     await requestKeyboardLock();
@@ -237,6 +237,7 @@ export default function WebRTCVideo() {
   const keyDownHandler = useCallback(
     (e: KeyboardEvent) => {
       e.preventDefault();
+      if (e.repeat) return;
       const code = getAdjustedKeyCode(e);
       const hidKey = keys[code];
 

ui/src/hooks/hidRpc.ts

@@ -6,6 +6,7 @@ export const HID_RPC_MESSAGE_TYPES = {
     PointerReport: 0x03,
     WheelReport: 0x04,
     KeypressReport: 0x05,
+    KeypressKeepAliveReport: 0x09,
     MouseReport: 0x06,
     KeyboardLedState: 0x32,
     KeysDownState: 0x33,
@@ -278,12 +279,23 @@ export class MouseReportMessage extends RpcMessage {
     }
 }
 
+export class KeypressKeepAliveMessage extends RpcMessage {
+    constructor() {
+        super(HID_RPC_MESSAGE_TYPES.KeypressKeepAliveReport);
+    }
+
+    marshal(): Uint8Array {
+        return new Uint8Array([this.messageType]);
+    }
+}
+
 export const messageRegistry = {
     [HID_RPC_MESSAGE_TYPES.Handshake]: HandshakeMessage,
     [HID_RPC_MESSAGE_TYPES.KeysDownState]: KeysDownStateMessage,
     [HID_RPC_MESSAGE_TYPES.KeyboardLedState]: KeyboardLedStateMessage,
     [HID_RPC_MESSAGE_TYPES.KeyboardReport]: KeyboardReportMessage,
     [HID_RPC_MESSAGE_TYPES.KeypressReport]: KeypressReportMessage,
+    [HID_RPC_MESSAGE_TYPES.KeypressKeepAliveReport]: KeypressKeepAliveMessage,
 }
 
 export const unmarshalHidRpcMessage = (data: Uint8Array): RpcMessage | undefined => {

ui/src/hooks/stores.ts

@@ -106,11 +106,17 @@ export interface RTCState {
   rpcDataChannel: RTCDataChannel | null;
 
   rpcHidProtocolVersion: number | null;
-  setRpcHidProtocolVersion: (version: number) => void;
+  setRpcHidProtocolVersion: (version: number | null) => void;
 
   rpcHidChannel: RTCDataChannel | null;
   setRpcHidChannel: (channel: RTCDataChannel) => void;
 
+  rpcHidUnreliableChannel: RTCDataChannel | null;
+  setRpcHidUnreliableChannel: (channel: RTCDataChannel) => void;
+
+  rpcHidUnreliableNonOrderedChannel: RTCDataChannel | null;
+  setRpcHidUnreliableNonOrderedChannel: (channel: RTCDataChannel) => void;
+
   peerConnectionState: RTCPeerConnectionState | null;
   setPeerConnectionState: (state: RTCPeerConnectionState) => void;
 
@@ -158,11 +164,17 @@ export const useRTCStore = create<RTCState>(set => ({
   setRpcDataChannel: (channel: RTCDataChannel) => set({ rpcDataChannel: channel }),
 
   rpcHidProtocolVersion: null,
-  setRpcHidProtocolVersion: (version: number) => set({ rpcHidProtocolVersion: version }),
+  setRpcHidProtocolVersion: (version: number | null) => set({ rpcHidProtocolVersion: version }),
 
   rpcHidChannel: null,
   setRpcHidChannel: (channel: RTCDataChannel) => set({ rpcHidChannel: channel }),
 
+  rpcHidUnreliableChannel: null,
+  setRpcHidUnreliableChannel: (channel: RTCDataChannel) => set({ rpcHidUnreliableChannel: channel }),
+
+  rpcHidUnreliableNonOrderedChannel: null,
+  setRpcHidUnreliableNonOrderedChannel: (channel: RTCDataChannel) => set({ rpcHidUnreliableNonOrderedChannel: channel }),
+
   transceiver: null,
   setTransceiver: (transceiver: RTCRtpTransceiver) => set({ transceiver }),
 

ui/src/hooks/useHidRpc.ts

@@ -6,6 +6,7 @@ import {
   HID_RPC_VERSION,
   HandshakeMessage,
   KeyboardReportMessage,
+  KeypressKeepAliveMessage,
   KeypressReportMessage,
   MouseReportMessage,
   PointerReportMessage,
@@ -13,38 +14,93 @@ import {
   unmarshalHidRpcMessage,
 } from "./hidRpc";
 
+const KEEPALIVE_MESSAGE = new KeypressKeepAliveMessage();
+
+interface sendMessageParams {
+  ignoreHandshakeState?: boolean;
+  useUnreliableChannel?: boolean;
+  requireOrdered?: boolean;
+}
+
 export function useHidRpc(onHidRpcMessage?: (payload: RpcMessage) => void) {
-  const { rpcHidChannel, setRpcHidProtocolVersion, rpcHidProtocolVersion } = useRTCStore();
+  const {
+    rpcHidChannel,
+    rpcHidUnreliableChannel,
+    rpcHidUnreliableNonOrderedChannel,
+    setRpcHidProtocolVersion,
+    rpcHidProtocolVersion,
+  } = useRTCStore();
+
   const rpcHidReady = useMemo(() => {
     return rpcHidChannel?.readyState === "open" && rpcHidProtocolVersion !== null;
   }, [rpcHidChannel, rpcHidProtocolVersion]);
 
+  const rpcHidUnreliableReady = useMemo(() => {
+    return (
+      rpcHidUnreliableChannel?.readyState === "open" && rpcHidProtocolVersion !== null
+    );
+  }, [rpcHidUnreliableChannel, rpcHidProtocolVersion]);
+
+  const rpcHidUnreliableNonOrderedReady = useMemo(() => {
+    return (
+      rpcHidUnreliableNonOrderedChannel?.readyState === "open" &&
+      rpcHidProtocolVersion !== null
+    );
+  }, [rpcHidUnreliableNonOrderedChannel, rpcHidProtocolVersion]);
+
   const rpcHidStatus = useMemo(() => {
     if (!rpcHidChannel) return "N/A";
     if (rpcHidChannel.readyState !== "open") return rpcHidChannel.readyState;
     if (!rpcHidProtocolVersion) return "handshaking";
-    return `ready (v${rpcHidProtocolVersion})`;
-  }, [rpcHidChannel, rpcHidProtocolVersion]);
+    return `ready (v${rpcHidProtocolVersion}${rpcHidUnreliableReady ? "+u" : ""})`;
+  }, [rpcHidChannel, rpcHidUnreliableReady, rpcHidProtocolVersion]);
 
-  const sendMessage = useCallback((message: RpcMessage, ignoreHandshakeState = false) => {
-    if (rpcHidChannel?.readyState !== "open") return;
-    if (!rpcHidReady && !ignoreHandshakeState) return;
+  const sendMessage = useCallback(
+    (
+      message: RpcMessage,
+      {
+        ignoreHandshakeState,
+        useUnreliableChannel,
+        requireOrdered = true,
+      }: sendMessageParams = {},
+    ) => {
+      if (rpcHidChannel?.readyState !== "open") return;
+      if (!rpcHidReady && !ignoreHandshakeState) return;
 
-    let data: Uint8Array | undefined;
-    try {
-      data = message.marshal();
-    } catch (e) {
-      console.error("Failed to send HID RPC message", e);
-    }
-    if (!data) return;
+      let data: Uint8Array | undefined;
+      try {
+        data = message.marshal();
+      } catch (e) {
+        console.error("Failed to send HID RPC message", e);
+      }
+      if (!data) return;
 
-    rpcHidChannel?.send(data as unknown as ArrayBuffer);
-  }, [rpcHidChannel, rpcHidReady]);
+      if (useUnreliableChannel) {
+        if (requireOrdered && rpcHidUnreliableReady) {
+          rpcHidUnreliableChannel?.send(data as unknown as ArrayBuffer);
+        } else if (!requireOrdered && rpcHidUnreliableNonOrderedReady) {
+          rpcHidUnreliableNonOrderedChannel?.send(data as unknown as ArrayBuffer);
+        }
+        return;
+      }
+
+      rpcHidChannel?.send(data as unknown as ArrayBuffer);
+    },
+    [
+      rpcHidChannel,
+      rpcHidUnreliableChannel,
+      rpcHidUnreliableNonOrderedChannel,
+      rpcHidReady,
+      rpcHidUnreliableReady,
+      rpcHidUnreliableNonOrderedReady,
+    ],
+  );
 
   const reportKeyboardEvent = useCallback(
     (keys: number[], modifier: number) => {
       sendMessage(new KeyboardReportMessage(keys, modifier));
-    }, [sendMessage],
+    },
+    [sendMessage],
   );
 
   const reportKeypressEvent = useCallback(
@@ -56,7 +112,9 @@ export function useHidRpc(onHidRpcMessage?: (payload: RpcMessage) => void) {
 
   const reportAbsMouseEvent = useCallback(
     (x: number, y: number, buttons: number) => {
-      sendMessage(new PointerReportMessage(x, y, buttons));
+      sendMessage(new PointerReportMessage(x, y, buttons), {
+        useUnreliableChannel: true,
+      });
     },
     [sendMessage],
   );
@@ -68,29 +126,36 @@ export function useHidRpc(onHidRpcMessage?: (payload: RpcMessage) => void) {
     [sendMessage],
   );
 
+  const reportKeypressKeepAlive = useCallback(() => {
+    sendMessage(KEEPALIVE_MESSAGE);
+  }, [sendMessage]);
+
   const sendHandshake = useCallback(() => {
     if (rpcHidProtocolVersion) return;
     if (!rpcHidChannel) return;
 
-    sendMessage(new HandshakeMessage(HID_RPC_VERSION), true);
+    sendMessage(new HandshakeMessage(HID_RPC_VERSION), { ignoreHandshakeState: true });
   }, [rpcHidChannel, rpcHidProtocolVersion, sendMessage]);
 
-  const handleHandshake = useCallback((message: HandshakeMessage) => {
-    if (!message.version) {
-      console.error("Received handshake message without version", message);
-      return;
-    }
+  const handleHandshake = useCallback(
+    (message: HandshakeMessage) => {
+      if (!message.version) {
+        console.error("Received handshake message without version", message);
+        return;
+      }
 
-    if (message.version > HID_RPC_VERSION) {
-      // we assume that the UI is always using the latest version of the HID RPC protocol
-      // so we can't support this
-      // TODO: use capabilities to determine rather than version number
-      console.error("Server is using a newer HID RPC version than the client", message);
-      return;
-    }
+      if (message.version > HID_RPC_VERSION) {
+        // we assume that the UI is always using the latest version of the HID RPC protocol
+        // so we can't support this
+        // TODO: use capabilities to determine rather than version number
+        console.error("Server is using a newer HID RPC version than the client", message);
+        return;
+      }
 
-    setRpcHidProtocolVersion(message.version);
-  }, [setRpcHidProtocolVersion]);
+      setRpcHidProtocolVersion(message.version);
+    },
+    [setRpcHidProtocolVersion],
+  );
 
   useEffect(() => {
     if (!rpcHidChannel) return;
@@ -123,26 +188,39 @@ export function useHidRpc(onHidRpcMessage?: (payload: RpcMessage) => void) {
       onHidRpcMessage?.(message);
     };
 
+    const openHandler = () => {
+      console.info("HID RPC channel opened");
+      sendHandshake();
+    };
+
+    const closeHandler = () => {
+      console.info("HID RPC channel closed");
+      setRpcHidProtocolVersion(null);
+    };
+
     rpcHidChannel.addEventListener("message", messageHandler);
+    rpcHidChannel.addEventListener("close", closeHandler);
+    rpcHidChannel.addEventListener("open", openHandler);
 
     return () => {
       rpcHidChannel.removeEventListener("message", messageHandler);
+      rpcHidChannel.removeEventListener("close", closeHandler);
+      rpcHidChannel.removeEventListener("open", openHandler);
     };
-  },
-    [
-      rpcHidChannel,
-      onHidRpcMessage,
-      setRpcHidProtocolVersion,
-      sendHandshake,
-      handleHandshake,
-    ],
-  );
+  }, [
+    rpcHidChannel,
+    onHidRpcMessage,
+    setRpcHidProtocolVersion,
+    sendHandshake,
+    handleHandshake,
+  ]);
 
   return {
     reportKeyboardEvent,
     reportKeypressEvent,
     reportAbsMouseEvent,
     reportRelMouseEvent,
+    reportKeypressKeepAlive,
     rpcHidProtocolVersion,
     rpcHidReady,
     rpcHidStatus,

ui/src/hooks/useKeyboard.ts

@@ -1,6 +1,12 @@
-import { useCallback } from "react";
+import { useCallback, useRef } from "react";
 
-import { hidErrorRollOver, hidKeyBufferSize, KeysDownState, useHidStore, useRTCStore } from "@/hooks/stores";
+import {
+  hidErrorRollOver,
+  hidKeyBufferSize,
+  KeysDownState,
+  useHidStore,
+  useRTCStore,
+} from "@/hooks/stores";
 import { JsonRpcResponse, useJsonRpc } from "@/hooks/useJsonRpc";
 import { useHidRpc } from "@/hooks/useHidRpc";
 import { KeyboardLedStateMessage, KeysDownStateMessage } from "@/hooks/hidRpc";
@@ -11,23 +17,27 @@ export default function useKeyboard() {
   const { rpcDataChannel } = useRTCStore();
   const { keysDownState, setKeysDownState, setKeyboardLedState } = useHidStore();
 
+  // Keepalive timer management
+  const keepAliveTimerRef = useRef<number | null>(null);
+
   // INTRODUCTION: The earlier version of the JetKVM device shipped with all keyboard state
   // being tracked on the browser/client-side. When adding the keyPressReport API to the
   // device-side code, we have to still support the situation where the browser/client-side code
   // is running on the cloud against a device that has not been updated yet and thus does not
   // support the keyPressReport API. In that case, we need to handle the key presses locally
   // and send the full state to the device, so it can behave like a real USB HID keyboard.
-  // This flag indicates whether the keyPressReport API is available on the device which is 
+  // This flag indicates whether the keyPressReport API is available on the device which is
   // dynamically set when the device responds to the first key press event or reports its
-  // keysDownState when queried since the keyPressReport was introduced together with the 
+  // keysDownState when queried since the keyPressReport was introduced together with the
   // getKeysDownState API.
 
   // HidRPC is a binary format for exchanging keyboard and mouse events
   const {
     reportKeyboardEvent: sendKeyboardEventHidRpc,
     reportKeypressEvent: sendKeypressEventHidRpc,
+    reportKeypressKeepAlive: sendKeypressKeepAliveHidRpc,
     rpcHidReady,
-  } = useHidRpc((message) => {
+  } = useHidRpc(message => {
     switch (message.constructor) {
       case KeysDownStateMessage:
         setKeysDownState((message as KeysDownStateMessage).keysDownState);
@@ -48,7 +58,9 @@ export default function useKeyboard() {
     async (state: KeysDownState) => {
       if (rpcDataChannel?.readyState !== "open" && !rpcHidReady) return;
 
-      console.debug(`Send keyboardReport keys: ${state.keys}, modifier: ${state.modifier}`);
+      console.debug(
+        `Send keyboardReport keys: ${state.keys}, modifier: ${state.modifier}`,
+      );
 
       if (rpcHidReady) {
         console.debug("Sending keyboard report via HidRPC");
@@ -56,42 +68,33 @@ export default function useKeyboard() {
         return;
       }
 
-      send("keyboardReport", { keys: state.keys, modifier: state.modifier }, (resp: JsonRpcResponse) => {
-        if ("error" in resp) {
-          console.error(`Failed to send keyboard report ${state}`, resp.error);
-        }
-      });
+      send(
+        "keyboardReport",
+        { keys: state.keys, modifier: state.modifier },
+        (resp: JsonRpcResponse) => {
+          if ("error" in resp) {
+            console.error(`Failed to send keyboard report ${state}`, resp.error);
+          }
+        },
+      );
     },
-    [
-      rpcDataChannel?.readyState,
-      rpcHidReady,
-      send,
-      sendKeyboardEventHidRpc,
-    ],
+    [rpcDataChannel?.readyState, rpcHidReady, send, sendKeyboardEventHidRpc],
   );
 
-  // resetKeyboardState is used to reset the keyboard state to no keys pressed and no modifiers.
-  // This is useful for macros and when the browser loses focus to ensure that the keyboard state
-  // is clean.
-  const resetKeyboardState = useCallback(
-    async () => {
-      // Reset the keys buffer to zeros and the modifier state to zero
-      keysDownState.keys.length = hidKeyBufferSize;
-      keysDownState.keys.fill(0);
-      keysDownState.modifier = 0;
-      sendKeyboardEvent(keysDownState);
-    }, [keysDownState, sendKeyboardEvent]);
-
   // executeMacro is used to execute a macro consisting of multiple steps.
   // Each step can have multiple keys, multiple modifiers and a delay.
   // The keys and modifiers are pressed together and held for the delay duration.
   // After the delay, the keys and modifiers are released and the next step is executed.
   // If a step has no keys or modifiers, it is treated as a delay-only step.
   // A small pause is added between steps to ensure that the device can process the events.
-  const executeMacro = async (steps: { keys: string[] | null; modifiers: string[] | null; delay: number }[]) => {
+  const executeMacro = async (
+    steps: { keys: string[] | null; modifiers: string[] | null; delay: number }[],
+  ) => {
     for (const [index, step] of steps.entries()) {
       const keyValues = (step.keys || []).map(key => keys[key]).filter(Boolean);
-      const modifierMask: number = (step.modifiers || []).map(mod => modifiers[mod]).reduce((acc, val) => acc + val, 0);
+      const modifierMask: number = (step.modifiers || [])
+        .map(mod => modifiers[mod])
+        .reduce((acc, val) => acc + val, 0);
 
       // If the step has keys and/or modifiers, press them and hold for the delay
       if (keyValues.length > 0 || modifierMask > 0) {
@@ -111,12 +114,63 @@ export default function useKeyboard() {
     }
   };
 
+  const KEEPALIVE_INTERVAL = 75; // TODO: use an adaptive interval based on RTT later
+
+  const cancelKeepAlive = useCallback(() => {
+    if (keepAliveTimerRef.current) {
+      clearInterval(keepAliveTimerRef.current);
+      keepAliveTimerRef.current = null;
+    }
+  }, []);
+
+  const scheduleKeepAlive = useCallback(() => {
+    // Clear existing timer if it exists
+    if (keepAliveTimerRef.current) {
+      clearInterval(keepAliveTimerRef.current);
+    }
+
+    sendKeypressKeepAliveHidRpc();
+
+    // Create new interval timer
+    keepAliveTimerRef.current = setInterval(() => {
+      sendKeypressKeepAliveHidRpc();
+    }, KEEPALIVE_INTERVAL);
+  }, [sendKeypressKeepAliveHidRpc]);
+
+  // resetKeyboardState is used to reset the keyboard state to no keys pressed and no modifiers.
+  // This is useful for macros and when the browser loses focus to ensure that the keyboard state
+  // is clean.
+  const resetKeyboardState = useCallback(async () => {
+    // Cancel keepalive since we're resetting the keyboard state
+    cancelKeepAlive();
+
+    // Reset the keys buffer to zeros and the modifier state to zero
+    keysDownState.keys.length = hidKeyBufferSize;
+    keysDownState.keys.fill(0);
+    keysDownState.modifier = 0;
+    sendKeyboardEvent(keysDownState);
+  }, [keysDownState, sendKeyboardEvent, cancelKeepAlive]);
+
   // handleKeyPress is used to handle a key press or release event.
   // This function handle both key press and key release events.
   // It checks if the keyPressReport API is available and sends the key press event.
   // If the keyPressReport API is not available, it simulates the device-side key
   // handling for legacy devices and updates the keysDownState accordingly.
   // It then sends the full keyboard state to the device.
+
+  const sendKeypress = useCallback(
+    (key: number, press: boolean) => {
+      cancelKeepAlive();
+
+      sendKeypressEventHidRpc(key, press);
+
+      if (press) {
+        scheduleKeepAlive();
+      }
+    },
+    [sendKeypressEventHidRpc, scheduleKeepAlive, cancelKeepAlive],
+  );
+
   const handleKeyPress = useCallback(
     async (key: number, press: boolean) => {
       if (rpcDataChannel?.readyState !== "open" && !rpcHidReady) return;
@@ -129,10 +183,14 @@ export default function useKeyboard() {
         // Older device version doesn't support this API, so we will switch to local key handling
         // In that case we will switch to local key handling and update the keysDownState
         // in client/browser-side code using simulateDeviceSideKeyHandlingForLegacyDevices.
-        sendKeypressEventHidRpc(key, press);
+        sendKeypress(key, press);
       } else {
         // if the keyPress api is not available, we need to handle the key locally
-        const downState = simulateDeviceSideKeyHandlingForLegacyDevices(keysDownState, key, press);
+        const downState = simulateDeviceSideKeyHandlingForLegacyDevices(
+          keysDownState,
+          key,
+          press,
+        );
         sendKeyboardEvent(downState); // then we send the full state
 
         // if we just sent ErrorRollOver, reset to empty state
@@ -147,12 +205,16 @@ export default function useKeyboard() {
       resetKeyboardState,
       rpcDataChannel?.readyState,
       sendKeyboardEvent,
-      sendKeypressEventHidRpc,
+      sendKeypress,
     ],
   );
 
   // IMPORTANT: See the keyPressReportApiAvailable comment above for the reason this exists
-  function simulateDeviceSideKeyHandlingForLegacyDevices(state: KeysDownState, key: number, press: boolean): KeysDownState {
+  function simulateDeviceSideKeyHandlingForLegacyDevices(
+    state: KeysDownState,
+    key: number,
+    press: boolean,
+  ): KeysDownState {
     // IMPORTANT: This code parallels the logic in the kernel's hid-gadget driver
     // for handling key presses and releases. It ensures that the USB gadget
     // behaves similarly to a real USB HID keyboard. This logic is paralleled
@@ -164,7 +226,7 @@ export default function useKeyboard() {
     if (modifierMask !== 0) {
       // If the key is a modifier key, we update the keyboardModifier state
       // by setting or clearing the corresponding bit in the modifier byte.
-      // This allows us to track the state of dynamic modifier keys like 
+      // This allows us to track the state of dynamic modifier keys like
       // Shift, Control, Alt, and Super.
       if (press) {
         modifiers |= modifierMask;
@@ -181,7 +243,7 @@ export default function useKeyboard() {
         // and if we find a zero byte, we can place the key there (if press is true)
         if (keys[i] === key || keys[i] === 0) {
           if (press) {
-            keys[i] = key // overwrites the zero byte or the same key if already pressed
+            keys[i] = key; // overwrites the zero byte or the same key if already pressed
           } else {
             // we are releasing the key, remove it from the buffer
             if (keys[i] !== 0) {
@@ -197,18 +259,25 @@ export default function useKeyboard() {
       // If we reach here it means we didn't find an empty slot or the key in the buffer
       if (overrun) {
         if (press) {
-          console.warn(`keyboard buffer overflow current keys ${keys}, key: ${key} not added`);
+          console.warn(
+            `keyboard buffer overflow current keys ${keys}, key: ${key} not added`,
+          );
           // Fill all key slots with ErrorRollOver (0x01) to indicate overflow
           keys.length = hidKeyBufferSize;
           keys.fill(hidErrorRollOver);
         } else {
           // If we are releasing a key, and we didn't find it in a slot, who cares?
-          console.debug(`key ${key} not found in buffer, nothing to release`)
+          console.debug(`key ${key} not found in buffer, nothing to release`);
         }
       }
     }
     return { modifier: modifiers, keys };
   }
 
-  return { handleKeyPress, resetKeyboardState, executeMacro };
+  // Cleanup function to cancel keepalive timer
+  const cleanup = useCallback(() => {
+    cancelKeepAlive();
+  }, [cancelKeepAlive]);
+
+  return { handleKeyPress, resetKeyboardState, executeMacro, cleanup };
 }

ui/src/routes/devices.$id.tsx

@@ -136,6 +136,8 @@ export default function KvmIdRoute() {
     rpcDataChannel,
     setTransceiver,
     setRpcHidChannel,
+    setRpcHidUnreliableNonOrderedChannel,
+    setRpcHidUnreliableChannel,
   } = useRTCStore();
 
   const location = useLocation();
@@ -488,6 +490,24 @@ export default function KvmIdRoute() {
       setRpcHidChannel(rpcHidChannel);
     };
 
+    const rpcHidUnreliableChannel = pc.createDataChannel("hidrpc-unreliable-ordered", {
+      ordered: true,
+      maxRetransmits: 0,
+    });
+    rpcHidUnreliableChannel.binaryType = "arraybuffer";
+    rpcHidUnreliableChannel.onopen = () => {
+      setRpcHidUnreliableChannel(rpcHidUnreliableChannel);
+    };
+
+    const rpcHidUnreliableNonOrderedChannel = pc.createDataChannel("hidrpc-unreliable-nonordered", {
+      ordered: false,
+      maxRetransmits: 0,
+    });
+    rpcHidUnreliableNonOrderedChannel.binaryType = "arraybuffer";
+    rpcHidUnreliableNonOrderedChannel.onopen = () => {
+      setRpcHidUnreliableNonOrderedChannel(rpcHidUnreliableNonOrderedChannel);
+    };
+
     setPeerConnection(pc);
   }, [
     cleanupAndStopReconnecting,
@@ -499,6 +519,8 @@ export default function KvmIdRoute() {
     setPeerConnectionState,
     setRpcDataChannel,
     setRpcHidChannel,
+    setRpcHidUnreliableNonOrderedChannel,
+    setRpcHidUnreliableChannel,
     setTransceiver,
   ]);
 

usb.go

@@ -33,7 +33,7 @@ func initUsbGadget() {
 
 	gadget.SetOnKeysDownChange(func(state usbgadget.KeysDownState) {
 		if currentSession != nil {
-			currentSession.reportHidRPCKeysDownState(state)
+			currentSession.enqueueKeysDownState(state)
 		}
 	})
 
@@ -43,11 +43,11 @@ func initUsbGadget() {
 	}
 }
 
-func rpcKeyboardReport(modifier byte, keys []byte) (usbgadget.KeysDownState, error) {
+func rpcKeyboardReport(modifier byte, keys []byte) error {
 	return gadget.KeyboardReport(modifier, keys)
 }
 
-func rpcKeypressReport(key byte, press bool) (usbgadget.KeysDownState, error) {
+func rpcKeypressReport(key byte, press bool) error {
 	return gadget.KeypressReport(key, press)
 }
 

webrtc.go

@@ -13,6 +13,7 @@ import (
 	"github.com/gin-gonic/gin"
 	"github.com/jetkvm/kvm/internal/hidrpc"
 	"github.com/jetkvm/kvm/internal/logging"
+	"github.com/jetkvm/kvm/internal/usbgadget"
 	"github.com/pion/webrtc/v4"
 	"github.com/rs/zerolog"
 )
@@ -29,7 +30,14 @@ type Session struct {
 
 	hidRPCAvailable bool
 	hidQueueLock    sync.Mutex
-	hidQueue        []chan webrtc.DataChannelMessage
+	hidQueue        []chan hidQueueMessage
+
+	keysDownStateQueue chan usbgadget.KeysDownState
+}
+
+type hidQueueMessage struct {
+	webrtc.DataChannelMessage
+	channel string
 }
 
 type SessionConfig struct {
@@ -78,16 +86,85 @@ func (s *Session) initQueues() {
 	s.hidQueueLock.Lock()
 	defer s.hidQueueLock.Unlock()
 
-	s.hidQueue = make([]chan webrtc.DataChannelMessage, 0)
+	s.hidQueue = make([]chan hidQueueMessage, 0)
 	for i := 0; i < 4; i++ {
-		q := make(chan webrtc.DataChannelMessage, 256)
+		q := make(chan hidQueueMessage, 256)
 		s.hidQueue = append(s.hidQueue, q)
 	}
 }
 
 func (s *Session) handleQueues(index int) {
 	for msg := range s.hidQueue[index] {
-		onHidMessage(msg.Data, s)
+		onHidMessage(msg, s)
+	}
+}
+
+const keysDownStateQueueSize = 256
+
+func (s *Session) initKeysDownStateQueue() {
+	// serialise outbound key state reports so unreliable links can't stall input handling
+	s.keysDownStateQueue = make(chan usbgadget.KeysDownState, keysDownStateQueueSize)
+	go s.handleKeysDownStateQueue()
+}
+
+func (s *Session) handleKeysDownStateQueue() {
+	for state := range s.keysDownStateQueue {
+		s.reportHidRPCKeysDownState(state)
+	}
+}
+
+func (s *Session) enqueueKeysDownState(state usbgadget.KeysDownState) {
+	if s == nil || s.keysDownStateQueue == nil {
+		return
+	}
+
+	select {
+	case s.keysDownStateQueue <- state:
+	default:
+		hidRPCLogger.Warn().Msg("dropping keys down state update; queue full")
+	}
+}
+
+func getOnHidMessageHandler(session *Session, scopedLogger *zerolog.Logger, channel string) func(msg webrtc.DataChannelMessage) {
+	return func(msg webrtc.DataChannelMessage) {
+		l := scopedLogger.With().
+			Str("channel", channel).
+			Int("length", len(msg.Data)).
+			Logger()
+		// only log data if the log level is debug or lower
+		if scopedLogger.GetLevel() > zerolog.DebugLevel {
+			l = l.With().Str("data", string(msg.Data)).Logger()
+		}
+
+		if msg.IsString {
+			l.Warn().Msg("received string data in HID RPC message handler")
+			return
+		}
+
+		if len(msg.Data) < 1 {
+			l.Warn().Msg("received empty data in HID RPC message handler")
+			return
+		}
+
+		l.Trace().Msg("received data in HID RPC message handler")
+
+		// Enqueue to ensure ordered processing
+		queueIndex := hidrpc.GetQueueIndex(hidrpc.MessageType(msg.Data[0]))
+		if queueIndex >= len(session.hidQueue) || queueIndex < 0 {
+			l.Warn().Int("queueIndex", queueIndex).Msg("received data in HID RPC message handler, but queue index not found")
+			queueIndex = 3
+		}
+
+		queue := session.hidQueue[queueIndex]
+		if queue != nil {
+			queue <- hidQueueMessage{
+				DataChannelMessage: msg,
+				channel:            channel,
+			}
+		} else {
+			l.Warn().Int("queueIndex", queueIndex).Msg("received data in HID RPC message handler, but queue is nil")
+			return
+		}
 	}
 }
 
@@ -133,6 +210,7 @@ func newSession(config SessionConfig) (*Session, error) {
 	session := &Session{peerConnection: peerConnection}
 	session.rpcQueue = make(chan webrtc.DataChannelMessage, 256)
 	session.initQueues()
+	session.initKeysDownStateQueue()
 
 	go func() {
 		for msg := range session.rpcQueue {
@@ -157,40 +235,12 @@ func newSession(config SessionConfig) (*Session, error) {
 		switch d.Label() {
 		case "hidrpc":
 			session.HidChannel = d
-			d.OnMessage(func(msg webrtc.DataChannelMessage) {
-				l := scopedLogger.With().Int("length", len(msg.Data)).Logger()
-				// only log data if the log level is debug or lower
-				if scopedLogger.GetLevel() > zerolog.DebugLevel {
-					l = l.With().Str("data", string(msg.Data)).Logger()
-				}
-
-				if msg.IsString {
-					l.Warn().Msg("received string data in HID RPC message handler")
-					return
-				}
-
-				if len(msg.Data) < 1 {
-					l.Warn().Msg("received empty data in HID RPC message handler")
-					return
-				}
-
-				l.Trace().Msg("received data in HID RPC message handler")
-
-				// Enqueue to ensure ordered processing
-				queueIndex := hidrpc.GetQueueIndex(hidrpc.MessageType(msg.Data[0]))
-				if queueIndex >= len(session.hidQueue) || queueIndex < 0 {
-					l.Warn().Int("queueIndex", queueIndex).Msg("received data in HID RPC message handler, but queue index not found")
-					queueIndex = 3
-				}
-
-				queue := session.hidQueue[queueIndex]
-				if queue != nil {
-					queue <- msg
-				} else {
-					l.Warn().Int("queueIndex", queueIndex).Msg("received data in HID RPC message handler, but queue is nil")
-					return
-				}
-			})
+			d.OnMessage(getOnHidMessageHandler(session, scopedLogger, "hidrpc"))
+		// we won't send anything over the unreliable channels
+		case "hidrpc-unreliable-ordered":
+			d.OnMessage(getOnHidMessageHandler(session, scopedLogger, "hidrpc-unreliable-ordered"))
+		case "hidrpc-unreliable-nonordered":
+			d.OnMessage(getOnHidMessageHandler(session, scopedLogger, "hidrpc-unreliable-nonordered"))
 		case "rpc":
 			session.RPCChannel = d
 			d.OnMessage(func(msg webrtc.DataChannelMessage) {