feat: hid rpc channel (#755)

* feat: use hidRpcChannel to save bandwidth

* chore: simplify handshake of hid rpc

* add logs

* chore: add timeout when writing to hid endpoints

* fix issues

* chore: show hid rpc version

* refactor hidrpc marshal / unmarshal

* add queues for keyboard / mouse event

* chore: change logging level of JSONRPC send event to trace

* minor changes related to logging

* fix: nil check

* chore: add comments and remove unused code

* add useMouse

* chore: log msg data only when debug or trace mode

* chore: make tslint happy

* chore: unlock keyboardStateLock before calling onKeysDownChange

* chore: remove keyPressReportApiAvailable

* chore: change version handle

* chore: clean up unused functions

* remove comments

internal/hidrpc/hidrpc.go

@@ -0,0 +1,100 @@
+package hidrpc
+
+import (
+	"fmt"
+
+	"github.com/jetkvm/kvm/internal/usbgadget"
+)
+
+// MessageType is the type of the HID RPC message
+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
+)
+
+const (
+	Version byte = 0x01 // Version of the HID RPC protocol
+)
+
+// GetQueueIndex returns the index of the queue to which the message should be enqueued.
+func GetQueueIndex(messageType MessageType) int {
+	switch messageType {
+	case TypeHandshake:
+		return 0
+	case TypeKeyboardReport, TypeKeypressReport, TypeKeyboardLedState, TypeKeydownState:
+		return 1
+	case TypePointerReport, TypeMouseReport, TypeWheelReport:
+		return 2
+	default:
+		return 3
+	}
+}
+
+// Unmarshal unmarshals the HID RPC message from the data.
+func Unmarshal(data []byte, message *Message) error {
+	l := len(data)
+	if l < 1 {
+		return fmt.Errorf("invalid data length: %d", l)
+	}
+
+	message.t = MessageType(data[0])
+	message.d = data[1:]
+	return nil
+}
+
+// Marshal marshals the HID RPC message to the data.
+func Marshal(message *Message) ([]byte, error) {
+	if message.t == 0 {
+		return nil, fmt.Errorf("invalid message type: %d", message.t)
+	}
+
+	data := make([]byte, len(message.d)+1)
+	data[0] = byte(message.t)
+	copy(data[1:], message.d)
+
+	return data, nil
+}
+
+// NewHandshakeMessage creates a new handshake message.
+func NewHandshakeMessage() *Message {
+	return &Message{
+		t: TypeHandshake,
+		d: []byte{Version},
+	}
+}
+
+// NewKeyboardReportMessage creates a new keyboard report message.
+func NewKeyboardReportMessage(keys []byte, modifier uint8) *Message {
+	return &Message{
+		t: TypeKeyboardReport,
+		d: append([]byte{modifier}, keys...),
+	}
+}
+
+// NewKeyboardLedMessage creates a new keyboard LED message.
+func NewKeyboardLedMessage(state usbgadget.KeyboardState) *Message {
+	return &Message{
+		t: TypeKeyboardLedState,
+		d: []byte{state.Byte()},
+	}
+}
+
+// NewKeydownStateMessage creates a new keydown state message.
+func NewKeydownStateMessage(state usbgadget.KeysDownState) *Message {
+	data := make([]byte, len(state.Keys)+1)
+	data[0] = state.Modifier
+	copy(data[1:], state.Keys)
+
+	return &Message{
+		t: TypeKeydownState,
+		d: data,
+	}
+}

internal/hidrpc/message.go

@@ -0,0 +1,133 @@
+package hidrpc
+
+import (
+	"fmt"
+)
+
+// Message ..
+type Message struct {
+	t MessageType
+	d []byte
+}
+
+// Marshal marshals the message to a byte array.
+func (m *Message) Marshal() ([]byte, error) {
+	return Marshal(m)
+}
+
+func (m *Message) Type() MessageType {
+	return m.t
+}
+
+func (m *Message) String() string {
+	switch m.t {
+	case TypeHandshake:
+		return "Handshake"
+	case TypeKeypressReport:
+		if len(m.d) < 2 {
+			return fmt.Sprintf("KeypressReport{Malformed: %v}", m.d)
+		}
+		return fmt.Sprintf("KeypressReport{Key: %d, Press: %v}", m.d[0], m.d[1] == uint8(1))
+	case TypeKeyboardReport:
+		if len(m.d) < 2 {
+			return fmt.Sprintf("KeyboardReport{Malformed: %v}", m.d)
+		}
+		return fmt.Sprintf("KeyboardReport{Modifier: %d, Keys: %v}", m.d[0], m.d[1:])
+	case TypePointerReport:
+		if len(m.d) < 9 {
+			return fmt.Sprintf("PointerReport{Malformed: %v}", m.d)
+		}
+		return fmt.Sprintf("PointerReport{X: %d, Y: %d, Button: %d}", m.d[0:4], m.d[4:8], m.d[8])
+	case TypeMouseReport:
+		if len(m.d) < 3 {
+			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])
+	default:
+		return fmt.Sprintf("Unknown{Type: %d, Data: %v}", m.t, m.d)
+	}
+}
+
+// KeypressReport ..
+type KeypressReport struct {
+	Key   byte
+	Press bool
+}
+
+// KeypressReport returns the keypress report from the message.
+func (m *Message) KeypressReport() (KeypressReport, error) {
+	if m.t != TypeKeypressReport {
+		return KeypressReport{}, fmt.Errorf("invalid message type: %d", m.t)
+	}
+
+	return KeypressReport{
+		Key:   m.d[0],
+		Press: m.d[1] == uint8(1),
+	}, nil
+}
+
+// KeyboardReport ..
+type KeyboardReport struct {
+	Modifier byte
+	Keys     []byte
+}
+
+// KeyboardReport returns the keyboard report from the message.
+func (m *Message) KeyboardReport() (KeyboardReport, error) {
+	if m.t != TypeKeyboardReport {
+		return KeyboardReport{}, fmt.Errorf("invalid message type: %d", m.t)
+	}
+
+	return KeyboardReport{
+		Modifier: m.d[0],
+		Keys:     m.d[1:],
+	}, nil
+}
+
+// PointerReport ..
+type PointerReport struct {
+	X      int
+	Y      int
+	Button uint8
+}
+
+func toInt(b []byte) int {
+	return int(b[0])<<24 + int(b[1])<<16 + int(b[2])<<8 + int(b[3])<<0
+}
+
+// PointerReport returns the point report from the message.
+func (m *Message) PointerReport() (PointerReport, error) {
+	if m.t != TypePointerReport {
+		return PointerReport{}, fmt.Errorf("invalid message type: %d", m.t)
+	}
+
+	if len(m.d) != 9 {
+		return PointerReport{}, fmt.Errorf("invalid message length: %d", len(m.d))
+	}
+
+	return PointerReport{
+		X:      toInt(m.d[0:4]),
+		Y:      toInt(m.d[4:8]),
+		Button: uint8(m.d[8]),
+	}, nil
+}
+
+// MouseReport ..
+type MouseReport struct {
+	DX     int8
+	DY     int8
+	Button uint8
+}
+
+// MouseReport returns the mouse report from the message.
+func (m *Message) MouseReport() (MouseReport, error) {
+	if m.t != TypeMouseReport {
+		return MouseReport{}, fmt.Errorf("invalid message type: %d", m.t)
+	}
+
+	return MouseReport{
+		DX:     int8(m.d[0]),
+		DY:     int8(m.d[1]),
+		Button: uint8(m.d[2]),
+	}, nil
+}

internal/usbgadget/consts.go

@@ -1,3 +1,7 @@
 package usbgadget
 
+import "time"
+
 const dwc3Path = "/sys/bus/platform/drivers/dwc3"
+
+const hidWriteTimeout = 10 * time.Millisecond

internal/usbgadget/hid_keyboard.go

@@ -86,6 +86,12 @@ type KeyboardState struct {
 	Compose    bool `json:"compose"`
 	Kana       bool `json:"kana"`
 	Shift      bool `json:"shift"` // This is not part of the main USB HID spec
+	raw        byte
+}
+
+// Byte returns the raw byte representation of the keyboard state.
+func (k *KeyboardState) Byte() byte {
+	return k.raw
 }
 
 func getKeyboardState(b byte) KeyboardState {
@@ -97,6 +103,7 @@ func getKeyboardState(b byte) KeyboardState {
 		Compose:    b&KeyboardLedMaskCompose != 0,
 		Kana:       b&KeyboardLedMaskKana != 0,
 		Shift:      b&KeyboardLedMaskShift != 0,
+		raw:        b,
 	}
 }
 
@@ -139,19 +146,26 @@ func (u *UsbGadget) GetKeysDownState() KeysDownState {
 }
 
 func (u *UsbGadget) updateKeyDownState(state KeysDownState) {
-	u.keyboardStateLock.Lock()
-	defer u.keyboardStateLock.Unlock()
+	u.log.Trace().Interface("old", u.keysDownState).Interface("new", state).Msg("acquiring keyboardStateLock for updateKeyDownState")
 
-	if u.keysDownState.Modifier == state.Modifier &&
-		bytes.Equal(u.keysDownState.Keys, state.Keys) {
-		return // No change in key down state
+	// this is intentional to unlock keyboard state lock before onKeysDownChange callback
+	{
+		u.keyboardStateLock.Lock()
+		defer u.keyboardStateLock.Unlock()
+
+		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
 	}
 
-	u.log.Trace().Interface("old", u.keysDownState).Interface("new", state).Msg("keysDownState updated")
-	u.keysDownState = state
-
 	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")
 	}
 }
 
@@ -233,7 +247,7 @@ func (u *UsbGadget) keyboardWriteHidFile(modifier byte, keys []byte) error {
 		return err
 	}
 
-	_, err := u.keyboardHidFile.Write(append([]byte{modifier, 0x00}, keys[:hidKeyBufferSize]...))
+	_, err := u.writeWithTimeout(u.keyboardHidFile, append([]byte{modifier, 0x00}, keys[:hidKeyBufferSize]...))
 	if err != nil {
 		u.logWithSuppression("keyboardWriteHidFile", 100, u.log, err, "failed to write to hidg0")
 		u.keyboardHidFile.Close()

internal/usbgadget/hid_mouse_absolute.go

@@ -74,7 +74,7 @@ func (u *UsbGadget) absMouseWriteHidFile(data []byte) error {
 		}
 	}
 
-	_, err := u.absMouseHidFile.Write(data)
+	_, err := u.writeWithTimeout(u.absMouseHidFile, data)
 	if err != nil {
 		u.logWithSuppression("absMouseWriteHidFile", 100, u.log, err, "failed to write to hidg1")
 		u.absMouseHidFile.Close()

internal/usbgadget/hid_mouse_relative.go

@@ -64,7 +64,7 @@ func (u *UsbGadget) relMouseWriteHidFile(data []byte) error {
 		}
 	}
 
-	_, err := u.relMouseHidFile.Write(data)
+	_, err := u.writeWithTimeout(u.relMouseHidFile, data)
 	if err != nil {
 		u.logWithSuppression("relMouseWriteHidFile", 100, u.log, err, "failed to write to hidg2")
 		u.relMouseHidFile.Close()

internal/usbgadget/utils.go

@@ -3,10 +3,13 @@ package usbgadget
 import (
 	"bytes"
 	"encoding/json"
+	"errors"
 	"fmt"
+	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"time"
 
 	"github.com/rs/zerolog"
 )
@@ -107,6 +110,31 @@ func compareFileContent(oldContent []byte, newContent []byte, looserMatch bool)
 	return false
 }
 
+func (u *UsbGadget) writeWithTimeout(file *os.File, data []byte) (n int, err error) {
+	if err := file.SetWriteDeadline(time.Now().Add(hidWriteTimeout)); err != nil {
+		return -1, err
+	}
+
+	n, err = file.Write(data)
+	if err == nil {
+		return
+	}
+
+	if errors.Is(err, os.ErrDeadlineExceeded) {
+		u.logWithSuppression(
+			fmt.Sprintf("writeWithTimeout_%s", file.Name()),
+			1000,
+			u.log,
+			err,
+			"write timed out: %s",
+			file.Name(),
+		)
+		err = nil
+	}
+
+	return
+}
+
 func (u *UsbGadget) logWithSuppression(counterName string, every int, logger *zerolog.Logger, err error, msg string, args ...any) {
 	u.logSuppressionLock.Lock()
 	defer u.logSuppressionLock.Unlock()