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/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()