feat(data-plane): implement phase3c gateway

gateway/input.go

@@ -0,0 +1,38 @@
+package gateway
+
+import (
+	"encoding/binary"
+	"errors"
+)
+
+var ErrInputMalformed = errors.New("input event malformed")
+
+func EncodeInputEvent(event InputEvent) ([]byte, error) {
+	if len(event.Device) == 0 || len(event.Device) > 64 || len(event.Payload) > 1024 {
+		return nil, ErrInputMalformed
+	}
+	encoded := make([]byte, 16+len(event.Device)+len(event.Payload))
+	copy(encoded[:4], "INP1")
+	binary.BigEndian.PutUint32(encoded[4:8], event.Sequence)
+	binary.BigEndian.PutUint32(encoded[8:12], uint32(event.Code))
+	if event.Pressed {
+		encoded[12] = 1
+	}
+	encoded[13] = byte(len(event.Device))
+	binary.BigEndian.PutUint16(encoded[14:16], uint16(len(event.Payload)))
+	copy(encoded[16:16+len(event.Device)], event.Device)
+	copy(encoded[16+len(event.Device):], event.Payload)
+	return encoded, nil
+}
+
+func DecodeInputEvent(data []byte) (InputEvent, error) {
+	if len(data) < 16 || len(data) > 1179 || string(data[:4]) != "INP1" || (data[12] != 0 && data[12] != 1) {
+		return InputEvent{}, ErrInputMalformed
+	}
+	deviceLength := int(data[13])
+	payloadLength := int(binary.BigEndian.Uint16(data[14:16]))
+	if deviceLength == 0 || deviceLength > 64 || payloadLength > 1024 || len(data) != 16+deviceLength+payloadLength {
+		return InputEvent{}, ErrInputMalformed
+	}
+	return InputEvent{Sequence: binary.BigEndian.Uint32(data[4:8]), Code: int32(binary.BigEndian.Uint32(data[8:12])), Pressed: data[12] == 1, Device: string(data[16 : 16+deviceLength]), Payload: append([]byte(nil), data[16+deviceLength:]...)}, nil
+}