new-server/internal/drivers/lifx/packet.go

package lifx

import (
	"encoding/binary"
	"fmt"
	"git.aiterp.net/lucifer/new-server/internal/lerrors"
	"log"
	"net"
)

func createPacket() Packet {
	p := make(Packet, 36)
	p.Reset()

	return p
}

type Packet []byte

func (p *Packet) Reset() {
	p.ensureHeader()
	copy(*p, blankHeader)
}

func (p *Packet) Size() int {
	return int(binary.LittleEndian.Uint16((*p)[0:2]))
}

func (p *Packet) Protocol() int {
	return int(binary.LittleEndian.Uint16((*p)[2:3]) & 0b00001111_11111111)
}

func (p *Packet) SetTagged(v bool) {
	if v {
		(*p)[3] |= uint8(0b00100000)
	} else {
		(*p)[3] &= ^uint8(0b00100000)
	}
}

func (p *Packet) Source() uint32 {
	return binary.LittleEndian.Uint32((*p)[4:8])
}

func (p *Packet) Target() net.HardwareAddr {
	return net.HardwareAddr((*p)[8:14])
}

func (p *Packet) SetSource(v uint32) {
	binary.LittleEndian.PutUint32((*p)[4:8], v)
}

func (p *Packet) CopyTargetFrom(other Packet) {
	copy((*p)[8:14], other[8:14])
}

func (p *Packet) SetTarget(v string) error {
	addr, err := net.ParseMAC(v)
	if err != nil {
		return err
	}
	if len(addr) != 6 {
		return lerrors.ErrInvalidAddress
	}

	copy((*p)[8:], addr)
	return nil
}

func (p *Packet) SetResRequired(v bool) {
	if v {
		(*p)[22] |= uint8(0b00000001)
	} else {
		(*p)[22] &= ^uint8(0b00000001)
	}
}

func (p *Packet) SetAckRequired(v bool) {
	if v {
		(*p)[22] |= uint8(0b00000010)
	} else {
		(*p)[22] &= ^uint8(0b00000010)
	}
}

func (p *Packet) Sequence() uint8 {
	return (*p)[23]
}

func (p *Packet) SetSequence(v uint8) {
	(*p)[23] = v
}

func (p *Packet) PacketType() uint16 {
	return binary.LittleEndian.Uint16((*p)[32:34])
}

func (p *Packet) SetRawPayload(packetType uint16, data []byte) {
	p.ensureSize(36 + len(data))
	copy((*p)[36:], data)
	binary.LittleEndian.PutUint16(*p, uint16(36+len(data)))
	binary.LittleEndian.PutUint16((*p)[32:34], packetType)
}

func (p *Packet) Payload() (res Payload, err error) {
	switch p.PacketType() {
	case 2:
		res = &GetService{}
	case 3:
		res = &StateService{}
		err = res.Decode((*p)[36:])
	case 14:
		res = &GetHostFirmware{}
	case 15:
		res = &StateHostFirmware{}
		err = res.Decode((*p)[36:])
	case 32:
		res = &GetVersion{}
	case 33:
		res = &StateVersion{}
		err = res.Decode((*p)[36:])
	case 45:
		res = &Acknowledgement{}
	case 101:
		res = &GetColor{}
	case 102:
		res = &SetColor{}
		err = res.Decode((*p)[36:])
	case 107:
		res = &LightState{}
		err = res.Decode((*p)[36:])
	case 117:
		res = &SetLightPower{}
		err = res.Decode((*p)[36:])
	default:
		err = lerrors.ErrUnrecognizedPacketType
	}

	if err != nil {
		res = nil
	}

	if res != nil && res.PacketType() != p.PacketType() {
		log.Println("BUG Incorrect packet type used in Packet.Payload")
		log.Println("BUG   Payload Type:", p.PacketType())
		log.Println("BUG   Panic Packet Type:", res.PacketType())
		log.Println("BUG   Panic Payload:", res.String())
	}

	return
}

func (p *Packet) SetPayload(payload Payload) {
	ackRequired, resRequired := payload.Flags()

	p.SetRawPayload(payload.PacketType(), payload.Encode())
	p.SetAckRequired(ackRequired)
	p.SetResRequired(resRequired)
}

func (p *Packet) ensureHeader() {
	p.ensureSize(36)
}

func (p *Packet) ensureSize(size int) {
	if len(*p) < size {
		newData := make([]byte, size)
		copy(newData, *p)
		*p = newData
	}
}

type Payload interface {
	fmt.Stringer
	Decode(data []byte) error
	Encode() []byte
	PacketType() uint16
	Flags() (ackRequired bool, resRequired bool)
}

var blankHeader = []byte{
	0x24, 0x00, 0x00, 0x14,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
	0x00, 0x00, 0x00, 0x00,
}