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packet.go
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packet.go
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// Package packet implements a LIFX LAN protocol version 2 packet.
//
// This package is not designed to be accessed by end users, all interaction
// should occur via the Client in the golifx package.
package packet
import (
"bytes"
"encoding/binary"
"math/rand"
"net"
"sync"
"github.com/lunixbochs/struc"
"github.com/pdf/golifx/common"
"github.com/pdf/golifx/protocol/v2/shared"
)
const (
headerBytes = 36
)
var (
ClientID uint32
)
type Response struct {
Result Packet
Error error
}
type Packet struct {
Frame
FrameAddress
ProtocolHeader
payload []byte
destination *net.UDPAddr
socket *net.UDPConn
mutex sync.RWMutex
}
type Chan chan Response
type Frame struct {
Size uint16 `struc:"little"` // Size of entire message in bytes including this field
// Origin (2-bit): Message origin indicator: must be zero (0)
// Tagged (1-bit): Determines usage of Frame Address *target* field
// Addressable (1-bit): Message includes a target address: must be one (1)
// Protocol (12-bit): Protocol number: must be 1024 (decimal)
OriginTaggedAddressableProtocol uint16 `struct:"little"`
Source uint32 `struc:"little"` // Source identifier: unique value set by the client, used by responses
}
type FrameAddress struct {
Target uint64 `struc:"little"` // Device address (MAC address) or zero (0) means all devices
Reserved [6]uint8 `struc:"little"`
// Reserved(6-bit)
// AckRequired(1-bit): Acknowledgement message required
// ResRequired(1-bit): Response message required
ReservedAckRequiredResRequired uint8 `struc:"little"`
Sequence uint8 `struc:"little"`
}
type ProtocolHeader struct {
Reserved0 uint64 `struc:"little"` // Reserved
Type uint16 `struc:"little"` // Message type determines the payload being used
Reserved1 uint16 `struc:"little"` // Reserved
}
func (f *Frame) SetSize(size uint16) {
f.Size = size
}
func (f *Frame) SetTagged(tagged bool) {
if tagged {
f.OriginTaggedAddressableProtocol = uint16(setBits(uint64(f.OriginTaggedAddressableProtocol), 16, 2, 1, 1))
} else {
f.OriginTaggedAddressableProtocol = uint16(setBits(uint64(f.OriginTaggedAddressableProtocol), 16, 2, 1, 0))
}
}
func (f *Frame) GetTagged() bool {
return getBits(uint64(f.OriginTaggedAddressableProtocol), 16, 2, 1) != 0
}
func (f *Frame) SetAddressable(addressable bool) {
if addressable {
f.OriginTaggedAddressableProtocol = uint16(setBits(uint64(f.OriginTaggedAddressableProtocol), 16, 3, 1, 1))
} else {
f.OriginTaggedAddressableProtocol = uint16(setBits(uint64(f.OriginTaggedAddressableProtocol), 16, 3, 1, 0))
}
}
func (f *Frame) GetAddressable() bool {
return getBits(uint64(f.OriginTaggedAddressableProtocol), 16, 3, 1) != 0
}
func (f *Frame) SetProtocol(protocol uint16) {
f.OriginTaggedAddressableProtocol = uint16(setBits(uint64(f.OriginTaggedAddressableProtocol), 16, 4, 12, uint64(protocol)))
}
func (f *Frame) GetProtocol() uint16 {
return uint16(getBits(uint64(f.OriginTaggedAddressableProtocol), 16, 4, 12))
}
func (f *Frame) SetSource(source uint32) {
f.Source = source
}
func (f *Frame) GetSource() uint32 {
return f.Source
}
func (f *FrameAddress) SetTarget(target uint64) {
f.Target = target
}
func (f *FrameAddress) GetTarget() uint64 {
return f.Target
}
func (f *FrameAddress) SetAckRequired(ackRequired bool) {
if ackRequired {
f.ReservedAckRequiredResRequired = uint8(setBits(uint64(f.ReservedAckRequiredResRequired), 8, 6, 1, 1))
} else {
f.ReservedAckRequiredResRequired = uint8(setBits(uint64(f.ReservedAckRequiredResRequired), 8, 6, 1, 0))
}
}
func (f *FrameAddress) GetAckRequired() bool {
return getBits(uint64(f.ReservedAckRequiredResRequired), 8, 6, 1) != 0
}
func (f *FrameAddress) SetResRequired(resRequired bool) {
if resRequired {
f.ReservedAckRequiredResRequired = uint8(setBits(uint64(f.ReservedAckRequiredResRequired), 8, 7, 1, 1))
} else {
f.ReservedAckRequiredResRequired = uint8(setBits(uint64(f.ReservedAckRequiredResRequired), 8, 7, 1, 1))
}
}
func (f *FrameAddress) GetResRequired() bool {
return getBits(uint64(f.ReservedAckRequiredResRequired), 8, 7, 1) != 0
}
func (f *FrameAddress) SetSequence(sequence uint8) {
f.Sequence = sequence
}
func (f *FrameAddress) GetSequence() uint8 {
//sequence := uint64(math.MaxUint8)
//sequence &= f.ReservedAckRequiredResRequiredSequence
return f.Sequence
}
func (h *ProtocolHeader) GetType() shared.Message {
return shared.Message(h.Type)
}
func (h *ProtocolHeader) SetType(msgType shared.Message) {
h.Type = uint16(msgType)
}
func (p *Packet) Write() error {
var (
err error
byteArr []byte
size []byte
sizeBuf *bytes.Buffer
)
// Encode
p.Frame.Size, byteArr, err = p.encode()
if err != nil {
return err
}
sizeBuf = new(bytes.Buffer)
if err := binary.Write(sizeBuf, binary.LittleEndian, p.Frame.Size); err != nil {
return err
}
size = sizeBuf.Bytes()
// Set size
for i, b := range size {
byteArr[i] = b
}
common.Log.Debugf("Writing packet data: source %v, type %v, sequence %v, target %v, protocol %v, tagged %v, resRequired %v, ackRequired %v, frameOrigin %b: %+v\n", p.GetSource(), p.GetType(), p.GetSequence(), p.GetTarget(), p.GetProtocol(), p.GetTagged(), p.GetResRequired(), p.GetAckRequired(), p.Frame.OriginTaggedAddressableProtocol, *p)
// Write the packet
_, err = p.socket.WriteToUDP(byteArr, p.destination)
return err
}
func (p *Packet) SetPayload(payload interface{}) error {
buf := new(bytes.Buffer)
if err := binary.Write(buf, binary.LittleEndian, payload); err != nil {
return err
}
p.mutex.Lock()
p.payload = buf.Bytes()
p.mutex.Unlock()
return nil
}
func (p *Packet) GetPayload() []byte {
return p.payload
}
func (p *Packet) DecodePayload(dest interface{}) error {
p.mutex.RLock()
if len(p.payload) == 0 {
p.mutex.RUnlock()
return common.ErrProtocol
}
err := binary.Read(bytes.NewBuffer(p.payload), binary.LittleEndian, dest)
p.mutex.RUnlock()
return err
}
func (p *Packet) encode() (length uint16, byteArr []byte, err error) {
buf := new(bytes.Buffer)
// Pack the packet
p.mutex.RLock()
err = binary.Write(buf, binary.LittleEndian, p.Frame)
if err != nil {
p.mutex.RUnlock()
return
}
err = binary.Write(buf, binary.LittleEndian, p.FrameAddress)
if err != nil {
p.mutex.RUnlock()
return
}
err = binary.Write(buf, binary.LittleEndian, p.ProtocolHeader)
if err != nil {
p.mutex.RUnlock()
return
}
//err = struc.Pack(buf, p)
p.mutex.RUnlock()
if err != nil {
return
}
// Append the packed payload
if len(p.payload) > 0 {
p.mutex.RLock()
_, err = buf.Write(p.payload)
p.mutex.RUnlock()
if err != nil {
return
}
}
return uint16(buf.Len()), buf.Bytes(), nil
}
func init() {
ClientID = rand.Uint32()
}
func New(destination *net.UDPAddr, socket *net.UDPConn) *Packet {
p := &Packet{
destination: destination,
socket: socket,
}
p.Frame.SetSource(ClientID)
p.Frame.SetAddressable(true) // Must be true
p.Frame.SetProtocol(1024) // Must be 1024
return p
}
func Decode(buf []byte) (*Packet, error) {
pkt := new(Packet)
err := struc.Unpack(bytes.NewBuffer(buf), pkt)
if err != nil {
return pkt, err
}
pkt.payload = buf[headerBytes:]
return pkt, nil
}
func bits(n uint8) uint64 {
return (1 << n) - 1
}
func bitMask(endLSB, startLSB uint8) uint64 {
return bits(endLSB) &^ bits(startLSB)
}
func rangeToLSB(size, index, length uint8) (endLSB, startLSB uint8) {
startLSB = size - index - length
endLSB = startLSB + length
return endLSB, startLSB
}
func setBits(input uint64, size, index, length uint8, value uint64) uint64 {
endLSB, startLSB := rangeToLSB(size, index, length)
return input&^bitMask(endLSB, startLSB) | (value << startLSB)
}
func getBits(input uint64, size, index, length uint8) uint64 {
endLSB, startLSB := rangeToLSB(size, index, length)
return (input & bitMask(endLSB, startLSB)) >> startLSB
}