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PacketReader.go
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PacketReader.go
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package peer
import (
"errors"
"fmt"
"log"
"strings"
"github.com/Gskartwii/roblox-dissector/datamodel"
"github.com/robloxapi/rbxfile"
"github.com/olebedev/emitter"
)
type decoderFunc func(*extendedReader, PacketReader, *PacketLayers) (RakNetPacket, error)
var packetDecoders = map[byte]decoderFunc{
0x05: (*extendedReader).DecodePacket05Layer,
0x06: (*extendedReader).DecodePacket06Layer,
0x07: (*extendedReader).DecodePacket07Layer,
0x08: (*extendedReader).DecodePacket08Layer,
0x00: (*extendedReader).DecodePacket00Layer,
0x03: (*extendedReader).DecodePacket03Layer,
0x09: (*extendedReader).DecodePacket09Layer,
0x10: (*extendedReader).DecodePacket10Layer,
0x13: (*extendedReader).DecodePacket13Layer,
0x15: (*extendedReader).DecodePacket15Layer,
0x1B: (*extendedReader).DecodePacket1BLayer,
0x81: (*extendedReader).DecodePacket81Layer,
0x83: (*extendedReader).DecodePacket83Layer,
0x84: (*extendedReader).DecodePacket84Layer,
0x85: (*extendedReader).DecodePacket85Layer,
0x86: (*extendedReader).DecodePacket86Layer,
0x8A: (*extendedReader).DecodePacket8ALayer,
0x8D: (*extendedReader).DecodePacket8DLayer,
0x8F: (*extendedReader).DecodePacket8FLayer,
0x90: (*extendedReader).DecodePacket90Layer,
0x92: (*extendedReader).DecodePacket92Layer,
0x93: (*extendedReader).DecodePacket93Layer,
0x96: (*extendedReader).DecodePacket96Layer,
0x97: (*extendedReader).DecodePacket97Layer,
0x9B: (*extendedReader).DecodePacket9BLayer,
}
// ContextualHandler is a generic interface for structs that
// provide a CommunicationContext and Caches
type ContextualHandler interface {
SetContext(*CommunicationContext)
Context() *CommunicationContext
SetCaches(*Caches)
Caches() *Caches
SharedStrings() map[string]rbxfile.ValueSharedString
}
// PacketReader is an interface that can be passed to packet decoders
type PacketReader interface {
ContextualHandler
SetIsClient(bool)
IsClient() bool
}
type contextualHandler struct {
context *CommunicationContext
caches *Caches
// sharedStrings contains a map of deferred strings indexed by their MD5 hash
sharedStrings map[string]rbxfile.ValueSharedString
}
func (handler *contextualHandler) Context() *CommunicationContext {
return handler.context
}
func (handler *contextualHandler) Caches() *Caches {
return handler.caches
}
func (handler *contextualHandler) SharedStrings() map[string]rbxfile.ValueSharedString {
return handler.sharedStrings
}
func (handler *contextualHandler) SetCaches(val *Caches) {
handler.caches = val
}
func (handler *contextualHandler) SetContext(val *CommunicationContext) {
handler.context = val
}
// DefaultPacketReader is a struct that can be used to read packets from a source
// Pass packets in using ReadPacket() and bind to the given callbacks
// to receive the results
type DefaultPacketReader struct {
contextualHandler
// LayerEmitter provides a low-level interface for receiving packets
// Topics: full-reliable, offline, reliable, reliability, ack
LayerEmitter *emitter.Emitter
// ErrorEmitter is the same as LayerEmitter, except invoked when layers.Error != nil ErrorEmitter *emitter.Emitter
ErrorEmitter *emitter.Emitter
// PacketEmitter provides a high-level interface for receiving offline and reliable packets
// Topics correspond to TypeString() return values
PacketEmitter *emitter.Emitter
// DataEmitter provides a high-level interface for receiving ID_DATA subpackets
// These topics correspond to TypeString() return values
DataEmitter *emitter.Emitter
isClient bool
rmState *reliableMessageState
sqState *sequenceState
ordQueue *orderingQueue
splitPackets splitPacketList
}
// IsClient implements PacketReader.IsClient()
func (reader *DefaultPacketReader) IsClient() bool {
return reader.isClient
}
// SetIsClient implements PacketReader.SetIsClient()
func (reader *DefaultPacketReader) SetIsClient(val bool) {
reader.isClient = val
}
// NewPacketReader initializes a new DefaultPacketReader
func NewPacketReader() *DefaultPacketReader {
var thisQ [32]map[uint32]*PacketLayers
for i := 0; i < 32; i++ {
thisQ[i] = make(map[uint32]*PacketLayers)
}
reader := &DefaultPacketReader{
LayerEmitter: emitter.New(0),
ErrorEmitter: emitter.New(0),
PacketEmitter: emitter.New(0),
DataEmitter: emitter.New(0),
contextualHandler: contextualHandler{
caches: new(Caches),
sharedStrings: make(map[string]rbxfile.ValueSharedString),
},
rmState: &reliableMessageState{
hasHandled: make(map[uint32]bool),
},
sqState: &sequenceState{},
ordQueue: &orderingQueue{
queue: thisQ,
},
}
reader.bindBasicPacketHandler()
reader.bindDataPacketHandler()
return reader
}
func (reader *DefaultPacketReader) emitLayers(topic string, layers *PacketLayers) {
if layers.Error != nil {
<-reader.ErrorEmitter.Emit(topic, layers)
} else {
<-reader.LayerEmitter.Emit(topic, layers)
}
}
func (reader *DefaultPacketReader) readOffline(stream *extendedReader, packetType uint8, layers *PacketLayers) {
var err error
layers.Root.logBuffer = new(strings.Builder)
layers.Root.Logger = log.New(layers.Root.logBuffer, "", log.Lmicroseconds|log.Ltime)
decoder := packetDecoders[packetType]
if decoder != nil {
layers.Main, err = decoder(stream, reader, layers)
if err != nil {
layers.Error = fmt.Errorf("Failed to decode offline packet %02X: %s", packetType, err.Error())
}
}
reader.emitLayers("offline", layers)
}
func (reader *DefaultPacketReader) readGeneric(stream *extendedReader, layers *PacketLayers) {
var err error
if layers.PacketType == 0x1B { // ID_TIMESTAMP
tsLayer, err := packetDecoders[0x1B](stream, reader, layers)
if err != nil {
layers.Reliability.SplitBuffer.Logger.Println("error:", err.Error())
layers.Error = fmt.Errorf("Failed to decode timestamped packet: %s", err.Error())
return
}
layers.Timestamp = tsLayer.(*Packet1BLayer)
packetType, err := stream.ReadByte()
if err != nil {
layers.Reliability.SplitBuffer.Logger.Println("error:", err.Error())
layers.Error = fmt.Errorf("Failed to decode timestamped packet: %s", err.Error())
return
}
layers.Reliability.SplitBuffer.PacketType = packetType
layers.Reliability.SplitBuffer.HasPacketType = true
layers.PacketType = packetType
}
decoder := packetDecoders[layers.PacketType]
// TODO: Should we really void partial deserializations?
if decoder != nil {
layers.Main, err = decoder(stream, reader, layers)
if err != nil {
layers.Main = nil
layers.Reliability.SplitBuffer.Logger.Println("error:", err.Error())
layers.Error = fmt.Errorf("Failed to decode reliable packet %02X: %s", layers.PacketType, err.Error())
}
} else {
layers.Error = fmt.Errorf("Unknown packetType %d", layers.PacketType)
}
}
func (reader *DefaultPacketReader) readOrdered(layers *PacketLayers) {
var err error
subPacket := layers.Reliability
buffer := subPacket.SplitBuffer
if buffer.IsFinal {
var packetType uint8
packetType, err = buffer.dataReader.ReadByte()
if err != nil {
subPacket.SplitBuffer.Logger.Println("error:", err.Error())
layers.Error = fmt.Errorf("Failed to decode reliablePacket type %d: %s", packetType, err.Error())
} else {
layers.PacketType = packetType
reader.readGeneric(buffer.dataReader, layers)
byteReader := buffer.byteReader
// The parser "successfully" parsed a packet, but there is still data remaining?
if byteReader.Len() != 0 && layers.Error == nil {
layers.Error = fmt.Errorf("parsed packet %02X but still have %d bytes remaining", layers.PacketType, byteReader.Len())
}
}
// fullreliablehandler, regardless of whether the parsing succeeded or not!
// this is because readGeneric will have set the Error and Main layers accordingly
reader.emitLayers("full-reliable", layers)
}
}
func (reader *DefaultPacketReader) readReliable(layers *PacketLayers) {
stream := layers.RakNet.payload
reliabilityLayer, err := stream.DecodeReliabilityLayer(reader, layers)
if err != nil {
layers.Error = errors.New("Failed to decode reliable packet: " + err.Error())
reader.emitLayers("reliability", layers)
return
}
reader.emitLayers("reliability", layers)
for _, subPacket := range reliabilityLayer.Packets {
reliablePacketLayers := &PacketLayers{Root: layers.Root, RakNet: layers.RakNet, Reliability: subPacket}
buffer, err := reader.handleSplitPacket(reliablePacketLayers)
reliablePacketLayers.SplitPacket = buffer
subPacket.SplitBuffer = buffer
reliablePacketLayers.PacketType = buffer.PacketType
if err != nil {
subPacket.SplitBuffer.Logger.Println("error while handling split:", err.Error())
reliablePacketLayers.Error = fmt.Errorf("Error while handling split packet: %s", err.Error())
reader.emitLayers("reliable", reliablePacketLayers)
return
}
reader.emitLayers("reliable", reliablePacketLayers)
thisRelPacket := reliablePacketLayers.Reliability
hasHandled := reader.rmState.hasHandled
switch thisRelPacket.Reliability {
case Unreliable:
reader.readOrdered(reliablePacketLayers)
case Reliable:
if !hasHandled[thisRelPacket.ReliableMessageNumber] {
hasHandled[thisRelPacket.ReliableMessageNumber] = true
reader.readOrdered(reliablePacketLayers)
}
case ReliableSequenced:
if !hasHandled[thisRelPacket.ReliableMessageNumber] {
hasHandled[thisRelPacket.ReliableMessageNumber] = true
if reader.sqState.highestIndex >= thisRelPacket.SequencingIndex {
reader.sqState.highestIndex = thisRelPacket.SequencingIndex
reader.readOrdered(reliablePacketLayers)
}
}
case ReliableOrdered:
if !hasHandled[thisRelPacket.ReliableMessageNumber] {
hasHandled[thisRelPacket.ReliableMessageNumber] = true
reader.ordQueue.add(reliablePacketLayers)
reliablePacketLayers = reader.ordQueue.next(subPacket.OrderingChannel)
for reliablePacketLayers != nil {
reader.readOrdered(reliablePacketLayers)
reliablePacketLayers = reader.ordQueue.next(subPacket.OrderingChannel)
}
}
default:
reliablePacketLayers.Error = fmt.Errorf("Unknown reliability: %d", reliablePacketLayers.Reliability.Reliability)
// TODO: Is it legal to emit the reliable packet twice?
reader.emitLayers("reliable", reliablePacketLayers)
return
}
}
}
// ReadPacket reads a single packet and invokes all according handler functions
func (reader *DefaultPacketReader) ReadPacket(payload []byte, layers *PacketLayers) {
var err error
if IsOfflineMessage(payload) {
layers.OfflinePayload = payload
layers.PacketType = payload[0]
layers.OfflinePayload = payload
reader.readOffline(bufferToStream(payload[1+0x10:]), layers.PacketType, layers)
return
}
stream := bufferToStream(payload)
// TODO: Should not create RakNetLayer if it's an offline message
rakNetLayer, err := stream.DecodeRakNetLayer(reader, payload[0], layers)
layers.PacketType = payload[0]
if err != nil {
layers.Error = err
reader.emitLayers("offline", layers)
return
}
layers.RakNet = rakNetLayer
if rakNetLayer.Flags.IsACK || rakNetLayer.Flags.IsNAK {
reader.emitLayers("ack", layers)
} else {
reader.readReliable(layers)
}
}
// HandlePacket01 is the default handler for ID_REPLIC_DELETE_INSTANCE packets
func (reader *DefaultPacketReader) HandlePacket01(e *emitter.Event) {
packet := e.Args[0].(*Packet83_01)
err := packet.Instance.SetParent(nil)
if err != nil {
e.Args[1].(*PacketLayers).Root.Logger.Println("delete error:", err.Error())
}
}
func (reader *DefaultPacketReader) handleReplicationInstance(inst *ReplicationInstance) error {
// First, assign the properties
inst.Instance.PropertiesMutex.Lock()
for name, val := range inst.Properties {
// Do not call Set() here. Nothing should be listening to PropertyEmitter
// and we have the lock
inst.Instance.Properties[name] = val
}
inst.Instance.PropertiesMutex.Unlock()
// Once they are assigned, we can release this instance to be used by the DataModel
return inst.Instance.SetParent(inst.Parent)
}
// HandlePacket02 is the default handler for ID_REPLIC_NEW_INSTANCE packets
func (reader *DefaultPacketReader) HandlePacket02(e *emitter.Event) {
packet := e.Args[0].(*Packet83_02)
err := reader.handleReplicationInstance(packet.ReplicationInstance)
if err != nil {
e.Args[1].(*PacketLayers).Error = err
}
}
// HandlePacket03 is the default handler for ID_REPLIC_PROP packets
func (reader *DefaultPacketReader) HandlePacket03(e *emitter.Event) {
packet := e.Args[0].(*Packet83_03)
if packet.Schema == nil {
// Parent handler
err := packet.Value.(datamodel.ValueReference).Instance.AddChild(packet.Instance)
if err != nil {
e.Args[1].(*PacketLayers).Error = err
}
return
}
packet.Instance.Set(packet.Schema.Name, packet.Value)
}
// HandlePacket07 is the default handler fo ID_REPLIC_EVENT packets
func (reader *DefaultPacketReader) HandlePacket07(e *emitter.Event) {
packet := e.Args[0].(*Packet83_07)
packet.Instance.FireEvent(packet.Schema.Name, packet.Event.Arguments...)
}
// HandlePacket0B is the default handler for ID_REPLIC_JOIN_DATA packets
func (reader *DefaultPacketReader) HandlePacket0B(e *emitter.Event) {
packet := e.Args[0].(*Packet83_0B)
for _, inst := range packet.Instances {
err := reader.handleReplicationInstance(inst)
if err != nil {
e.Args[1].(*PacketLayers).Error = err
return
}
}
}
// HandlePacket13 is the default handler for ID_REPLIC_ATOMIC packets
func (reader *DefaultPacketReader) HandlePacket13(e *emitter.Event) {
packet := e.Args[0].(*Packet83_13)
packet.Instance.SetParent(packet.Parent)
}
// HandlePacket81 is the default handler for ID_SET_GLOBALS packets
func (reader *DefaultPacketReader) HandlePacket81(e *emitter.Event) {
packet := e.Args[0].(*Packet81Layer)
for _, item := range packet.Items {
reader.context.DataModel.AddService(item.Instance)
}
}
// BindDataModelHandlers binds the default handlers so that the PacketReader
// will update the DataModel based on what it reads
func (reader *DefaultPacketReader) BindDataModelHandlers() {
reader.PacketEmitter.On("ID_SET_GLOBALS", reader.HandlePacket81, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_DELETE_INSTANCE", reader.HandlePacket01, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_NEW_INSTANCE", reader.HandlePacket02, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_PROP", reader.HandlePacket03, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_EVENT", reader.HandlePacket07, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_JOIN_DATA", reader.HandlePacket0B, emitter.Void)
reader.DataEmitter.On("ID_REPLIC_ATOMIC", reader.HandlePacket13, emitter.Void)
}
func (reader *DefaultPacketReader) bindBasicPacketHandler() {
// important: sync!
reader.LayerEmitter.On("full-reliable", func(e *emitter.Event) {
layers := e.Args[0].(*PacketLayers)
<-reader.PacketEmitter.Emit(layers.Main.TypeString(), layers.Main, layers)
}, emitter.Void)
reader.LayerEmitter.On("offline", func(e *emitter.Event) {
layers := e.Args[0].(*PacketLayers)
<-reader.PacketEmitter.Emit(layers.Main.TypeString(), layers.Main, layers)
}, emitter.Void)
}
func (reader *DefaultPacketReader) bindDataPacketHandler() {
// important: sync!
reader.PacketEmitter.On("ID_DATA", func(e *emitter.Event) {
layers := e.Args[1].(*PacketLayers)
for _, sub := range layers.Main.(*Packet83Layer).SubPackets {
subLayers := &PacketLayers{
Root: layers.Root,
RakNet: layers.RakNet,
Reliability: layers.Reliability,
SplitPacket: layers.SplitPacket,
Timestamp: layers.Timestamp,
Main: layers.Main,
Error: layers.Error,
PacketType: sub.Type(),
Subpacket: sub,
}
<-reader.DataEmitter.Emit(sub.TypeString(), sub, subLayers)
}
}, emitter.Void)
}
// Layers returns the emitter for successfully parsed packets
func (reader *DefaultPacketReader) Layers() *emitter.Emitter {
return reader.LayerEmitter
}
// Errors returns the emitter for parser errors
func (reader *DefaultPacketReader) Errors() *emitter.Emitter {
return reader.ErrorEmitter
}