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ExtendedReader.go
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ExtendedReader.go
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package peer
import (
"bytes"
"compress/gzip"
"crypto/aes"
"crypto/cipher"
"encoding/binary"
"errors"
"fmt"
"io"
"math"
"net"
"github.com/DataDog/zstd"
"github.com/Gskartwii/roblox-dissector/datamodel"
"github.com/robloxapi/rbxfile"
)
// TODO: Move extendedReader to its own package (roblox-dissector/parser)?
type extendedReader struct {
r io.Reader
}
func (b *extendedReader) ReadByte() (byte, error) {
var byt [1]byte
n, err := b.r.Read(byt[:])
if n != 1 {
return 0, err
}
return byt[0], nil
}
func (b *extendedReader) Read(dest []byte) (int, error) {
return b.r.Read(dest)
}
func (b *extendedReader) bytes(dest []byte, length int) error {
n, err := b.Read(dest[:length])
if n != length {
return err
}
return nil
}
func (b *extendedReader) readUint16BE() (uint16, error) {
dest := make([]byte, 2)
err := b.bytes(dest, 2)
return binary.BigEndian.Uint16(dest), err
}
func (b *extendedReader) readUint16LE() (uint16, error) {
dest := make([]byte, 2)
err := b.bytes(dest, 2)
return binary.LittleEndian.Uint16(dest), err
}
func (b *extendedReader) readBoolByte() (bool, error) {
res, err := b.ReadByte()
if err != nil {
return false, err
}
switch res {
case 0:
return false, err
case 1:
return true, err
default:
return false, errors.New("invalid bool byte")
}
}
func (b *extendedReader) readUint24LE() (uint32, error) {
dest := make([]byte, 4)
err := b.bytes(dest, 3)
return binary.LittleEndian.Uint32(dest), err
}
func (b *extendedReader) readUint32BE() (uint32, error) {
dest := make([]byte, 4)
err := b.bytes(dest, 4)
return binary.BigEndian.Uint32(dest), err
}
func (b *extendedReader) readUint32LE() (uint32, error) {
dest := make([]byte, 4)
err := b.bytes(dest, 4)
return binary.LittleEndian.Uint32(dest), err
}
func (b *extendedReader) readUint64BE() (uint64, error) {
dest := make([]byte, 8)
err := b.bytes(dest, 8)
return binary.BigEndian.Uint64(dest), err
}
func (b *extendedReader) readUint8() (uint8, error) {
res, err := b.ReadByte()
return uint8(res), err
}
func (b *extendedReader) readString(length int) ([]byte, error) {
var dest []byte
if uint(length) > 0x1000000 {
return dest, errors.New("Sanity check: string too long")
}
dest = make([]byte, length)
err := b.bytes(dest, length)
return dest, err
}
func (b *extendedReader) readLengthAndString() (string, error) {
var ret []byte
thisLen, err := b.readUint16BE()
if err != nil {
return "", err
}
ret, err = b.readString(int(thisLen))
return string(ret), err
}
func (b *extendedReader) readASCII(length int) (string, error) {
res, err := b.readString(length)
return string(res), err
}
func (b *extendedReader) readAddress() (*net.UDPAddr, error) {
version, err := b.readUint8()
if err != nil {
return nil, err
}
if version != 4 {
return nil, errors.New("Unsupported version")
}
var address net.IP = make([]byte, 4)
err = b.bytes(address, 4)
if err != nil {
return nil, err
}
for i := 0; i < 4; i++ {
address[i] = address[i] ^ 0xFF // bitwise NOT
}
port, err := b.readUint16BE()
if err != nil {
return nil, err
}
return &net.UDPAddr{IP: address, Port: int(port)}, nil
}
func (b *extendedReader) readFloat32LE() (float32, error) {
intf, err := b.readUint32LE()
if err != nil {
return 0.0, err
}
return math.Float32frombits(intf), err
}
func (b *extendedReader) readFloat32BE() (float32, error) {
intf, err := b.readUint32BE()
if err != nil {
return 0.0, err
}
return math.Float32frombits(intf), err
}
func (b *extendedReader) readFloat64BE() (float64, error) {
intf, err := b.readUint64BE()
if err != nil {
return 0.0, err
}
return math.Float64frombits(intf), err
}
func (b *extendedReader) RegionToGZipStream() (*extendedReader, error) {
compressedLen, err := b.readUint32BE()
if err != nil {
return nil, err
}
println("compressedLen:", compressedLen)
compressed := make([]byte, compressedLen)
err = b.bytes(compressed, int(compressedLen))
if err != nil {
return nil, err
}
fmt.Printf("compressed start: %v\n", compressed[:0x20])
gzipStream, err := gzip.NewReader(bytes.NewReader(compressed))
if err != nil {
return nil, err
}
return &extendedReader{gzipStream}, err
}
func (b *extendedReader) RegionToZStdStream() (*extendedReader, error) {
compressedLen, err := b.readUint32BE()
if err != nil {
return nil, err
}
_, err = b.readUint32BE()
if err != nil {
return nil, err
}
compressed := make([]byte, compressedLen)
err = b.bytes(compressed, int(compressedLen))
if err != nil {
return nil, err
}
/*decompressed, err := zstd.Decompress(nil, compressed)
println("decomp len", len(decompressed))
if len(decompressed) > 0x20 {
fmt.Printf("first bytes %#X\n", decompressed[:0x20])
} else {
fmt.Printf("first bytes %#X\n", decompressed)
}*/
zstdStream := zstd.NewReader(bytes.NewReader(compressed))
return &extendedReader{zstdStream}, nil
}
func (b *extendedReader) readObjectPeerID(context *CommunicationContext) (datamodel.Reference, error) {
ref := datamodel.Reference{}
peerID, err := b.readVarint64()
if err != nil {
return ref, err
}
ref.PeerId = uint32(peerID)
if peerID == 0 {
ref.IsNull = true
ref.Scope = "null"
return ref, err
// Approximately reflects handling in client?
} else if uint32(peerID) == context.ServerPeerID {
ref.Scope = "RBXServer"
} else {
ref.Scope = fmt.Sprintf("RBXPID%d", peerID)
}
ref.Id, err = b.readUint32LE()
return ref, nil
}
func (b *extendedReader) readJoinObject(context *CommunicationContext) (datamodel.Reference, error) {
ref := datamodel.Reference{}
if context.ServerPeerID == 0 {
// read scope using old system
stringLen, err := b.readUint8()
if err != nil {
return ref, err
}
if stringLen == 0x00 {
ref.IsNull = true
ref.Scope = "null"
return ref, err
}
var refString string
if stringLen != 0xFF {
refString, err = b.readASCII(int(stringLen))
if err != nil {
return ref, err
}
if len(refString) != 0x23 {
return ref, errors.New("wrong scope len")
}
ref.Scope = refString
} else {
ref.Scope = context.InstanceTopScope
}
ref.Id, err = b.readUint32LE()
return ref, err
}
return b.readObjectPeerID(context)
}
func (b *extendedReader) readFloat16BE(floatMin float32, floatMax float32) (float32, error) {
scale, err := b.readUint16BE()
if err != nil {
return 0.0, err
}
outFloat := float32(scale)/65535.0*(floatMax-floatMin) + floatMin
if outFloat < floatMin {
return floatMin, nil
} else if outFloat > floatMax {
return floatMax, nil
}
return outFloat, nil
}
type cacheReadCallback func(*extendedReader) (interface{}, error)
// ErrCacheReadOOB is an error specifying that there was a cache
// miss, i.e. a cached used before it was initialized
var ErrCacheReadOOB = errors.New("cache read is out of bounds")
func (b *extendedReader) readWithCache(cache Cache, readCallback cacheReadCallback) (interface{}, error) {
var result interface{}
var err error
cacheIndex, err := b.readUint8()
if err != nil {
return "", err
}
if cacheIndex == 0x00 {
return "NULL", nil
}
if cacheIndex < 0x80 {
result, _ = cache.Get(cacheIndex)
} else {
result, err = readCallback(b)
if err != nil {
return "", err
}
cache.Put(result, cacheIndex&0x7F)
}
if result == nil {
return "", ErrCacheReadOOB
}
return result, err
}
func (b *extendedReader) readUint32AndString() (interface{}, error) {
stringLen, err := b.readUint32BE()
if err != nil {
return "", err
}
return b.readASCII(int(stringLen))
}
func (b *extendedReader) readScope() (interface{}, error) {
stringLen, err := b.readUint32BE()
if err != nil {
return "", err
}
if stringLen != 0x23 {
return "", errors.New("invalid scope len")
}
return b.readASCII(int(stringLen))
}
// TODO: Perhaps make readWithCache() operate with a member function of the cache instead?
func (b *extendedReader) readCached(caches *Caches) (string, error) {
cache := &caches.String
thisString, err := b.readWithCache(cache, (*extendedReader).readUint32AndString)
return thisString.(string), err
}
func (b *extendedReader) readCachedScope(caches *Caches) (string, error) {
cache := &caches.Object
thisString, err := b.readWithCache(cache, (*extendedReader).readScope)
return thisString.(string), err
}
func (b *extendedReader) readCachedContent(caches *Caches) (string, error) {
cache := &caches.Content
thisString, err := b.readWithCache(cache, (*extendedReader).readUint32AndString)
return thisString.(string), err
}
func (b *extendedReader) readNewCachedProtectedString(caches *Caches) ([]byte, error) {
cache := &caches.ProtectedString
thisString, err := b.readWithCache(cache, func(b *extendedReader) (interface{}, error) {
stringLen, err := b.readUint32BE()
if err != nil {
return []byte{}, err
}
thisString, err := b.readString(int(stringLen))
return thisString, err
})
if _, ok := thisString.(string); ok {
return nil, err
}
return thisString.([]byte), err
}
func shuffleSlice(src []byte) []byte {
ShuffledSrc := make([]byte, 0, len(src))
ShuffledSrc = append(ShuffledSrc, src[:0x10]...)
for j := len(src) - 0x10; j >= 0x10; j -= 0x10 {
ShuffledSrc = append(ShuffledSrc, src[j:j+0x10]...)
}
return ShuffledSrc
}
func calculateChecksum(data []byte) uint32 {
var sum uint32
var r uint16 = 55665
var c1 uint16 = 52845
var c2 uint16 = 22719
for i := 0; i < len(data); i++ {
char := data[i]
cipher := (char ^ byte(r>>8)) & 0xFF
r = (uint16(cipher)+r)*c1 + c2
sum += uint32(cipher)
}
return sum
}
var packet90AESKey = [...]byte{0xFE, 0xF9, 0xF0, 0xEB, 0xE2, 0xDD, 0xD4, 0xCF, 0xC6, 0xC1, 0xB8, 0xB3, 0xAA, 0xA5, 0x9C, 0x97}
func (b *extendedReader) aesDecrypt(lenBytes int, key [0x10]byte) (*extendedReader, error) {
data, err := b.readString(lenBytes)
if err != nil {
return nil, err
}
block, err := aes.NewCipher(key[:])
if err != nil {
return nil, err
}
dest := make([]byte, len(data))
// "Invalid" initialization for debug
for i := range dest {
dest[i] = 0xBA
}
c := cipher.NewCBCDecrypter(block, []byte{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0})
ShuffledSrc := shuffleSlice(data)
c.CryptBlocks(dest, ShuffledSrc)
dest = shuffleSlice(dest)
checkSum := calculateChecksum(dest[4:])
thisStream := &extendedReader{bytes.NewReader(dest)}
storedChecksum, err := thisStream.readUint32LE()
if err != nil {
return thisStream, err
}
if storedChecksum != checkSum {
println("checksum check failed!", storedChecksum, checkSum)
return thisStream, errors.New("checksum check fail")
}
_, err = thisStream.ReadByte()
if err != nil {
return thisStream, err
}
paddingSizeByte, err := thisStream.ReadByte()
if err != nil {
return thisStream, err
}
PaddingSize := paddingSizeByte & 0xF
void := make([]byte, PaddingSize)
err = thisStream.bytes(void, int(PaddingSize))
if err != nil {
return thisStream, err
}
return thisStream, nil
}
// RakNetFlags contains a set of flags which outline basic
// information about a RakNet layer packet
type RakNetFlags struct {
// IsValid specifies whether the packet can be considered valid.
IsValid bool
// IsACK specifies whether the packet is an acknowledgement packet
IsACK bool
// IsNAK specifies whether the packet is a not-acknowledged packet
IsNAK bool
IsPacketPair bool
IsContinuousSend bool
NeedsBAndAS bool
HasBAndAS bool
}
func (b *extendedReader) readRakNetFlags() (RakNetFlags, error) {
val := RakNetFlags{}
flags, err := b.ReadByte()
if err != nil {
return val, err
}
val.IsValid = flags>>7&1 == 1
val.IsACK = flags>>6&1 == 1
if val.IsACK {
val.HasBAndAS = flags>>5&1 == 1
return val, nil
}
val.IsNAK = flags>>5&1 == 1
if val.IsNAK {
val.HasBAndAS = flags>>4&1 == 1
return val, nil
}
val.IsPacketPair = flags>>4&1 == 1
val.IsContinuousSend = flags>>3&1 == 1
val.NeedsBAndAS = flags>>2&1 == 1
return val, nil
}
func (b *extendedReader) readReliabilityFlags() (uint8, bool, error) {
flags, err := b.ReadByte()
return flags >> 5, flags>>4&1 == 1, err
}
type deferredStrings struct {
m map[string][]*datamodel.ValueDeferredString
underlyingDictionary map[string]rbxfile.ValueSharedString
}
func newDeferredStrings(reader PacketReader) deferredStrings {
return deferredStrings{
m: make(map[string][]*datamodel.ValueDeferredString),
underlyingDictionary: reader.SharedStrings(),
}
}
func (m deferredStrings) NewValue(md5 string) *datamodel.ValueDeferredString {
val := &datamodel.ValueDeferredString{Hash: md5}
if resolved, ok := m.underlyingDictionary[md5]; ok {
val.Value = resolved
return val
}
// doesn't matter if it's nil, we need to update it in the map anyway
m.m[md5] = append(m.m[md5], val)
return val
}
func (m deferredStrings) Resolve(md5 string, value rbxfile.ValueSharedString) {
for _, resolvable := range m.m[md5] {
resolvable.Value = value
}
}
type writeDeferredStrings struct {
m map[string]rbxfile.ValueSharedString
underlyingDictionary map[string]rbxfile.ValueSharedString
}
func (b *extendedReader) resolveDeferredStrings(defers deferredStrings) error {
for len(defers.m) > 0 {
md5, err := b.readASCII(0x10)
if err != nil {
return err
}
format, err := b.ReadByte()
if err != nil {
return err
}
_, isValid := defers.m[md5]
if !isValid {
return fmt.Errorf("didn't defer with md5 = %X", md5)
}
cachedValue, cachedExists := defers.underlyingDictionary[md5]
switch format {
case 0:
if cachedExists {
return fmt.Errorf("duplicated deferred resolve for %X", md5)
}
resolvedValue, err := b.readVarLengthString()
if err != nil {
return err
}
defers.Resolve(md5, rbxfile.ValueSharedString(resolvedValue))
delete(defers.m, md5)
defers.underlyingDictionary[md5] = rbxfile.ValueSharedString(resolvedValue)
case 1:
if !cachedExists {
return fmt.Errorf("couldn't resolve deferred %X", md5)
}
defers.Resolve(md5, cachedValue)
delete(defers.m, md5)
default:
return errors.New("invalid deferred string dictionary format")
}
}
return nil
}