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package encoding
import (
"crypto/md5"
"encoding/binary"
"hash/fnv"
"io"
"sync"
"time"
"golang.org/x/crypto/chacha20poly1305"
"v2ray.com/core/common"
"v2ray.com/core/common/bitmask"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/crypto"
"v2ray.com/core/common/net"
"v2ray.com/core/common/protocol"
"v2ray.com/core/common/task"
"v2ray.com/core/proxy/vmess"
)
type sessionId struct {
user [16]byte
key [16]byte
nonce [16]byte
}
// SessionHistory keeps track of historical session ids, to prevent replay attacks.
type SessionHistory struct {
sync.RWMutex
cache map[sessionId]time.Time
task *task.Periodic
}
// NewSessionHistory creates a new SessionHistory object.
func NewSessionHistory() *SessionHistory {
h := &SessionHistory{
cache: make(map[sessionId]time.Time, 128),
}
h.task = &task.Periodic{
Interval: time.Second * 30,
Execute: h.removeExpiredEntries,
}
return h
}
// Close implements common.Closable.
func (h *SessionHistory) Close() error {
return h.task.Close()
}
func (h *SessionHistory) addIfNotExits(session sessionId) bool {
h.Lock()
if expire, found := h.cache[session]; found && expire.After(time.Now()) {
h.Unlock()
return false
}
h.cache[session] = time.Now().Add(time.Minute * 3)
h.Unlock()
common.Must(h.task.Start())
return true
}
func (h *SessionHistory) removeExpiredEntries() error {
now := time.Now()
h.Lock()
defer h.Unlock()
if len(h.cache) == 0 {
return newError("nothing to do")
}
for session, expire := range h.cache {
if expire.Before(now) {
delete(h.cache, session)
}
}
if len(h.cache) == 0 {
h.cache = make(map[sessionId]time.Time, 128)
}
return nil
}
// ServerSession keeps information for a session in VMess server.
type ServerSession struct {
userValidator *vmess.TimedUserValidator
sessionHistory *SessionHistory
requestBodyKey [16]byte
requestBodyIV [16]byte
responseBodyKey [16]byte
responseBodyIV [16]byte
responseWriter io.Writer
responseHeader byte
}
// NewServerSession creates a new ServerSession, using the given UserValidator.
// The ServerSession instance doesn't take ownership of the validator.
func NewServerSession(validator *vmess.TimedUserValidator, sessionHistory *SessionHistory) *ServerSession {
return &ServerSession{
userValidator: validator,
sessionHistory: sessionHistory,
}
}
func parseSecurityType(b byte) protocol.SecurityType {
if _, f := protocol.SecurityType_name[int32(b)]; f {
st := protocol.SecurityType(b)
// For backward compatibility.
if st == protocol.SecurityType_UNKNOWN {
st = protocol.SecurityType_LEGACY
}
return st
}
return protocol.SecurityType_UNKNOWN
}
// DecodeRequestHeader decodes and returns (if successful) a RequestHeader from an input stream.
func (s *ServerSession) DecodeRequestHeader(reader io.Reader) (*protocol.RequestHeader, error) {
buffer := buf.New()
defer buffer.Release()
if _, err := buffer.ReadFullFrom(reader, protocol.IDBytesLen); err != nil {
return nil, newError("failed to read request header").Base(err)
}
user, timestamp, valid := s.userValidator.Get(buffer.Bytes())
if !valid {
return nil, newError("invalid user")
}
iv := hashTimestamp(md5.New(), timestamp)
vmessAccount := user.Account.(*vmess.MemoryAccount)
aesStream := crypto.NewAesDecryptionStream(vmessAccount.ID.CmdKey(), iv[:])
decryptor := crypto.NewCryptionReader(aesStream, reader)
buffer.Clear()
if _, err := buffer.ReadFullFrom(decryptor, 38); err != nil {
return nil, newError("failed to read request header").Base(err)
}
request := &protocol.RequestHeader{
User: user,
Version: buffer.Byte(0),
}
copy(s.requestBodyIV[:], buffer.BytesRange(1, 17)) // 16 bytes
copy(s.requestBodyKey[:], buffer.BytesRange(17, 33)) // 16 bytes
var sid sessionId
copy(sid.user[:], vmessAccount.ID.Bytes())
sid.key = s.requestBodyKey
sid.nonce = s.requestBodyIV
if !s.sessionHistory.addIfNotExits(sid) {
return nil, newError("duplicated session id, possibly under replay attack")
}
s.responseHeader = buffer.Byte(33) // 1 byte
request.Option = bitmask.Byte(buffer.Byte(34)) // 1 byte
padingLen := int(buffer.Byte(35) >> 4)
request.Security = parseSecurityType(buffer.Byte(35) & 0x0F)
// 1 bytes reserved
request.Command = protocol.RequestCommand(buffer.Byte(37))
switch request.Command {
case protocol.RequestCommandMux:
request.Address = net.DomainAddress("v1.mux.cool")
request.Port = 0
case protocol.RequestCommandTCP, protocol.RequestCommandUDP:
if addr, port, err := addrParser.ReadAddressPort(buffer, decryptor); err == nil {
request.Address = addr
request.Port = port
}
}
if padingLen > 0 {
if _, err := buffer.ReadFullFrom(decryptor, int32(padingLen)); err != nil {
return nil, newError("failed to read padding").Base(err)
}
}
if _, err := buffer.ReadFullFrom(decryptor, 4); err != nil {
return nil, newError("failed to read checksum").Base(err)
}
fnv1a := fnv.New32a()
common.Must2(fnv1a.Write(buffer.BytesTo(-4)))
actualHash := fnv1a.Sum32()
expectedHash := binary.BigEndian.Uint32(buffer.BytesFrom(-4))
if actualHash != expectedHash {
return nil, newError("invalid auth")
}
if request.Address == nil {
return nil, newError("invalid remote address")
}
if request.Security == protocol.SecurityType_UNKNOWN || request.Security == protocol.SecurityType_AUTO {
return nil, newError("unknown security type: ", request.Security)
}
return request, nil
}
// DecodeRequestBody returns Reader from which caller can fetch decrypted body.
func (s *ServerSession) DecodeRequestBody(request *protocol.RequestHeader, reader io.Reader) buf.Reader {
var sizeParser crypto.ChunkSizeDecoder = crypto.PlainChunkSizeParser{}
if request.Option.Has(protocol.RequestOptionChunkMasking) {
sizeParser = NewShakeSizeParser(s.requestBodyIV[:])
}
var padding crypto.PaddingLengthGenerator
if request.Option.Has(protocol.RequestOptionGlobalPadding) {
padding = sizeParser.(crypto.PaddingLengthGenerator)
}
switch request.Security {
case protocol.SecurityType_NONE:
if request.Option.Has(protocol.RequestOptionChunkStream) {
if request.Command.TransferType() == protocol.TransferTypeStream {
return crypto.NewChunkStreamReader(sizeParser, reader)
}
auth := &crypto.AEADAuthenticator{
AEAD: new(NoOpAuthenticator),
NonceGenerator: crypto.GenerateEmptyBytes(),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationReader(auth, sizeParser, reader, protocol.TransferTypePacket, padding)
}
return buf.NewReader(reader)
case protocol.SecurityType_LEGACY:
aesStream := crypto.NewAesDecryptionStream(s.requestBodyKey[:], s.requestBodyIV[:])
cryptionReader := crypto.NewCryptionReader(aesStream, reader)
if request.Option.Has(protocol.RequestOptionChunkStream) {
auth := &crypto.AEADAuthenticator{
AEAD: new(FnvAuthenticator),
NonceGenerator: crypto.GenerateEmptyBytes(),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationReader(auth, sizeParser, cryptionReader, request.Command.TransferType(), padding)
}
return buf.NewReader(cryptionReader)
case protocol.SecurityType_AES128_GCM:
aead := crypto.NewAesGcm(s.requestBodyKey[:])
auth := &crypto.AEADAuthenticator{
AEAD: aead,
NonceGenerator: GenerateChunkNonce(s.requestBodyIV[:], uint32(aead.NonceSize())),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationReader(auth, sizeParser, reader, request.Command.TransferType(), padding)
case protocol.SecurityType_CHACHA20_POLY1305:
aead, _ := chacha20poly1305.New(GenerateChacha20Poly1305Key(s.requestBodyKey[:]))
auth := &crypto.AEADAuthenticator{
AEAD: aead,
NonceGenerator: GenerateChunkNonce(s.requestBodyIV[:], uint32(aead.NonceSize())),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationReader(auth, sizeParser, reader, request.Command.TransferType(), padding)
default:
panic("Unknown security type.")
}
}
// EncodeResponseHeader writes encoded response header into the given writer.
func (s *ServerSession) EncodeResponseHeader(header *protocol.ResponseHeader, writer io.Writer) {
s.responseBodyKey = md5.Sum(s.requestBodyKey[:])
s.responseBodyIV = md5.Sum(s.requestBodyIV[:])
aesStream := crypto.NewAesEncryptionStream(s.responseBodyKey[:], s.responseBodyIV[:])
encryptionWriter := crypto.NewCryptionWriter(aesStream, writer)
s.responseWriter = encryptionWriter
common.Must2(encryptionWriter.Write([]byte{s.responseHeader, byte(header.Option)}))
err := MarshalCommand(header.Command, encryptionWriter)
if err != nil {
common.Must2(encryptionWriter.Write([]byte{0x00, 0x00}))
}
}
// EncodeResponseBody returns a Writer that auto-encrypt content written by caller.
func (s *ServerSession) EncodeResponseBody(request *protocol.RequestHeader, writer io.Writer) buf.Writer {
var sizeParser crypto.ChunkSizeEncoder = crypto.PlainChunkSizeParser{}
if request.Option.Has(protocol.RequestOptionChunkMasking) {
sizeParser = NewShakeSizeParser(s.responseBodyIV[:])
}
var padding crypto.PaddingLengthGenerator
if request.Option.Has(protocol.RequestOptionGlobalPadding) {
padding = sizeParser.(crypto.PaddingLengthGenerator)
}
switch request.Security {
case protocol.SecurityType_NONE:
if request.Option.Has(protocol.RequestOptionChunkStream) {
if request.Command.TransferType() == protocol.TransferTypeStream {
return crypto.NewChunkStreamWriter(sizeParser, writer)
}
auth := &crypto.AEADAuthenticator{
AEAD: new(NoOpAuthenticator),
NonceGenerator: crypto.GenerateEmptyBytes(),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationWriter(auth, sizeParser, writer, protocol.TransferTypePacket, padding)
}
return buf.NewWriter(writer)
case protocol.SecurityType_LEGACY:
if request.Option.Has(protocol.RequestOptionChunkStream) {
auth := &crypto.AEADAuthenticator{
AEAD: new(FnvAuthenticator),
NonceGenerator: crypto.GenerateEmptyBytes(),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationWriter(auth, sizeParser, s.responseWriter, request.Command.TransferType(), padding)
}
return &buf.SequentialWriter{Writer: s.responseWriter}
case protocol.SecurityType_AES128_GCM:
aead := crypto.NewAesGcm(s.responseBodyKey[:])
auth := &crypto.AEADAuthenticator{
AEAD: aead,
NonceGenerator: GenerateChunkNonce(s.responseBodyIV[:], uint32(aead.NonceSize())),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationWriter(auth, sizeParser, writer, request.Command.TransferType(), padding)
case protocol.SecurityType_CHACHA20_POLY1305:
aead, _ := chacha20poly1305.New(GenerateChacha20Poly1305Key(s.responseBodyKey[:]))
auth := &crypto.AEADAuthenticator{
AEAD: aead,
NonceGenerator: GenerateChunkNonce(s.responseBodyIV[:], uint32(aead.NonceSize())),
AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
}
return crypto.NewAuthenticationWriter(auth, sizeParser, writer, request.Command.TransferType(), padding)
default:
panic("Unknown security type.")
}
}
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