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493 lines
17 KiB
493 lines
17 KiB
package encoding
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import (
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"bytes"
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"crypto/aes"
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"crypto/cipher"
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"crypto/md5"
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"crypto/sha256"
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"encoding/binary"
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"hash/fnv"
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"io"
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"io/ioutil"
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"sync"
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"time"
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"github.com/xtls/xray-core/common"
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"github.com/xtls/xray-core/common/bitmask"
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"github.com/xtls/xray-core/common/buf"
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"github.com/xtls/xray-core/common/crypto"
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"github.com/xtls/xray-core/common/dice"
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"github.com/xtls/xray-core/common/net"
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"github.com/xtls/xray-core/common/protocol"
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"github.com/xtls/xray-core/common/task"
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"github.com/xtls/xray-core/proxy/vmess"
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vmessaead "github.com/xtls/xray-core/proxy/vmess/aead"
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"golang.org/x/crypto/chacha20poly1305"
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)
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type sessionID struct {
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user [16]byte
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key [16]byte
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nonce [16]byte
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}
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// SessionHistory keeps track of historical session ids, to prevent replay attacks.
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type SessionHistory struct {
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sync.RWMutex
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cache map[sessionID]time.Time
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task *task.Periodic
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}
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// NewSessionHistory creates a new SessionHistory object.
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func NewSessionHistory() *SessionHistory {
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h := &SessionHistory{
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cache: make(map[sessionID]time.Time, 128),
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}
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h.task = &task.Periodic{
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Interval: time.Second * 30,
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Execute: h.removeExpiredEntries,
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}
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return h
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}
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// Close implements common.Closable.
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func (h *SessionHistory) Close() error {
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return h.task.Close()
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}
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func (h *SessionHistory) addIfNotExits(session sessionID) bool {
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h.Lock()
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if expire, found := h.cache[session]; found && expire.After(time.Now()) {
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h.Unlock()
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return false
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}
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h.cache[session] = time.Now().Add(time.Minute * 3)
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h.Unlock()
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common.Must(h.task.Start())
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return true
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}
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func (h *SessionHistory) removeExpiredEntries() error {
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now := time.Now()
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h.Lock()
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defer h.Unlock()
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if len(h.cache) == 0 {
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return newError("nothing to do")
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}
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for session, expire := range h.cache {
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if expire.Before(now) {
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delete(h.cache, session)
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}
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}
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if len(h.cache) == 0 {
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h.cache = make(map[sessionID]time.Time, 128)
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}
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return nil
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}
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// ServerSession keeps information for a session in VMess server.
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type ServerSession struct {
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userValidator *vmess.TimedUserValidator
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sessionHistory *SessionHistory
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requestBodyKey [16]byte
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requestBodyIV [16]byte
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responseBodyKey [16]byte
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responseBodyIV [16]byte
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responseWriter io.Writer
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responseHeader byte
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isAEADRequest bool
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isAEADForced bool
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}
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// NewServerSession creates a new ServerSession, using the given UserValidator.
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// The ServerSession instance doesn't take ownership of the validator.
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func NewServerSession(validator *vmess.TimedUserValidator, sessionHistory *SessionHistory) *ServerSession {
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return &ServerSession{
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userValidator: validator,
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sessionHistory: sessionHistory,
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}
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}
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func parseSecurityType(b byte) protocol.SecurityType {
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if _, f := protocol.SecurityType_name[int32(b)]; f {
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st := protocol.SecurityType(b)
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// For backward compatibility.
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if st == protocol.SecurityType_UNKNOWN {
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st = protocol.SecurityType_LEGACY
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}
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return st
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}
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return protocol.SecurityType_UNKNOWN
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}
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// DecodeRequestHeader decodes and returns (if successful) a RequestHeader from an input stream.
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func (s *ServerSession) DecodeRequestHeader(reader io.Reader, isDrain bool) (*protocol.RequestHeader, error) {
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buffer := buf.New()
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behaviorRand := dice.NewDeterministicDice(int64(s.userValidator.GetBehaviorSeed()))
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BaseDrainSize := behaviorRand.Roll(3266)
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RandDrainMax := behaviorRand.Roll(64) + 1
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RandDrainRolled := dice.Roll(RandDrainMax)
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DrainSize := BaseDrainSize + 16 + 38 + RandDrainRolled
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readSizeRemain := DrainSize
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drainConnection := func(e error) error {
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// We read a deterministic generated length of data before closing the connection to offset padding read pattern
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readSizeRemain -= int(buffer.Len())
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if readSizeRemain > 0 && isDrain {
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err := s.DrainConnN(reader, readSizeRemain)
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if err != nil {
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return newError("failed to drain connection DrainSize = ", BaseDrainSize, " ", RandDrainMax, " ", RandDrainRolled).Base(err).Base(e)
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}
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return newError("connection drained DrainSize = ", BaseDrainSize, " ", RandDrainMax, " ", RandDrainRolled).Base(e)
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}
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return e
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}
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defer func() {
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buffer.Release()
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}()
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if _, err := buffer.ReadFullFrom(reader, protocol.IDBytesLen); err != nil {
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return nil, newError("failed to read request header").Base(err)
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}
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var decryptor io.Reader
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var vmessAccount *vmess.MemoryAccount
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user, foundAEAD, errorAEAD := s.userValidator.GetAEAD(buffer.Bytes())
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var fixedSizeAuthID [16]byte
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copy(fixedSizeAuthID[:], buffer.Bytes())
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switch {
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case foundAEAD:
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vmessAccount = user.Account.(*vmess.MemoryAccount)
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var fixedSizeCmdKey [16]byte
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copy(fixedSizeCmdKey[:], vmessAccount.ID.CmdKey())
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aeadData, shouldDrain, bytesRead, errorReason := vmessaead.OpenVMessAEADHeader(fixedSizeCmdKey, fixedSizeAuthID, reader)
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if errorReason != nil {
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if shouldDrain {
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readSizeRemain -= bytesRead
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return nil, drainConnection(newError("AEAD read failed").Base(errorReason))
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} else {
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return nil, drainConnection(newError("AEAD read failed, drain skipped").Base(errorReason))
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}
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}
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decryptor = bytes.NewReader(aeadData)
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s.isAEADRequest = true
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case !s.isAEADForced && errorAEAD == vmessaead.ErrNotFound:
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userLegacy, timestamp, valid, userValidationError := s.userValidator.Get(buffer.Bytes())
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if !valid || userValidationError != nil {
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return nil, drainConnection(newError("invalid user").Base(userValidationError))
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}
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user = userLegacy
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iv := hashTimestamp(md5.New(), timestamp)
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vmessAccount = userLegacy.Account.(*vmess.MemoryAccount)
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aesStream := crypto.NewAesDecryptionStream(vmessAccount.ID.CmdKey(), iv)
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decryptor = crypto.NewCryptionReader(aesStream, reader)
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default:
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return nil, drainConnection(newError("invalid user").Base(errorAEAD))
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}
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readSizeRemain -= int(buffer.Len())
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buffer.Clear()
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if _, err := buffer.ReadFullFrom(decryptor, 38); err != nil {
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return nil, newError("failed to read request header").Base(err)
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}
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request := &protocol.RequestHeader{
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User: user,
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Version: buffer.Byte(0),
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}
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copy(s.requestBodyIV[:], buffer.BytesRange(1, 17)) // 16 bytes
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copy(s.requestBodyKey[:], buffer.BytesRange(17, 33)) // 16 bytes
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var sid sessionID
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copy(sid.user[:], vmessAccount.ID.Bytes())
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sid.key = s.requestBodyKey
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sid.nonce = s.requestBodyIV
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if !s.sessionHistory.addIfNotExits(sid) {
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if !s.isAEADRequest {
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drainErr := s.userValidator.BurnTaintFuse(fixedSizeAuthID[:])
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if drainErr != nil {
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return nil, drainConnection(newError("duplicated session id, possibly under replay attack, and failed to taint userHash").Base(drainErr))
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}
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return nil, drainConnection(newError("duplicated session id, possibly under replay attack, userHash tainted"))
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} else {
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return nil, newError("duplicated session id, possibly under replay attack, but this is a AEAD request")
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}
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}
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s.responseHeader = buffer.Byte(33) // 1 byte
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request.Option = bitmask.Byte(buffer.Byte(34)) // 1 byte
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paddingLen := int(buffer.Byte(35) >> 4)
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request.Security = parseSecurityType(buffer.Byte(35) & 0x0F)
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// 1 bytes reserved
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request.Command = protocol.RequestCommand(buffer.Byte(37))
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switch request.Command {
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case protocol.RequestCommandMux:
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request.Address = net.DomainAddress("v1.mux.cool")
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request.Port = 0
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case protocol.RequestCommandTCP, protocol.RequestCommandUDP:
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if addr, port, err := addrParser.ReadAddressPort(buffer, decryptor); err == nil {
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request.Address = addr
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request.Port = port
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}
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}
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if paddingLen > 0 {
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if _, err := buffer.ReadFullFrom(decryptor, int32(paddingLen)); err != nil {
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if !s.isAEADRequest {
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burnErr := s.userValidator.BurnTaintFuse(fixedSizeAuthID[:])
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if burnErr != nil {
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return nil, newError("failed to read padding, failed to taint userHash").Base(burnErr).Base(err)
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}
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return nil, newError("failed to read padding, userHash tainted").Base(err)
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}
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return nil, newError("failed to read padding").Base(err)
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}
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}
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if _, err := buffer.ReadFullFrom(decryptor, 4); err != nil {
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if !s.isAEADRequest {
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burnErr := s.userValidator.BurnTaintFuse(fixedSizeAuthID[:])
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if burnErr != nil {
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return nil, newError("failed to read checksum, failed to taint userHash").Base(burnErr).Base(err)
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}
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return nil, newError("failed to read checksum, userHash tainted").Base(err)
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}
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return nil, newError("failed to read checksum").Base(err)
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}
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fnv1a := fnv.New32a()
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common.Must2(fnv1a.Write(buffer.BytesTo(-4)))
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actualHash := fnv1a.Sum32()
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expectedHash := binary.BigEndian.Uint32(buffer.BytesFrom(-4))
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if actualHash != expectedHash {
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if !s.isAEADRequest {
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Autherr := newError("invalid auth, legacy userHash tainted")
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burnErr := s.userValidator.BurnTaintFuse(fixedSizeAuthID[:])
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if burnErr != nil {
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Autherr = newError("invalid auth, can't taint legacy userHash").Base(burnErr)
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}
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// It is possible that we are under attack described in https://github.com/xray/xray-core/issues/2523
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return nil, drainConnection(Autherr)
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} else {
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return nil, newError("invalid auth, but this is a AEAD request")
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}
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}
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if request.Address == nil {
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return nil, newError("invalid remote address")
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}
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if request.Security == protocol.SecurityType_UNKNOWN || request.Security == protocol.SecurityType_AUTO {
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return nil, newError("unknown security type: ", request.Security)
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}
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return request, nil
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}
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// DecodeRequestBody returns Reader from which caller can fetch decrypted body.
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func (s *ServerSession) DecodeRequestBody(request *protocol.RequestHeader, reader io.Reader) buf.Reader {
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var sizeParser crypto.ChunkSizeDecoder = crypto.PlainChunkSizeParser{}
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if request.Option.Has(protocol.RequestOptionChunkMasking) {
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sizeParser = NewShakeSizeParser(s.requestBodyIV[:])
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}
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var padding crypto.PaddingLengthGenerator
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if request.Option.Has(protocol.RequestOptionGlobalPadding) {
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padding = sizeParser.(crypto.PaddingLengthGenerator)
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}
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switch request.Security {
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case protocol.SecurityType_NONE:
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if request.Option.Has(protocol.RequestOptionChunkStream) {
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if request.Command.TransferType() == protocol.TransferTypeStream {
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return crypto.NewChunkStreamReader(sizeParser, reader)
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}
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auth := &crypto.AEADAuthenticator{
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AEAD: new(NoOpAuthenticator),
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NonceGenerator: crypto.GenerateEmptyBytes(),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationReader(auth, sizeParser, reader, protocol.TransferTypePacket, padding)
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}
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return buf.NewReader(reader)
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case protocol.SecurityType_LEGACY:
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aesStream := crypto.NewAesDecryptionStream(s.requestBodyKey[:], s.requestBodyIV[:])
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cryptionReader := crypto.NewCryptionReader(aesStream, reader)
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if request.Option.Has(protocol.RequestOptionChunkStream) {
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auth := &crypto.AEADAuthenticator{
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AEAD: new(FnvAuthenticator),
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NonceGenerator: crypto.GenerateEmptyBytes(),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationReader(auth, sizeParser, cryptionReader, request.Command.TransferType(), padding)
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}
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return buf.NewReader(cryptionReader)
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case protocol.SecurityType_AES128_GCM:
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aead := crypto.NewAesGcm(s.requestBodyKey[:])
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auth := &crypto.AEADAuthenticator{
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AEAD: aead,
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NonceGenerator: GenerateChunkNonce(s.requestBodyIV[:], uint32(aead.NonceSize())),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationReader(auth, sizeParser, reader, request.Command.TransferType(), padding)
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case protocol.SecurityType_CHACHA20_POLY1305:
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aead, _ := chacha20poly1305.New(GenerateChacha20Poly1305Key(s.requestBodyKey[:]))
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auth := &crypto.AEADAuthenticator{
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AEAD: aead,
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NonceGenerator: GenerateChunkNonce(s.requestBodyIV[:], uint32(aead.NonceSize())),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationReader(auth, sizeParser, reader, request.Command.TransferType(), padding)
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default:
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panic("Unknown security type.")
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}
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}
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// EncodeResponseHeader writes encoded response header into the given writer.
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func (s *ServerSession) EncodeResponseHeader(header *protocol.ResponseHeader, writer io.Writer) {
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var encryptionWriter io.Writer
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if !s.isAEADRequest {
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s.responseBodyKey = md5.Sum(s.requestBodyKey[:])
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s.responseBodyIV = md5.Sum(s.requestBodyIV[:])
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} else {
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BodyKey := sha256.Sum256(s.requestBodyKey[:])
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copy(s.responseBodyKey[:], BodyKey[:16])
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BodyIV := sha256.Sum256(s.requestBodyIV[:])
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copy(s.responseBodyIV[:], BodyIV[:16])
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}
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aesStream := crypto.NewAesEncryptionStream(s.responseBodyKey[:], s.responseBodyIV[:])
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encryptionWriter = crypto.NewCryptionWriter(aesStream, writer)
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s.responseWriter = encryptionWriter
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aeadEncryptedHeaderBuffer := bytes.NewBuffer(nil)
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if s.isAEADRequest {
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encryptionWriter = aeadEncryptedHeaderBuffer
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}
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common.Must2(encryptionWriter.Write([]byte{s.responseHeader, byte(header.Option)}))
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err := MarshalCommand(header.Command, encryptionWriter)
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if err != nil {
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common.Must2(encryptionWriter.Write([]byte{0x00, 0x00}))
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}
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if s.isAEADRequest {
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aeadResponseHeaderLengthEncryptionKey := vmessaead.KDF16(s.responseBodyKey[:], vmessaead.KDFSaltConstAEADRespHeaderLenKey)
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aeadResponseHeaderLengthEncryptionIV := vmessaead.KDF(s.responseBodyIV[:], vmessaead.KDFSaltConstAEADRespHeaderLenIV)[:12]
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aeadResponseHeaderLengthEncryptionKeyAESBlock := common.Must2(aes.NewCipher(aeadResponseHeaderLengthEncryptionKey)).(cipher.Block)
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aeadResponseHeaderLengthEncryptionAEAD := common.Must2(cipher.NewGCM(aeadResponseHeaderLengthEncryptionKeyAESBlock)).(cipher.AEAD)
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aeadResponseHeaderLengthEncryptionBuffer := bytes.NewBuffer(nil)
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decryptedResponseHeaderLengthBinaryDeserializeBuffer := uint16(aeadEncryptedHeaderBuffer.Len())
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common.Must(binary.Write(aeadResponseHeaderLengthEncryptionBuffer, binary.BigEndian, decryptedResponseHeaderLengthBinaryDeserializeBuffer))
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AEADEncryptedLength := aeadResponseHeaderLengthEncryptionAEAD.Seal(nil, aeadResponseHeaderLengthEncryptionIV, aeadResponseHeaderLengthEncryptionBuffer.Bytes(), nil)
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common.Must2(io.Copy(writer, bytes.NewReader(AEADEncryptedLength)))
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aeadResponseHeaderPayloadEncryptionKey := vmessaead.KDF16(s.responseBodyKey[:], vmessaead.KDFSaltConstAEADRespHeaderPayloadKey)
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aeadResponseHeaderPayloadEncryptionIV := vmessaead.KDF(s.responseBodyIV[:], vmessaead.KDFSaltConstAEADRespHeaderPayloadIV)[:12]
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aeadResponseHeaderPayloadEncryptionKeyAESBlock := common.Must2(aes.NewCipher(aeadResponseHeaderPayloadEncryptionKey)).(cipher.Block)
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aeadResponseHeaderPayloadEncryptionAEAD := common.Must2(cipher.NewGCM(aeadResponseHeaderPayloadEncryptionKeyAESBlock)).(cipher.AEAD)
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aeadEncryptedHeaderPayload := aeadResponseHeaderPayloadEncryptionAEAD.Seal(nil, aeadResponseHeaderPayloadEncryptionIV, aeadEncryptedHeaderBuffer.Bytes(), nil)
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common.Must2(io.Copy(writer, bytes.NewReader(aeadEncryptedHeaderPayload)))
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}
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}
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// EncodeResponseBody returns a Writer that auto-encrypt content written by caller.
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func (s *ServerSession) EncodeResponseBody(request *protocol.RequestHeader, writer io.Writer) buf.Writer {
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var sizeParser crypto.ChunkSizeEncoder = crypto.PlainChunkSizeParser{}
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if request.Option.Has(protocol.RequestOptionChunkMasking) {
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sizeParser = NewShakeSizeParser(s.responseBodyIV[:])
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}
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var padding crypto.PaddingLengthGenerator
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if request.Option.Has(protocol.RequestOptionGlobalPadding) {
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padding = sizeParser.(crypto.PaddingLengthGenerator)
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}
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switch request.Security {
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case protocol.SecurityType_NONE:
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if request.Option.Has(protocol.RequestOptionChunkStream) {
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if request.Command.TransferType() == protocol.TransferTypeStream {
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return crypto.NewChunkStreamWriter(sizeParser, writer)
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}
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auth := &crypto.AEADAuthenticator{
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AEAD: new(NoOpAuthenticator),
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NonceGenerator: crypto.GenerateEmptyBytes(),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationWriter(auth, sizeParser, writer, protocol.TransferTypePacket, padding)
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}
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return buf.NewWriter(writer)
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case protocol.SecurityType_LEGACY:
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if request.Option.Has(protocol.RequestOptionChunkStream) {
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auth := &crypto.AEADAuthenticator{
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AEAD: new(FnvAuthenticator),
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NonceGenerator: crypto.GenerateEmptyBytes(),
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AdditionalDataGenerator: crypto.GenerateEmptyBytes(),
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}
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return crypto.NewAuthenticationWriter(auth, sizeParser, s.responseWriter, request.Command.TransferType(), padding)
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}
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return &buf.SequentialWriter{Writer: s.responseWriter}
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case protocol.SecurityType_AES128_GCM:
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aead := crypto.NewAesGcm(s.responseBodyKey[:])
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auth := &crypto.AEADAuthenticator{
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AEAD: aead,
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NonceGenerator: GenerateChunkNonce(s.responseBodyIV[:], uint32(aead.NonceSize())),
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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.")
|
|
}
|
|
}
|
|
|
|
func (s *ServerSession) DrainConnN(reader io.Reader, n int) error {
|
|
_, err := io.CopyN(ioutil.Discard, reader, int64(n))
|
|
return err
|
|
}
|