Xray-core/proxy/shadowsocks/protocol.go

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2020-11-25 11:01:53 +00:00
package shadowsocks
import (
"crypto/hmac"
"crypto/rand"
"crypto/sha256"
"hash/crc32"
"io"
"io/ioutil"
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"github.com/xtls/xray-core/common"
"github.com/xtls/xray-core/common/buf"
"github.com/xtls/xray-core/common/dice"
"github.com/xtls/xray-core/common/net"
"github.com/xtls/xray-core/common/protocol"
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)
const (
Version = 1
)
var addrParser = protocol.NewAddressParser(
protocol.AddressFamilyByte(0x01, net.AddressFamilyIPv4),
protocol.AddressFamilyByte(0x04, net.AddressFamilyIPv6),
protocol.AddressFamilyByte(0x03, net.AddressFamilyDomain),
protocol.WithAddressTypeParser(func(b byte) byte {
return b & 0x0F
}),
)
// ReadTCPSession reads a Shadowsocks TCP session from the given reader, returns its header and remaining parts.
func ReadTCPSession(user *protocol.MemoryUser, reader io.Reader) (*protocol.RequestHeader, buf.Reader, error) {
account := user.Account.(*MemoryAccount)
hashkdf := hmac.New(sha256.New, []byte("SSBSKDF"))
hashkdf.Write(account.Key)
behaviorSeed := crc32.ChecksumIEEE(hashkdf.Sum(nil))
behaviorRand := dice.NewDeterministicDice(int64(behaviorSeed))
BaseDrainSize := behaviorRand.Roll(3266)
RandDrainMax := behaviorRand.Roll(64) + 1
RandDrainRolled := dice.Roll(RandDrainMax)
DrainSize := BaseDrainSize + 16 + 38 + RandDrainRolled
readSizeRemain := DrainSize
buffer := buf.New()
defer buffer.Release()
ivLen := account.Cipher.IVSize()
var iv []byte
if ivLen > 0 {
if _, err := buffer.ReadFullFrom(reader, ivLen); err != nil {
readSizeRemain -= int(buffer.Len())
DrainConnN(reader, readSizeRemain)
return nil, nil, newError("failed to read IV").Base(err)
}
iv = append([]byte(nil), buffer.BytesTo(ivLen)...)
}
r, err := account.Cipher.NewDecryptionReader(account.Key, iv, reader)
if err != nil {
readSizeRemain -= int(buffer.Len())
DrainConnN(reader, readSizeRemain)
return nil, nil, newError("failed to initialize decoding stream").Base(err).AtError()
}
br := &buf.BufferedReader{Reader: r}
request := &protocol.RequestHeader{
Version: Version,
User: user,
Command: protocol.RequestCommandTCP,
}
readSizeRemain -= int(buffer.Len())
buffer.Clear()
addr, port, err := addrParser.ReadAddressPort(buffer, br)
if err != nil {
readSizeRemain -= int(buffer.Len())
DrainConnN(reader, readSizeRemain)
return nil, nil, newError("failed to read address").Base(err)
}
request.Address = addr
request.Port = port
if request.Address == nil {
readSizeRemain -= int(buffer.Len())
DrainConnN(reader, readSizeRemain)
return nil, nil, newError("invalid remote address.")
}
return request, br, nil
}
func DrainConnN(reader io.Reader, n int) error {
_, err := io.CopyN(ioutil.Discard, reader, int64(n))
return err
}
// WriteTCPRequest writes Shadowsocks request into the given writer, and returns a writer for body.
func WriteTCPRequest(request *protocol.RequestHeader, writer io.Writer) (buf.Writer, error) {
user := request.User
account := user.Account.(*MemoryAccount)
var iv []byte
if account.Cipher.IVSize() > 0 {
iv = make([]byte, account.Cipher.IVSize())
common.Must2(rand.Read(iv))
if err := buf.WriteAllBytes(writer, iv); err != nil {
return nil, newError("failed to write IV")
}
}
w, err := account.Cipher.NewEncryptionWriter(account.Key, iv, writer)
if err != nil {
return nil, newError("failed to create encoding stream").Base(err).AtError()
}
header := buf.New()
if err := addrParser.WriteAddressPort(header, request.Address, request.Port); err != nil {
return nil, newError("failed to write address").Base(err)
}
if err := w.WriteMultiBuffer(buf.MultiBuffer{header}); err != nil {
return nil, newError("failed to write header").Base(err)
}
return w, nil
}
func ReadTCPResponse(user *protocol.MemoryUser, reader io.Reader) (buf.Reader, error) {
account := user.Account.(*MemoryAccount)
var iv []byte
if account.Cipher.IVSize() > 0 {
iv = make([]byte, account.Cipher.IVSize())
if _, err := io.ReadFull(reader, iv); err != nil {
return nil, newError("failed to read IV").Base(err)
}
}
return account.Cipher.NewDecryptionReader(account.Key, iv, reader)
}
func WriteTCPResponse(request *protocol.RequestHeader, writer io.Writer) (buf.Writer, error) {
user := request.User
account := user.Account.(*MemoryAccount)
var iv []byte
if account.Cipher.IVSize() > 0 {
iv = make([]byte, account.Cipher.IVSize())
common.Must2(rand.Read(iv))
if err := buf.WriteAllBytes(writer, iv); err != nil {
return nil, newError("failed to write IV.").Base(err)
}
}
return account.Cipher.NewEncryptionWriter(account.Key, iv, writer)
}
func EncodeUDPPacket(request *protocol.RequestHeader, payload []byte) (*buf.Buffer, error) {
user := request.User
account := user.Account.(*MemoryAccount)
buffer := buf.New()
ivLen := account.Cipher.IVSize()
if ivLen > 0 {
common.Must2(buffer.ReadFullFrom(rand.Reader, ivLen))
}
if err := addrParser.WriteAddressPort(buffer, request.Address, request.Port); err != nil {
return nil, newError("failed to write address").Base(err)
}
buffer.Write(payload)
if err := account.Cipher.EncodePacket(account.Key, buffer); err != nil {
return nil, newError("failed to encrypt UDP payload").Base(err)
}
return buffer, nil
}
func DecodeUDPPacket(user *protocol.MemoryUser, payload *buf.Buffer) (*protocol.RequestHeader, *buf.Buffer, error) {
account := user.Account.(*MemoryAccount)
var iv []byte
if !account.Cipher.IsAEAD() && account.Cipher.IVSize() > 0 {
// Keep track of IV as it gets removed from payload in DecodePacket.
iv = make([]byte, account.Cipher.IVSize())
copy(iv, payload.BytesTo(account.Cipher.IVSize()))
}
if err := account.Cipher.DecodePacket(account.Key, payload); err != nil {
return nil, nil, newError("failed to decrypt UDP payload").Base(err)
}
request := &protocol.RequestHeader{
Version: Version,
User: user,
Command: protocol.RequestCommandUDP,
}
payload.SetByte(0, payload.Byte(0)&0x0F)
addr, port, err := addrParser.ReadAddressPort(nil, payload)
if err != nil {
return nil, nil, newError("failed to parse address").Base(err)
}
request.Address = addr
request.Port = port
return request, payload, nil
}
type UDPReader struct {
Reader io.Reader
User *protocol.MemoryUser
}
func (v *UDPReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
buffer := buf.New()
_, err := buffer.ReadFrom(v.Reader)
if err != nil {
buffer.Release()
return nil, err
}
_, payload, err := DecodeUDPPacket(v.User, buffer)
if err != nil {
buffer.Release()
return nil, err
}
return buf.MultiBuffer{payload}, nil
}
type UDPWriter struct {
Writer io.Writer
Request *protocol.RequestHeader
}
// Write implements io.Writer.
func (w *UDPWriter) Write(payload []byte) (int, error) {
packet, err := EncodeUDPPacket(w.Request, payload)
if err != nil {
return 0, err
}
_, err = w.Writer.Write(packet.Bytes())
packet.Release()
return len(payload), err
}