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protocol.go
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protocol.go
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package shadowsocks
import (
"bytes"
"crypto/rand"
"io"
"v2ray.com/core/common"
"v2ray.com/core/common/bitmask"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/net"
"v2ray.com/core/common/protocol"
)
const (
Version = 1
RequestOptionOneTimeAuth bitmask.Byte = 0x01
)
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)
buffer := buf.New()
defer buffer.Release()
ivLen := account.Cipher.IVSize()
var iv []byte
if ivLen > 0 {
if _, err := buffer.ReadFullFrom(reader, ivLen); err != nil {
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 {
return nil, nil, newError("failed to initialize decoding stream").Base(err).AtError()
}
br := &buf.BufferedReader{Reader: r}
reader = nil
authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv))
request := &protocol.RequestHeader{
Version: Version,
User: user,
Command: protocol.RequestCommandTCP,
}
buffer.Clear()
addr, port, err := addrParser.ReadAddressPort(buffer, br)
if err != nil {
return nil, nil, newError("failed to read address").Base(err)
}
request.Address = addr
request.Port = port
if !account.Cipher.IsAEAD() {
if (buffer.Byte(0) & 0x10) == 0x10 {
request.Option.Set(RequestOptionOneTimeAuth)
}
if request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Disabled {
return nil, nil, newError("rejecting connection with OTA enabled, while server disables OTA")
}
if !request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Enabled {
return nil, nil, newError("rejecting connection with OTA disabled, while server enables OTA")
}
}
if request.Option.Has(RequestOptionOneTimeAuth) {
actualAuth := make([]byte, AuthSize)
authenticator.Authenticate(buffer.Bytes(), actualAuth)
_, err := buffer.ReadFullFrom(br, AuthSize)
if err != nil {
return nil, nil, newError("Failed to read OTA").Base(err)
}
if !bytes.Equal(actualAuth, buffer.BytesFrom(-AuthSize)) {
return nil, nil, newError("invalid OTA")
}
}
if request.Address == nil {
return nil, nil, newError("invalid remote address.")
}
var chunkReader buf.Reader
if request.Option.Has(RequestOptionOneTimeAuth) {
chunkReader = NewChunkReader(br, NewAuthenticator(ChunkKeyGenerator(iv)))
} else {
chunkReader = buf.NewReader(br)
}
return request, chunkReader, nil
}
// 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)
if account.Cipher.IsAEAD() {
request.Option.Clear(RequestOptionOneTimeAuth)
}
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 request.Option.Has(RequestOptionOneTimeAuth) {
header.SetByte(0, header.Byte(0)|0x10)
authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv))
authPayload := header.Bytes()
authBuffer := header.Extend(AuthSize)
authenticator.Authenticate(authPayload, authBuffer)
}
if err := w.WriteMultiBuffer(buf.MultiBuffer{header}); err != nil {
return nil, newError("failed to write header").Base(err)
}
var chunkWriter buf.Writer
if request.Option.Has(RequestOptionOneTimeAuth) {
chunkWriter = NewChunkWriter(w.(io.Writer), NewAuthenticator(ChunkKeyGenerator(iv)))
} else {
chunkWriter = w
}
return chunkWriter, 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))
}
iv := buffer.Bytes()
if err := addrParser.WriteAddressPort(buffer, request.Address, request.Port); err != nil {
return nil, newError("failed to write address").Base(err)
}
buffer.Write(payload)
if !account.Cipher.IsAEAD() && request.Option.Has(RequestOptionOneTimeAuth) {
authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv))
buffer.SetByte(ivLen, buffer.Byte(ivLen)|0x10)
authPayload := buffer.BytesFrom(ivLen)
authBuffer := buffer.Extend(AuthSize)
authenticator.Authenticate(authPayload, authBuffer)
}
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,
}
if !account.Cipher.IsAEAD() {
if (payload.Byte(0) & 0x10) == 0x10 {
request.Option |= RequestOptionOneTimeAuth
}
if request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Disabled {
return nil, nil, newError("rejecting packet with OTA enabled, while server disables OTA").AtWarning()
}
if !request.Option.Has(RequestOptionOneTimeAuth) && account.OneTimeAuth == Account_Enabled {
return nil, nil, newError("rejecting packet with OTA disabled, while server enables OTA").AtWarning()
}
if request.Option.Has(RequestOptionOneTimeAuth) {
payloadLen := payload.Len() - AuthSize
authBytes := payload.BytesFrom(payloadLen)
authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv))
actualAuth := make([]byte, AuthSize)
authenticator.Authenticate(payload.BytesTo(payloadLen), actualAuth)
if !bytes.Equal(actualAuth, authBytes) {
return nil, nil, newError("invalid OTA")
}
payload.Resize(0, payloadLen)
}
}
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
}