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/dice" "v2ray.com/core/common/net" "v2ray.com/core/common/protocol" "v2ray.com/core/proxy/socks" ) const ( Version = 1 RequestOptionOneTimeAuth bitmask.Byte = 0x01 AddrTypeIPv4 = 1 AddrTypeIPv6 = 4 AddrTypeDomain = 3 ) // ReadTCPSession reads a Shadowsocks TCP session from the given reader, returns its header and remaining parts. func ReadTCPSession(user *protocol.User, reader io.Reader) (*protocol.RequestHeader, buf.Reader, error) { rawAccount, err := user.GetTypedAccount() if err != nil { return nil, nil, newError("failed to parse account").Base(err).AtError() } account := rawAccount.(*MemoryAccount) buffer := buf.NewLocal(512) defer buffer.Release() ivLen := account.Cipher.IVSize() var iv []byte if ivLen > 0 { if err := buffer.AppendSupplier(buf.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.NewBufferedReader(r) reader = nil authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv)) request := &protocol.RequestHeader{ Version: Version, User: user, Command: protocol.RequestCommandTCP, } if err := buffer.Reset(buf.ReadFullFrom(br, 1)); err != nil { return nil, nil, newError("failed to read address type").Base(err) } 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") } } addrType := (buffer.Byte(0) & 0x0F) addr, port, err := socks.ReadAddress(buffer, addrType, br) if err != nil { // Invalid address. Continue to read some bytes to confuse client. nBytes := dice.Roll(32) buffer.Clear() buffer.AppendSupplier(buf.ReadFullFrom(br, nBytes)) return nil, nil, newError("failed to read address").Base(err) } request.Address = addr request.Port = port if request.Option.Has(RequestOptionOneTimeAuth) { actualAuth := make([]byte, AuthSize) authenticator.Authenticate(buffer.Bytes())(actualAuth) err := buffer.AppendSupplier(buf.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.") } br.SetBuffered(false) 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 rawAccount, err := user.GetTypedAccount() if err != nil { return nil, newError("failed to parse account").Base(err).AtError() } account := rawAccount.(*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)) _, err = writer.Write(iv) if 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.NewLocal(512) if err := socks.AppendAddress(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)) common.Must(header.AppendSupplier(authenticator.Authenticate(header.Bytes()))) } if err := w.WriteMultiBuffer(buf.NewMultiBufferValue(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.User, reader io.Reader) (buf.Reader, error) { rawAccount, err := user.GetTypedAccount() if err != nil { return nil, newError("failed to parse account").Base(err).AtError() } account := rawAccount.(*MemoryAccount) var iv []byte if account.Cipher.IVSize() > 0 { iv = make([]byte, account.Cipher.IVSize()) _, err = io.ReadFull(reader, iv) if 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 rawAccount, err := user.GetTypedAccount() if err != nil { return nil, newError("failed to parse account.").Base(err).AtError() } account := rawAccount.(*MemoryAccount) var iv []byte if account.Cipher.IVSize() > 0 { iv = make([]byte, account.Cipher.IVSize()) common.Must2(rand.Read(iv)) _, err = writer.Write(iv) if 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 rawAccount, err := user.GetTypedAccount() if err != nil { return nil, newError("failed to parse account.").Base(err).AtError() } account := rawAccount.(*MemoryAccount) buffer := buf.New() ivLen := account.Cipher.IVSize() if ivLen > 0 { common.Must(buffer.Reset(buf.ReadFullFrom(rand.Reader, ivLen))) } iv := buffer.Bytes() if err := socks.AppendAddress(buffer, request.Address, request.Port); err != nil { return nil, newError("failed to write address").Base(err) } buffer.Append(payload) if !account.Cipher.IsAEAD() && request.Option.Has(RequestOptionOneTimeAuth) { authenticator := NewAuthenticator(HeaderKeyGenerator(account.Key, iv)) buffer.SetByte(ivLen, buffer.Byte(ivLen)|0x10) common.Must(buffer.AppendSupplier(authenticator.Authenticate(buffer.BytesFrom(ivLen)))) } 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.User, payload *buf.Buffer) (*protocol.RequestHeader, *buf.Buffer, error) { rawAccount, err := user.GetTypedAccount() if err != nil { return nil, nil, newError("failed to parse account").Base(err).AtError() } account := rawAccount.(*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.Slice(0, payloadLen) } } addrType := (payload.Byte(0) & 0x0F) payload.SliceFrom(1) switch addrType { case AddrTypeIPv4: request.Address = net.IPAddress(payload.BytesTo(4)) payload.SliceFrom(4) case AddrTypeIPv6: request.Address = net.IPAddress(payload.BytesTo(16)) payload.SliceFrom(16) case AddrTypeDomain: domainLength := int(payload.Byte(0)) request.Address = net.DomainAddress(string(payload.BytesRange(1, 1+domainLength))) payload.SliceFrom(1 + domainLength) default: return nil, nil, newError("unknown address type: ", addrType).AtError() } request.Port = net.PortFromBytes(payload.BytesTo(2)) payload.SliceFrom(2) return request, payload, nil } type UDPReader struct { Reader io.Reader User *protocol.User } func (v *UDPReader) ReadMultiBuffer() (buf.MultiBuffer, error) { buffer := buf.New() err := buffer.AppendSupplier(buf.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.NewMultiBufferValue(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 }