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udp_aes.go
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udp_aes.go
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package shadowsocks2022
import (
"bytes"
"crypto/cipher"
"io"
"github.com/lunixbochs/struc"
"github.com/v2fly/v2ray-core/v5/common/buf"
"github.com/v2fly/v2ray-core/v5/common/net"
)
type AESUDPClientPacketProcessor struct {
requestSeparateHeaderBlockCipher cipher.Block
responseSeparateHeaderBlockCipher cipher.Block
mainPacketAEAD func([]byte) cipher.AEAD
EIHGenerator func([]byte) ExtensibleIdentityHeaders
}
func NewAESUDPClientPacketProcessor(requestSeparateHeaderBlockCipher, responseSeparateHeaderBlockCipher cipher.Block, mainPacketAEAD func([]byte) cipher.AEAD, eih func([]byte) ExtensibleIdentityHeaders) *AESUDPClientPacketProcessor {
return &AESUDPClientPacketProcessor{
requestSeparateHeaderBlockCipher: requestSeparateHeaderBlockCipher,
responseSeparateHeaderBlockCipher: responseSeparateHeaderBlockCipher,
mainPacketAEAD: mainPacketAEAD,
EIHGenerator: eih,
}
}
type separateHeader struct {
SessionID [8]byte
PacketID uint64
}
type header struct {
Type byte
TimeStamp uint64
PaddingLength uint16 `struc:"sizeof=Padding"`
Padding []byte
}
type respHeader struct {
Type byte
TimeStamp uint64
ClientSessionID [8]byte
PaddingLength uint16 `struc:"sizeof=Padding"`
Padding []byte
}
type cachedUDPState struct {
sessionAEAD cipher.AEAD
sessionRecvAEAD cipher.AEAD
}
func (p *AESUDPClientPacketProcessor) EncodeUDPRequest(request *UDPRequest, out *buf.Buffer,
cache UDPClientPacketProcessorCachedStateContainer,
) error {
separateHeaderStruct := separateHeader{PacketID: request.PacketID, SessionID: request.SessionID}
separateHeaderBuffer := buf.New()
defer separateHeaderBuffer.Release()
{
err := struc.Pack(separateHeaderBuffer, &separateHeaderStruct)
if err != nil {
return newError("failed to pack separateHeader").Base(err)
}
}
separateHeaderBufferBytes := separateHeaderBuffer.Bytes()
{
encryptedDest := out.Extend(16)
p.requestSeparateHeaderBlockCipher.Encrypt(encryptedDest, separateHeaderBufferBytes)
}
if p.EIHGenerator != nil {
eih := p.EIHGenerator(separateHeaderBufferBytes[0:16])
eihHeader := struct {
EIH ExtensibleIdentityHeaders
}{
EIH: eih,
}
err := struc.Pack(out, &eihHeader)
if err != nil {
return newError("failed to pack eih").Base(err)
}
}
headerStruct := header{
Type: UDPHeaderTypeClientToServerStream,
TimeStamp: request.TimeStamp,
PaddingLength: 0,
Padding: nil,
}
requestBodyBuffer := buf.New()
{
err := struc.Pack(requestBodyBuffer, &headerStruct)
if err != nil {
return newError("failed to header").Base(err)
}
}
{
err := addrParser.WriteAddressPort(requestBodyBuffer, request.Address, net.Port(request.Port))
if err != nil {
return newError("failed to write address port").Base(err)
}
}
{
_, err := io.Copy(requestBodyBuffer, bytes.NewReader(request.Payload.Bytes()))
if err != nil {
return newError("failed to copy payload").Base(err)
}
}
{
cacheKey := string(separateHeaderBufferBytes[0:8])
receivedCacheInterface := cache.GetCachedState(cacheKey)
cachedState := &cachedUDPState{}
if receivedCacheInterface != nil {
cachedState = receivedCacheInterface.(*cachedUDPState)
}
if cachedState.sessionAEAD == nil {
cachedState.sessionAEAD = p.mainPacketAEAD(separateHeaderBufferBytes[0:8])
cache.PutCachedState(cacheKey, cachedState)
}
mainPacketAEADMaterialized := cachedState.sessionAEAD
encryptedDest := out.Extend(int32(mainPacketAEADMaterialized.Overhead()) + requestBodyBuffer.Len())
mainPacketAEADMaterialized.Seal(encryptedDest[:0], separateHeaderBuffer.Bytes()[4:16], requestBodyBuffer.Bytes(), nil)
}
return nil
}
func (p *AESUDPClientPacketProcessor) DecodeUDPResp(input []byte, resp *UDPResponse,
cache UDPClientPacketProcessorCachedStateContainer,
) error {
separateHeaderBuffer := buf.New()
defer separateHeaderBuffer.Release()
{
encryptedDest := separateHeaderBuffer.Extend(16)
p.responseSeparateHeaderBlockCipher.Decrypt(encryptedDest, input)
}
separateHeaderStruct := separateHeader{}
{
err := struc.Unpack(separateHeaderBuffer, &separateHeaderStruct)
if err != nil {
return newError("failed to unpack separateHeader").Base(err)
}
}
resp.PacketID = separateHeaderStruct.PacketID
resp.SessionID = separateHeaderStruct.SessionID
{
cacheKey := string(separateHeaderBuffer.Bytes()[0:8])
receivedCacheInterface := cache.GetCachedServerState(cacheKey)
cachedState := &cachedUDPState{}
if receivedCacheInterface != nil {
cachedState = receivedCacheInterface.(*cachedUDPState)
}
if cachedState.sessionRecvAEAD == nil {
cachedState.sessionRecvAEAD = p.mainPacketAEAD(separateHeaderBuffer.Bytes()[0:8])
cache.PutCachedServerState(cacheKey, cachedState)
}
mainPacketAEADMaterialized := cachedState.sessionRecvAEAD
decryptedDestBuffer := buf.New()
decryptedDest := decryptedDestBuffer.Extend(int32(len(input)) - 16 - int32(mainPacketAEADMaterialized.Overhead()))
_, err := mainPacketAEADMaterialized.Open(decryptedDest[:0], separateHeaderBuffer.Bytes()[4:16], input[16:], nil)
if err != nil {
return newError("failed to open main packet").Base(err)
}
decryptedDestReader := bytes.NewReader(decryptedDest)
headerStruct := respHeader{}
{
err := struc.Unpack(decryptedDestReader, &headerStruct)
if err != nil {
return newError("failed to unpack header").Base(err)
}
}
resp.TimeStamp = headerStruct.TimeStamp
addressReaderBuf := buf.New()
defer addressReaderBuf.Release()
var port net.Port
resp.Address, port, err = addrParser.ReadAddressPort(addressReaderBuf, decryptedDestReader)
if err != nil {
return newError("failed to read address port").Base(err)
}
resp.Port = int(port)
readedLength := decryptedDestReader.Size() - int64(decryptedDestReader.Len())
decryptedDestBuffer.Advance(int32(readedLength))
resp.Payload = decryptedDestBuffer
resp.ClientSessionID = headerStruct.ClientSessionID
return nil
}
}