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auth.go
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auth.go
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package crypto
import (
"crypto/cipher"
"io"
"golang.org/x/crypto/sha3"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/serial"
)
var (
errInsufficientBuffer = newError("insufficient buffer")
)
type BytesGenerator interface {
Next() []byte
}
type NoOpBytesGenerator struct {
buffer [1]byte
}
func (v NoOpBytesGenerator) Next() []byte {
return v.buffer[:0]
}
type StaticBytesGenerator struct {
Content []byte
}
func (v StaticBytesGenerator) Next() []byte {
return v.Content
}
type Authenticator interface {
NonceSize() int
Overhead() int
Open(dst, cipherText []byte) ([]byte, error)
Seal(dst, plainText []byte) ([]byte, error)
}
type AEADAuthenticator struct {
cipher.AEAD
NonceGenerator BytesGenerator
AdditionalDataGenerator BytesGenerator
}
func (v *AEADAuthenticator) Open(dst, cipherText []byte) ([]byte, error) {
iv := v.NonceGenerator.Next()
if len(iv) != v.AEAD.NonceSize() {
return nil, newError("invalid AEAD nonce size: ", len(iv))
}
additionalData := v.AdditionalDataGenerator.Next()
return v.AEAD.Open(dst, iv, cipherText, additionalData)
}
func (v *AEADAuthenticator) Seal(dst, plainText []byte) ([]byte, error) {
iv := v.NonceGenerator.Next()
if len(iv) != v.AEAD.NonceSize() {
return nil, newError("invalid AEAD nonce size: ", len(iv))
}
additionalData := v.AdditionalDataGenerator.Next()
return v.AEAD.Seal(dst, iv, plainText, additionalData), nil
}
type Uint16Generator interface {
Next() uint16
}
type StaticUint16Generator uint16
func (g StaticUint16Generator) Next() uint16 {
return uint16(g)
}
type ShakeUint16Generator struct {
shake sha3.ShakeHash
buffer [2]byte
}
func NewShakeUint16Generator(nonce []byte) *ShakeUint16Generator {
shake := sha3.NewShake128()
shake.Write(nonce)
return &ShakeUint16Generator{
shake: shake,
}
}
func (g *ShakeUint16Generator) Next() uint16 {
g.shake.Read(g.buffer[:])
return serial.BytesToUint16(g.buffer[:])
}
type AuthenticationReader struct {
auth Authenticator
buffer *buf.Buffer
reader io.Reader
sizeMask Uint16Generator
chunk []byte
}
const (
readerBufferSize = 32 * 1024
)
func NewAuthenticationReader(auth Authenticator, reader io.Reader, sizeMask Uint16Generator) *AuthenticationReader {
return &AuthenticationReader{
auth: auth,
buffer: buf.NewLocal(readerBufferSize),
reader: reader,
sizeMask: sizeMask,
}
}
func (v *AuthenticationReader) nextChunk(mask uint16) error {
if v.buffer.Len() < 2 {
return errInsufficientBuffer
}
size := int(serial.BytesToUint16(v.buffer.BytesTo(2)) ^ mask)
if size > v.buffer.Len()-2 {
return errInsufficientBuffer
}
if size > readerBufferSize-2 {
return newError("size too large: ", size)
}
if size == v.auth.Overhead() {
return io.EOF
}
if size < v.auth.Overhead() {
return newError("invalid packet size: ", size)
}
cipherChunk := v.buffer.BytesRange(2, size+2)
plainChunk, err := v.auth.Open(cipherChunk[:0], cipherChunk)
if err != nil {
return err
}
v.chunk = plainChunk
v.buffer.SliceFrom(size + 2)
return nil
}
func (v *AuthenticationReader) copyChunk(b []byte) int {
if len(v.chunk) == 0 {
return 0
}
nBytes := copy(b, v.chunk)
if nBytes == len(v.chunk) {
v.chunk = nil
} else {
v.chunk = v.chunk[nBytes:]
}
return nBytes
}
func (v *AuthenticationReader) ensureChunk() error {
atHead := false
if v.buffer.IsEmpty() {
v.buffer.Clear()
atHead = true
}
mask := v.sizeMask.Next()
for {
err := v.nextChunk(mask)
if err != errInsufficientBuffer {
return err
}
leftover := v.buffer.Bytes()
if !atHead && len(leftover) > 0 {
common.Must(v.buffer.Reset(func(b []byte) (int, error) {
return copy(b, leftover), nil
}))
}
if err := v.buffer.AppendSupplier(buf.ReadFrom(v.reader)); err != nil {
return err
}
}
}
func (v *AuthenticationReader) Read(b []byte) (int, error) {
if len(v.chunk) > 0 {
nBytes := v.copyChunk(b)
return nBytes, nil
}
err := v.ensureChunk()
if err != nil {
return 0, err
}
return v.copyChunk(b), nil
}
func (r *AuthenticationReader) ReadMultiBuffer() (buf.MultiBuffer, error) {
err := r.ensureChunk()
if err != nil {
return nil, err
}
mb := buf.NewMultiBuffer()
for len(r.chunk) > 0 {
b := buf.New()
nBytes, _ := b.Write(r.chunk)
mb.Append(b)
r.chunk = r.chunk[nBytes:]
}
r.chunk = nil
return mb, nil
}
type AuthenticationWriter struct {
auth Authenticator
buffer []byte
writer io.Writer
sizeMask Uint16Generator
}
func NewAuthenticationWriter(auth Authenticator, writer io.Writer, sizeMask Uint16Generator) *AuthenticationWriter {
return &AuthenticationWriter{
auth: auth,
buffer: make([]byte, 32*1024),
writer: writer,
sizeMask: sizeMask,
}
}
func (w *AuthenticationWriter) Write(b []byte) (int, error) {
cipherChunk, err := w.auth.Seal(w.buffer[2:2], b)
if err != nil {
return 0, err
}
size := uint16(len(cipherChunk)) ^ w.sizeMask.Next()
serial.Uint16ToBytes(size, w.buffer[:0])
_, err = w.writer.Write(w.buffer[:2+len(cipherChunk)])
return len(b), err
}
func (w *AuthenticationWriter) WriteMultiBuffer(mb buf.MultiBuffer) (int, error) {
defer mb.Release()
const StartIndex = 17 * 1024
var totalBytes int
for {
payloadLen, err := mb.Read(w.buffer[StartIndex:])
if err != nil {
return 0, err
}
nBytes, err := w.Write(w.buffer[StartIndex : StartIndex+payloadLen])
totalBytes += nBytes
if err != nil {
return totalBytes, err
}
if mb.IsEmpty() {
break
}
}
return totalBytes, nil
}