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auth.go
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auth.go
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package crypto
import (
"crypto/cipher"
"errors"
"io"
"v2ray.com/core/common"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/serial"
)
var (
ErrAuthenticationFailed = errors.New("Authentication failed.")
errInsufficientBuffer = errors.New("Insufficient buffer.")
errInvalidNonce = errors.New("Invalid nonce.")
)
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, errInvalidNonce
}
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, errInvalidNonce
}
additionalData := v.AdditionalDataGenerator.Next()
return v.AEAD.Seal(dst, iv, plainText, additionalData), nil
}
type AuthenticationReader struct {
auth Authenticator
buffer *buf.Buffer
reader io.Reader
chunk []byte
aggressive bool
}
func NewAuthenticationReader(auth Authenticator, reader io.Reader, aggressive bool) *AuthenticationReader {
return &AuthenticationReader{
auth: auth,
buffer: buf.NewLocal(32 * 1024),
reader: reader,
aggressive: aggressive,
}
}
func (v *AuthenticationReader) NextChunk() error {
if v.buffer.Len() < 2 {
return errInsufficientBuffer
}
size := int(serial.BytesToUint16(v.buffer.BytesTo(2)))
if size > v.buffer.Len()-2 {
return errInsufficientBuffer
}
if size == v.auth.Overhead() {
return io.EOF
}
if size < v.auth.Overhead() {
return errors.New("AuthenticationReader: invalid packet 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 {
for {
err := v.NextChunk()
if err == nil {
return nil
}
if err == errInsufficientBuffer {
if v.buffer.IsEmpty() {
v.buffer.Clear()
} else {
leftover := v.buffer.Bytes()
common.Must(v.buffer.Reset(func(b []byte) (int, error) {
return copy(b, leftover), nil
}))
}
err = v.buffer.AppendSupplier(buf.ReadFrom(v.reader))
if err == nil {
continue
}
}
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
}
totalBytes := v.CopyChunk(b)
for v.aggressive && totalBytes < len(b) {
if err := v.NextChunk(); err != nil {
break
}
totalBytes += v.CopyChunk(b[totalBytes:])
}
return totalBytes, nil
}
type AuthenticationWriter struct {
auth Authenticator
buffer []byte
writer io.Writer
}
func NewAuthenticationWriter(auth Authenticator, writer io.Writer) *AuthenticationWriter {
return &AuthenticationWriter{
auth: auth,
buffer: make([]byte, 32*1024),
writer: writer,
}
}
func (v *AuthenticationWriter) Write(b []byte) (int, error) {
cipherChunk, err := v.auth.Seal(v.buffer[2:2], b)
if err != nil {
return 0, err
}
serial.Uint16ToBytes(uint16(len(cipherChunk)), v.buffer[:0])
_, err = v.writer.Write(v.buffer[:2+len(cipherChunk)])
return len(b), err
}