1
0
mirror of https://github.com/v2fly/v2ray-core.git synced 2024-12-22 18:17:52 -05:00
v2fly/proxy/shadowsocks/ota.go
2016-12-09 12:08:25 +01:00

138 lines
3.0 KiB
Go

package shadowsocks
import (
"bytes"
"crypto/hmac"
"crypto/sha1"
"io"
"v2ray.com/core/common/buf"
"v2ray.com/core/common/errors"
"v2ray.com/core/common/serial"
)
const (
AuthSize = 10
)
type KeyGenerator func() []byte
type Authenticator struct {
key KeyGenerator
}
func NewAuthenticator(keygen KeyGenerator) *Authenticator {
return &Authenticator{
key: keygen,
}
}
func (v *Authenticator) Authenticate(data []byte) buf.Supplier {
hasher := hmac.New(sha1.New, v.key())
hasher.Write(data)
res := hasher.Sum(nil)
return func(b []byte) (int, error) {
return copy(b, res[:AuthSize]), nil
}
}
func HeaderKeyGenerator(key []byte, iv []byte) func() []byte {
return func() []byte {
newKey := make([]byte, 0, len(key)+len(iv))
newKey = append(newKey, iv...)
newKey = append(newKey, key...)
return newKey
}
}
func ChunkKeyGenerator(iv []byte) func() []byte {
chunkId := 0
return func() []byte {
newKey := make([]byte, 0, len(iv)+4)
newKey = append(newKey, iv...)
newKey = serial.IntToBytes(chunkId, newKey)
chunkId++
return newKey
}
}
type ChunkReader struct {
reader io.Reader
auth *Authenticator
}
func NewChunkReader(reader io.Reader, auth *Authenticator) *ChunkReader {
return &ChunkReader{
reader: reader,
auth: auth,
}
}
func (v *ChunkReader) Release() {
v.reader = nil
v.auth = nil
}
func (v *ChunkReader) Read() (*buf.Buffer, error) {
buffer := buf.New()
if err := buffer.AppendSupplier(buf.ReadFullFrom(v.reader, 2)); err != nil {
buffer.Release()
return nil, err
}
// There is a potential buffer overflow here. Large buffer is 64K bytes,
// while uin16 + 10 will be more than that
length := serial.BytesToUint16(buffer.BytesTo(2)) + AuthSize
if length > buf.Size {
// Theoretically the size of a chunk is 64K, but most Shadowsocks implementations used <4K buffer.
buffer.Release()
buffer = buf.NewLocal(int(length) + 128)
}
buffer.Clear()
if err := buffer.AppendSupplier(buf.ReadFullFrom(v.reader, int(length))); err != nil {
buffer.Release()
return nil, err
}
authBytes := buffer.BytesTo(AuthSize)
payload := buffer.BytesFrom(AuthSize)
actualAuthBytes := make([]byte, AuthSize)
v.auth.Authenticate(payload)(actualAuthBytes)
if !bytes.Equal(authBytes, actualAuthBytes) {
buffer.Release()
return nil, errors.New("Shadowsocks|AuthenticationReader: Invalid auth.")
}
buffer.SliceFrom(AuthSize)
return buffer, nil
}
type ChunkWriter struct {
writer io.Writer
auth *Authenticator
buffer []byte
}
func NewChunkWriter(writer io.Writer, auth *Authenticator) *ChunkWriter {
return &ChunkWriter{
writer: writer,
auth: auth,
buffer: make([]byte, 32*1024),
}
}
func (v *ChunkWriter) Release() {
v.writer = nil
v.auth = nil
}
func (v *ChunkWriter) Write(payload *buf.Buffer) error {
totalLength := payload.Len()
serial.Uint16ToBytes(uint16(totalLength), v.buffer[:0])
v.auth.Authenticate(payload.Bytes())(v.buffer[2:])
copy(v.buffer[2+AuthSize:], payload.Bytes())
_, err := v.writer.Write(v.buffer[:2+AuthSize+payload.Len()])
return err
}