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103 lines
2.2 KiB
103 lines
2.2 KiB
package shadowsocks
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import (
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"bytes"
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"crypto/hmac"
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"crypto/sha1"
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"io"
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"v2ray.com/core/common/alloc"
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"v2ray.com/core/common/log"
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"v2ray.com/core/common/serial"
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"v2ray.com/core/transport"
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)
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const (
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AuthSize = 10
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)
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type KeyGenerator func() []byte
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type Authenticator struct {
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key KeyGenerator
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}
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func NewAuthenticator(keygen KeyGenerator) *Authenticator {
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return &Authenticator{
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key: keygen,
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}
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}
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func (this *Authenticator) Authenticate(auth []byte, data []byte) []byte {
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hasher := hmac.New(sha1.New, this.key())
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hasher.Write(data)
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res := hasher.Sum(nil)
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return append(auth, res[:AuthSize]...)
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}
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func HeaderKeyGenerator(key []byte, iv []byte) func() []byte {
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return func() []byte {
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newKey := make([]byte, 0, len(key)+len(iv))
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newKey = append(newKey, iv...)
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newKey = append(newKey, key...)
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return newKey
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}
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}
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func ChunkKeyGenerator(iv []byte) func() []byte {
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chunkId := 0
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return func() []byte {
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newKey := make([]byte, 0, len(iv)+4)
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newKey = append(newKey, iv...)
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newKey = serial.IntToBytes(chunkId, newKey)
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chunkId++
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return newKey
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}
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}
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type ChunkReader struct {
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reader io.Reader
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auth *Authenticator
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}
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func NewChunkReader(reader io.Reader, auth *Authenticator) *ChunkReader {
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return &ChunkReader{
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reader: reader,
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auth: auth,
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}
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}
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func (this *ChunkReader) Release() {
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this.reader = nil
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this.auth = nil
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}
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func (this *ChunkReader) Read() (*alloc.Buffer, error) {
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buffer := alloc.NewLargeBuffer()
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if _, err := io.ReadFull(this.reader, buffer.Value[:2]); err != nil {
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buffer.Release()
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return nil, err
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}
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// There is a potential buffer overflow here. Large buffer is 64K bytes,
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// while uin16 + 10 will be more than that
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length := serial.BytesToUint16(buffer.Value[:2]) + AuthSize
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if _, err := io.ReadFull(this.reader, buffer.Value[:length]); err != nil {
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buffer.Release()
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return nil, err
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}
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buffer.Slice(0, int(length))
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authBytes := buffer.Value[:AuthSize]
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payload := buffer.Value[AuthSize:]
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actualAuthBytes := this.auth.Authenticate(nil, payload)
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if !bytes.Equal(authBytes, actualAuthBytes) {
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buffer.Release()
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log.Debug("AuthenticationReader: Unexpected auth: ", authBytes)
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return nil, transport.ErrCorruptedPacket
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}
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buffer.SliceFrom(AuthSize)
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return buffer, nil
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}
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