// copyOta copies data from src to dst with ota verification.
//
// This function is copied from shadowsocks library with some modification.
func (s *ShadowServer) copyOta(dst net.Conn, src *ss.Conn) (int64, error) {
// sometimes it have to fill large block
buf := make([]byte, LargeBufferSize)
for {
src.SetReadDeadline(time.Now().Add(ReadTimeout))
if n, err := io.ReadFull(src, buf[:dataLenLen+hmacSha1Len]); err != nil {
return int64(n), err
}
src.SetReadDeadline(time.Time{})
dataLen := binary.BigEndian.Uint16(buf[:dataLenLen])
expectedHmacSha1 := buf[dataLenLen:idxData0]
var dataBuf []byte
if len(buf) < int(idxData0+dataLen) {
dataBuf = make([]byte, dataLen)
} else {
dataBuf = buf[idxData0 : idxData0+dataLen]
}
if n, err := io.ReadFull(src, dataBuf); err != nil {
return int64(n), err
}
chunkIdBytes := make([]byte, 4)
chunkId := src.GetAndIncrChunkId()
binary.BigEndian.PutUint32(chunkIdBytes, chunkId)
actualHmacSha1 := ss.HmacSha1(append(src.GetIv(), chunkIdBytes...), dataBuf)
if !bytes.Equal(expectedHmacSha1, actualHmacSha1) {
return 0, errors.New("ota error: mismatch")
}
if n, err := dst.Write(dataBuf); err != nil {
return int64(n), err
}
}
}
