code: private void parseHeaderFromBuffer() {
      int magic = header[0];
      assert magic == RES_MAGIC : "Invalid magic:  " + magic;
      responseCmd = header[1];
      assert cmd == DUMMY_OPCODE || responseCmd == cmd
        : "Unexpected response command value";
      keyLen = decodeShort(header, 2);
      errorCode = decodeShort(header, 6);
      int bytesToRead = decodeInt(header, 8);
      payload = new byte[bytesToRead];
      responseOpaque = decodeInt(header, 12);
      responseCas = decodeLong(header, 16);
      assert opaqueIsValid() : "Opaque is not valid";
    }
docs: Parse the header info out of the buffer.