improve rand
improve rand

shadowsocksR-private/shadowsocksR,shadowsocksR-private/shadowsocksR,ZeroClover/shadowsocksr,shadowsocksr-backup/shadowsocksr,shadowsocksr-backup/shadowsocksr,monokoo/shadowsocks,monokoo/shadowsocks,loveward/yingsuo,loveward/yingsuo