nox实现nat功能

if (setup_flows && out_port != -1)
{
    auto fm = v1::ofp_flow_mod().match(flow).buffer_id(pi.buffer_id())
               .cookie(0).command(v1::ofp_flow_mod::OFPFC_ADD).idle_timeout(5)
               .hard_timeout(v1::OFP_FLOW_PERMANENT)
               .priority(v1::OFP_DEFAULT_PRIORITY);
    if (pi.in_port()== 1) //将in_port为1的数据进行nat转换
    {   
        nat_ip = uint32_t(inet_addr("10.0.168.192"));//由于机器中字节序和网络字节序不一样，所以ip为倒序，你可以使用函数将变成网络字节序
        cout<<">>nat_ip:"<<nat_ip<<endl;
        src_ip= flow.nw_src();//保存src_ip
        cout<<">>src_ip:"<<src_ip<<endl;
        auto aset = v1::ofp_action_nw_src().nw_addr(nat_ip);
        fm.add_action(&aset);//添加动作，修改数据的src_ip为nat_ip
        cout<<">>set_nw_src:"<<nat_ip<<endl;
    }

    cout<<">>flow.nw_dst:"<<flow.nw_dst()<<endl;  
    cout<<">>nat_ip:"<<nat_ip<<endl;
    if ((nat_ip!=0)&&(flow.nw_dst()==nat_ip))//若dst_ip为nat_ip，则修改为src_ip，完成对接
    {
        auto aset_dst = v1::ofp_action_nw_dst().nw_addr(src_ip);
        fm.add_action(&aset_dst);
        cout<<">>set_nw_dst:"<<src_ip<<endl;
    }
    auto ao = v1::ofp_action_output().port(out_port);
    fm.add_action(&ao);
    dp.send(&fm);
}