rtthread lwip keep alive 添加保活机制流程

lwip 版本 2.1.2

1 更改lwip配置

1 rt-thread/components/net/lwip/lwip-2.1.2/port lwipopts.h 修改

#define LWIP_TCP_KEEPALIVE        1 // 默认为开, 基本上无需修改

2 修改 rt-thread/components/net/lwip/lwip-2.1.2/src/include/lwip/priv/tcp_priv.h

#define TCP_KEEPIDLE_DEFAULT  2000UL //保活超时时长 单位ms
#define TCP_KEEPINTVL_DEFAULT  1000UL // 保活发送间隔
#define TCP_KEEPCNT_DEFAULT   5U         // 保活超时次数 
/* 默认值7200秒, 比较长, 根据需求修改 */

2 应用代码中使用方法

2.1 tcp 服务器端

int32_t flag = 1; 
if(setsockopt(server_socket, SOL_SOCKET, SO_KEEPALIVE, (void *)&keepalive, sizeof(keepalive)) < 0)
{
  rt_kprintf(" set keep alive fail
"); 
}
// 此段代码放在 accept 之前

setsockopt(accept_ret, IPPROTO_TCP, TCP_KEEPIDLE, (void*)&flag , sizeof(flag));
setsockopt(accept_ret, IPPROTO_TCP, TCP_KEEPINTVL, (void *)&flag , sizeof(flag));
setsockopt(accept_ret, IPPROTO_TCP, TCP_KEEPCNT, (void *)&flag , sizeof(flag));
setsockopt(accept_ret, IPPROTO_TCP, TCP_NODELAY, (void *)&flag , sizeof(flag));
// 此段代码放在 accept 之后, accept_ret 为客户端的句柄