基于 LwIP_HTTP_Server_Netconn_RTOS 示例，在 FreeRTOS 上搭建了一个 Telnet 服务器。

现在我需要在程序的不同位置，通过这个连接转发 / 发送数据给客户端，因此必须知道连接状态，判断客户端是否已连接。

我用以下方法进行测试，但发现即使客户端已成功连接，conn->state 始终为 NETCONN_NONE，说明这种判断方式不可行：

void relay_str_to_socket(char *pch, int sz)

{

struct netconn *conn = {0};

conn = curr_con_get();

if (conn->state != NETCONN_NONE) {

if (netconn_err(conn) == ERR_OK) {

    netconn_write(conn, pch, sz, NETCONN_NOCOPY);

}

} }

void telnet_server_serve(struct netconn *conn) {

struct netbuf *inbuf;

err_t recv_err;

char* buf;

u16_t buflen;

char *resp_ok = "OK, data parsed successfully!\n";

char *resp_err = "ERR, data could not be parsed\n is first char '{'?\n";

// Keep the connection open to continuously handle data

while (1) {

// Read the data from the port, blocking if nothing yet there

recv_err = netconn_recv(conn, &inbuf);





if (recv_err == ERR_OK) {

    if (netconn_err(conn) == ERR_OK) {

    curr_con_set(conn);

        netbuf_data(inbuf, (void**)&buf, &buflen);

        if (buflen > 0 && buf[0] == '{') {

            // Extract data from JSON string

            int rv = ethdataDecode(&m_dat, buf);

            need_conf_set(1);  // Set signal that new command needs processing

            if (rv == OK) {

            relay_str_to_socket(resp_ok, strlen(resp_ok));

            }

        } else {

        relay_str_to_socket(resp_err, strlen(resp_err));

        }

    }

    netbuf_delete(inbuf);  // Clean up the buffer

} else if (recv_err == ERR_CLSD || recv_err == ERR_CONN) {

    // Close the connection if the client disconnected

    break;

}

} 如果在未连接时尝试发送数据，程序会卡死不返回。