Linux: network:tcp: option: TCP_INFO

https://www.man7.org/linux/man-pages/man7/tcp.7.html
https://www.man7.org/linux/man-pages/man8/ss.8.html

从TCP的使用手册上看，这个选项的作用是返回一个结构体数据。2.4 就引入了，其实大家可以用起来这个选项。
TCP_INFO (since Linux 2.4)
Used to collect information about this socket. The kernel returns a struct tcp_info as defined in the file /usr/include/linux/tcp.h. This option should not be used in code intended to be portable.

而这个结构体返回的内容如下：

struct tcp_info {
   
	__u8	tcpi_state;
	__u8	tcpi_ca_state;
	__u8	tcpi_retransmits;
	__u8	tcpi_probes;
	__u8	tcpi_backoff;
	__u8	tcpi_options;
	__u8	tcp