clear the server_addr.sin_zero to '0'.

1.close dir before return;
2.fixed indentation.

Fixed indentation

Fixed  pointer check, indentation

tcpclient->udpclient

申请内存失败时，直接return，此前代码goto _exit进行rt_free空指针，会造成内存泄漏

接收->发送

This is 'tcp server', not is 'tcp client'
tcpclient -> tcpserver

This is 'udp server', not is 'tcp client'
tcpclient -> udpserver

This is 'udp client', not is 'tcp client', so 
tcpclient -> udpclient

also:
- change static buffer to dynamiclly allocated buffer.
- replace Chinese comment to English comment in some files.
- add apache-2 license

Signed-off-by: NMurphyZhao <d2014zjt@163.com>

Signed-off-by: NMurphyZhao <d2014zjt@163.com>

Signed-off-by: NMurphyZhao <d2014zjt@163.com>

1. cleanup for posix dfs_net.
2. fixed recv buf overwrite.
3. format code.

1. Add termios test. 2.Add termios.h