Re: [lwip-users] Detection remote closed TCP connection

[Jonathan Larmour]

Muhamad Ikhwan Ismail wrote:
> 
> while(1){
> int s = accept(); //blocks untill the connection is accepted
> 
> for(;;){
>        //runs IO
>     }
> }
> 
> I have a slight problem when the remote host closes the connection. I
> would want to include a connection status check and jump back
> to accept() if the connection is closed from the remote host. Is there
> anyway to do this ? It also has to be non-blocking and can be lwip specific.
> 
> So far I have heard few suggestions from the old thread :
> 
> 1. read/write 0 bytes. //blocks ?
> 2. Use of MSG_PEEK read (in 2003 was not yet implemented ).

Yes, if the connection is closed remotely you will read 0 bytes (as opposed
to no data available when you get the EWOULDBLOCK error). If you write to
it when closed you will get an error. If you are using select() in that
loop to process I/O, then the socket will be marked readable, and when you
read it you will get 0 bytes.

Jifl
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