Re: RPG socket not closing

[Scott Klement <rpg400-l@xxxxxxxxxxxxxxxx>]

Franz,

Can you explain why you are closing the listener socket and then trying 
to re-open it?   Why not close the connection (the "accept" socket) and 
keep the listener open?   That is the way this is meant to be done.

It is normal for a listener to take some time to close.  This is 
necessary because even after you stop accepting new connections, 
sometimes it is needed to be able to respond to communications for the 
old connections in order to handle possible network errors and 
acknowledgements properly.  It typically takes about 2 minutes after you 
close the listener socket before it will be available to re-use it.

Therefore, the best solution is to write your application so that it is 
not necessary to close the listener and re-open it.  Simply keep it 
active to use for subsequent connections.  If you cannot do that for 
some reason, the other possible approach is to allow bind to re-use the 
port with the SO_REUSEADDR socket option. This allows you to re-use the 
port while the old listener is still active to handle the potential 
errors and acknowledgements.


On 8/16/2019 7:17 AM, Franz.Rauscher@xxxxxxxxxxx wrote:
> Hi!
>
> i have a problem with my rpg server program.
>
> i am followig the code from Scott Klement to wite a simple server program.
>
> i create a socket, bind it, listen and accept a connection. the i send a
> small string and receive a small string.
>
> after that i close the accepted socket and the original server socket used
> for bind.
>
> But sometimes the connection stay open and the close of the socket is not
> successfull. i cannot restart the serer because the socket is already
> bound.
>
> when i do netstat *cnn i  see the connection is in state time_wait and the
> listening socket is not closed.
>
> both close calls return withaout an error so why does the os not close the
> sockets?
>
> Grettings,
> Fanz
>
> Here is the Code:
>
>    message = 'TEST';
>    address = *allx'00';
>    address.sin_family = AF_INET;
>    address.sin_port = 9001;
>    address.sin_addr.s_addr = INADDR_ANY;
>
>    connection =  socket(AF_INET:SOCK_STREAM:IPPROTO_TCP);
>    if bind(connection:%addr(address):%size(address) ) = -1;
>      rc = close(connection);
>      return;
>    endif;
>
>    if listen(connection:1 ) < 0;
>      rc =  close(connection);
>      return;
>    endif;
>
>    newsock = accept(connection:p_address2:len);
>    len = send(newsock:%addr(message:*data):%size(message):0);
>    len = recv(newsock:%addr(ret):%size(ret):0);
>    rc = close(newsock);
>    rc1 = close(connection);
>    printf('message: %s %s %s <<%s>>' + x'25' : %char(rc) : %char(rc1):
> %char(len): ret);
>