Re: [lwip-users] Problem re-opening listening pbc

[Keith Rubow]

I tried the backlog feature (not very well documented). I put #define 
TCP_LISTEN_BACKLOG 1 in my lwipopts.h file. I changed tcp_listen() to 
tcp_listen_with_backlog(), passing it the maximum number of simultaneous 
connection I want. I added tcp_backlog_delayed() to my accept callback. 
I added tcp_backlog_accepted() before tcp_close() when the connection 
was closed in either the receive data callback (with p=NULL), or when my 
application times out the connection.

This does limit the number of connections that can be opened 
simultaneously. However, once the limit is reached, additional 
connection attempts are not refused (which is what I would prefer), 
rather the connection attempts simply time out. Still, this might be 
better than my initial approach of aborting additional unwanted 
connections, which resulted in the connection opening, but immediately 
closing again.

Still, the question remains why lwip will not allow binding to a port 
number that has no current listening pcb, but does have one or more open 
connections. I don't understand why this would cause a problem.

Keith Rubow

On 5/11/2018 5:51 AM, Sergio R. Caprile wrote:
> Check this answer:
> http://lists.nongnu.org/archive/html/lwip-users/2016-08/msg00093.html
>
> I guess your option is to play with the backlog
>
>
> _______________________________________________
> lwip-users mailing list
> address@hidden
> https://lists.nongnu.org/mailman/listinfo/lwip-users