Re: [lwip-users] lwIP in multi-thread environment mixed with raw-api

[Mark Phillips]

Hi, Alex,

I have a similar situation, and I am having great problems with it. 
(Thanks, Kieran for your response to my question).

I am trying to do multiple servers and clients with lwIP.  It's 
basically a protocol converter, that has to connect to a number of 
remote devices and poll them for data, and at the same time listen on 
other sockets for someone upstream to connect and poll me.

The problem I am having is that certain operations (like connect) don't 
seem to return until either the connection is made, or it times out. 
This is a problem, since (particularly if one of the downstream devices 
is offline) the whole stack stops while we wait for the connection to be 
made.  Additionally, since this is a standalone unit, we need to 
continuously try connecting to devices we haven't connected to yet.

I can set things up so that all the socket operations happen from a 
single task, but I can't have this task get stuck while waiting to make 
connections.  I am using the netconn api; would I be better off using 
the low-level API, or the BSD API?  Or is my understanding of what's 
happening wrong?

The application works great for multiple servers (listeners), and also 
for a single client (with no servers).  But, whenever I try to mix the 
two, either the whole process stops (if I prevent multiple requests to 
be pending simultaneously) or I get nasty memory-corruption/segfaults 
(if I DO allow multiple requests).

I get the feeling that I'm using the wrong API (or that what I'm trying 
to do is beyond what lwIP can handle).  Any advice would be greatly 
appreciated!

Thanks,
-Mark


Alexander Heidt wrote:
> Hello!
>
> I am getting familiar with lwIP right now, on a STM32-Microcontroller. 
> Right now I have the lwIP running in a single thread, works fine. I even 
> built a veeeery simple http-server using the raw-api.
> Now I am trying to use lwIP with FreeRTOS. My question: As it is stated 
> in the wiki, only ONE application thread using the lwIP-api is 
> permitted. In my application I would like to 1. have the http-server 
> running to serve a config-website and 2. connect to a server to upload 
> some data. As I am not familiar with the lwIP-api yet: Is this possible 
> via the api in one single task? Or is it possible, to leave the 
> http-server I have already as it is (totally done via callbacks), and 
> just use the api to do the data-uploading in my application task?
>
> And one another question regarding PPP: Afaik now PPP needs a 
> multithreaded environment, cause the PPP-daemon runs in its own thread. 
> But what is the status of the PPP-part of lwIP?? Is it still very buggy, 
> or is there somebody having had a good experience with it?? Just to 
> know, if it is worth, trying to use it, or not!
>
> Regards, Alex
>
>
>
>
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