Re: [lwip-users] netbuf_data() netconnwrite() problem

[address@hidden]

Francois Bouchard wrote:
> > The other thing that makes me slightly nervous is the use of
> > NETCONN_NOCOPY.  How/when are you freeing inbuf?
> >     
>
>     I'm doing a netbuf_delete after each receive. Grosso modo:
>
>           inbuf = netconn_recv(conn);
>                if (no errors)
>                     netconn_write()
>                else
>                     netconn_close()
>           netbuf_delete(inbuf);
>   
In that case, using the NETCONN_NOCOPY flag with netconn_write() is 
wrong. With _NOCOPY, you have to make sure the data is *not changed* 
until it is completely sent and acked by the remote side. Especially 
regarding retransmission, this can be a long time. In contrast to that, 
you *free* the data you passe with _NOCOPY right after executing the 
write, which may mean it is not even sent, let alone acked.

I don't know if that's your problem, but you should not use _NOCOPY 
there. In fact, there are very few scenarios where _NOCOPY can really be 
used!

Simon