[lwip-users] Example tcpecho_raw (contrib-2.1.0)

[Matthias Paul]

Hello lwIP users,

questions are about tcpecho_raw example in contrib-2.1.0. The example is 
chosen as an entry point for testing / developing a simple TCP-based 
protocol on a bare-metal microcontroller system.

1. The "enum tcpecho_raw_states" contains states ES_ACCEPTED and 
ES_RECEIVED, which seem to be identical to me. Is there any difference 
in those states other than distinguishing between a client which _did_ 
sent data at least once and a client which never did?

2. If the client closes the connection to the server, "struct 
tcpecho_raw_state.state" switches to ES_CLOSING to allow sending more 
yet unset data to the client. After all data has been sent out to the 
client, the server finally closes the connection. What's the benefit of 
this behaviour? Is it special for this example or is it  a common 
"best-practice" in TCP?

3. The example looks sort of WIP. For example, "struct 
tcpecho_raw_state.retries" is never used. Is there a more complete 
example out there?


Best regards,
Paul