I am working on Linux and have just started learning about lwIP functionality. So, studying the example ..../contrib/ports/unix/proj/minimal
There seem to be 2 different types of implementation examples provided.
1) using echo.c In this tcp_new(), tcp_bind(), and tcp_accept() are used. I am really confused about working of this implementation. tcp_accept() has specified echo_accept() as a callback function for all packets received over the network interface. But echo_accept() never seems to be called when I ping the IP address.
Could somebody please give me some pointers about what is happening here and whether I am doing something wrong?
2) using mintapif.c This works perfectly fine for replying to ping. I have the following doubts:
1) Does lwIP communicate directly over the Ethernet "eth0"? or the "tap" driver is always required? 2) Is it mandatory for all applications to write code for low_level_init(), low_level_input(), and low_level_output() ?