如何在 lwip 的 udp_recv 中调用回调 function

Question

I am going through an example code of udp lwip server , and I am confused as to how the udp_recv_perf_traffic callback function is called from the udp_recv function.How does the system know that it has received a datagram, is there a flag the udp_recv function checks?

Answer 1

https://doc.ecoscentric.com/ref/lwip-api-raw-udp-recv.html

The routine udp_recv_perf_traffic() isn't called from upd_recv; it's registered as a callback function, meaning that udp_recv_perf_traffic() is invoked when a UDP datagram is received.