[FreeRTOS+TCP API Reference]
void vApplicationPingReplyHook( ePingReplyStatus_t eStatus, uint16_t usIdentifier );
vApplicationPingReplyHook() is an application defined hook (or callback) function that is called by the TCP/IP stack when the stack receives a reply to an ICMP echo (ping) request that was generated using the FreeRTOS_SendPingRequest() function.
Callback functions are implemented by the application writer, but called by the TCP/IP stack. The prototype of the callback function must exactly match the prototype above (including the function name).
eStatus will be set (by the TCP/IP stack) to one of the
The identifier received in the echo reply.
Each echo request has a unique identifier to allow replies to be matched to the requests. The FreeRTOS_SendPingRequest() function returns the identifier of the outgoing echo request it generated.
The example on the FreeRTOS_SendPingRequest() documentation page includes an example implementation of vApplicationPingReplyHook().