how to register and use a hook in c++?

Question

I need to construct an AODV network that exchanges UDP packets. One of its hosts should be able to replay the packet it receives, so I'm modifying udpBasicApp.cc in omnet++ inet framework. I'm trying to refer to a particular host inside the class udpBasicApp to specify a certain behavior for host[3] when it receives a packet. e.g.:

if(host->getIndex()== 3)
{ //replay the received packet }

Apparently, I cannot refer to any element of my network in the previous simple matter. There's no function inside udpBasicApp.cc that can get the index of the current host. I was advised to use hook mechanism to be able to access the index of the current host using the application: udpBasicApp How to do this using hook mechanism?

Second related question, If I cannot refer to the host index inside udpBasicApp.cc, how can I compare the IP address of the current host at least to the IP address I'm trying to refer to?

IPXAddress srcAddr;
if (srcAddr=="host[3]")

is not comparable as the error shows.

Answer 1

1.To obtain the index of a StandardHost from vector you should refer to the parent module of udpApp:

if (getParentModule()->getIndex() == 3) {
// ...
}

2.The IPv4 address of current host may be obtained using L3AddressResolver class:

#include "inet/networklayer/common/L3AddressResolver.h"

// ...
L3Address layer3addr = L3AddressResolver().addressOf(getParentModule(),
             L3AddressResolver::ADDR_IPv4);
IPv4Address ownaddr = layer3addr.toIPv4();