PIM_Route_Msg.c

/************************************************************************************
* Copyright (C) 2023                                                               *
* TETCOS, Bangalore. India                                                         *
*                                                                                  *
* Tetcos owns the intellectual property rights in the Product and its content.     *
* The copying, redistribution, reselling or publication of any or all of the       *
* Product or its content without express prior written consent of Tetcos is        *
* prohibited. Ownership and / or any other right relating to the software and all  *
* intellectual property rights therein shall remain at all times with Tetcos.      *
*                                                                                  *
* Author:    Shashi Kant Suman                                                     *
*                                                                                  *
* ---------------------------------------------------------------------------------*/
 
#include "main.h"
#include "List.h"
#include "IP.h"
#include "PIM_SM.h"
#include "PIM_Msg.h"
 
static bool isInPresentInRoute(NETSIM_ID d, NETSIM_ID in, ptrIP_FORWARD_ROUTE route)
{
    UINT i;
    for (i = 0; i < route->count; i++)
    {
        if (!IP_COMPARE(DEVICE_NWADDRESS(d, in), route->gateway[i]))
            return true;
    }
    return false;
}
 
static bool isIamSrc(NetSim_PACKET* packet, NETSIM_ID d)
{
    NETSIM_ID i;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (!IP_COMPARE(DEVICE_NWADDRESS(d, i + 1), packet->pstruNetworkData->szSourceIP))
            return true;
    }
    return false;
}
 
#define isBroadcastInterface(d,i) (DEVICE_INTERFACE(d,i)->nInterfaceType != INTERFACE_WAN_ROUTER)
static bool isIamDR(NETSIM_ID d, NETSIM_ID in)
{
    ptrPIM_VAR pim = GET_PIM_VAR(d);
 
    if (isBroadcastInterface(d, in))
    {
        if (!pim->DR[in - 1] || !IP_COMPARE(pim->DR[in - 1],
                                            DEVICE_NWADDRESS(d, in)))
            return true;
        else
            return false;
    }
    return true;
}
 
int pim_route_msg()
{
    bool isMsgArrivesFromBroadcastInterface = false;
    int ret = -1;
    NETSIM_ID d = pstruEventDetails->nDeviceId;
    NetSim_PACKET* packet = pstruEventDetails->pPacket;
    NETSIM_IPAddress gip = packet->pstruNetworkData->szDestIP;
 
    if (!isMulticastIP(gip))
        return ret--; //Not a multicast packet
 
    NETSIM_IPAddress src = packet->pstruNetworkData->szSourceIP;
    ptrPIM_GROUP gr = pim_find_group(d, gip);
    ptrPIM_VAR pim = GET_PIM_VAR(d);
    NETSIM_ID in = pstruEventDetails->nInterfaceId;
 
    
    if (!gr)
        return ret--; //Group is not register.
 
    if (isIamSrc(packet, d))
        return ret--; // Let normal routing work
 
    if (DEVICE_INTERFACE(d, in)->nInterfaceType != INTERFACE_WAN_ROUTER)
        isMsgArrivesFromBroadcastInterface = true;
    NetSim_PACKET* dummy = fn_NetSim_Packet_CreatePacket(NETWORK_LAYER);
    NETSIM_ID sid, sin;
    sid = fn_NetSim_Stack_GetDeviceId_asIP(src, &sin);
    dummy->pstruNetworkData->szDestIP = DEVICE_PUBLICIP(sid, sin);
    dummy->pstruNetworkData->szSourceIP = DEVICE_NWADDRESS(d, 1);
 
    ptrIP_FORWARD_ROUTE route = fn_NetSim_IP_RoutePacket(dummy, d);
 
    
    if (!route)
        fnNetSimError("Packet is reached to router without valid route to source\n");
 
    fn_NetSim_Packet_FreePacket(dummy);
 
    if (!isMsgArrivesFromBroadcastInterface)
    {
        if (!isInPresentInRoute(d, in, route))
            goto DROP; //Packet is arrived from non source interface.
    }
 
    NETSIM_ID i;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (i + 1 == in)
            continue; //Incoming interface
 
        if (isBroadcastInterface(d, i + 1))
        {
            NETSIM_IPAddress subnet = DEVICE_INTERFACE(d, i + 1)->szSubnetMask;
            if (IP_IS_IN_SAME_NETWORK_IPV4(src, DEVICE_NWADDRESS(d, i + 1), subnet))
                continue;
        }
 
        if (isInPresentInRoute(d, i+1, route) && !isMsgArrivesFromBroadcastInterface)
            continue;
 
        if (!isIamDR(d, i + 1))
            continue;
 
 
        NetSim_PACKET* fpacket = fn_NetSim_Packet_CopyPacket(packet);
        if (isBroadcastInterface(d, i + 1))
        {
            fpacket->pstruNetworkData->szNextHopIp = gip;
        }
        fpacket->pstruNetworkData->szGatewayIP = DEVICE_NWADDRESS(d, i + 1);
        NETSIM_ID c, ci;
        NETSIM_ID l = fn_NetSim_Stack_GetConnectedDevice(d, i + 1, &c, &ci);
        if (DEVICE_NWADDRESS(c, ci))
            fpacket->pstruNetworkData->szNextHopIp = DEVICE_NWADDRESS(c, ci);
 
        NetSim_EVENTDETAILS pevent;
        memcpy(&pevent, pstruEventDetails, sizeof pevent);
        pevent.dPacketSize = fpacket->pstruNetworkData->dPacketSize;
        pevent.nEventType = NETWORK_OUT_EVENT;
        pevent.nInterfaceId = i + 1;
        pevent.pPacket = fpacket;
        fnpAddEvent(&pevent);
    }
    DROP:
    fn_NetSim_Packet_FreePacket(packet);
    pstruEventDetails->pPacket = NULL;
    return 0;
}