Arp.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:   Basamma YB 
 * Date  :    23-April-2012
 ************************************************************************************/
#define _CRT_SECURE_NO_DEPRECATE
#include "main.h"
#include "ARP.h"
/**
    This function is called by NetworkStack.dll, whenever the event gets triggered      
    inside the NetworkStack.dll for the ARP protocol                                    
*/
_declspec (dllexport) int fn_NetSim_ARP_Run()
{
    SUB_EVENT nSub_Event_Type;
    int nDestionation;      
    /* Get the Event and subevent Type from Event details */
    nEventType=pstruEventDetails->nEventType;
    nSub_Event_Type = pstruEventDetails->nSubEventType;
    
    switch(nEventType)  //Check  event type
    {           
    case NETWORK_OUT_EVENT:
            switch(nSub_Event_Type)     //Check the subevent type
            {           
            case GENERATE_ARP_REQUEST: // Generate ARP Request
                fn_NetSim_Generate_ARP_Request(pstruEventDetails,NETWORK);
                break;
            default:                     // READ_ARP_TABLE:     
                fn_NetSim_Read_ARP_Table(pstruEventDetails,NETWORK);                
                break;
            }
        break;
 
    case TIMER_EVENT:
        switch(nSub_Event_Type)
        {
        case ARP_REQUEST_TIMEOUT:// Request Time out event
            fn_NetSim_ARP_Request_Timeout(pstruEventDetails,NETWORK);
            break;
        }
        break;
 
    case NETWORK_IN_EVENT:
        switch(nSub_Event_Type)
        {       
        case GENERATE_ARP_REPLY: // To generate ARP Reply
 
            fn_NetSim_Generate_ARP_Reply(pstruEventDetails,NETWORK);
            break;
        case UPDATE_ARP_TABLE_FWD_PKT: // To Forward the buffered packet
            fn_NetSim_Update_ARP_Table_ForwardPacket(pstruEventDetails,NETWORK);
            break;      
        default: 
            switch(pstruEventDetails->pPacket->nControlDataType)//Check the Controlpacket type
            {
            case REQUEST_PACKET: // Add this subevent to generate reply packet
                nDestionation = fn_Netsim_ARP_CheckDestinationDevice(pstruEventDetails,NETWORK);
                if(nDestionation) // Destined device only generate reply
                {
                    pstruEventDetails->nSubEventType = GENERATE_ARP_REPLY;
                    fnpAddEvent(pstruEventDetails);                 
                }
                pstruEventDetails->pPacket = NULL;
                break;
            case REPLY_PACKET: // Add this subevent to forward the buffered packet
                pstruEventDetails->nSubEventType = UPDATE_ARP_TABLE_FWD_PKT;
                fnpAddEvent(pstruEventDetails);
                pstruEventDetails->pPacket = NULL;
                break;
            default: // For other than ARP control packet.
                //Do nothing.
                break;
            }       
            break;
        }
        break;          
    default:
        fnNetSimError("Unknown event type for ARP protocol");
        break;
    }   
 
    return 0;
}       
/**
 The Following functions are present in the Arp.lib.                            
 so NetworkStack.dll can not call Arp.lib. It is calling Arp.dll.               
 From Arp.dll, Arp.lib functions are called.                                    
*/
_declspec (dllexport) int fn_NetSim_ARP_Init(struct stru_NetSim_Network *NETWORK_Formal,\
 NetSim_EVENTDETAILS *pstruEventDetails_Formal,char *pszAppPath_Formal,\
 char *pszWritePath_Formal,int nVersion_Type,void **fnPointer)
{
    fn_NetSim_ARP_Init_F(NETWORK_Formal,pstruEventDetails_Formal,pszAppPath_Formal,\
        pszWritePath_Formal,nVersion_Type,fnPointer);
    return 0;
}
/**
    This function is called by NetworkStack.dll, once simulation end to free the 
    allocated memory for the network.   
*/
_declspec(dllexport) int fn_NetSim_ARP_Finish()
{
        fn_NetSim_ARP_Finish_F();
        return 0;
}   
/**
    This function is called by NetworkStack.dll, while writing the evnt trace 
    to get the sub event as a string.
*/
_declspec (dllexport) char *fn_NetSim_ARP_Trace(int nSubEvent)
{
    return (fn_NetSim_ARP_Trace_F(nSubEvent));
}
/**
    This function is called by NetworkStack.dll, while configuring the device 
    for ARP protocol.   
*/
_declspec(dllexport) int fn_NetSim_ARP_Configure(void** var)
{
    return fn_NetSim_ARP_Configure_F(var);
}
/**
    This function is called by NetworkStack.dll, to free the ARP protocol.
*/
_declspec(dllexport) int fn_NetSim_ARP_FreePacket(NetSim_PACKET* pstruPacket)
{
    return fn_NetSim_ARP_FreePacket_F(pstruPacket); 
}
/**
    This function is called by NetworkStack.dll, to copy the ARP protocol
    details from source packet to destination.
*/
_declspec(dllexport) int fn_NetSim_ARP_CopyPacket(NetSim_PACKET* pstruDestPacket,NetSim_PACKET* pstruSrcPacket)
{
    return fn_NetSim_ARP_CopyPacket_F(pstruDestPacket,pstruSrcPacket);  
}
/**
This function write the Metrics     
*/
_declspec(dllexport) int fn_NetSim_ARP_Metrics(PMETRICSWRITER writer)
{
    return 0;
}
/**
This function will return the string to write packet trace heading.
*/
_declspec(dllexport) char* fn_NetSim_ARP_ConfigPacketTrace()
{
    return "";
}
/**
 This function will return the string to write packet trace.                                                                                                    
*/
_declspec(dllexport) char* fn_NetSim_ARP_WritePacketTrace(NetSim_PACKET* pstruPacket, char** ppszTrace)
{
    return "NULL";
}
 
 
 
/**
    This function is called for NETWORK_IN_EVENT with packet type = REQUEST_PACKET.
    Check the request packet received device is the destination. If so it add the 
    GENERATE ARP REPLY sub event, else update the table and drop the request packet.                                        
*/
int fn_Netsim_ARP_CheckDestinationDevice(NetSim_EVENTDETAILS *pstruEventDetails, struct stru_NetSim_Network *NETWORK)
{
    NETSIM_ID nDeviceId;
    NETSIM_ID nInterfaceId;     
    int nMerge_flag = 0;
    int nType;
    NETSIM_IPAddress szSrcIPadd;    
    NetSim_PACKET *pstruTemp_Data;  // To store the packet from the event details   
    ARP_PACKET *pstruArpRequestPkt; // ARP PACKET to store ARP pcaket data      
    ARP_TABLE  *pstruTableHead,*pstruCurrentTable;  //Type casting Arp Table and variables 
    ARP_VARIABLES *pstruArpVariables; //Type casting Arp and variables 
 
    //Get the packet from the event 
    pstruTemp_Data =pstruEventDetails->pPacket; 
    // Get the device and interface Id from the event
    nInterfaceId = pstruEventDetails->nInterfaceId;
    nDeviceId = pstruEventDetails->nDeviceId;
    // Get the Arp Packet from the NetworkData of temp packet
    pstruArpRequestPkt = pstruTemp_Data->pstruNetworkData->Packet_NetworkProtocol;
    // check for destination, if so Add the GENERATE ARP REPLY subevent, else drop the packet   
    if(IP_COMPARE(pstruArpRequestPkt->sz_ar$tpa,DEVICE_NWADDRESS(nDeviceId,nInterfaceId)) == 0)
    {       
        return 1;
    }
    else // Update ARP table and drop the packet
    {
        // Get the Arp variables from device ipVar
        pstruArpVariables = DEVICE_INTERFACE(nDeviceId,nInterfaceId)->ipVar;    
        pstruTableHead = pstruArpVariables->pstruArpTable;  
        pstruCurrentTable = pstruTableHead;
        // Get the source IP address from the packet
        szSrcIPadd = IP_COPY(pstruArpRequestPkt->sz_ar$spa);
        // Check the Source entry in the ARP TABLE 
        while(pstruCurrentTable != NULL)
        {
            if(IP_COMPARE(pstruCurrentTable->szIPAddress,szSrcIPadd)== 0)
            {   // set the merge flag if entry exists
                nMerge_flag = 1;            
                break;
            }
            else // 
            pstruCurrentTable = pstruCurrentTable->pstruNextEntry;
        }           
        // Source entry not there in the ARP table, update the table.
        if(nMerge_flag == 0)
        {       
            nType = DYNAMIC;
            fn_NetSim_Add_IP_MAC_AddressTo_ARP_Table(&pstruTableHead,pstruArpRequestPkt->sz_ar$spa,pstruArpRequestPkt->sz_ar$sha,nType);  
            pstruArpVariables->pstruArpTable = pstruTableHead;
            nMerge_flag =1;
        }
        IP_FREE(szSrcIPadd);
        //Drop the packet       
        fn_NetSim_Packet_FreePacket(pstruTemp_Data);
        pstruTemp_Data = NULL;
        pstruEventDetails->pPacket = NULL;          
        return 0;
    }   
}