DNS.c

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/************************************************************************************
 * Copyright (C) 2020                                                               *
 * 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"
/** This function is to find the gateway */
NETSIM_ID fnFindGateway(NETSIM_ID nDeviceId)
{
    NETSIM_ID i,j;
    for(i=0;i<NETWORK->ppstruDeviceList[nDeviceId-1]->nNumOfInterface;i++)
    {
        if(NETWORK->ppstruDeviceList[nDeviceId-1]->ppstruInterfaceList[i]->szDefaultGateWay)
        {
            return fn_NetSim_Stack_GetDeviceId_asIP(NETWORK->ppstruDeviceList[nDeviceId-1]->ppstruInterfaceList[i]->szDefaultGateWay,&j);
        }
    }
    return nDeviceId;
}
/**
The DOMAIN NAME SPACE and RESOURCE RECORDS, which are
specifications for a tree structured name space and data
associated with the names. Conceptually, each node and leaf
of the domain name space tree names a set of information, and
query operations are attempts to extract specific types of
information from a particular set. A query names the domain
name of interest and describes the type of resource
information that is desired. For example, the Internet
uses some of its domain names to identify hosts; queries for
address resources return Internet host addresses.
*/
_declspec(dllexport) NETSIM_IPAddress dns_query(NETSIM_ID nDeviceId,NETSIM_ID id)
{
    DNS* dns;
    IP_DEVVAR* devVar;
    NETSIM_ID ngatewayId=fnFindGateway(nDeviceId);
    if(!ngatewayId)
    {
        fnNetSimError("Gateway is not configured for device %d",nDeviceId);
        assert(false);
    }
    if(!DEVICE_NWLAYER(ngatewayId))
        fnNetSimError("DNS-- Netwok layer is not configured for device %d",ngatewayId);
    devVar=DEVICE_NWLAYER(ngatewayId)->ipVar;
    dns=devVar->dnsList;
    while(dns)
    {
        if(dns->deviceId==id)
            return dns->ip;
        dns=LIST_NEXT(dns);
    }
    dns=DNS_ALLOC();
    dns->deviceId=id;
    dns->ip=fn_NetSim_Stack_GetFirstIPAddressAsId(id,0);
    LIST_ADD_LAST(&(devVar->dnsList),dns);
    return dns->ip;
}
/** This function is free the memory allocated for DNS */
int freeDNS(DNS* dns)
{
    while(dns)
        LIST_FREE(&dns,dns);
    return 1;
}