IP_Utility.c

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/************************************************************************************
* Copyright (C) 2021                                                                *
* 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.       *
*                                                                                   *
* This source code is licensed per the NetSim license agreement.                    *
*                                                                                   *
* No portion of this source code may be used as the basis for a derivative work,    *
* or used, for any purpose other than its intended use per the NetSim license       *
* agreement.                                                                        *
*                                                                                   *
* This source code and the algorithms contained within it are confidential trade    *
* secrets of TETCOS and may not be used as the basis for any other software,        *
* hardware, product or service.                                                     *
*                                                                                   *
* Author:    Shashi Kant Suman                                                      *
*                                                                                   *
* ----------------------------------------------------------------------------------*/
#include "main.h"
#include "List.h"
#include "IP.h"
 
static bool isPublicIPReqd(NETSIM_ID d)
{
    NETSIM_ID i;
    bool ret = false;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_INTERFACE(d, i + 1)->nInterfaceType == INTERFACE_WAN_ROUTER)
            return false;
 
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay)
            ret = true;
    }
    return ret;
}
 
static NETSIM_IPAddress find_default_gateway(NETSIM_ID d,NETSIM_ID* di)
{
    NETSIM_ID i;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay)
        {
            *di = i + 1;
            return DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay;
        }
    }
    *di = 0;
    return NULL;
}
 
static NETSIM_IPAddress find_wan_ip(NETSIM_ID d, NETSIM_ID* wi)
{
    NETSIM_ID i;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_INTERFACE(d, i + 1)->nInterfaceType == INTERFACE_WAN_ROUTER)
        {
            *wi = i + 1;
            return DEVICE_INTERFACE(d, i + 1)->szAddress;
        }
    }
    *wi = 0;
    return NULL;
}
 
static void assign_public_ip(NETSIM_ID d, NETSIM_IPAddress ip)
{
    NETSIM_ID i;
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay)
        {
            DEVICE_PUBLICIP(d, i + 1) = ip;
            fprintf(stdout, "Public IP of %d-%d is %s\n",
                    d, i + 1, ip->str_ip);
        }
    }
}
 
typedef struct stru_ip_list
{
    NETSIM_IPAddress ip;
    NETSIM_IPAddress subnet;
    UINT prefix_len;
    struct stru_ip_list* next;
}IPLIST, * ptrIPLIST;
 
static void add_route(NETSIM_ID d, ptrIPLIST list,
                      NETSIM_IPAddress interfaceAddress,NETSIM_IPAddress nextHop)
{
    NETSIM_ID di = fn_NetSim_Stack_GetInterfaceIdFromIP(d, interfaceAddress);
    while (list)
    {
        NETSIM_IPAddress dest = IP_NETWORK_ADDRESS(list->ip, list->subnet,list->prefix_len);
 
        iptable_add(IP_WRAPPER_GET(d),
                    dest, list->subnet, list->prefix_len,
                    nextHop, 1, &interfaceAddress, &di, 1, "IP");
        list = list->next;
    }
}
 
static void setup_route_table_for_all_network(NETSIM_ID d, NETSIM_ID w, NETSIM_ID wi,
                                              ptrIPLIST ipList)
{
    NETSIM_ID c = 0;
    NETSIM_ID ci = 0;
    NETSIM_ID di = 0;
 
    while (true)
    {
        NETSIM_IPAddress defaultGateway = find_default_gateway(d, &di);
        c = fn_NetSim_Stack_GetDeviceId_asIP(defaultGateway, &ci);
        add_route(c, ipList, defaultGateway, DEVICE_NWADDRESS(d, di));
 
        if (c == w)
            break;
 
        d = c;
    }
}
 
static void setup_route_table(NETSIM_ID d, NETSIM_ID w, NETSIM_ID wi)
{
    NETSIM_IPAddress pubIP = DEVICE_NWADDRESS(w, wi);
 
    ptrIPLIST head = NULL;
    ptrIPLIST tail = NULL;
    NETSIM_IPAddress defaultGateway = NULL;
    NETSIM_ID i;
 
    for (i = 0; i < DEVICE(d)->nNumOfInterface; i++)
    {
        if (DEVICE_INTERFACE(d, i + 1) &&
            DEVICE_NWADDRESS(d, i + 1))
        {
            if (DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay && !defaultGateway)
            {
                defaultGateway = DEVICE_INTERFACE(d, i + 1)->szDefaultGateWay;
            }
            else
            {
                ptrIPLIST l = calloc(1, sizeof * l);
                l->ip = DEVICE_INTERFACE(d, i + 1)->szAddress;
                l->subnet = DEVICE_INTERFACE(d, i + 1)->szSubnetMask;
                l->prefix_len = DEVICE_INTERFACE(d, i + 1)->prefix_len;;
 
                if (head)
                {
                    tail->next = l;
                    tail = l;
                }
                else
                {
                    head = l;
                    tail = l;
                }
            }
        }
    }
 
    if(head)
        setup_route_table_for_all_network(d, w, wi, head);
 
    while (head)
    {
        ptrIPLIST t = head;
        head = head->next;
        free(t);
    }
}
 
void set_public_ip(NETSIM_ID d)
{
    if (!isPublicIPReqd(d))
        return;
 
    NETSIM_ID c = d;
    NETSIM_ID ci = 0;
    while (true)
    {
        NETSIM_IPAddress defaultGateway = find_default_gateway(c, &ci);
        if (!defaultGateway)
            break;
 
        c = fn_NetSim_Stack_GetDeviceId_asIP(defaultGateway, &ci);
 
        NETSIM_IPAddress wanIP = find_wan_ip(c, &ci);
 
        if (wanIP)
        {
            assign_public_ip(d, wanIP);
            c = fn_NetSim_Stack_GetDeviceId_asIP(wanIP, &ci);
            setup_route_table(d, c, ci);
            break;
        }
    }
    
}