LinuxQuestions.org - [SOLVED] Problem to set gateway using c++ program

Hi,

I'm trying to set the gateway with my c++ program. My function receive the gateway on the first parameter.

The return of execution of ioctl() is 0, so it's working good, but when I run the "route" command on console, the configured gateway isn't there.

Check the output and the function below:

$ route

Quote:

Destination Gateway Genmask Flags Metric Ref Use Iface
10.0.0.0 * 255.0.0.0 U 0 0 0 eth0

Code:

int gateWayConfig(string gateWay) {

    int result = ERROR; //retorno da função

    try {

        int sockfd = socket(AF_INET, SOCK_DGRAM, 0);

        gateWay = formatIp(gateWay); //converts 192.168.000.001 to 192.168.0.1



        if (sockfd > 0) {

            struct sockaddr_in *dst, *gw, *mask;

            struct rtentry route;



            printf("gateway: %s\n", gateWay.c_str());

            printf("gateway: %d\n", inet_addr(gateWay.c_str()));



            memset(&route, 0, sizeof (struct rtentry));



            dst = (struct sockaddr_in *) (&(route.rt_dst));

            gw = (struct sockaddr_in *) (&(route.rt_gateway));

            mask = (struct sockaddr_in *) (&(route.rt_genmask));



            // Make sure we're talking about IP here

            dst->sin_family = AF_INET;

            gw->sin_family = AF_INET;

            mask->sin_family = AF_INET;



            // Set up the data for removing the default route

            dst->sin_addr.s_addr = 0;

            gw->sin_addr.s_addr = 0;

            mask->sin_addr.s_addr = 0;

            route.rt_flags = RTF_UP | RTF_GATEWAY;



            // Remove the default route

            ioctl(sockfd, SIOCDELRT, &route);



            // Set up the data for adding the default route

            dst->sin_addr.s_addr = 0;

            gw->sin_addr.s_addr = inet_addr(gateWay.c_str());

            mask->sin_addr.s_addr = 0;

            route.rt_metric = 1;

            route.rt_flags = RTF_UP | RTF_GATEWAY;



            // Remove this route if it already exists

            ioctl(sockfd, SIOCDELRT, &route);



            // Add the default route

            if (ioctl(sockfd, SIOCADDRT, &route) == -1) {

                // *** The error never occurs ***

                fprintf(stderr, "Adding default route: %d", errno);

            }

            shutdown(sockfd, SHUT_RDWR);

            close(sockfd);

        }

        printf("result: %d\n", result); 

        

    } catch (...) {



    }

    return result;

}

Could someone help me to solve this issue?

I tried to use system() function to set the gateway using:
system("route del default");
system("route add default gw 10.100.40.1 dev eth0");

But didn't work too. :/

Thanks in advance