Getting gateway to use for a given ip in ANSI C

Question

I have looked around like crazy but don\'t get a real answer. I got one example, but that depended on the individuals own library so not much good.

At first I wanted

Answer 1

Maybe this is very old question but I had same problem and I can't find better result. Finally I solved my problem with these code that it has a few changes. So I decide to share it.

char* GetGatewayForInterface(const char* interface) 
{
    char* gateway = NULL;

    char cmd [1000] = {0x0};
    sprintf(cmd,"route -n | grep %s  | grep 'UG[ \t]' | awk '{print $2}'", interface);
    FILE* fp = popen(cmd, "r");
    char line[256]={0x0};

    if(fgets(line, sizeof(line), fp) != NULL)
        gateway = string(line);


    pclose(fp);
}