query defaultrouter from within

int getdefaultgateway(in_addr_t * addr){  FILE *p;  char ip[20];  p=popen("/usr/sbin/route -n get 0.0.0.0 | grep gateway | awk -e '{print $2}'","r");  fscanf(p,"%s", &ip);  *addr=inet_addr(ip);  return 0;}