extern int setsockopt(int socket, int level, int option_name, const void *option_value, socklen_t option_len);
extern int getsockopt(int socket, int level, int option_name, void *option_value, socklen_t *option_len);
extern int setsockopt(int socket, int level, int option_name, const void *option_value, socklen_t option_len);
extern int getsockopt(int socket, int level, int option_name, void *option_value, socklen_t *option_len);