set- or getsockopt()

#include <sys/types.h>
#include <sys/socket.h>

int getsockopt(int s, int level, int optname, void *optval,
               socklen_t *optlen);
int setsockopt(int s, int level, int optname, const void *optval,
               socklen_t optlen);

Parameters

getsockopt:

• int socket: ID of our created socket
• int level
• int option_name
• void *retrict option_value
• socklen_t *restrict option_len

setsockopt:

• int socket: ID of our created socket
• int level:
• int option_name: name of the option, that gets manipulated
• const void *option_value
• socklen_t option_len

options:

• SO_REUSEADDR: indicates that the rules used in validating addresses supplied in a bind(2) call should allow reuse of local addresses.

return values:

• 0: if successful
• -1: otherwise and errno is set