Here are the functions for examining and modifying socket options. They are declared in sys/socket.h.
getsockoptfunction gets information about the value of option optname at level level for socket socket.
The option value is stored in a buffer that optval points to. Before the call, you should supply in
*optlen-ptr the size of this buffer; on return, it contains the number of bytes of information actually stored in the buffer.
Most options interpret the optval buffer as a single
The actual return value of
0on success and
-1on failure. The following
errnoerror conditions are defined:
- The socket argument is not a valid file descriptor.
- The descriptor socket is not a socket.
- The optname doesn't make sense for the given level.