Function nanomsg_sys::nn_getsockopt

pub unsafe extern "C" fn nn_getsockopt(
    socket: c_int, 
    level: c_int, 
    option: c_int, 
    optval: *mut c_void, 
    optvallen: *mut size_t
) -> c_int

"Retrieves the value for the option. The level argument specifies the protocol level at which the option resides. For generic socket-level options use NN_SOL_SOCKET level. For socket-type-specific options use socket type for level argument (e.g. NN_SUB). For transport-specific options use ID of the transport as the level argument (e.g. NN_TCP).

The value is stored in the buffer pointed to by optval argument. Size of the buffer is specified by the optvallen argument. If the size of the option is greater than size of the buffer, the value will be silently truncated. Otherwise, the optvallen will be modified to indicate the actual length of the option."

http://nanomsg.org/v0.4/nn_getsockopt.3.html