Function nanomsg_sys::nn_send

pub unsafe extern "C" fn nn_send(
    socket: c_int, 
    buf: *const c_void, 
    len: size_t, 
    flags: c_int
) -> c_int

"The function will send a message containing the data from buffer pointed to by buf parameter to the socket s. The message will be len bytes long. Alternatively, to send a buffer allocated by nn_allocmsg(3) function set the buf parameter to point to the pointer to the buffer and len parameter to NN_MSG constant. In this case a successful call to nn_send will deallocate the buffer. Trying to deallocate it afterwards will result in undefined behaviour.

Which of the peers the message will be sent to is determined by the particular socket type."

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