Function sendto 

pub unsafe fn sendto(
    socket: CSocket,
    buf: Buf,
    len: BufLen,
    flags: c_int,
    addr: *const SockAddr,
    addrlen: SockLen,
) -> CouldFail

Call sendto(2) using raw socket arguments.

Safety

buf must be valid for reads of len bytes. addr must point to a valid socket address of length addrlen.