Function nrf_send 

pub unsafe extern "C" fn nrf_send(
    socket: c_int,
    buffer: *const c_void,
    length: usize,
    flags: c_int,
) -> isize

Send a message on a connected socket.

@details See POSIX.1-2017 article for normative description.

In addition, the function may return -1 and set the following errno:

• NRF_ESHUTDOWN Modem was shut down.
• NRF_ECANCELED Operation canceled because of APN rate control.
• NRF_ENOMEM TCP stream interrupted because of no heap memory.
• NRF_EPROTO Request failed because DTLS context was serialized.