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use bytes::buf::Buf;
use bytes::BytesMut;
use tokio_util::codec::{Decoder, Encoder};
use std::io;
use std::io::{Cursor, ErrorKind::TimedOut, ErrorKind::UnexpectedEof, ErrorKind::WouldBlock};
use crate::mqtt4::Packet;
use crate::mqtt4::{MqttRead, MqttWrite};
use crate::Error;
pub struct MqttCodec {
max_payload_size: usize,
}
impl MqttCodec {
pub fn new(max_payload_size: usize) -> Self {
MqttCodec { max_payload_size }
}
}
impl Decoder for MqttCodec {
type Item = Packet;
type Error = Error;
fn decode(&mut self, buf: &mut BytesMut) -> Result<Option<Packet>, Error> {
if buf.len() < 2 {
return Ok(None);
}
let mut buf_ref = buf.as_ref();
let (packet_type, remaining_len) = match buf_ref.read_packet_type_and_remaining_length() {
Ok(len) => len,
Err(Error::Io(e)) if e.kind() == TimedOut || e.kind() == WouldBlock || e.kind() == UnexpectedEof => return Ok(None),
Err(e) => return Err(e.into()),
};
if remaining_len > self.max_payload_size {
return Err(Error::PayloadSizeLimitExceeded);
}
let header_len = buf_ref.header_len(remaining_len);
let len = header_len + remaining_len;
if buf.len() < len {
return Ok(None);
}
let packet = buf_ref.deserialize(packet_type, remaining_len)?;
buf.advance(len);
Ok(Some(packet))
}
}
impl Encoder<Packet> for MqttCodec {
type Error = io::Error;
fn encode(&mut self, msg: Packet, buf: &mut BytesMut) -> Result<(), io::Error> {
let mut stream = Cursor::new(Vec::new());
if let Err(_) = stream.mqtt_write(&msg) {
return Err(io::Error::new(io::ErrorKind::Other, "Unable to encode!"));
}
buf.extend(stream.get_ref());
Ok(())
}
}