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//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.
//
use mqtt_format::v5::packets::MqttPacket as FormatMqttPacket;
use tokio_util::codec::Decoder;
use tokio_util::codec::Encoder;
use winnow::Partial;
use yoke::Yoke;
use crate::packets::MqttPacket;
use crate::packets::MqttWriterError;
#[derive(Debug, thiserror::Error)]
pub enum MqttPacketCodecError {
#[error("A codec error")]
Io(#[from] std::io::Error),
#[error("An error occured while writing to a buffer")]
Writer(#[from] MqttWriterError),
#[error("A protocol error occurred")]
Protocol,
}
pub(crate) struct MqttPacketCodec;
impl Decoder for MqttPacketCodec {
type Item = MqttPacket;
type Error = MqttPacketCodecError;
fn decode(
&mut self,
src: &mut tokio_util::bytes::BytesMut,
) -> Result<Option<Self::Item>, Self::Error> {
// 1. Byte: FixedHeader
// 2-5. Byte: Variable-Size
if src.len() < 2 {
src.reserve(2 - src.len());
return Ok(None);
}
let packet_size =
match mqtt_format::v5::integers::parse_variable_u32(&mut Partial::new(&src[1..])) {
Ok(size) => size,
Err(winnow::error::ErrMode::Incomplete(winnow::error::Needed::Size(needed))) => {
src.reserve(needed.into());
return Ok(None);
}
_ => {
return Err(MqttPacketCodecError::Protocol);
}
};
let remaining_length = packet_size as usize;
let total_packet_length = 1
+ mqtt_format::v5::integers::variable_u32_binary_size(packet_size) as usize
+ remaining_length;
if src.len() < total_packet_length {
src.reserve(total_packet_length - src.len());
return Ok(None);
}
let cart = src.split_to(total_packet_length).freeze();
let packet = Yoke::try_attach_to_cart(
crate::packets::StableBytes(cart),
|data| -> Result<_, MqttPacketCodecError> {
FormatMqttPacket::parse_complete(data).map_err(|_| MqttPacketCodecError::Protocol)
},
)?;
Ok(Some(MqttPacket { packet }))
}
}
impl Encoder<FormatMqttPacket<'_>> for MqttPacketCodec {
type Error = MqttPacketCodecError;
fn encode(
&mut self,
packet: FormatMqttPacket<'_>,
dst: &mut tokio_util::bytes::BytesMut,
) -> Result<(), Self::Error> {
packet.write(&mut crate::packets::MqttWriter(dst))?;
Ok(())
}
}
#[cfg(test)]
mod tests {
use futures::SinkExt;
use futures::StreamExt;
use mqtt_format::v5::packets::pingreq::MPingreq;
use mqtt_format::v5::packets::MqttPacket as FormatMqttPacket;
use tokio_util::bytes::BytesMut;
use tokio_util::codec::Framed;
use super::MqttPacketCodec;
use crate::packet::MqttWriter;
#[tokio::test]
async fn simple_test_codec() {
let (client, server) = tokio::io::duplex(100);
let mut framed_client = Framed::new(client, MqttPacketCodec);
let mut framed_server = Framed::new(server, MqttPacketCodec);
let mut data = BytesMut::new();
let packet = FormatMqttPacket::Pingreq(MPingreq);
tokio::spawn(async move {
framed_client.send(packet).await.unwrap();
});
let recv_packet = framed_server.next().await.unwrap().unwrap();
assert_eq!(packet, *recv_packet.get());
}
}
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