kadmium 0.6.0

A broadcast protocol implementation based on Kadcast.
Documentation 
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//! Encoding and decoding utilities for messages.

use std::io;

use bytes::{Bytes, BytesMut};
use tokio_util::codec::{Decoder, Encoder, LengthDelimitedCodec};

use crate::core::message::Message;

/// Backed by Bincode and Tokio's [`LengthDelimitedCodec`], this codec implements the [`Encoder`] and
/// [`Decoder`] traits for [`Message`].
pub struct MessageCodec {
    codec: LengthDelimitedCodec,
}

impl MessageCodec {
    /// Returns a new message codec.
    pub fn new() -> Self {
        Self {
            codec: LengthDelimitedCodec::new(),
        }
    }
}

impl Default for MessageCodec {
    fn default() -> Self {
        Self::new()
    }
}

impl Decoder for MessageCodec {
    type Item = Message;
    type Error = io::Error;

    fn decode(&mut self, src: &mut BytesMut) -> Result<Option<Self::Item>, Self::Error> {
        let bytes = match self.codec.decode(src)? {
            Some(bytes) => bytes,
            None => return Ok(None),
        };

        match bincode::decode_from_slice(&bytes, bincode::config::standard()) {
            Ok((message, _length)) => Ok(Some(message)),
            Err(e) => Err(io::Error::new(io::ErrorKind::Other, e)),
        }
    }
}

impl Encoder<Message> for MessageCodec {
    type Error = io::Error;

    fn encode(&mut self, message: Message, dst: &mut BytesMut) -> Result<(), Self::Error> {
        let _ = match bincode::encode_to_vec(message, bincode::config::standard()) {
            Ok(bytes) => self.codec.encode(Bytes::copy_from_slice(&bytes), dst),
            Err(e) => return Err(io::Error::new(io::ErrorKind::Other, e)),
        };

        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use rand::{thread_rng, Rng};

    use super::*;
    use crate::{
        core::id::Id,
        message::{Chunk, FindKNodes, KNodes, Ping, Pong},
    };

    #[test]
    fn codec_ping() {
        let mut rng = thread_rng();

        let message = Message::Ping(Ping {
            nonce: rng.gen(),
            id: Id::rand(),
        });

        let mut codec = MessageCodec::new();
        let mut dst = BytesMut::new();

        assert!(codec.encode(message.clone(), &mut dst).is_ok());
        assert_eq!(codec.decode(&mut dst).unwrap().unwrap(), message);
    }

    #[test]
    fn codec_pong() {
        let mut rng = thread_rng();

        let message = Message::Pong(Pong {
            nonce: rng.gen(),
            id: Id::rand(),
        });

        let mut codec = MessageCodec::new();
        let mut dst = BytesMut::new();

        assert!(codec.encode(message.clone(), &mut dst).is_ok());
        assert_eq!(codec.decode(&mut dst).unwrap().unwrap(), message);
    }

    #[test]
    fn codec_find_k_nodes() {
        let mut rng = thread_rng();

        let message = Message::FindKNodes(FindKNodes {
            nonce: rng.gen(),
            id: Id::rand(),
        });

        let mut codec = MessageCodec::new();
        let mut dst = BytesMut::new();

        assert!(codec.encode(message.clone(), &mut dst).is_ok());
        assert_eq!(codec.decode(&mut dst).unwrap().unwrap(), message);
    }

    #[test]
    fn codec_k_nodes() {
        let mut rng = thread_rng();

        let message = Message::KNodes(KNodes {
            nonce: rng.gen(),
            nodes: vec![(Id::from_u16(0), "127.0.0.1:0".parse().unwrap())],
        });

        let mut codec = MessageCodec::new();
        let mut dst = BytesMut::new();

        assert!(codec.encode(message.clone(), &mut dst).is_ok());
        assert_eq!(codec.decode(&mut dst).unwrap().unwrap(), message);
    }

    #[test]
    fn codec_chunk() {
        use rand::Fill;

        let mut rng = thread_rng();
        let mut data = [0u8; 32];
        data.try_fill(&mut rng).unwrap();

        let message = Message::Chunk(Chunk {
            nonce: rng.gen(),
            height: rng.gen(),
            data: Bytes::copy_from_slice(&data),
        });

        let mut codec = MessageCodec::new();
        let mut dst = BytesMut::new();

        assert!(codec.encode(message.clone(), &mut dst).is_ok());
        assert_eq!(codec.decode(&mut dst).unwrap().unwrap(), message);
    }
}