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use futures::future::BoxFuture; use futures::io::{AsyncRead, AsyncWrite}; use libp2p::core::{upgrade, InboundUpgrade, OutboundUpgrade, UpgradeInfo}; use std::io::{Error, ErrorKind, Result}; use std::sync::Arc; const PROTOCOL_INFO: &[u8] = b"/ax/broadcast/1.0.0"; #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)] pub struct Topic { len: u8, bytes: [u8; 64], } impl Topic { pub const MAX_TOPIC_LENGTH: usize = 64; pub fn new(topic: &[u8]) -> Self { let mut bytes = [0u8; 64]; bytes[..topic.len()].copy_from_slice(topic); Self { len: topic.len() as _, bytes, } } } impl std::ops::Deref for Topic { type Target = [u8]; fn deref(&self) -> &Self::Target { self.as_ref() } } impl AsRef<[u8]> for Topic { fn as_ref(&self) -> &[u8] { &self.bytes[..(self.len as usize)] } } #[derive(Clone, Debug, PartialEq)] pub enum Message { Subscribe(Topic), Broadcast(Topic, Arc<[u8]>), Unsubscribe(Topic), } impl Message { fn from_bytes(bytes: &[u8]) -> Result<Self> { let topic_len = (bytes[0] >> 2) as usize; if bytes.len() < topic_len + 1 { return Err(Error::new(ErrorKind::InvalidData, "topic length out of range")); } let msg_len = bytes.len() - topic_len - 1; let topic = Topic::new(&bytes[1..topic_len + 1]); Ok(match bytes[0] & 0b11 { 0b00 => Message::Subscribe(topic), 0b10 => Message::Unsubscribe(topic), 0b01 => { let mut msg = Vec::with_capacity(msg_len); msg.extend_from_slice(&bytes[(topic_len + 1)..]); Message::Broadcast(topic, msg.into()) } _ => return Err(Error::new(ErrorKind::InvalidData, "invalid header")), }) } fn to_bytes(&self) -> Vec<u8> { use Message::*; match self { Subscribe(topic) => { let mut buf = Vec::with_capacity(topic.len() + 1); buf.push((topic.len() as u8) << 2); buf.extend_from_slice(topic); buf } Unsubscribe(topic) => { let mut buf = Vec::with_capacity(topic.len() + 1); buf.push((topic.len() as u8) << 2 | 0b10); buf.extend_from_slice(topic); buf } Broadcast(topic, msg) => { let mut buf = Vec::with_capacity(topic.len() + msg.len() + 1); buf.push((topic.len() as u8) << 2 | 0b01); buf.extend_from_slice(topic); buf.extend_from_slice(msg); buf } } } } #[derive(Clone, Debug)] pub struct BroadcastConfig { max_buf_size: usize, } impl Default for BroadcastConfig { fn default() -> Self { Self { max_buf_size: 1024 * 1024 * 4, } } } impl UpgradeInfo for BroadcastConfig { type Info = &'static [u8]; type InfoIter = std::iter::Once<Self::Info>; fn protocol_info(&self) -> Self::InfoIter { std::iter::once(PROTOCOL_INFO) } } impl<TSocket> InboundUpgrade<TSocket> for BroadcastConfig where TSocket: AsyncRead + AsyncWrite + Send + Unpin + 'static, { type Output = Message; type Error = Error; type Future = BoxFuture<'static, Result<Self::Output>>; fn upgrade_inbound(self, mut socket: TSocket, _info: Self::Info) -> Self::Future { Box::pin(async move { let packet = upgrade::read_one(&mut socket, self.max_buf_size).await.map_err(|err| { use upgrade::ReadOneError::*; match err { Io(err) => err, TooLarge { .. } => Error::new(ErrorKind::InvalidData, format!("{}", err)), } })?; let request = Message::from_bytes(&packet)?; Ok(request) }) } } impl UpgradeInfo for Message { type Info = &'static [u8]; type InfoIter = std::iter::Once<Self::Info>; fn protocol_info(&self) -> Self::InfoIter { std::iter::once(PROTOCOL_INFO) } } impl<TSocket> OutboundUpgrade<TSocket> for Message where TSocket: AsyncRead + AsyncWrite + Send + Unpin + 'static, { type Output = (); type Error = Error; type Future = BoxFuture<'static, Result<Self::Output>>; fn upgrade_outbound(self, mut socket: TSocket, _info: Self::Info) -> Self::Future { Box::pin(async move { let bytes = self.to_bytes(); upgrade::write_one(&mut socket, bytes).await?; Ok(()) }) } } #[cfg(test)] mod tests { use super::*; #[test] fn test_roundtrip() { let topic = Topic::new(b"topic"); let msgs = [ Message::Broadcast(Topic::new(b""), Arc::new(*b"")), Message::Subscribe(topic), Message::Unsubscribe(topic), Message::Broadcast(topic, Arc::new(*b"content")), ]; for msg in &msgs { let msg2 = Message::from_bytes(&msg.to_bytes()).unwrap(); assert_eq!(msg, &msg2); } } #[test] #[should_panic] fn test_invalid_message() { let out_of_range = [0b0000_0100]; Message::from_bytes(&out_of_range).unwrap(); } }