Initial commit

crates/ocs_plugin_api/src/ipc/transport.rs

@@ -0,0 +1,52 @@
+//! Length-framed transport over `interprocess::local_socket` streams.
+
+use std::io::{Read, Write};
+
+use interprocess::local_socket::Stream;
+use serde::{de::DeserializeOwned, Serialize};
+
+/// Maximum serialized message size accepted over the wire (64 MiB). Prevents
+/// a malicious or buggy peer from exhausting host/runner memory.
+const MAX_MESSAGE_SIZE: usize = 64 * 1024 * 1024;
+
+/// Errors that can occur during transport.
+#[derive(Debug, thiserror::Error)]
+pub enum TransportError {
+    #[error("IO error: {0}")]
+    Io(#[from] std::io::Error),
+    #[error("serialization error: {0}")]
+    Encode(#[from] bincode::Error),
+    #[error("empty message")]
+    Empty,
+    #[error("message too large: {0} bytes")]
+    TooLarge(usize),
+}
+
+/// Send a length-framed serialized message.
+pub fn send<T: Serialize>(stream: &mut Stream, msg: &T) -> Result<(), TransportError> {
+    let bytes = bincode::serialize(msg)?;
+    if bytes.len() > MAX_MESSAGE_SIZE {
+        return Err(TransportError::TooLarge(bytes.len()));
+    }
+    let len = bytes.len() as u64;
+    stream.write_all(&len.to_le_bytes())?;
+    stream.write_all(&bytes)?;
+    stream.flush()?;
+    Ok(())
+}
+
+/// Receive a length-framed serialized message.
+pub fn recv<T: DeserializeOwned>(stream: &mut Stream) -> Result<T, TransportError> {
+    let mut len_buf = [0u8; 8];
+    stream.read_exact(&mut len_buf)?;
+    let len = u64::from_le_bytes(len_buf) as usize;
+    if len == 0 {
+        return Err(TransportError::Empty);
+    }
+    if len > MAX_MESSAGE_SIZE {
+        return Err(TransportError::TooLarge(len));
+    }
+    let mut buf = vec![0u8; len];
+    stream.read_exact(&mut buf)?;
+    Ok(bincode::deserialize(&buf)?)
+}