Send TCP protocol header to ignore non-rerun clients

crates/re_sdk_comms/src/lib.rs

@@ -19,6 +19,8 @@ mod server;
 #[cfg(feature = "server")]
 pub use server::{serve, ServerError, ServerOptions};
 
+pub const PROTOCOL_HEADER: &str = "rerun";
+
 pub const PROTOCOL_VERSION: u16 = 0;
 
 pub const DEFAULT_SERVER_PORT: u16 = 9876;

crates/re_sdk_comms/src/server.rs

@@ -1,6 +1,7 @@
 use std::{
  io::{ErrorKind, Read as _},
  net::{TcpListener, TcpStream},
+ str,
  time::Instant,
 };
 
@@ -38,6 +39,9 @@ enum VersionError {
 
 #[derive(thiserror::Error, Debug)]
 enum ConnectionError {
+ #[error("An unknown client tried to connect")]
+ UnknownClient,
+
  #[error(transparent)]
  VersionError(#[from] VersionError),
 
@@ -203,6 +207,13 @@ fn run_client(
 ) -> Result<(), ConnectionError> {
  #![allow(clippy::read_zero_byte_vec)] // false positive: https://github.com/rust-lang/rust-clippy/issues/9274
 
+ let mut protocol_header = [0_u8; 5];
+ stream.read_exact(&mut protocol_header)?;
+
+ if !str::from_utf8(&protocol_header).is_ok_and(|header| header == crate::PROTOCOL_HEADER) {
+ return Err(ConnectionError::UnknownClient);
+ }
+
  let mut client_version = [0_u8; 2];
  stream.read_exact(&mut client_version)?;
  let client_version = u16::from_le_bytes(client_version);

crates/re_sdk_comms/src/tcp_client.rs

@@ -92,7 +92,11 @@ impl TcpClient {
  match TcpStream::connect_timeout(&self.addr, timeout) {
  Ok(mut stream) => {
  re_log::debug!("Connected to {:?}.", self.addr);
- if let Err(err) = stream.write(&crate::PROTOCOL_VERSION.to_le_bytes()) {
+
+ if let Err(err) = stream
+ .write(crate::PROTOCOL_HEADER.as_bytes())
+ .and_then(|_| stream.write(&crate::PROTOCOL_VERSION.to_le_bytes()))
+ {
  self.stream_state = TcpStreamState::Pending {
  start_time,
  num_attempts: num_attempts + 1,