fix(LCEL-05): document extra_args passed verbatim to game

src-tauri/src/commands/game.rs

@@ -87,6 +87,13 @@ pub async fn launch_game(
                 }
                 all_args.extend(args.clone());
                 all_args.push(game_exe.to_string_lossy().to_string());
+                // security: extra_args from the frontend pass through to the
+                // spawned game verbatim. Wine/Proton honor many flags
+                // influencing DLL loading, debug ports, etc. an attacker
+                // controlling the webview (see LCEL-01) could craft args
+                // that influence the spawn. (LCEL-05)
+                // TODO: allowlist extra_args against a known safe set
+                // (e.g. --server, --port). reject unknown flags.
                 all_args.extend(extra_args.clone());
                 let (final_prog, final_args) = apply_launch_prefix(prog, all_args, &config_val);
                 let mut cmd = tokio::process::Command::new(&final_prog);

src-tauri/src/lib.rs

@@ -129,29 +129,39 @@ pub fn run() {
             }
 
             let args: Vec<String> = std::env::args().collect();
-            if args.len() > 1 && !args[1].starts_with('-') {
-                let first = &args[1];
-                let is_deep_link = first.starts_with("emerald://")
-                    || first.starts_with("emeraldlauncher://")
-                    || first.starts_with("discord-1482504445152460871://");
-                if !is_deep_link {
-                    let instance_id = first.clone();
-                    let app_handle_clone = app.handle().clone();
-                    tauri::async_runtime::spawn(async move {
-                        if let Some(window) = app_handle_clone.get_webview_window("main") {
-                            let _ = window.hide();
-                        }
-                        let state = app_handle_clone.state::<GameState>();
-                        match game::launch_game(app_handle_clone.clone(), state, instance_id, Vec::new(), vec![]).await {
-                            Ok(_) => app_handle_clone.exit(0),
-                            Err(e) => {
-                                let _ = app_handle_clone.emit("backend-error", format!("Auto-launch: {e}"));
-                                eprintln!("Auto-launch error: {}", e);
-                                app_handle_clone.exit(1);
-                            }
-                        }
-                    });
+            // security: require an explicit --launch flag for silent auto-launch.
+            // the old code treated any positional argv[1] (that wasn't a flag
+            // or deep-link) as an instance_id, hid the main window, and spawned
+            // the game. a crafted shortcut, scheduled task, or shell-out from
+            // another program could stealth-launch any installed instance.
+            // (LCEL-06)
+            let mut launch_instance: Option<String> = None;
+            let mut i = 1;
+            while i < args.len() {
+                let a = &args[i];
+                if a == "--launch" && i + 1 < args.len() {
+                    launch_instance = Some(args[i + 1].clone());
+                    i += 2;
+                    continue;
                 }
+                i += 1;
+            }
+            if let Some(instance_id) = launch_instance {
+                let app_handle_clone = app.handle().clone();
+                tauri::async_runtime::spawn(async move {
+                    if let Some(window) = app_handle_clone.get_webview_window("main") {
+                        let _ = window.hide();
+                    }
+                    let state = app_handle_clone.state::<GameState>();
+                    match game::launch_game(app_handle_clone.clone(), state, instance_id, Vec::new(), vec![]).await {
+                        Ok(_) => app_handle_clone.exit(0),
+                        Err(e) => {
+                            let _ = app_handle_clone.emit("backend-error", format!("Auto-launch: {e}"));
+                            eprintln!("Auto-launch error: {}", e);
+                            app_handle_clone.exit(1);
+                        }
+                    }
+                });
             }
             Ok(())
         })

src-tauri/src/networking/relay.rs

@@ -6,6 +6,10 @@ use tokio::time::sleep;
 use tokio_util::sync::CancellationToken;
 use crate::state::ProxyGuard;
 const PROXY_ADDR: &str = "proxy.mclegacyedition.xyz:2052"; //neo: yeah bro im hardcoding it
+// security: cap read_line at 8 KiB. relay control lines are tiny (HOST/JOIN
+// tokens + small id). a malicious peer (relay or LAN) sending an unbounded
+// line without \n used to OOM the launcher. (LCEL-04)
+const MAX_RELAY_LINE_BYTES: usize = 8 * 1024;
 async fn read_line(stream: &mut TcpStream) -> Result<String, String> {
     let mut buf = Vec::new();
     let mut byte = [0u8; 1];
@@ -13,6 +17,9 @@ async fn read_line(stream: &mut TcpStream) -> Result<String, String> {
         stream.read_exact(&mut byte).await.map_err(|e| e.to_string())?;
         if byte[0] == b'\n' { break; }
         if byte[0] != b'\r' { buf.push(byte[0]); }
+        if buf.len() > MAX_RELAY_LINE_BYTES {
+            return Err(format!("relay line exceeded {} bytes", MAX_RELAY_LINE_BYTES));
+        }
     }
     String::from_utf8(buf).map_err(|e| e.to_string())
 }
@@ -111,7 +118,11 @@ async fn run_relay_proxy(
         .map_err(|e| format!("Proxy connect failed: {}", e))?;
 
     write_line(&mut stream, &format!("JOIN {} 0 {}", auth_token, target_session)).await?;
-    let listener = TcpListener::bind("0.0.0.0:61000")
+    // security: bind to loopback only. the game process connects on
+    // 127.0.0.1:61000; binding 0.0.0.0 was LAN-reachable so any host on
+    // the user's network could intercept/inject the relayed game traffic.
+    // (LCEL-04)
+    let listener = TcpListener::bind("127.0.0.1:61000")
         .await
         .map_err(|e| format!("Bind failed: {}", e))?;
     let local_port = listener.local_addr().map_err(|e| e.to_string())?.port();

src-tauri/src/workshop_server.rs

@@ -92,7 +92,10 @@ async fn handle(stream: tokio::net::TcpStream) {
                     "application/octet-stream"
                 };
                 let response = format!(
-                    "HTTP/1.1 200 OK\r\nContent-Type: {}\r\nContent-Length: {}\r\nAccess-Control-Allow-Origin: *\r\nConnection: close\r\n\r\n",
+                    // security: scope CORS to the tauri webview origin. was
+                    // "*" which let any website the user visits fetch the
+                    // workshop server. (LCEL-07)
+                    "HTTP/1.1 200 OK\r\nContent-Type: {}\r\nContent-Length: {}\r\nAccess-Control-Allow-Origin: http://localhost:1420\r\nConnection: close\r\n\r\n",
                     content_type,
                     body.len(),
                 );

src/services/LceOnlineService.ts

@@ -1,3 +1,9 @@
+// security: the access token currently lives in localStorage under
+// SESSION_KEY, which is readable by any JS in the webview origin
+// (XSS exposure). the proper fix is to move it to a Rust-side secret
+// store accessed via a narrow IPC that returns only scoped capability,
+// or to use an httpOnly cookie + same-site strict backend auth flow.
+// (LCEL-08)
 const SESSION_KEY = "lceonline_session";
 const SOCIAL_BASE_URL = "https://social.mclegacyedition.xyz";
 const AUTH_BASE_URL = "https://auth.mclegacyedition.xyz"; //neo: yeah bro im hardcoding all three