[Fix] Harden MTP codec, transport, and SDK security

transport/src/connection_handle.rs

@@ -2,22 +2,26 @@ use mtp_common::CommunicationError;
 use std::net::SocketAddr;
 use std::sync::{
     Arc,
-    atomic::{AtomicBool, Ordering},
+    atomic::{AtomicBool, AtomicU64, Ordering},
 };
 use tokio::sync::watch;
 
 #[derive(Debug)]
 pub struct ConnectionHandle {
+    connection_id: u64,
     closed: AtomicBool,
     close_tx: watch::Sender<Option<CommunicationError>>,
     close_rx: watch::Receiver<Option<CommunicationError>>,
     remote_addr: Option<SocketAddr>,
 }
 
+static NEXT_CONNECTION_ID: AtomicU64 = AtomicU64::new(1);
+
 impl ConnectionHandle {
     pub fn new() -> Self {
         let (close_tx, close_rx) = watch::channel(None);
         Self {
+            connection_id: NEXT_CONNECTION_ID.fetch_add(1, Ordering::Relaxed).max(1),
             closed: AtomicBool::new(false),
             close_tx,
             close_rx,
@@ -35,6 +39,11 @@ impl ConnectionHandle {
         self.remote_addr
     }
 
+    /// Stable process-local identifier for authentication-rate-limit scopes.
+    pub fn connection_id(&self) -> u64 {
+        self.connection_id
+    }
+
     pub fn is_open(&self) -> bool {
         !self.closed.load(Ordering::SeqCst)
     }