Harden native auth and SDK datagram handling

src/bin/dosh-server.rs

@@ -433,6 +433,7 @@ struct PendingStreamOpen {
     attempts: u32,
 }
 
+#[derive(Clone)]
 struct PendingNativeAuth {
     client: dosh::native::NativeClientHello,
     server: NativeServerHello,
@@ -992,8 +993,8 @@ async fn handle_native_user_auth(
     packet: &protocol::Packet,
 ) -> Result<()> {
     let pending = {
-        let mut locked = state.lock().expect("server state poisoned");
-        locked.pending_native.remove(&packet.header.conn_id)
+        let locked = state.lock().expect("server state poisoned");
+        locked.pending_native.get(&packet.header.conn_id).cloned()
     };
     let Some(pending) = pending else {
         return send_reject_to_client(socket, peer, packet.header.conn_id, "unknown native auth")
@@ -1009,11 +1010,38 @@ async fn handle_native_user_auth(
         .await;
     }
     if pending.created_at.elapsed() > Duration::from_secs(30) {
+        state
+            .lock()
+            .expect("server state poisoned")
+            .pending_native
+            .remove(&packet.header.conn_id);
         return send_reject_to_client(socket, peer, packet.header.conn_id, "native auth expired")
             .await;
     }
-    let body = protocol::decrypt_body(packet, &pending.session_key, CLIENT_TO_SERVER)?;
-    let req: NativeUserAuthBody = protocol::from_body(&body)?;
+    let body = match protocol::decrypt_body(packet, &pending.session_key, CLIENT_TO_SERVER) {
+        Ok(body) => body,
+        Err(_) => {
+            return send_reject_to_client(
+                socket,
+                peer,
+                packet.header.conn_id,
+                "native auth decrypt failed",
+            )
+            .await;
+        }
+    };
+    let req: NativeUserAuthBody = match protocol::from_body(&body) {
+        Ok(req) => req,
+        Err(_) => {
+            return send_reject_to_client(
+                socket,
+                peer,
+                packet.header.conn_id,
+                "invalid native auth body",
+            )
+            .await;
+        }
+    };
     if pending.client.requested_mode == "doctor" {
         let check_result = {
             let locked = state.lock().expect("server state poisoned");
@@ -1049,6 +1077,11 @@ async fn handle_native_user_auth(
                 .await;
             }
         };
+        state
+            .lock()
+            .expect("server state poisoned")
+            .pending_native
+            .remove(&packet.header.conn_id);
         let body = protocol::to_body(&check)?;
         let out = protocol::encode_encrypted(
             PacketKind::NativeAuthCheckOk,
@@ -1229,6 +1262,11 @@ async fn handle_native_user_auth(
     if let Some((listener, path)) = agent_listener {
         spawn_agent_forward(state, socket, client_id, listener, path);
     }
+    state
+        .lock()
+        .expect("server state poisoned")
+        .pending_native
+        .remove(&packet.header.conn_id);
 
     let ok = NativeAuthOk {
         client_id,