Fix IMAP: Pipelined STORE and EXPUNGE can execute out of order

crates/imap/src/core/client.rs

@@ -30,11 +30,14 @@ impl<T: SessionStream> Session<T> {
         let mut bytes = bytes.iter();
         let mut requests = Vec::with_capacity(2);
         let mut needs_literal = None;
+        let mut has_expunge = false;
 
         loop {
             match self.receiver.parse(&mut bytes) {
                 Ok(request) => match self.is_allowed(request).await {
                     Ok(request) => {
+                        has_expunge |=
+                            matches!(request.command, Command::Expunge(_) | Command::Close);
                         requests.push(request);
                     }
                     Err(err) => {
@@ -140,7 +143,7 @@ impl<T: SessionStream> Session<T> {
                     .await
                     .map(|_| SessionResult::Continue),
                 Command::Store(is_uid) => self
-                    .handle_store(request, is_uid)
+                    .handle_store(request, is_uid, !has_expunge)
                     .await
                     .map(|_| SessionResult::Continue),
                 Command::Copy(is_uid) => self

crates/imap/src/op/store.rs

@@ -43,6 +43,7 @@ impl<T: SessionStream> Session<T> {
         &mut self,
         request: Request<Command>,
         is_uid: bool,
+        spawn: bool,
     ) -> trc::Result<()> {
         // Validate access
         self.assert_has_permission(Permission::ImapStore)?;
@@ -52,13 +53,21 @@ impl<T: SessionStream> Session<T> {
         let (data, mailbox) = self.state.select_data();
         let is_condstore = self.is_condstore || mailbox.is_condstore;
 
-        spawn_op!(data, {
+        if spawn {
+            spawn_op!(data, {
+                let response = data
+                    .store(arguments, mailbox, is_uid, is_condstore, op_start)
+                    .await?;
+
+                data.write_bytes(response).await
+            })
+        } else {
             let response = data
                 .store(arguments, mailbox, is_uid, is_condstore, op_start)
                 .await?;
 
             data.write_bytes(response).await
-        })
+        }
     }
 }