api: add clear_all_relay_storage API

src/scheduler.rs

@@ -250,6 +250,16 @@ impl SchedulerState {
         }
     }
 
+    pub(crate) async fn clear_all_relay_storage(&self) -> Result<()> {
+        let inner = self.inner.read().await;
+        if let InnerSchedulerState::Started(ref scheduler) = *inner {
+            scheduler.clear_all_relay_storage();
+            Ok(())
+        } else {
+            bail!("IO is not started");
+        }
+    }
+
     pub(crate) async fn interrupt_smtp(&self) {
         let inner = self.inner.read().await;
         if let InnerSchedulerState::Started(ref scheduler) = *inner {
@@ -348,6 +358,7 @@ async fn inbox_loop(
     let ImapConnectionHandlers {
         mut connection,
         stop_token,
+        clear_storage_request_receiver,
     } = inbox_handlers;
 
     let transport_id = connection.transport_id();
@@ -386,7 +397,14 @@ async fn inbox_loop(
                 }
             };
 
-            match inbox_fetch_idle(&ctx, &mut connection, session).await {
+            match inbox_fetch_idle(
+                &ctx,
+                &mut connection,
+                session,
+                &clear_storage_request_receiver,
+            )
+            .await
+            {
                 Err(err) => warn!(
                     ctx,
                     "Transport {transport_id}: Failed inbox fetch_idle: {err:#}."
@@ -407,11 +425,29 @@ async fn inbox_loop(
         .await;
 }
 
-async fn inbox_fetch_idle(ctx: &Context, imap: &mut Imap, mut session: Session) -> Result<Session> {
+async fn inbox_fetch_idle(
+    ctx: &Context,
+    imap: &mut Imap,
+    mut session: Session,
+    clear_storage_request_receiver: &Receiver<()>,
+) -> Result<Session> {
     let transport_id = session.transport_id();
 
+    // Clear IMAP storage on request.
+    //
+    // Only doing this for chatmail relays to avoid
+    // accidentally deleting all emails in a shared mailbox.
+    let should_clear_imap_storage =
+        clear_storage_request_receiver.try_recv().is_ok() && session.is_chatmail();
+    if should_clear_imap_storage {
+        info!(ctx, "Transport {transport_id}: Clearing IMAP storage.");
+        session.delete_all_messages(ctx, &imap.folder).await?;
+    }
+
     // Update quota no more than once a minute.
-    if ctx.quota_needs_update(session.transport_id(), 60).await
+    //
+    // Always update if we just cleared IMAP storage.
+    if (ctx.quota_needs_update(session.transport_id(), 60).await || should_clear_imap_storage)
         && let Err(err) = ctx.update_recent_quota(&mut session, &imap.folder).await
     {
         warn!(
@@ -737,6 +773,12 @@ impl Scheduler {
         }
     }
 
+    fn clear_all_relay_storage(&self) {
+        for b in &self.inboxes {
+            b.conn_state.clear_relay_storage();
+        }
+    }
+
     fn interrupt_smtp(&self) {
         self.smtp.interrupt();
     }
@@ -870,6 +912,13 @@ struct SmtpConnectionHandlers {
 #[derive(Debug)]
 pub(crate) struct ImapConnectionState {
     state: ConnectionState,
+
+    /// Channel to request clearing the folder.
+    ///
+    /// IMAP loop receiving this should clear the folder
+    /// on the next iteration if IMAP server is a chatmail relay
+    /// and otherwise ignore the request.
+    clear_storage_request_sender: Sender<()>,
 }
 
 impl ImapConnectionState {
@@ -881,11 +930,13 @@ impl ImapConnectionState {
     ) -> Result<(Self, ImapConnectionHandlers)> {
         let stop_token = CancellationToken::new();
         let (idle_interrupt_sender, idle_interrupt_receiver) = channel::bounded(1);
+        let (clear_storage_request_sender, clear_storage_request_receiver) = channel::bounded(1);
 
         let handlers = ImapConnectionHandlers {
             connection: Imap::new(context, transport_id, login_param, idle_interrupt_receiver)
                 .await?,
             stop_token: stop_token.clone(),
+            clear_storage_request_receiver,
         };
 
         let state = ConnectionState {
@@ -894,7 +945,10 @@ impl ImapConnectionState {
             connectivity: handlers.connection.connectivity.clone(),
         };
 
-        let conn = ImapConnectionState { state };
+        let conn = ImapConnectionState {
+            state,
+            clear_storage_request_sender,
+        };
 
         Ok((conn, handlers))
     }
@@ -908,10 +962,19 @@ impl ImapConnectionState {
     fn stop(&self) {
         self.state.stop();
     }
+
+    /// Requests clearing relay storage and interrupts the inbox.
+    fn clear_relay_storage(&self) {
+        self.clear_storage_request_sender.try_send(()).ok();
+        self.state.interrupt();
+    }
 }
 
 #[derive(Debug)]
 struct ImapConnectionHandlers {
     connection: Imap,
     stop_token: CancellationToken,
+
+    /// Channel receiver to get requests to clear IMAP storage.
+    pub(crate) clear_storage_request_receiver: Receiver<()>,
 }