Add support for IMAP ID extension

src/configure.rs

@@ -416,6 +416,9 @@ async fn configure(ctx: &Context, param: &mut LoginParam) -> Result<()> {
 
     let create_mvbox = ctx.should_watch_mvbox().await?;
 
+    // Send client ID as soon as possible before doing anything else.
+    imap.determine_capabilities(ctx).await?;
+
     imap.configure_folders(ctx, create_mvbox).await?;
 
     imap.select_with_uidvalidity(ctx, "INBOX")

src/context.rs

@@ -61,6 +61,11 @@ pub struct InnerContext {
     /// Set to `None` if quota was never tried to load.
     pub(crate) quota: RwLock<Option<QuotaInfo>>,
 
+    /// Server ID response if ID capability is supported
+    /// and the server returned non-NIL on the inbox connection.
+    /// <https://datatracker.ietf.org/doc/html/rfc2971>
+    pub(crate) server_id: RwLock<Option<HashMap<String, String>>>,
+
     pub(crate) last_full_folder_scan: Mutex<Option<Instant>>,
 
     /// ID for this `Context` in the current process.
@@ -190,6 +195,7 @@ impl Context {
             scheduler: RwLock::new(None),
             ratelimit: RwLock::new(Ratelimit::new(Duration::new(60, 0), 3.0)), // Allow to send 3 messages immediately, no more than once every 20 seconds.
             quota: RwLock::new(None),
+            server_id: RwLock::new(None),
             creation_time: std::time::SystemTime::now(),
             last_full_folder_scan: Mutex::new(None),
             last_error: std::sync::RwLock::new("".to_string()),
@@ -429,6 +435,11 @@ impl Context {
         res.insert("socks5_enabled", socks5_enabled.to_string());
         res.insert("entered_account_settings", l.to_string());
         res.insert("used_account_settings", l2.to_string());
+
+        let server_id = self.server_id.read().await;
+        res.insert("imap_server_id", format!("{:?}", server_id));
+        drop(server_id);
+
         res.insert("secondary_addrs", secondary_addrs);
         res.insert(
             "fetch_existing_msgs",

src/imap.rs

@@ -451,7 +451,9 @@ impl Imap {
     }
 
     /// Determine server capabilities if not done yet.
-    async fn determine_capabilities(&mut self) -> Result<()> {
+    ///
+    /// If server supports ID capability, send our client ID.
+    pub(crate) async fn determine_capabilities(&mut self, context: &Context) -> Result<()> {
         if self.capabilities_determined {
             return Ok(());
         }
@@ -463,6 +465,12 @@ impl Imap {
             .capabilities()
             .await
             .context("CAPABILITY command error")?;
+        if caps.has_str("ID") {
+            let server_id = session.id([("name", Some("Delta Chat"))]).await?;
+            info!(context, "Server ID: {:?}", server_id);
+            let mut lock = context.server_id.write().await;
+            *lock = server_id;
+        }
         self.config.can_idle = caps.has_str("IDLE");
         self.config.can_move = caps.has_str("MOVE");
         self.config.can_check_quota = caps.has_str("QUOTA");
@@ -481,8 +489,8 @@ impl Imap {
             return Err(err);
         }
 
+        self.determine_capabilities(context).await?;
         self.ensure_configured_folders(context, true).await?;
-        self.determine_capabilities().await?;
         Ok(())
     }