api: dc_accounts_set_push_device_token and dc_get_push_state APIs

src/imap/capabilities.rs

@@ -25,6 +25,13 @@ pub(crate) struct Capabilities {
     /// <https://tools.ietf.org/html/rfc5464>
     pub can_metadata: bool,
 
+    /// True if the server supports XDELTAPUSH capability.
+    /// This capability means setting /private/devicetoken IMAP METADATA
+    /// on the INBOX results in new mail notifications
+    /// via notifications.delta.chat service.
+    /// This is supported by <https://github.com/deltachat/chatmail>
+    pub can_push: bool,
+
     /// Server ID if the server supports ID capability.
     pub server_id: Option<HashMap<String, String>>,
 }

src/imap/client.rs

@@ -60,6 +60,7 @@ async fn determine_capabilities(
         can_check_quota: caps.has_str("QUOTA"),
         can_condstore: caps.has_str("CONDSTORE"),
         can_metadata: caps.has_str("METADATA"),
+        can_push: caps.has_str("XDELTAPUSH"),
         server_id,
     };
     Ok(capabilities)

src/imap/session.rs

@@ -90,6 +90,10 @@ impl Session {
         self.capabilities.can_metadata
     }
 
+    pub fn can_push(&self) -> bool {
+        self.capabilities.can_push
+    }
+
     /// Returns the names of all folders on the IMAP server.
     pub async fn list_folders(&mut self) -> Result<Vec<async_imap::types::Name>> {
         let list = self.list(Some(""), Some("*")).await?.try_collect().await?;