Fix #1791 Receive group system messages from blocked users (#1823)

Fix #1791 and show all group messages if the user already is in the group, even if the sender is blocked
Also fix a comment
Co-authored-by: link2xt <ilabdsf@gmail.com>

python/src/deltachat/contact.py

@@ -51,6 +51,10 @@ class Contact(object):
         """ Return True if the contact is blocked. """
         return lib.dc_contact_is_blocked(self._dc_contact)
 
+    def set_blocked(self, block=True):
+        """ Block or unblock a contact. """
+        return lib.dc_block_contact(self.account._dc_context, self.id, block)
+
     def is_verified(self):
         """ Return True if the contact is verified. """
         return lib.dc_contact_is_verified(self._dc_contact)

python/tests/test_account.py

@@ -1402,6 +1402,46 @@ class TestOnlineAccount:
         assert ev.action == "removed"
         assert ev.message.get_sender_contact().addr == ac1_addr
 
+    def test_system_group_msg_from_blocked_user(self, acfactory, lp):
+        """
+        Tests that a blocked user removes you from a group.
+        The message has to be fetched even though the user is blocked
+        to avoid inconsistent group state.
+        Also tests blocking in general.
+        """
+        lp.sec("Create a group chat with ac1 and ac2")
+        (ac1, ac2) = acfactory.get_two_online_accounts()
+        acfactory.introduce_each_other((ac1, ac2))
+        chat_on_ac1 = ac1.create_group_chat("title", contacts=[ac2])
+        chat_on_ac1.send_text("First group message")
+        chat_on_ac2 = ac2._evtracker.wait_next_incoming_message().chat
+
+        lp.sec("ac1 blocks ac2")
+        contact = ac1.create_contact(ac2)
+        contact.set_blocked()
+        assert contact.is_blocked()
+
+        lp.sec("ac2 sends a message to ac1 that does not arrive because it is blocked")
+        ac2.create_chat(ac1).send_text("This will not arrive!")
+
+        lp.sec("ac2 sends a group message to ac1 that arrives")
+        # Groups would be hardly usable otherwise: If you have blocked some
+        # users, they write messages and you only see replies to them without context
+        chat_on_ac2.send_text("This will arrive")
+        msg = ac1._evtracker.wait_next_incoming_message()
+        assert msg.text == "This will arrive"
+        message_texts = [m.text for m in chat_on_ac1.get_messages()]
+        assert len(message_texts) == 2
+        assert "First group message" in message_texts
+        assert "This will arrive" in message_texts
+
+        lp.sec("ac2 removes ac1 from their group")
+        assert ac1.get_self_contact() in chat_on_ac1.get_contacts()
+        assert contact.is_blocked()
+        chat_on_ac2.remove_contact(ac1)
+        ac1._evtracker.get_matching("DC_EVENT_CHAT_MODIFIED")
+        assert not ac1.get_self_contact() in chat_on_ac1.get_contacts()
+
     def test_set_get_group_image(self, acfactory, data, lp):
         ac1, ac2 = acfactory.get_two_online_accounts()
 

src/dc_receive_imf.rs

@@ -111,7 +111,7 @@ pub async fn dc_receive_imf(
     // or if From: is equal to SELF (in this case, it is any outgoing messages,
     // we do not check Return-Path any more as this is unreliable, see
     // https://github.com/deltachat/deltachat-core/issues/150)
-    let (from_id, from_id_blocked, incoming_origin) =
+    let (from_id, _from_id_blocked, incoming_origin) =
         from_field_to_contact_id(context, &mime_parser.from).await?;
 
     let incoming = from_id != DC_CONTACT_ID_SELF;
@@ -162,7 +162,6 @@ pub async fn dc_receive_imf(
             &rfc724_mid,
             &mut sent_timestamp,
             from_id,
-            from_id_blocked,
             &mut hidden,
             &mut chat_id,
             seen,
@@ -329,7 +328,6 @@ async fn add_parts(
     rfc724_mid: &str,
     sent_timestamp: &mut i64,
     from_id: u32,
-    from_id_blocked: bool,
     hidden: &mut bool,
     chat_id: &mut ChatId,
     seen: bool,
@@ -432,6 +430,8 @@ async fn add_parts(
                 .await
                 .unwrap_or_default();
 
+        // get the chat_id - a chat_id here is no indicator that the chat is displayed in the normal list,
+        // it might also be blocked and displayed in the deaddrop as a result
         if chat_id.is_unset() && mime_parser.failure_report.is_some() {
             *chat_id = ChatId::new(DC_CHAT_ID_TRASH);
             info!(
@@ -440,11 +440,8 @@ async fn add_parts(
             );
         }
 
-        // get the chat_id - a chat_id here is no indicator that the chat is displayed in the normal list,
-        // it might also be blocked and displayed in the deaddrop as a result
         if chat_id.is_unset() {
             // try to create a group
-            // (groups appear automatically only if the _sender_ is known, see core issue #54)
 
             let create_blocked =
                 if !test_normal_chat_id.is_unset() && test_normal_chat_id_blocked == Blocked::Not {
@@ -840,9 +837,7 @@ async fn add_parts(
     if chat_id.is_trash() || *hidden {
         *create_event_to_send = None;
     } else if incoming && state == MessageState::InFresh {
-        if from_id_blocked {
+        if Blocked::Not != chat_id_blocked {
-            *create_event_to_send = None;
-        } else if Blocked::Not != chat_id_blocked {
             *create_event_to_send = Some(CreateEvent::MsgsChanged);
         } else {
             *create_event_to_send = Some(CreateEvent::IncomingMsg);

src/imap/mod.rs

@@ -28,13 +28,16 @@ use crate::mimeparser;
 use crate::oauth2::dc_get_oauth2_access_token;
 use crate::param::Params;
 use crate::provider::get_provider_info;
-use crate::{chat, scheduler::InterruptInfo, stock::StockMessage};
+use crate::{
+    chat, dc_tools::dc_extract_grpid_from_rfc724_mid, scheduler::InterruptInfo, stock::StockMessage,
+};
 
 mod client;
 mod idle;
 pub mod select_folder;
 mod session;
 
+use chat::get_chat_id_by_grpid;
 use client::Client;
 use message::Message;
 use session::Session;
@@ -1501,6 +1504,18 @@ pub(crate) async fn prefetch_should_download(
     headers: &[mailparse::MailHeader<'_>],
     show_emails: ShowEmails,
 ) -> Result<bool> {
+    if let Some(rfc724_mid) = headers.get_header_value(HeaderDef::MessageId) {
+        if let Some(group_id) = dc_extract_grpid_from_rfc724_mid(&rfc724_mid) {
+            if let Ok((chat_id, _, _)) = get_chat_id_by_grpid(context, group_id).await {
+                if !chat_id.is_unset() {
+                    // This might be a group command, like removing a group member.
+                    // We really need to fetch this to avoid inconsistent group state.
+                    return Ok(true);
+                }
+            }
+        }
+    }
+
     let is_chat_message = headers.get_header_value(HeaderDef::ChatVersion).is_some();
     let is_reply_to_chat_message = prefetch_is_reply_to_chat_message(context, &headers).await;