fix: Update the channel title after joining if the QR code included a wrong title (#8260)

Fix https://github.com/chatmail/core/issues/8250. Not sure why anyone
would tamper with the link, but maybe the name gets ellipsized because
it is very long, or maybe we decide to ellipsize more aggressively in
the future.

The fix is easy enough, just set the GroupNameTimestamp when creating
the channel, so that `HeaderDef::ChatGroupNameTimestamp` gets set when
sending a message and the logic in
`apply_chat_name_avatar_and_description_changes()` recognizes the
incoming name's timestamp as newer than `chat_group_name_timestamp`
(which is 0 right after joining a chat).

The test is somewhat hacky and depends on the title being the last
parameter in the invite code URL, but this is fine; if we ever change
that, then the test will fail and we need to modify it.

This also removes some wrong doc comments.

Since groups are unpromoted until sending a first message, the same fix isn't needed for groups.

deltachat-jsonrpc/src/api.rs

@@ -1106,9 +1106,6 @@ impl CommandApi {
     /// because the word "channel" already appears a lot in the code,
     /// which would make it hard to grep for it.
     ///
-    /// After creation, the chat contains no recipients and is in _unpromoted_ state;
-    /// see [`CommandApi::create_group_chat`] for more information on the unpromoted state.
-    ///
     /// Returns the created chat's id.
     async fn create_broadcast(&self, account_id: u32, chat_name: String) -> Result<u32> {
         let ctx = self.get_context(account_id).await?;

deltachat-rpc-client/src/deltachat_rpc_client/account.py

@@ -340,9 +340,6 @@ class Account:
         because the word "channel" already appears a lot in the code,
         which would make it hard to grep for it.
 
-        After creation, the chat contains no recipients and is in _unpromoted_ state;
-        see `create_group()` for more information on the unpromoted state.
-
         Returns the created chat.
         """
         return Chat(self, self._rpc.create_broadcast(self.id, name))

src/chat.rs

@@ -32,6 +32,7 @@ use crate::debug_logging::maybe_set_logging_xdc;
 use crate::download::{
     DownloadState, PRE_MSG_ATTACHMENT_SIZE_THRESHOLD, PRE_MSG_SIZE_WARNING_THRESHOLD,
 };
+use crate::ensure_and_debug_assert_eq;
 use crate::ephemeral::{Timer as EphemeralTimer, start_chat_ephemeral_timers};
 use crate::events::EventType;
 use crate::key::{Fingerprint, self_fingerprint};
@@ -1782,9 +1783,8 @@ impl Chat {
                 );
                 bail!("Cannot set message, contact for {} not found.", self.id);
             }
-        } else if matches!(self.typ, Chattype::Group | Chattype::OutBroadcast)
-            && self.param.get_int(Param::Unpromoted).unwrap_or_default() == 1
-        {
+        } else if self.param.get_int(Param::Unpromoted).unwrap_or_default() == 1 {
+            ensure_and_debug_assert_eq!(self.typ, Chattype::Group,);
             msg.param.set_int(Param::AttachChatAvatarAndDescription, 1);
             self.param
                 .remove(Param::Unpromoted)
@@ -3626,9 +3626,6 @@ pub(crate) async fn create_group_ex(
 /// because the word "channel" already appears a lot in the code,
 /// which would make it hard to grep for it.
 ///
-/// After creation, the chat contains no recipients and is in _unpromoted_ state;
-/// see [`create_group`] for more information on the unpromoted state.
-///
 /// Returns the created chat's id.
 pub async fn create_broadcast(context: &Context, chat_name: String) -> Result<ChatId> {
     let grpid = create_id();
@@ -3660,17 +3657,20 @@ pub(crate) async fn create_out_broadcast_ex(
             |row| row.get(0),
         )?;
         ensure!(cnt == 0, "{cnt} chats exist with grpid {grpid}");
+        let mut params: Params = Params::new();
+        params.update_timestamp(Param::GroupNameTimestamp, time())?;
 
         t.execute(
             "INSERT INTO chats
-            (type, name, name_normalized, grpid, created_timestamp)
-            VALUES(?, ?, ?, ?, ?)",
+            (type, name, name_normalized, grpid, created_timestamp, param)
+            VALUES(?, ?, ?, ?, ?, ?)",
             (
                 Chattype::OutBroadcast,
                 &chat_name,
                 normalize_text(&chat_name),
                 &grpid,
                 timestamp,
+                params.to_string(),
             ),
         )?;
         let chat_id = ChatId::new(t.last_insert_rowid().try_into()?);

src/chat/chat_tests.rs

@@ -9,6 +9,7 @@ use crate::headerdef::HeaderDef;
 use crate::imex::{ImexMode, has_backup, imex};
 use crate::message::{Message, MessengerMessage, delete_msgs};
 use crate::mimeparser::{self, MimeMessage};
+use crate::qr::{Qr, check_qr};
 use crate::receive_imf::receive_imf;
 use crate::securejoin::{get_securejoin_qr, join_securejoin};
 use crate::test_utils;
@@ -2922,10 +2923,24 @@ async fn test_broadcast_change_name() -> Result<()> {
     let fiona = &tcm.fiona().await;
 
     let broadcast_id = create_broadcast(alice, "Channel".to_string()).await?;
-    let qr = get_securejoin_qr(alice, Some(broadcast_id)).await.unwrap();
+    let mut qr = get_securejoin_qr(alice, Some(broadcast_id)).await.unwrap();
+    // Something goes wrong with the title, e.g. maybe it gets ellipsized
+    // Note that the title always comes at the end for human readability
+    qr += "+modified+title";
+
+    {
+        tcm.section("Alice invites Bob to her channel");
+        let Qr::AskJoinBroadcast { name, .. } = check_qr(bob, &qr).await? else {
+            panic!();
+        };
+        assert_eq!(name, "Channel modified title");
+
+        // The channel's name gets fixed after actually joining the channel:
+        let bob_chat_id = tcm.exec_securejoin_qr(bob, alice, &qr).await;
+        let bob_chat = Chat::load_from_db(bob, bob_chat_id).await?;
+        assert_eq!(bob_chat.name, "Channel");
+    }
 
-    tcm.section("Alice invites Bob to her channel");
-    tcm.exec_securejoin_qr(bob, alice, &qr).await;
     tcm.section("Alice invites Fiona to her channel");
     tcm.exec_securejoin_qr(fiona, alice, &qr).await;