wip

simplex-chat.cabal

@@ -144,6 +144,7 @@ library
           Simplex.Chat.Store.Postgres.Migrations.M20260531_member_removed_at
           Simplex.Chat.Store.Postgres.Migrations.M20260601_relay_sent_web_domain
           Simplex.Chat.Store.Postgres.Migrations.M20260602_group_roster
+          Simplex.Chat.Store.Postgres.Migrations.M20260629_member_roster_served
   else
       exposed-modules:
           Simplex.Chat.Archive
@@ -306,6 +307,7 @@ library
           Simplex.Chat.Store.SQLite.Migrations.M20260531_member_removed_at
           Simplex.Chat.Store.SQLite.Migrations.M20260601_relay_sent_web_domain
           Simplex.Chat.Store.SQLite.Migrations.M20260602_group_roster
+          Simplex.Chat.Store.SQLite.Migrations.M20260629_member_roster_served
   other-modules:
       Paths_simplex_chat
   hs-source-dirs:

src/Simplex/Chat/Library/Internal.hs

@@ -1186,8 +1186,9 @@ serveRoster :: User -> GroupInfo -> GroupMember -> CM ()
 serveRoster user gInfo member =
   when (member `supportsVersion` groupRosterVersion) $ do
     cxt <- chatStoreCxt
-    withStore' (\db -> getGroupRoster db gInfo) >>= \case
-      Just (ownerGMId, brokerTs, sm@SignedMsg {signedBody}, blob_) ->
+    -- read the served version with the blob, so the recorded served version matches what is served
+    withStore' (\db -> (,) <$> getGroupRoster db gInfo <*> getGroupRosterVersion db gInfo) >>= \case
+      (Just (ownerGMId, brokerTs, sm@SignedMsg {signedBody}, blob_), rosterVer_) ->
         case J.eitherDecodeStrict' signedBody :: Either String (ChatMessage 'Json) of
           Left e -> logError $ "serveRoster: cannot decode saved roster message: " <> tshow e
           Right chatMsg@ChatMessage {msgId} ->
@@ -1197,8 +1198,10 @@ serveRoster user gInfo member =
                 sendFwdMemberMessage member fwd (VMSigned MSSVerified sm chatMsg)
                 forM_ ((,) <$> msgId <*> blob_) $ \(sid, blob) ->
                   sendInlineBlobChunks user gInfo [member] sid blob
+                -- record the served version so a member can't re-trigger a full serve at a version it already got
+                forM_ rosterVer_ $ \v -> withStore' $ \db -> setMemberRosterServedVersion db member v
               Left e -> logError $ "serveRoster: roster owner not found: " <> tshow e
-      Nothing -> pure ()
+      (Nothing, _) -> pure ()
 
 -- Used in groups with relays to introduce moderators and above to a new member,
 -- and to announce the new member to moderators and above.

src/Simplex/Chat/Library/Subscriber.hs

@@ -3497,13 +3497,16 @@ processAgentMessageConn cxt user@User {userId} corrId agentConnId agentMessage =
         _ -> pure ()
 
     -- A relay re-serves the full roster to a subscriber that detected a version gap, but only when it holds
-    -- something newer than the requester's pre-gap version (rate-limiting same-version requests). serveRoster
-    -- is the join/resume path: signed header + inline blob chunks to the one requester; a no-op without a roster.
+    -- something newer than BOTH the requester's claimed version and the version it last served this member -
+    -- the latter bounds reflected amplification (a member can't re-trigger a full serve with reqVer = 0).
+    -- serveRoster records the served version (on all serve paths) and is a no-op without a roster.
     xGrpRosterRequest :: GroupInfo -> GroupMember -> VersionRoster -> CM ()
     xGrpRosterRequest gInfo m reqVer =
       when (isUserGrpFwdRelay gInfo) $ do
-        cur <- withStore' $ \db -> getGroupRosterVersion db gInfo
-        when (maybe True (> reqVer) cur) $ serveRoster user gInfo m
+        (cur_, served_) <- withStore' $ \db ->
+          (,) <$> getGroupRosterVersion db gInfo <*> getMemberRosterServedVersion db m
+        forM_ cur_ $ \cur ->
+          when (cur > reqVer && maybe True (cur >) served_) $ serveRoster user gInfo m
 
     checkHostRole :: GroupMember -> GroupMemberRole -> CM ()
     checkHostRole GroupMember {memberRole, localDisplayName} memRole =

src/Simplex/Chat/Store/Groups.hs

@@ -90,6 +90,8 @@ module Simplex.Chat.Store.Groups
     getPublishableGroupRelays,
     setGroupRosterVersion,
     getGroupRosterVersion,
+    setMemberRosterServedVersion,
+    getMemberRosterServedVersion,
     getGroupRoster,
     RcvRosterTransfer (..),
     createRosterTransfer,
@@ -1478,6 +1480,18 @@ getGroupRosterVersion db GroupInfo {groupId} =
   fmap join . maybeFirstRow fromOnly $
     DB.query db "SELECT roster_version FROM groups WHERE group_id = ?" (Only groupId)
 
+-- The newest roster version a relay re-served to this member on its catch-up request: bounds reflected
+-- amplification, so a member can't re-trigger a full serve at a version it was already served.
+setMemberRosterServedVersion :: DB.Connection -> GroupMember -> VersionRoster -> IO ()
+setMemberRosterServedVersion db GroupMember {groupMemberId} v = do
+  currentTs <- getCurrentTime
+  DB.execute db "UPDATE group_members SET roster_served_version = ?, updated_at = ? WHERE group_member_id = ?" (v, currentTs, groupMemberId)
+
+getMemberRosterServedVersion :: DB.Connection -> GroupMember -> IO (Maybe VersionRoster)
+getMemberRosterServedVersion db GroupMember {groupMemberId} =
+  fmap join . maybeFirstRow fromOnly $
+    DB.query db "SELECT roster_served_version FROM group_members WHERE group_member_id = ?" (Only groupMemberId)
+
 -- The live roster header a relay re-serves to joiners, with the completed blob served alongside it
 -- (both are written together at completion, so the blob is present whenever the header is).
 getGroupRoster :: DB.Connection -> GroupInfo -> IO (Maybe (GroupMemberId, UTCTime, SignedMsg, Maybe ByteString))

src/Simplex/Chat/Store/Postgres/Migrations.hs

@@ -38,6 +38,7 @@ import Simplex.Chat.Store.Postgres.Migrations.M20260530_client_services
 import Simplex.Chat.Store.Postgres.Migrations.M20260531_member_removed_at
 import Simplex.Chat.Store.Postgres.Migrations.M20260601_relay_sent_web_domain
 import Simplex.Chat.Store.Postgres.Migrations.M20260602_group_roster
+import Simplex.Chat.Store.Postgres.Migrations.M20260629_member_roster_served
 import Simplex.Messaging.Agent.Store.Shared (Migration (..))
 
 schemaMigrations :: [(String, Text, Maybe Text)]
@@ -75,7 +76,8 @@ schemaMigrations =
     ("20260530_client_services", m20260530_client_services, Just down_m20260530_client_services),
     ("20260531_member_removed_at", m20260531_member_removed_at, Just down_m20260531_member_removed_at),
     ("20260601_relay_sent_web_domain", m20260601_relay_sent_web_domain, Just down_m20260601_relay_sent_web_domain),
-    ("20260602_group_roster", m20260602_group_roster, Just down_m20260602_group_roster)
+    ("20260602_group_roster", m20260602_group_roster, Just down_m20260602_group_roster),
+    ("20260629_member_roster_served", m20260629_member_roster_served, Just down_m20260629_member_roster_served)
   ]
 
 -- | The list of migrations in ascending order by date

src/Simplex/Chat/Store/Postgres/Migrations/M20260629_member_roster_served.hs

@@ -0,0 +1,19 @@
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Chat.Store.Postgres.Migrations.M20260629_member_roster_served where
+
+import Data.Text (Text)
+import Text.RawString.QQ (r)
+
+m20260629_member_roster_served :: Text
+m20260629_member_roster_served =
+  [r|
+ALTER TABLE group_members ADD COLUMN roster_served_version BIGINT;
+|]
+
+down_m20260629_member_roster_served :: Text
+down_m20260629_member_roster_served =
+  [r|
+ALTER TABLE group_members DROP COLUMN roster_served_version;
+|]

src/Simplex/Chat/Store/SQLite/Migrations.hs

@@ -161,6 +161,7 @@ import Simplex.Chat.Store.SQLite.Migrations.M20260530_client_services
 import Simplex.Chat.Store.SQLite.Migrations.M20260531_member_removed_at
 import Simplex.Chat.Store.SQLite.Migrations.M20260601_relay_sent_web_domain
 import Simplex.Chat.Store.SQLite.Migrations.M20260602_group_roster
+import Simplex.Chat.Store.SQLite.Migrations.M20260629_member_roster_served
 import Simplex.Messaging.Agent.Store.Shared (Migration (..))
 
 schemaMigrations :: [(String, Query, Maybe Query)]
@@ -321,7 +322,8 @@ schemaMigrations =
     ("20260530_client_services", m20260530_client_services, Just down_m20260530_client_services),
     ("20260531_member_removed_at", m20260531_member_removed_at, Just down_m20260531_member_removed_at),
     ("20260601_relay_sent_web_domain", m20260601_relay_sent_web_domain, Just down_m20260601_relay_sent_web_domain),
-    ("20260602_group_roster", m20260602_group_roster, Just down_m20260602_group_roster)
+    ("20260602_group_roster", m20260602_group_roster, Just down_m20260602_group_roster),
+    ("20260629_member_roster_served", m20260629_member_roster_served, Just down_m20260629_member_roster_served)
   ]
 
 -- | The list of migrations in ascending order by date

src/Simplex/Chat/Store/SQLite/Migrations/M20260629_member_roster_served.hs

@@ -0,0 +1,18 @@
+{-# LANGUAGE QuasiQuotes #-}
+
+module Simplex.Chat.Store.SQLite.Migrations.M20260629_member_roster_served where
+
+import Database.SQLite.Simple (Query)
+import Database.SQLite.Simple.QQ (sql)
+
+m20260629_member_roster_served :: Query
+m20260629_member_roster_served =
+  [sql|
+ALTER TABLE group_members ADD COLUMN roster_served_version INTEGER;
+|]
+
+down_m20260629_member_roster_served :: Query
+down_m20260629_member_roster_served =
+  [sql|
+ALTER TABLE group_members DROP COLUMN roster_served_version;
+|]