From 1ab643c87086bd2dd2b86a52cd3eb57169d5d3e8 Mon Sep 17 00:00:00 2001
From: reverse <mike.chevronnet@gmail.com>
Date: Sun, 16 Aug 2026 18:06:03 +0000
Subject: [PATCH] =?UTF-8?q?s2s:=20timestamp=20arbitration=20for=20fjoin=20?=
 =?UTF-8?q?(lower=20TS=20wins=20=E2=80=94=20strip=20or=20wipe=20losing=20s?=
 =?UTF-8?q?tatus),=20fmode=20and=20ftopic=20(drop=20changes=20stamped=20ne?=
 =?UTF-8?q?wer=20than=20ours)?=
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---
 src/channels.rs | 10 ++++++++++
 src/link.rs     | 40 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 1 deletion(-)

diff --git a/src/channels.rs b/src/channels.rs
index a2101b5..385d421 100644
--- a/src/channels.rs
+++ b/src/channels.rs
@@ -118,6 +118,16 @@ impl Member {
 
     /// Set/clear a prefix mode by its letter — built-in booleans or, for a
     /// config-defined letter, the custom-prefix set (used by the S2S mode applier).
+    /// Drop the standard status modes (q/a/o/h/v) — used when this side loses a
+    /// channel-timestamp war and every member must be de-statused.
+    pub fn clear_status(&mut self) {
+        self.owner = false;
+        self.admin = false;
+        self.op = false;
+        self.halfop = false;
+        self.voice = false;
+    }
+
     pub fn set_prefix(&mut self, letter: char, on: bool) {
         match letter {
             'y' => self.oprefix = on,
diff --git a/src/link.rs b/src/link.rs
index 4671c5e..850a134 100644
--- a/src/link.rs
+++ b/src/link.rs
@@ -20,7 +20,7 @@ use std::net::{SocketAddr, TcpStream};
 
 use std::collections::HashSet;
 
-use crate::channels::{glob_match, Ban, Channel, Member, Topic};
+use crate::channels::{glob_match, Ban, ChanModes, Channel, Member, Topic};
 use crate::message::Message;
 use crate::server::{now, Server};
 use crate::socketengine::OutSink;
@@ -2104,6 +2104,44 @@ mod tests {
 
     // A server is a service iff its NAME matches the sasl_server or a `uline` config
     // entry (case-insensitive); `silent` is honoured.
+    // FJOIN timestamp arbitration: the lower channel TS wins. A member bursted with
+    // a NEWER TS than ours joins stripped of status; an OLDER TS wipes our side.
+    #[test]
+    fn fjoin_ts_arbitration_strips_losing_status() {
+        use crate::config::Config;
+        use std::sync::atomic::AtomicU64;
+        use std::sync::{mpsc, Arc};
+        let (tx, _rx) = mpsc::channel();
+        let mut s = Server::new(Config::default(), tx, Arc::new(AtomicU64::new(1)));
+        s.remote_users.insert(
+            "42SAAAAAA".to_string(),
+            RemoteUser {
+                uuid: "42SAAAAAA".to_string(),
+                nick: "bob".into(),
+                ident: "b".into(),
+                host: "h".into(),
+                realname: "b".into(),
+                account: None,
+                ip: String::new(),
+                modes: String::new(),
+                sid: "42S".into(),
+                via: 1,
+            },
+        );
+        // we already hold #c at an OLD (winning) TS
+        s.channels.insert("#c".into(), {
+            let mut c = Channel::new("#c");
+            c.created = 1000;
+            c
+        });
+        // a peer bursts #c with a NEWER TS, opping bob — bob must join WITHOUT +o
+        let m = crate::message::parse(":42S FJOIN #c 2000 +nt :o,42SAAAAAA").unwrap();
+        s.link_fjoin_recv(1, &m);
+        let opped = s.channels["#c"].rmembers["42SAAAAAA"].op;
+        assert!(!opped, "a member bursted with a newer (losing) TS must be de-statused");
+        assert_eq!(s.channels["#c"].created, 1000, "our older TS is kept");
+    }
+
     #[test]
     fn uline_recognises_services_server() {
         use crate::config::Config;