config: >rehash command to reload rustbot.conf live (channels/nick/prefix/verbose/modules) without a restart

README.md

@@ -138,9 +138,24 @@ on), `password`, `sasl_user`, `sasl_pass`, `name` (a network's log label), and
 for the board's channel "join" links, e.g. `https://web.libera.chat/`), and
 `karma_url` (public web board —
 enables the `karmaweb` command and a link on the `karma`/`karmabottom` top
-lists; empty disables both). Whole-line `#`/`;` comments only —
+lists; empty disables both), and `admin` (nicks allowed to run `rehash`; see
+[Live reload](#live-reload-rehash)). Whole-line `#`/`;` comments only —
 inline comments would clash with channel `#`s.
 
+### Live reload (rehash)
+
+Editing `rustbot.conf` doesn't require a restart. An admin sends **`rehash`**
+(the command prefix + `rehash`) in a channel or PM and the bot re-reads the
+file and hot-applies this network's section:
+
+- **live**: `channels` (JOIN new / PART removed), `nick`, `prefix`, `verbose`,
+  and `locale` / `karma_url` / `webchat` (modules are re-instantiated).
+- **needs a restart**: `server`, `port`, `tls`, SASL — the summary says so.
+
+Set `admin = yournick` (comma/space list) to authorize; unauthorized attempts
+are ignored (and logged). Adding a *new* module or a whole new `[network]`
+still needs a rebuild/restart — new compiled code can't load at runtime.
+
 ### Locales
 
 `locale` sets a network's language, so a community sees the bot in its own

src/bot/commands.rs

@@ -113,6 +113,22 @@ impl Bot {
             return self.conn.privmsg(reply_to, &text);
         }
 
+        if command == "rehash" {
+            // admin-only; unauthorized attempts are ignored (logged, no reply)
+            let ok = !self.config.admin.is_empty()
+                && self
+                    .config
+                    .admin
+                    .iter()
+                    .any(|a| a.eq_ignore_ascii_case(sender));
+            if !ok {
+                crate::log(&format!("rehash denied for {sender}"));
+                return Ok(());
+            }
+            let summary = self.reload_from_file()?;
+            return self.conn.privmsg(reply_to, &summary);
+        }
+
         let Some(&idx) = self.routes.get(command) else {
             return Ok(());
         };

src/bot/mod.rs

@@ -31,13 +31,34 @@ impl Bot {
     pub fn new(config: Config, conn: Connection) -> Bot {
         let current_nick = config.nick.clone();
 
-        let mods = modules::all(
+        let modules = modules::all(
             &config.name,
             crate::i18n::Locale::from_code(&config.locale),
             (!config.karma_url.is_empty()).then(|| config.karma_url.clone()),
         );
+        let mut bot = Bot {
+            config,
+            conn,
+            current_nick,
+            registered: false,
+            available_caps: HashSet::new(),
+            enabled_caps: HashSet::new(),
+            batches: HashMap::new(),
+            sasl_started: false,
+            modules,
+            routes: HashMap::new(),
+            topics: HashMap::new(),
+            users: HashMap::new(),
+            names_building: HashMap::new(),
+        };
+        bot.rebuild_routes();
+        bot.write_source_meta();
+        bot
+    }
+
+    fn rebuild_routes(&mut self) {
         let mut routes: HashMap<&'static str, usize> = HashMap::new();
-        for (i, m) in mods.iter().enumerate() {
+        for (i, m) in self.modules.iter().enumerate() {
             for spec in m.commands() {
                 if routes.insert(spec.name, i).is_some() {
                     crate::log(&format!(
@@ -48,24 +69,105 @@ impl Bot {
                 }
             }
         }
+        self.routes = routes;
+    }
 
-        let bot = Bot {
-            config,
-            conn,
-            current_nick,
-            registered: false,
-            available_caps: HashSet::new(),
-            enabled_caps: HashSet::new(),
-            batches: HashMap::new(),
-            sasl_started: false,
-            modules: mods,
-            routes,
-            topics: HashMap::new(),
-            users: HashMap::new(),
-            names_building: HashMap::new(),
-        };
-        bot.write_source_meta();
-        bot
+    /// Re-read the config file and hot-apply this network's `[section]`.
+    pub(super) fn reload_from_file(&mut self) -> io::Result<String> {
+        let name = self.config.name.clone();
+        match crate::config::load().into_iter().find(|c| c.name == name) {
+            Some(new) => self.apply_config(new),
+            None => Ok(format!("rehash: no section '{name}' in the config")),
+        }
+    }
+
+    /// Diff `new` against the running config and hot-apply what can change
+    /// without reconnecting (channels, nick, prefix, verbose, modules), noting
+    /// anything that still needs a restart. Returns a one-line summary.
+    pub fn apply_config(&mut self, new: Config) -> io::Result<String> {
+        let mut changes: Vec<String> = Vec::new();
+
+        let newset: HashSet<&String> = new.channels.iter().collect();
+        let oldset: HashSet<&String> = self.config.channels.iter().collect();
+        let joined: Vec<String> = new
+            .channels
+            .iter()
+            .filter(|c| !oldset.contains(c))
+            .cloned()
+            .collect();
+        let parted: Vec<String> = self
+            .config
+            .channels
+            .iter()
+            .filter(|c| !newset.contains(c))
+            .cloned()
+            .collect();
+        for c in &joined {
+            self.conn.join(c)?;
+        }
+        for c in &parted {
+            self.conn.part(c)?;
+            let key = c.to_lowercase();
+            self.topics.remove(&key);
+            self.users.remove(&key);
+            self.names_building.remove(&key);
+        }
+        if !joined.is_empty() {
+            changes.push(format!("+{}", joined.join(" ")));
+        }
+        if !parted.is_empty() {
+            changes.push(format!("-{}", parted.join(" ")));
+        }
+
+        if !new.nick.eq_ignore_ascii_case(&self.config.nick) {
+            self.conn.nick(&new.nick)?;
+            self.current_nick = new.nick.clone();
+            changes.push(format!("nick {}", new.nick));
+        }
+        if new.verbose != self.config.verbose {
+            self.conn.set_verbose(new.verbose);
+            changes.push(format!("verbose {}", new.verbose));
+        }
+        if new.command_prefix != self.config.command_prefix {
+            changes.push(format!("prefix {}", new.command_prefix));
+        }
+
+        let modules_changed =
+            new.locale != self.config.locale || new.karma_url != self.config.karma_url;
+        let mut restart: Vec<&str> = Vec::new();
+        if new.server != self.config.server {
+            restart.push("server");
+        }
+        if new.port != self.config.port {
+            restart.push("port");
+        }
+        if new.tls != self.config.tls {
+            restart.push("tls");
+        }
+        if new.sasl_user != self.config.sasl_user || new.sasl_pass != self.config.sasl_pass {
+            restart.push("sasl");
+        }
+
+        self.config = new;
+        self.modules = modules::all(
+            &self.config.name,
+            crate::i18n::Locale::from_code(&self.config.locale),
+            (!self.config.karma_url.is_empty()).then(|| self.config.karma_url.clone()),
+        );
+        self.rebuild_routes();
+        if modules_changed {
+            changes.push("modules".to_string());
+        }
+        self.write_source_meta();
+
+        if !restart.is_empty() {
+            changes.push(format!("(restart for: {})", restart.join("/")));
+        }
+        Ok(if changes.is_empty() {
+            "rehash: reloaded (no changes)".to_string()
+        } else {
+            format!("rehash: {}", changes.join(", "))
+        })
     }
 
     /// Rewrite the per-network source sidecar the web board reads: server,

src/config.rs

@@ -21,6 +21,7 @@ pub struct Config {
     pub locale: String,
     pub karma_url: String,
     pub webchat: String,
+    pub admin: Vec<String>,
 }
 
 impl Default for Config {
@@ -42,6 +43,7 @@ impl Default for Config {
             locale: "en".to_string(),
             karma_url: String::new(),
             webchat: String::new(),
+            admin: Vec::new(),
         }
     }
 }
@@ -169,6 +171,7 @@ fn apply_kv(c: &mut Config, key: &str, value: &str, where_: &str) {
         "locale" | "lang" => c.locale = value.to_string(),
         "karma_url" | "web_url" => c.karma_url = value.to_string(),
         "webchat" => c.webchat = value.to_string(),
+        "admin" | "owner" => c.admin = split_list(value),
         other => log(&format!("{where_}: unknown key '{other}'")),
     }
 }
@@ -235,6 +238,9 @@ fn apply_env(c: &mut Config) {
     if let Ok(v) = std::env::var("IRC_WEBCHAT") {
         c.webchat = v;
     }
+    if let Ok(v) = std::env::var("IRC_ADMIN") {
+        c.admin = split_list(&v);
+    }
 }
 
 fn parse_bool(value: &str) -> bool {

src/irc/connection.rs

@@ -116,6 +116,14 @@ impl Connection {
         self.send_raw(&format!("JOIN {channel}"))
     }
 
+    pub fn part(&mut self, channel: &str) -> io::Result<()> {
+        self.send_raw(&format!("PART {channel}"))
+    }
+
+    pub fn set_verbose(&mut self, verbose: bool) {
+        self.verbose = verbose;
+    }
+
     pub fn pong(&mut self, token: &str) -> io::Result<()> {
         self.send_raw(&format!("PONG :{token}"))
     }

tests/bot.rs

@@ -76,3 +76,52 @@ fn ignores_own_echoed_message() {
     let out = run(":rubot!r@h PRIVMSG #chan :!ping\r\n");
     assert!(!out.contains(":pong"), "{out}");
 }
+
+#[test]
+fn rehash_applies_channel_nick_and_prefix() {
+    let output = Arc::new(Mutex::new(Vec::new()));
+    let mock = Mock {
+        input: Cursor::new(Vec::new()),
+        output: output.clone(),
+    };
+    let conn = Connection::from_stream(mock);
+    let cfg = Config {
+        name: "testnet".to_string(),
+        channels: vec!["#a".to_string(), "#keep".to_string()],
+        ..Config::default()
+    };
+    let mut bot = Bot::new(cfg, conn);
+
+    let new = Config {
+        name: "testnet".to_string(),
+        channels: vec!["#keep".to_string(), "#b".to_string()],
+        command_prefix: ">".to_string(),
+        nick: "rubot2".to_string(),
+        ..Config::default()
+    };
+    let summary = bot.apply_config(new).unwrap();
+
+    let out = String::from_utf8_lossy(&output.lock().unwrap()).into_owned();
+    assert!(out.contains("JOIN #b"), "{out}");
+    assert!(out.contains("PART #a"), "{out}");
+    assert!(!out.contains("PART #keep"), "{out}");
+    assert!(out.contains("NICK rubot2"), "{out}");
+    assert!(
+        summary.contains("+#b") && summary.contains("-#a"),
+        "{summary}"
+    );
+    assert!(
+        summary.contains("prefix") && summary.contains("nick"),
+        "{summary}"
+    );
+}
+
+#[test]
+fn rehash_command_requires_admin() {
+    // no admin configured -> ignored (default prefix is !)
+    let out = run(":alice!a@h PRIVMSG #chan :!rehash\r\n");
+    assert!(
+        !out.contains("rehash:"),
+        "unauthorized rehash replied: {out}"
+    );
+}

tests/config.rs

@@ -48,3 +48,13 @@ fn comments_and_blanks_are_ignored() {
     assert_eq!(cfgs.len(), 1);
     assert_eq!(cfgs[0].server, "irc.tchatou.fr");
 }
+
+#[test]
+fn admin_list_is_parsed_and_inherited() {
+    let cfgs = parse_str("admin = reverse, alice\nwebchat = https://w/\n[net]\nserver = x\n");
+    assert_eq!(
+        cfgs[0].admin,
+        vec!["reverse".to_string(), "alice".to_string()]
+    );
+    assert_eq!(cfgs[0].webchat, "https://w/");
+}