permchannels: persist +P channels (modes, topic, ts, list modes) to disk and restore them at startup

echoircd.conf.example

@@ -235,6 +235,10 @@ amu_target    = both
 # reputationexpire = * 90d                 # any score decays after 90d
 # extban usage:  MODE #chan +b y:<100   (ban score below 100)   +b y:>500 (above 500)
 
+# --- permanent channels (+P): oper-only mode; the channel survives an empty
+#     member list AND a restart (its modes, topic, TS and ban lists are saved). ---
+# permchannels_database = permchannels.db  # default: <conf>.permchannels
+
 # --- whoisport: opers see the target's listener port in WHOIS (always on) ---
 # --- ircv3_network_icon: advertise a network icon via draft/ICON ISUPPORT ---
 # network_icon = https://example.org/icon.png

src/ircd.rs

@@ -131,6 +131,7 @@ impl Ircd {
         server.load_xlines(); // restore persisted bans
         crate::modules::metadata::load(&mut server); // restore channel metadata
         crate::modules::reputation::load(&mut server); // restore per-IP reputation
+        crate::modules::permchannels::load(&mut server); // recreate +P channels (pre-link)
         crate::modules::geoip::init(&mut server); // load the GeoIP database
         crate::modules::customprefix::init(&server); // load prefix config
         crate::mode::init_custom_prefixes(); // register any config-defined prefix modes

src/modules/mod.rs

@@ -53,6 +53,7 @@ pub mod ojoin;
 pub mod operlevels;
 pub mod operprefix;
 pub mod password_hash;
+pub mod permchannels;
 pub mod profilelink;
 pub mod randquote;
 pub mod realnameban;
@@ -109,6 +110,7 @@ pub fn default_modules() -> Vec<Box<dyn Module>> {
         Box::new(autoop::AutoOp),
         Box::new(autodrop::AutoDrop),
         Box::new(operprefix::OperPrefix),
+        Box::new(permchannels::PermChannels::default()),
     ]
 }
 

src/modules/permchannels.rs

@@ -0,0 +1,281 @@
+//! Permanent-channel persistence. A `+P` channel already survives an empty
+//! member list in memory (see `Channel::keep_alive`); this module makes it also
+//! survive a restart by writing every `+P` channel — its creation TS, modes (with
+//! parameters), topic and list modes — to a database file and recreating them at
+//! startup, before any server link is established. The file is refreshed whenever
+//! a mode/topic change touches a permanent channel (and on the timer as a backstop),
+//! with an atomic temp-file+rename write so a crash mid-write can't corrupt it.
+//!
+//! Config: `permchannels_database` (path; default `<conf>.permchannels`).
+
+use std::fs;
+use std::io;
+
+use crate::channels::{Ban, Channel, Topic};
+use crate::module::Module;
+use crate::server::Server;
+use crate::Uid;
+
+/// The database path: the `permchannels_database` conf key, or `<conf>.permchannels`.
+fn db_path(s: &Server) -> String {
+    match s.conf("permchannels_database") {
+        Some(p) if !p.is_empty() => p.to_string(),
+        _ => format!("{}.permchannels", s.conf_path),
+    }
+}
+
+/// Serialise every permanent channel. Empty string when there are none, so the
+/// caller can drop a stale database instead of leaving resurrectable channels.
+/// Channels are emitted name-sorted so an unchanged network yields identical bytes
+/// (the dirty check below then skips the write).
+fn serialize(s: &Server) -> String {
+    let mut chans: Vec<&Channel> = s.channels.values().filter(|c| c.modes.permanent).collect();
+    if chans.is_empty() {
+        return String::new();
+    }
+    chans.sort_by(|a, b| a.name.cmp(&b.name));
+
+    let mut out = String::from("# echoircd permanent channels — auto-generated; manual edits are overwritten\n");
+    for c in chans {
+        out.push_str(&format!("C {} {}\n", c.name, c.created));
+        out.push_str(&format!("M {}\n", c.modes.render(true)));
+        if let Some(t) = &c.topic {
+            if !t.text.is_empty() {
+                out.push_str(&format!("T {} {} :{}\n", t.ts, t.setter, t.text));
+            }
+        }
+        // list modes: mask/setter/ts, skipping timed (TBAN) entries — those are
+        // ephemeral and shouldn't be resurrected as permanent bans.
+        for (tag, list) in [
+            ('b', &c.bans),
+            ('e', &c.excepts),
+            ('I', &c.invex),
+            ('g', &c.filters),
+            ('X', &c.exemptchanops),
+            ('w', &c.autoop),
+        ] {
+            for b in list.iter().filter(|b| b.expires.is_none()) {
+                out.push_str(&format!("{tag} {} {} {}\n", b.ts, b.setter, b.mask));
+            }
+        }
+    }
+    out
+}
+
+/// Atomic write: a full temp file then rename over the target, so a reader (or a
+/// crash) never sees a half-written database.
+fn atomic_write(path: &str, content: &str) -> io::Result<()> {
+    let tmp = format!("{path}.tmp");
+    fs::write(&tmp, content)?;
+    fs::rename(&tmp, path)
+}
+
+/// One channel record accumulated while parsing the database.
+#[derive(Default)]
+struct Record {
+    name: String,
+    created: u64,
+    modes: String,
+    topic: Option<Topic>,
+    lists: Vec<(char, Ban)>,
+}
+
+/// Apply a rendered mode string (`+ntPl 50`) to an existing channel as the server,
+/// bypassing the oper/rank gates and without propagating (there are no links yet
+/// at load time). Mirrors the applier the MODE path uses, minus the side effects.
+fn apply_modes(s: &mut Server, name: &str, key: &str, modes: &str) {
+    let mut it = modes.split_whitespace();
+    let Some(letters) = it.next() else {
+        return;
+    };
+    let args: Vec<&str> = it.collect();
+    let mut ai = 0usize;
+    let mut adding = true;
+    s.mode_sudo = true;
+    for c in letters.chars() {
+        match c {
+            '+' => {
+                adding = true;
+                continue;
+            }
+            '-' => {
+                adding = false;
+                continue;
+            }
+            _ => {}
+        }
+        let Some(h) = crate::mode::chan_mode(c) else {
+            continue;
+        };
+        let param = if h.wants_param(adding) {
+            let p = args.get(ai).copied();
+            if p.is_some() {
+                ai += 1;
+            }
+            p
+        } else {
+            None
+        };
+        let _ = h.apply(s, name, key, 0, adding, param);
+    }
+    s.mode_sudo = false;
+}
+
+/// Recreate one parsed record as a live (member-less) channel.
+fn build(s: &mut Server, rec: Record) {
+    if rec.name.is_empty() {
+        return;
+    }
+    let key = rec.name.to_ascii_lowercase();
+    if s.channels.contains_key(&key) {
+        return; // never clobber a channel that already exists
+    }
+    let mut c = Channel::new(&rec.name);
+    c.created = rec.created;
+    c.topic = rec.topic;
+    for (tag, ban) in rec.lists {
+        match tag {
+            'b' => c.bans.push(ban),
+            'e' => c.excepts.push(ban),
+            'I' => c.invex.push(ban),
+            'g' => c.filters.push(ban),
+            'X' => c.exemptchanops.push(ban),
+            'w' => c.autoop.push(ban),
+            _ => {}
+        }
+    }
+    s.channels.insert(key.clone(), c);
+    apply_modes(s, &rec.name, &key, &rec.modes);
+    // guarantee permanence even if the stored mode string somehow lost the 'P'
+    if let Some(c) = s.channels.get_mut(&key) {
+        c.modes.permanent = true;
+    }
+}
+
+/// Restore permanent channels from disk. Called once at startup, before links come
+/// up (so the TS we assign can't desync a peer, matching how the DB is written).
+pub fn load(s: &mut Server) {
+    let Ok(text) = fs::read_to_string(db_path(s)) else {
+        return;
+    };
+    let mut cur: Option<Record> = None;
+    let mut count = 0usize;
+    for line in text.lines() {
+        if line.is_empty() || line.starts_with('#') {
+            continue;
+        }
+        let Some((tag, rest)) = line.split_once(' ') else {
+            continue;
+        };
+        match tag {
+            "C" => {
+                if let Some(rec) = cur.take() {
+                    build(s, rec);
+                    count += 1;
+                }
+                let mut it = rest.split_whitespace();
+                let name = it.next().unwrap_or_default().to_string();
+                let created = it.next().and_then(|v| v.parse().ok()).unwrap_or_else(crate::server::now);
+                cur = Some(Record {
+                    name,
+                    created,
+                    ..Record::default()
+                });
+            }
+            "M" => {
+                if let Some(rec) = cur.as_mut() {
+                    rec.modes = rest.to_string();
+                }
+            }
+            "T" => {
+                if let Some(rec) = cur.as_mut() {
+                    // "<ts> <setter> :<text>"
+                    let mut it = rest.splitn(3, ' ');
+                    if let (Some(ts), Some(setter), Some(text)) = (it.next(), it.next(), it.next()) {
+                        if let Ok(ts) = ts.parse() {
+                            rec.topic = Some(Topic {
+                                text: text.strip_prefix(':').unwrap_or(text).to_string(),
+                                setter: setter.to_string(),
+                                ts,
+                            });
+                        }
+                    }
+                }
+            }
+            "b" | "e" | "I" | "g" | "X" | "w" => {
+                if let Some(rec) = cur.as_mut() {
+                    // "<ts> <setter> <mask>"
+                    let mut it = rest.splitn(3, ' ');
+                    if let (Some(ts), Some(setter), Some(mask)) = (it.next(), it.next(), it.next()) {
+                        if let Ok(ts) = ts.parse() {
+                            rec.lists.push((
+                                tag.chars().next().unwrap(),
+                                Ban {
+                                    mask: mask.to_string(),
+                                    setter: setter.to_string(),
+                                    ts,
+                                    expires: None,
+                                },
+                            ));
+                        }
+                    }
+                }
+            }
+            _ => {}
+        }
+    }
+    if let Some(rec) = cur.take() {
+        build(s, rec);
+        count += 1;
+    }
+    if count > 0 {
+        eprintln!("[permchannels] restored {count} permanent channel(s)");
+    }
+}
+
+/// Timer/command-driven persister. Holds the last bytes written so an unchanged
+/// network never rewrites the file.
+#[derive(Default)]
+pub struct PermChannels {
+    last: String,
+}
+
+impl PermChannels {
+    /// Re-serialise and, if anything changed, write the database (or remove it when
+    /// the last permanent channel is gone).
+    fn flush(&mut self, s: &Server) {
+        let cur = serialize(s);
+        if cur == self.last {
+            return;
+        }
+        let path = db_path(s);
+        if cur.is_empty() {
+            let _ = fs::remove_file(&path);
+        } else if let Err(e) = atomic_write(&path, &cur) {
+            eprintln!("[permchannels] cannot write {path}: {e}");
+            return; // leave `last` stale so the next tick retries
+        }
+        self.last = cur;
+    }
+}
+
+impl Module for PermChannels {
+    fn name(&self) -> &'static str {
+        "permchannels"
+    }
+
+    fn on_post_command(&mut self, srv: &mut Server, _uid: Uid, cmd: &str) {
+        // Persist promptly when a command could have changed a permanent channel's
+        // stored state (its modes, incl. +P/-P itself, or its topic).
+        if cmd.eq_ignore_ascii_case("MODE")
+            || cmd.eq_ignore_ascii_case("SAMODE")
+            || cmd.eq_ignore_ascii_case("TOPIC")
+        {
+            self.flush(srv);
+        }
+    }
+
+    fn on_tick(&mut self, srv: &mut Server) {
+        self.flush(srv); // backstop for changes that arrived off the command path (e.g. S2S)
+    }
+}