modules: port securelist and denychans (badchan/goodchan with redirect)

src/modules/denychans.rs

@@ -0,0 +1,131 @@
+//! denychans — forbid joining channels whose name matches a `badchan` glob, with
+//! an optional redirect to a safe channel and an `allowopers` bypass. A `goodchan`
+//! glob whitelists names back out of a broad `badchan` pattern. Config:
+//!
+//! ```text
+//! badchan  = #evil* reason="That channel is off-limits." redirect=#lobby allowopers=yes
+//! goodchan = #evilgenius
+//! ```
+//!
+//! Dispatched straight from `Server::join` (like the CBAN check), so it works
+//! per-channel even when several are joined at once. All config-driven; nothing
+//! lives on `Server`.
+//!
+//! Behaviour reference: InspIRCd's `m_denychans`. Original native Rust.
+
+use crate::channels::glob_match;
+use crate::numeric::{ERR_BADCHANNEL, ERR_LINKCHANNEL};
+use crate::server::Server;
+use crate::Uid;
+
+/// One parsed `badchan` line.
+struct BadChan {
+    glob: String,
+    reason: String,
+    redirect: Option<String>,
+    allowopers: bool,
+}
+
+/// Reuse the quoted-attribute tokenizer shape: split on whitespace but keep
+/// `key="quoted value"` together.
+fn tokenize(line: &str) -> Vec<String> {
+    let mut out = Vec::new();
+    let mut cur = String::new();
+    let (mut in_q, mut has) = (false, false);
+    for ch in line.chars() {
+        match ch {
+            '"' => {
+                in_q = !in_q;
+                has = true;
+            }
+            c if c.is_whitespace() && !in_q => {
+                if has {
+                    out.push(std::mem::take(&mut cur));
+                    has = false;
+                }
+            }
+            c => {
+                cur.push(c);
+                has = true;
+            }
+        }
+    }
+    if has {
+        out.push(cur);
+    }
+    out
+}
+
+fn parse(s: &Server) -> Vec<BadChan> {
+    let mut out = Vec::new();
+    for line in s.conf_all("badchan") {
+        let toks = tokenize(line);
+        let Some((glob, attrs)) = toks.split_first() else {
+            continue;
+        };
+        if glob.is_empty() {
+            continue;
+        }
+        let mut bc = BadChan {
+            glob: glob.clone(),
+            reason: "Channel is forbidden.".to_string(),
+            redirect: None,
+            allowopers: false,
+        };
+        for tok in attrs {
+            let Some((k, v)) = tok.split_once('=') else {
+                continue;
+            };
+            match k {
+                "reason" => bc.reason = v.to_string(),
+                "redirect" => {
+                    if !v.is_empty() {
+                        bc.redirect = Some(v.to_string())
+                    }
+                }
+                "allowopers" => bc.allowopers = crate::config::yesish(v),
+                _ => {}
+            }
+        }
+        out.push(bc);
+    }
+    out
+}
+
+/// Whether `name` is whitelisted by any `goodchan` glob.
+fn is_good(s: &Server, name: &str) -> bool {
+    s.conf_all("goodchan").iter().any(|g| glob_match(g, name))
+}
+
+/// Called from `Server::join`. Returns `true` when the join to `name` should be
+/// blocked (the caller returns without joining); emits the numeric and performs a
+/// redirect join if configured. `is_oper` lets an `allowopers` badchan through.
+pub fn intercept(s: &mut Server, uid: Uid, name: &str, is_oper: bool) -> bool {
+    if s.conf_all("badchan").is_empty() {
+        return false;
+    }
+    if is_good(s, name) {
+        return false;
+    }
+    let bad = parse(s);
+    let Some(bc) = bad.iter().find(|b| glob_match(&b.glob, name)) else {
+        return false;
+    };
+    if is_oper && bc.allowopers {
+        return false;
+    }
+
+    s.numeric(uid, ERR_BADCHANNEL, &format!("{name} :{}", bc.reason));
+    if let Some(redir) = &bc.redirect {
+        if !redir.eq_ignore_ascii_case(name) {
+            let redir = redir.clone();
+            s.numeric(
+                uid,
+                ERR_LINKCHANNEL,
+                &format!("{name} {redir} :You have been redirected."),
+            );
+            s.join(uid, &redir, None);
+        }
+    }
+    true
+}

src/modules/mod.rs

@@ -11,6 +11,7 @@ pub mod chathistory;
 pub mod cloak;
 pub mod connectban;
 pub mod connflood;
+pub mod denychans;
 pub mod dnsbl;
 pub mod filter;
 pub mod flood;
@@ -24,6 +25,7 @@ pub mod realnameban;
 pub mod reputation;
 pub mod restrictcommands;
 pub mod restrictmsg;
+pub mod securelist;
 pub mod securitygroups;
 pub mod serverban;
 pub mod snoop;
@@ -50,6 +52,7 @@ pub fn default_modules() -> Vec<Box<dyn Module>> {
         Box::new(restrictmsg::RestrictMsg),
         Box::new(blockamsg::BlockAmsg),
         Box::new(connectban::ConnectBan),
+        Box::new(securelist::SecureList),
     ]
 }
 

src/modules/securelist.rs

@@ -0,0 +1,134 @@
+//! securelist — hold back the `/LIST` command until a user has been connected for
+//! a while, which defeats spambots that connect, `LIST`, spam every channel and
+//! leave. Non-exempt users who `LIST` too early get an optional notice and a
+//! throwaway *fake* channel list (so a bot waiting on the reply is satisfied and
+//! wastes its time), then the real `LIST` is denied. Exempt: opers, logged-in
+//! accounts (when `securelist_exemptregistered`), and hosts matching a
+//! `securelist_exception` glob. Off unless `securelist = yes`; all config-driven.
+//!
+//! Behaviour reference: InspIRCd's `m_securelist`. Original native Rust; the fake
+//! names use OpenSSL's CSPRNG (already a dependency) rather than any new crate.
+
+use openssl::rand::rand_bytes;
+
+use crate::channels::glob_match;
+use crate::module::{ModResult, Module};
+use crate::numeric::{RPL_LIST, RPL_LISTEND, RPL_LISTSTART};
+use crate::server::{now, Server};
+use crate::Uid;
+
+/// A small unsigned int from the CSPRNG in `0..bound` (bound>0), else 0.
+fn rand_below(bound: u32) -> u32 {
+    if bound == 0 {
+        return 0;
+    }
+    let mut b = [0u8; 4];
+    if rand_bytes(&mut b).is_err() {
+        return 0;
+    }
+    u32::from_le_bytes(b) % bound
+}
+
+/// A random lowercase-alnum string of `len` chars (for a fake channel suffix).
+fn rand_name(len: usize) -> String {
+    const ALPHABET: &[u8] = b"abcdefghijklmnopqrstuvwxyz0123456789";
+    let mut buf = vec![0u8; len];
+    if rand_bytes(&mut buf).is_err() {
+        return "channel".to_string();
+    }
+    buf.iter()
+        .map(|&b| ALPHABET[b as usize % ALPHABET.len()] as char)
+        .collect()
+}
+
+/// Is `uid` exempt from the LIST hold?
+fn is_exempt(s: &Server, uid: Uid) -> bool {
+    if s.is_oper(uid) {
+        return true;
+    }
+    if s.conf_bool("securelist_exemptregistered", true) && s.is_logged_in(uid) {
+        return true;
+    }
+    let exceptions = s.conf_all("securelist_exception");
+    if exceptions.is_empty() {
+        return false;
+    }
+    let Some(u) = s.users.get(&uid) else {
+        return false;
+    };
+    let forms = [
+        format!("{}@{}", u.ident, u.host),
+        format!("{}@{}", u.ident, u.addr.ip()),
+    ];
+    exceptions
+        .iter()
+        .any(|mask| forms.iter().any(|f| glob_match(mask, f)))
+}
+
+pub struct SecureList;
+
+impl Module for SecureList {
+    fn name(&self) -> &'static str {
+        "securelist"
+    }
+
+    fn on_pre_command(
+        &mut self,
+        srv: &mut Server,
+        uid: Uid,
+        cmd: &str,
+        _params: &[String],
+    ) -> ModResult {
+        if !srv.conf_bool("securelist", false) || !cmd.eq_ignore_ascii_case("LIST") {
+            return ModResult::Passthru;
+        }
+        if is_exempt(srv, uid) {
+            return ModResult::Passthru;
+        }
+        let waittime = srv.conf_num("securelist_waittime", 60u64);
+        let signon = srv.users.get(&uid).map(|u| u.signon).unwrap_or(0);
+        let elapsed = now().saturating_sub(signon);
+        if waittime > 0 && elapsed >= waittime {
+            return ModResult::Passthru;
+        }
+
+        // tell them to wait
+        if srv.conf_bool("securelist_showmsg", true) {
+            let remain = waittime.saturating_sub(elapsed);
+            let nick = srv
+                .users
+                .get(&uid)
+                .map(|u| u.nick.clone())
+                .unwrap_or_default();
+            srv.send(
+                uid,
+                format!(
+                    ":{} NOTICE {nick} :*** You cannot view the channel list yet. \
+                     Please try again in {remain} seconds (or log in to an account).",
+                    srv.name
+                ),
+            );
+        }
+
+        // throwaway fake list so a bot waiting on the reply is satisfied
+        let fakechans = srv.conf_num("securelist_fakechans", 5u32);
+        let prefix = srv
+            .conf("securelist_fakechanprefix")
+            .unwrap_or("#")
+            .to_string();
+        let topic = srv
+            .conf("securelist_fakechantopic")
+            .unwrap_or("Fake channel for confusing spambots")
+            .to_string();
+        let usercount = srv.users.len().max(1) as u32;
+
+        srv.numeric(uid, RPL_LISTSTART, "Channel :Users Name");
+        for _ in 0..fakechans {
+            let suffix = rand_name((rand_below(8) + 3) as usize);
+            let count = rand_below(usercount) + 1;
+            srv.numeric(uid, RPL_LIST, &format!("{prefix}{suffix} {count} :{topic}"));
+        }
+        srv.numeric(uid, RPL_LISTEND, ":End of channel list.");
+        ModResult::Deny
+    }
+}