nickserv/chanserv: catch styled/fullwidth look-alike names too, and add a [register] confusable_check toggle (REHASH-reloadable)

api/src/lib.rs

@@ -1935,6 +1935,11 @@ pub trait Store {
     // Whether account identity is owned externally (website); when true, IRC
     // can't register or change credentials — it only authenticates.
     fn external_accounts(&self) -> bool;
+    // Whether REGISTER should reject look-alike / mixed-script names ([register]
+    // confusable_check). Defaults on; a mock store need not override it.
+    fn confusable_check_enabled(&self) -> bool {
+        true
+    }
     // Staff notes on accounts/channels (oper-only), shown in INFO to operators.
     fn set_account_note(&mut self, account: &str, note: Option<String>) -> bool;
     fn account_note(&self, account: &str) -> Option<String>;
@@ -2175,6 +2180,12 @@ pub fn confusable_reason(name: &str) -> Option<&'static str> {
     fn is_invisible(cp: u32) -> bool {
         matches!(cp, 0xAD | 0x180E | 0x200B..=0x200F | 0x202A..=0x202E | 0x2060 | 0x2066..=0x2069 | 0xFEFF)
     }
+    // "Styled" Latin that renders as normal-looking ASCII: fullwidth (Ａｄｍｉｎ),
+    // mathematical alphanumerics (𝐚𝐝𝐦𝐢𝐧), and enclosed/circled/squared letters.
+    // Nobody types a whole name this way except to imitate one.
+    fn is_fancy_latin(cp: u32) -> bool {
+        matches!(cp, 0xFF21..=0xFF5A | 0x1D400..=0x1D7FF | 0x1F130..=0x1F189 | 0x24B6..=0x24E9 | 0x2460..=0x24FF)
+    }
     // Non-Latin letters that look like an ASCII Latin letter — the homoglyphs a
     // spoofer swaps in. Catches an all-look-alike name that pure script-mixing
     // would miss (e.g. an entirely-Cyrillic name that reads as Latin).
@@ -2198,6 +2209,9 @@ pub fn confusable_reason(name: &str) -> Option<&'static str> {
         if is_invisible(cp) {
             return Some("That name uses invisible or text-direction characters. Please choose a plain name.");
         }
+        if is_fancy_latin(cp) {
+            return Some("That name uses styled look-alike letters (fullwidth or symbol fonts). Please choose a plain name.");
+        }
         if let Some((script, id)) = script_id(cp) {
             letters += 1;
             if script == Script::Latin {
@@ -2349,6 +2363,8 @@ mod tests {
             "аеосх",      // all-Cyrillic Latin look-alikes — homoglyph
             "ad\u{200b}min", // zero-width space
             "\u{202e}nimda", // right-to-left override
+            "Ａｄｍｉｎ",     // fullwidth Latin
+            "\u{1D41A}\u{1D41D}\u{1D426}\u{1D422}\u{1D427}", // 𝐚𝐝𝐦𝐢𝐧 mathematical bold
         ] {
             assert!(confusable_reason(bad).is_some(), "should be rejected: {bad}");
         }

config.example.toml

@@ -103,3 +103,12 @@ protocol = 1206            # InspIRCd link protocol version (1206 = insp4, 1205
 # channel is unaffected; keep this off if you don't want echo talking to dict.org.
 # [dictserv]
 # server = "dict.org:2628"
+
+# Registration policy. The look-alike guard refuses REGISTER of a nick or channel
+# that mixes alphabets (Cyrillic "аdmin"), is built from homoglyphs or styled
+# (fullwidth/math) letters imitating Latin, or hides invisible/bidi characters —
+# while genuine monolingual text (including accented French) passes. It's on by
+# default; turn it off for a community that legitimately uses mixed/non-Latin
+# names. Reloadable with OperServ REHASH.
+# [register]
+# confusable_check = false

modules/chanserv/src/lib.rs

@@ -132,11 +132,13 @@ impl Service for ChanServ {
                     return;
                 }
                 // Refuse a look-alike / mixed-script channel name (e.g. a Cyrillic
-                // homoglyph of a real channel).
+                // homoglyph of a real channel), unless the guard is turned off.
+                if db.confusable_check_enabled() {
                     if let Some(reason) = echo_api::confusable_reason(chan) {
                         ctx.notice(me, from.uid, reason);
                         return;
                     }
+                }
                 match db.register_channel(chan, account) {
                     Ok(()) => {
                         ctx.channel_mode(me, chan, "+r"); // mark the channel registered

modules/nickserv/src/lib.rs

@@ -110,7 +110,7 @@ impl Service for NickServ {
             return;
         }
         match cmd.as_deref() {
-            Some("REGISTER") => register::handle(me, from, args, ctx),
+            Some("REGISTER") => register::handle(me, from, args, ctx, db),
             Some("IDENTIFY") | Some("ID") => identify::handle(me, from, args, ctx, db),
             Some("LOGOUT") | Some("LOGOFF") => logout::handle(me, &self.guest_nick, &mut self.guest_seq, from, ctx),
             Some("CERT") => cert::handle(me, from, args, ctx, db),

modules/nickserv/src/register.rs

@@ -1,9 +1,9 @@
-use echo_api::{Sender, ServiceCtx};
+use echo_api::{Sender, ServiceCtx, Store};
 use echo_api::RegReply;
 
 // REGISTER <password> [email]: register the sender's current nick. The engine
 // derives the password off-thread, commits, and answers.
-pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx) {
+pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx, db: &dyn Store) {
     let Some(password) = args.get(1) else {
         ctx.notice(me, from.uid, "Syntax: REGISTER <password> [email]");
         return;
@@ -12,11 +12,14 @@ pub fn handle(me: &str, from: &Sender, args: &[&str], ctx: &mut ServiceCtx) {
         ctx.notice(me, from.uid, reason);
         return;
     }
-    // Refuse a look-alike / mixed-script nick before it can be used to impersonate.
+    // Refuse a look-alike / mixed-script nick before it can be used to impersonate,
+    // unless the guard is turned off.
+    if db.confusable_check_enabled() {
         if let Some(reason) = echo_api::confusable_reason(from.nick) {
             ctx.notice(me, from.uid, reason);
             return;
         }
+    }
     let email = args.get(2).map(|s| s.to_string());
     ctx.defer_register(from.nick, *password, email, RegReply::NickServ {
         agent: me.to_string(),

src/config.rs

@@ -49,6 +49,9 @@ pub struct Config {
     // not load and echo makes no outbound lookup requests. Opt-in on purpose.
     #[serde(default)]
     pub dictserv: Option<Dict>,
+    // Registration policy. Absent = defaults (the look-alike guard is on).
+    #[serde(default)]
+    pub register: Register,
     // Which InspIRCd matching-extbans AKICK may use. Absent = every extban echo
     // knows (full compatibility). List `enabled` to restrict it — e.g. drop the
     // ones your ircd doesn't provide.
@@ -85,6 +88,22 @@ fn default_dict_server() -> String {
     "dict.org:2628".to_string()
 }
 
+// Registration policy.
+#[derive(Debug, Deserialize, Clone)]
+#[serde(default)]
+pub struct Register {
+    // Reject look-alike / mixed-script / invisible registration names. On by
+    // default; turn it off for a community that legitimately uses mixed or
+    // non-Latin names. Reloadable with REHASH.
+    pub confusable_check: bool,
+}
+
+impl Default for Register {
+    fn default() -> Self {
+        Self { confusable_check: true }
+    }
+}
+
 // Account-authority configuration.
 #[derive(Debug, Deserialize, Clone)]
 pub struct Auth {

src/engine/db/mod.rs

@@ -1056,6 +1056,7 @@ pub struct Db {
     // website): IRC can't register or change credentials, only authenticate
     // against accounts pushed in (via the gRPC Accounts API). Node-local config.
     external_accounts: bool,
+    confusable_check: bool, // reject look-alike / mixed-script REGISTER names
 }
 
 // A juped server: the held name, the fake server id we allocated for it, and why.
@@ -1124,7 +1125,7 @@ impl Db {
             apply(&mut accounts, &mut channels, &mut grouped, &mut bots, &mut host_cfg, &mut net, event);
         }
         tracing::info!(accounts = accounts.len(), channels = channels.len(), "account store loaded");
-        Self { accounts, channels, grouped, log, extban_enabled: None, notify_exclude: Vec::new(), live_extbans: None, live_chanmodes: None, scram_iterations: scram::DEFAULT_ITERATIONS, email_enabled: false, email_brand: "Network Services".to_string(), email_accent: "#4f46e5".to_string(), email_logo: String::new(), codes: HashMap::new(), auth_fails: HashMap::new(), vhost_req_times: HashMap::new(), report_times: HashMap::new(), bots, host_cfg, net, ignores: Vec::new(), defcon: 5, external_accounts: false }
+        Self { accounts, channels, grouped, log, extban_enabled: None, notify_exclude: Vec::new(), live_extbans: None, live_chanmodes: None, scram_iterations: scram::DEFAULT_ITERATIONS, email_enabled: false, email_brand: "Network Services".to_string(), email_accent: "#4f46e5".to_string(), email_logo: String::new(), codes: HashMap::new(), auth_fails: HashMap::new(), vhost_req_times: HashMap::new(), report_times: HashMap::new(), bots, host_cfg, net, ignores: Vec::new(), defcon: 5, external_accounts: false, confusable_check: true }
     }
 
     /// Fold an entry authored by another node into the store — the services-side

src/engine/db/network.rs

@@ -338,6 +338,11 @@ impl Db {
         self.external_accounts = on;
     }
 
+    /// Toggle the look-alike / mixed-script REGISTER guard (from `[register]`).
+    pub fn set_confusable_check(&mut self, on: bool) {
+        self.confusable_check = on;
+    }
+
     /// The network defence level (5 = normal, 1 = full lockdown).
     pub fn defcon(&self) -> u8 {
         self.defcon

src/engine/db/store.rs

@@ -320,6 +320,9 @@ impl Store for Db {
     fn external_accounts(&self) -> bool {
         Db::external_accounts(self)
     }
+    fn confusable_check_enabled(&self) -> bool {
+        self.confusable_check
+    }
     fn set_account_note(&mut self, account: &str, note: Option<String>) -> bool {
         Db::set_account_note(self, account, note)
     }

src/engine/mod.rs

@@ -897,6 +897,7 @@ impl Engine {
         self.set_standard_replies(cfg.server.standard_replies);
         self.set_log_channel(cfg.log.as_ref().map(|l| l.channel.clone()));
         self.db.set_notify_exclude(cfg.log.as_ref().map(|l| l.notify_exclude.clone()).unwrap_or_default());
+        self.db.set_confusable_check(cfg.register.confusable_check);
         self.set_guest_nick(&cfg.server.guest_nick);
         if let Some(expire) = &cfg.expire {
             self.set_expiry(expire.account_ttl(), expire.channel_ttl(), expire.warn_ttl());

src/main.rs

@@ -186,6 +186,7 @@ async fn main() -> Result<()> {
     db.set_outbound(gossip_tx.clone());
     db.set_email_enabled(cfg.email.is_some());
     db.set_external_accounts(cfg.auth.as_ref().is_some_and(|a| a.external));
+    db.set_confusable_check(cfg.register.confusable_check);
     match cfg.extban.as_ref().map(|e| e.enabled.as_slice()) {
         Some(list) if !list.is_empty() => {
             db.set_extban_enabled(list.to_vec());