From 06883ced9fbc466d1fafaddd099df4152de759b0 Mon Sep 17 00:00:00 2001
From: reverse <mike.chevronnet@gmail.com>
Date: Mon, 10 Aug 2026 09:37:51 +0000
Subject: [PATCH] extbanbanlist: matching extban b:#chan (share another
 channel's ban list)

---
 echoircd.conf.example        |  3 +++
 src/channels.rs              |  3 ++-
 src/modules/extbanbanlist.rs | 37 ++++++++++++++++++++++++++++++++++++
 src/modules/mod.rs           |  1 +
 src/server.rs                |  2 +-
 5 files changed, 44 insertions(+), 2 deletions(-)
 create mode 100644 src/modules/extbanbanlist.rs

diff --git a/echoircd.conf.example b/echoircd.conf.example
index 64567f5..76ff73f 100644
--- a/echoircd.conf.example
+++ b/echoircd.conf.example
@@ -120,6 +120,9 @@ amu_target    = both
 # --- chanlog (m_chanlog): mirror the oper server-notice stream into a channel so
 #     staff can watch it in a normal window. Set the channel (create/keep it opped):
 # chanlog = #snotices
+# --- extbanbanlist (m_extbanbanlist): no config — adds the matching extban
+#     `b:<#channel>`, so `+b b:#staff` catches everyone banned in #staff (shares a
+#     ban list between channels).
 # --- relaymsg (m_relaymsg / draft/relaymsg): a member whose client negotiated the
 #     capability can /RELAYMSG <#chan> <nick> <text> to speak under a spoofed relay
 #     nick (for bridges). The nick must contain a separator and not collide.
diff --git a/src/channels.rs b/src/channels.rs
index e9ba574..dc8043f 100644
--- a/src/channels.rs
+++ b/src/channels.rs
@@ -939,6 +939,7 @@ impl Server {
                     Some(b'j') => crate::modules::channelban::matches(self, uid, &b.mask[2..]),
                     Some(b's') => crate::modules::serverban::matches(self, uid, &b.mask[2..]),
                     Some(b'G') => crate::modules::geoip::geoban_match(self, uid, &b.mask[2..]),
+                    Some(b'b') => crate::modules::extbanbanlist::matches(self, uid, &b.mask[2..]),
                     _ => false,
                 }
             } else {
@@ -1151,7 +1152,7 @@ pub fn normalize_ban_mask(m: &str) -> String {
         // These extbans carry a name / spec / channel / server, not a host mask,
         // so they must not be host-normalised: g: (security group), y: (reputation
         // score), r: (realname), j: (channel), s: (server name).
-        if matches!(b[0], b'g' | b'y' | b'r' | b'j' | b's' | b'G') {
+        if matches!(b[0], b'g' | b'y' | b'r' | b'j' | b's' | b'G' | b'b') {
             return m.to_string();
         }
         return format!("{}:{}", &m[..1], normalize_mask(&m[2..]));
diff --git a/src/modules/extbanbanlist.rs b/src/modules/extbanbanlist.rs
new file mode 100644
index 0000000..f6f520f
--- /dev/null
+++ b/src/modules/extbanbanlist.rs
@@ -0,0 +1,37 @@
+//! extbanbanlist — the matching extban `b:<#channel>`: a user is caught if they are
+//! on `#channel`'s ban list. Lets one channel share (borrow) another's bans, e.g.
+//! `+b b:#staff` bans everyone banned in #staff. Reference: InspIRCd's
+//! `m_extbanbanlist`. Original native Rust.
+//!
+//! The match is deliberately *non-recursive* — it only tests the referenced
+//! channel's plain host-mask bans (and its plain excepts), never that channel's own
+//! extbans, so two channels referencing each other can't loop.
+
+use crate::channels::glob_match;
+use crate::server::Server;
+use crate::Uid;
+
+/// A plain host-mask ban entry (not itself an extban).
+fn is_plain(mask: &str) -> bool {
+    mask.as_bytes().get(1) != Some(&b':')
+}
+
+/// True if `uid` is on `chan`'s (plain) ban list with no matching plain exception.
+pub fn matches(s: &Server, uid: Uid, chan: &str) -> bool {
+    let Some(who) = s.users.get(&uid).map(|u| u.prefix()) else {
+        return false;
+    };
+    let Some(ch) = s.channels.get(&chan.to_ascii_lowercase()) else {
+        return false;
+    };
+    if ch
+        .excepts
+        .iter()
+        .any(|e| is_plain(&e.mask) && glob_match(&e.mask, &who))
+    {
+        return false;
+    }
+    ch.bans
+        .iter()
+        .any(|b| is_plain(&b.mask) && glob_match(&b.mask, &who))
+}
diff --git a/src/modules/mod.rs b/src/modules/mod.rs
index d0a065d..c84b2dc 100644
--- a/src/modules/mod.rs
+++ b/src/modules/mod.rs
@@ -24,6 +24,7 @@ pub mod dccallow;
 pub mod denychans;
 pub mod disable;
 pub mod dnsbl;
+pub mod extbanbanlist;
 pub mod extended_isupport;
 pub mod extjwt;
 pub mod filehost;
diff --git a/src/server.rs b/src/server.rs
index fe8b655..98230b4 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -596,7 +596,7 @@ impl Server {
         let maxnick = self.conf_num("maxnick", 30usize);
         let maxchan = self.conf_num("maxchannel", 50usize);
         let mut lines = vec![format!(
-            "CHANTYPES=# PREFIX=(qaohv)~&@%+ CHANMODES=beIgXw,k,lfjFLHBJdK,ACDGMNOPQRSTUcimnpstuz EXTBAN=,Gcgjmnrsy WATCH={maxwatch} MONITOR={maxmon} SILENCE={maxsil} CALLERID=g WHOX CHATHISTORY={chathist} MSGREFTYPES=timestamp,msgid UTF8ONLY CASEMAPPING=ascii NICKLEN={maxnick} CHANNELLEN={maxchan} NETWORK={}",
+            "CHANTYPES=# PREFIX=(qaohv)~&@%+ CHANMODES=beIgXw,k,lfjFLHBJdK,ACDGMNOPQRSTUcimnpstuz EXTBAN=,Gbcgjmnrsy WATCH={maxwatch} MONITOR={maxmon} SILENCE={maxsil} CALLERID=g WHOX CHATHISTORY={chathist} MSGREFTYPES=timestamp,msgid UTF8ONLY CASEMAPPING=ascii NICKLEN={maxnick} CHANNELLEN={maxchan} NETWORK={}",
             self.network
         )];
         if let Some(tok) = crate::modules::network_icon::isupport(self) {