extban: add r: realnameban, j: channelban, s: serverban matching extbans

src/modules/channelban.rs

@@ -0,0 +1,47 @@
+//! channelban — the `j:` matching extban: match a user by another channel they
+//! are in. `+b j:#lobby` bans everyone who is also in `#lobby`; an optional status
+//! prefix narrows it to members at/above that rank, e.g. `+b j:@#staff` matches
+//! only ops-or-higher in `#staff`. The channel part is a glob. Dispatched from the
+//! channel ban matcher; the logic lives here in its own file.
+//!
+//! Behaviour reference: InspIRCd's `m_channelban`. Original native Rust.
+
+use crate::channels::{glob_match, RANK_ADMIN, RANK_HALFOP, RANK_OP, RANK_OWNER, RANK_VOICE};
+use crate::server::Server;
+use crate::Uid;
+
+/// Map a leading status prefix to the minimum rank it requires; `None` if the
+/// first char isn't a prefix (so the whole string is the channel glob).
+fn split_prefix(mask: &str) -> (u8, &str) {
+    match mask.chars().next() {
+        Some('~') => (RANK_OWNER, &mask[1..]),
+        Some('&') => (RANK_ADMIN, &mask[1..]),
+        Some('@') => (RANK_OP, &mask[1..]),
+        Some('%') => (RANK_HALFOP, &mask[1..]),
+        Some('+') => (RANK_VOICE, &mask[1..]),
+        _ => (0, mask),
+    }
+}
+
+/// Is `uid` a member (at/above the required rank) of a channel matching the glob
+/// in `mask` (the part after `j:`)?
+pub fn matches(s: &Server, uid: Uid, mask: &str) -> bool {
+    let (min_rank, changlob) = split_prefix(mask);
+    let changlob = changlob.to_ascii_lowercase();
+    let Some(u) = s.users.get(&uid) else {
+        return false;
+    };
+    u.channels.iter().any(|key| {
+        if !glob_match(&changlob, key) {
+            return false;
+        }
+        if min_rank == 0 {
+            return true;
+        }
+        s.channels
+            .get(key)
+            .and_then(|ch| ch.members.get(&uid))
+            .map(|m| m.rank() >= min_rank)
+            .unwrap_or(false)
+    })
+}