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

src/modules/serverban.rs

@@ -0,0 +1,20 @@
+//! serverban — the `s:` matching extban: match a user by the name of the server
+//! they are connected to. `+b s:irc.example.net` bans everyone on that server.
+//! Ban matching only ever runs against local users (join happens locally), so a
+//! matched user is on this server — we glob the mask against our own name.
+//! Dispatched from the channel ban matcher; the logic lives here.
+//!
+//! Behaviour reference: InspIRCd's `m_serverban`. Original native Rust.
+
+use crate::channels::glob_match;
+use crate::server::Server;
+use crate::Uid;
+
+/// Does `uid`'s server name match the glob `mask` (the part after `s:`)?
+pub fn matches(s: &Server, uid: Uid, mask: &str) -> bool {
+    // local users are on this server; guard on the user still existing
+    if !s.users.contains_key(&uid) {
+        return false;
+    }
+    glob_match(mask, &s.name)
+}