customprefix: config-override channel-prefix sigils per tier (customprefix = <tier> <sigil>); PREFIX/NAMES/FJOIN consistent

src/modules/customprefix.rs

@@ -0,0 +1,67 @@
+//! customprefix — override the *symbol* (sigil) of the channel prefix tiers from
+//! config, e.g. show `!` for op instead of `@`. One line per tier:
+//!
+//! ```text
+//! customprefix = op *          # ops show as *nick, PREFIX advertises it too
+//! customprefix = voice -
+//! ```
+//!
+//! Tiers: `oper founder admin op halfop voice`. Only the displayed symbol changes —
+//! the mode letters (`yqaohv`) and ranks stay fixed, so NAMES/WHO, ISUPPORT PREFIX
+//! and the S2S FJOIN burst stay consistent (a linked network must share this config,
+//! as with InspIRCd). Loaded once at boot; unset tiers keep their default sigil.
+
+use std::sync::OnceLock;
+
+use crate::server::Server;
+
+const TIER_NAMES: [&str; 6] = ["oper", "founder", "admin", "op", "halfop", "voice"];
+const LETTERS: [char; 6] = ['y', 'q', 'a', 'o', 'h', 'v'];
+const DEFAULT_SIGILS: [&str; 6] = ["!", "~", "&", "@", "%", "+"];
+
+/// The configured sigils, indexed by tier. Being a `static` its `String`s live for
+/// the program, so `sigil()` can hand out `&'static str` without leaking.
+static SIGILS: OnceLock<[String; 6]> = OnceLock::new();
+
+/// Load the `customprefix` overrides once, at boot.
+pub fn init(s: &Server) {
+    let mut a: [String; 6] = DEFAULT_SIGILS.map(String::from);
+    for line in s.conf_all("customprefix") {
+        let mut it = line.split_whitespace();
+        if let (Some(name), Some(sym)) = (it.next(), it.next()) {
+            if let Some(i) = TIER_NAMES.iter().position(|t| t.eq_ignore_ascii_case(name)) {
+                if let Some(c) = sym.chars().next() {
+                    a[i] = c.to_string();
+                }
+            }
+        }
+    }
+    let _ = SIGILS.set(a);
+}
+
+/// The sigil for tier `i` (0 = oper … 5 = voice).
+pub fn sigil(i: usize) -> &'static str {
+    SIGILS
+        .get()
+        .map(|a| a[i].as_str())
+        .unwrap_or(DEFAULT_SIGILS[i])
+}
+
+/// The prefix mode letter for a sigil char (used by the FJOIN decode); `' '` if the
+/// char isn't a prefix sigil.
+pub fn letter_for_sigil(c: char) -> char {
+    let cs = c.to_string();
+    (0..6)
+        .find(|&i| sigil(i) == cs)
+        .map(|i| LETTERS[i])
+        .unwrap_or(' ')
+}
+
+/// The ISUPPORT `PREFIX=(modes)symbols` token; `include_oper` adds the `y` tier
+/// (operprefix/ojoin).
+pub fn isupport(include_oper: bool) -> String {
+    let start = if include_oper { 0 } else { 1 };
+    let letters: String = LETTERS[start..].iter().collect();
+    let sigils: String = (start..6).map(sigil).collect();
+    format!("({letters}){sigils}")
+}

src/modules/mod.rs

@@ -20,6 +20,7 @@ pub mod conn_waitpong;
 pub mod connclass;
 pub mod connectban;
 pub mod connflood;
+pub mod customprefix;
 pub mod customtitle;
 pub mod dccallow;
 pub mod denychans;