NAMES/WHO: Only send multiple prefixes after negotiating multi-prefix

It is incorrect without this capability, and may break clients.

sable_ircd/src/capability/mod.rs

@@ -74,6 +74,7 @@ define_capabilities! (
         UserhostInNames:        0x40 => ("userhost-in-names", true),
         AwayNotify:             0x80 => ("away-notify", true),
         AccountTag:             0x100 => ("account-tag", true),
+        MultiPrefix:            0x200 => ("multi-prefix", true),
 
         // Draft and experimental caps
         ChatHistory:            0x1_0000 => ("draft/chathistory", true),

sable_ircd/src/command/handlers/who.rs

@@ -1,4 +1,5 @@
 use super::*;
+use crate::capability::ClientCapability;
 use crate::utils::make_numeric;
 
 #[command_handler("WHO")]
@@ -20,19 +21,15 @@ fn handle_who(
                     continue;
                 }
 
-                response.numeric(make_who_reply(
-                    &member.user()?,
-                    Some(&channel),
-                    Some(&member),
-                ));
+                send_who_reply(response, &member.user()?, Some(&channel), Some(&member));
             }
         }
     } else if let Ok(nick) = Nickname::from_str(target) {
         if let Ok(user) = network.user_by_nick(&nick) {
-            response.numeric(make_who_reply(
-                &user, None, // channel
+            send_who_reply(
+                response, &user, None, // channel
                 None, // membership
-            ));
+            );
         }
     }
 
@@ -42,22 +39,35 @@ fn handle_who(
     Ok(())
 }
 
-fn make_who_reply(
+fn send_who_reply(
+    response: &dyn CommandResponse,
     target: &wrapper::User,
     channel: Option<&wrapper::Channel>,
     membership: Option<&wrapper::Membership>,
-) -> UntargetedNumeric {
+) {
     let chname = channel.map(|c| c.name().value() as &str).unwrap_or("*");
     let away_letter = match target.away_reason() {
         None => 'H',    // Here
         Some(_) => 'G', // Gone
     };
-    let status = format!(
-        "{}{}",
-        away_letter,
-        membership
-            .map(|m| m.permissions().to_prefixes())
-            .unwrap_or_else(|| "".to_string())
-    );
-    make_numeric!(WhoReply, chname, target, &status, 0)
+    let status = if response.capabilities().has(ClientCapability::MultiPrefix) {
+        format!(
+            "{}{}",
+            away_letter,
+            membership
+                .map(|m| m.permissions().to_prefixes())
+                .unwrap_or_else(|| "".to_string())
+        )
+    } else {
+        format!(
+            "{}{}",
+            away_letter,
+            membership
+                .and_then(|m| m.permissions().to_highest_prefix())
+                .as_ref()
+                .map(char::to_string)
+                .unwrap_or_else(|| "".to_string())
+        )
+    };
+    response.numeric(make_numeric!(WhoReply, chname, target, &status, 0))
 }

sable_ircd/src/utils/channel_names.rs

@@ -27,6 +27,7 @@ pub fn send_channel_names(
     let user_is_on_chan = to_user.is_in_channel(channel.id()).is_some();
 
     let with_userhost = to.capabilities().has(ClientCapability::UserhostInNames);
+    let with_multiprefix = to.capabilities().has(ClientCapability::MultiPrefix);
 
     for member in channel.members() {
         if !user_is_on_chan
@@ -38,7 +39,16 @@ pub fn send_channel_names(
             continue;
         }
 
-        let p = member.permissions().to_prefixes();
+        let p = if with_multiprefix {
+            member.permissions().to_prefixes()
+        } else {
+            member
+                .permissions()
+                .to_highest_prefix()
+                .as_ref()
+                .map(char::to_string)
+                .unwrap_or_else(|| "".to_string())
+        };
         let user = member.user()?;
         let n = if with_userhost {
             format!("{}!{}@{}", user.nick(), user.user(), user.visible_host())

sable_macros/src/modeflags.rs

@@ -236,6 +236,20 @@ pub fn mode_flags(input: TokenStream) -> TokenStream {
                     return s;
                 }
 
+                /// [`to_prefixes`] fallback for clients without
+                /// [`multi-prefix`](https://ircv3.net/specs/extensions/multi-prefix)
+                pub fn to_highest_prefix(&self) -> Option<char>
+                {
+                    for v in Self::ALL
+                    {
+                        if (self.is_set(v.0))
+                        {
+                            return Some(v.2)
+                        }
+                    }
+                    return None;
+                }
+
                 pub fn prefix_for(flag: #name_one) -> char
                 {
                     for v in Self::ALL