labeled-response + batch: capture a labeled command's replies and wrap them (single label tag / BATCH / ACK)

src/ircd.rs

@@ -46,6 +46,19 @@ pub enum Event {
     Tick,
 }
 
+/// Insert an extra IRCv3 tag into a wire line's tag block, creating the `@…`
+/// block if the line has none. Used to fold `label=`/`batch=` onto captured lines.
+fn with_extra_tag(line: &str, tag: &str) -> String {
+    if let Some(rest) = line.strip_prefix('@') {
+        match rest.split_once(' ') {
+            Some((tags, body)) => format!("@{tags};{tag} {body}"),
+            None => format!("@{rest};{tag}"),
+        }
+    } else {
+        format!("@{tag} {line}")
+    }
+}
+
 pub struct Ircd {
     server: Server,
     commands: HashMap<&'static str, Box<dyn Command>>,
@@ -126,7 +139,6 @@ impl Ircd {
             u.last_active = crate::server::now();
             u.ping_sent = false;
         }
-        let cmd = msg.command.as_str();
         let registered = self
             .server
             .users
@@ -140,6 +152,36 @@ impl Ircd {
             return;
         }
 
+        // labeled-response: if the client tagged this command with `label` and
+        // negotiated the cap, capture its own replies and wrap them with the label.
+        let label = msg.label.clone().filter(|_| {
+            self.server
+                .users
+                .get(&uid)
+                .map(|u| u.caps.labeled_response)
+                .unwrap_or(false)
+        });
+        if let Some(label) = label {
+            *self.server.label_capture.borrow_mut() = Some((uid, Vec::new()));
+            self.dispatch(uid, &msg, registered);
+            let lines = self
+                .server
+                .label_capture
+                .borrow_mut()
+                .take()
+                .map(|(_, l)| l)
+                .unwrap_or_default();
+            self.emit_labeled(uid, &label, lines);
+        } else {
+            self.dispatch(uid, &msg, registered);
+        }
+    }
+
+    /// Run one parsed command: module gates, handler dispatch, post-hooks, and the
+    /// registration/quit follow-ups. Output goes through `Server::send`, so it's
+    /// transparently captured when a labeled command wraps this call.
+    fn dispatch(&mut self, uid: Uid, msg: &message::Message, registered: bool) {
+        let cmd = msg.command.as_str();
         // module pre-command gate
         for m in &mut self.modules {
             if m.on_pre_command(&mut self.server, uid, cmd, &msg.params) == ModResult::Deny {
@@ -193,6 +235,34 @@ impl Ircd {
         }
     }
 
+    /// Emit a labeled command's captured replies (labeled-response): `ACK` if it
+    /// produced none, the single line label-tagged if one, else a `BATCH`-wrapped
+    /// group. Runs after the capture is taken, so these go straight to the wire.
+    fn emit_labeled(&mut self, uid: Uid, label: &str, lines: Vec<String>) {
+        let server = self.server.name.clone();
+        match lines.len() {
+            0 => self
+                .server
+                .send(uid, format!("@label={label} :{server} ACK")),
+            1 => {
+                let l = with_extra_tag(&lines[0], &format!("label={label}"));
+                self.server.send(uid, l);
+            }
+            _ => {
+                let bref = self.server.next_msgid().replace('-', ""); // batch ref: alnum only
+                self.server.send(
+                    uid,
+                    format!("@label={label} :{server} BATCH +{bref} labeled-response"),
+                );
+                for l in lines {
+                    self.server
+                        .send(uid, with_extra_tag(&l, &format!("batch={bref}")));
+                }
+                self.server.send(uid, format!(":{server} BATCH -{bref}"));
+            }
+        }
+    }
+
     /// Finish registration if NICK, USER, CAP and the reverse-DNS lookup are all
     /// done. Called after each command and when a DNS result arrives.
     fn try_register(&mut self, uid: Uid) {

src/link.rs

@@ -496,6 +496,7 @@ impl Server {
                 command: msg.params[1].to_ascii_uppercase(),
                 params: msg.params[2..].to_vec(),
                 ctags: String::new(),
+                label: None,
             };
             self.on_link(via, &sub);
         }

src/message.rs

@@ -12,6 +12,9 @@ pub struct Message {
     pub params: Vec<String>,
     /// Client-only IRCv3 tags (`+key=val;…`) re-serialised for relay; `""` if none.
     pub ctags: String,
+    /// The IRCv3 `label` tag value, if the client tagged this command (for
+    /// labeled-response); `None` otherwise.
+    pub label: Option<String>,
 }
 
 /// Parse one wire line. Returns `None` for an empty/garbage line.
@@ -20,6 +23,7 @@ pub fn parse(line: &str) -> Option<Message> {
 
     // IRCv3 message tags — keep the client-only (`+`) tags for relay, drop the rest.
     let mut ctags = String::new();
+    let mut label = None;
     if let Some(after_at) = rest.strip_prefix('@') {
         let (tags, r) = after_at.split_once(' ')?;
         ctags = tags
@@ -27,6 +31,10 @@ pub fn parse(line: &str) -> Option<Message> {
             .filter(|t| t.starts_with('+'))
             .collect::<Vec<_>>()
             .join(";");
+        label = tags
+            .split(';')
+            .find_map(|t| t.strip_prefix("label="))
+            .map(|v| v.to_string());
         rest = r.trim_start();
     }
 
@@ -68,6 +76,7 @@ pub fn parse(line: &str) -> Option<Message> {
         command: cmd.to_ascii_uppercase(),
         params,
         ctags,
+        label,
     })
 }
 

src/server.rs

@@ -5,6 +5,7 @@
 //! keeps usermanager / channelmanager separate from the core. No locks: only the
 //! single core thread ever holds a `Server`.
 
+use std::cell::RefCell;
 use std::collections::{HashMap, HashSet, VecDeque};
 use std::net::{SocketAddr, TcpStream};
 use std::sync::mpsc::Sender;
@@ -105,7 +106,12 @@ pub struct Server {
     pub dnsbl_reason: String,                      // ban reason on a DNSBL hit
     pub sasl_server: String,                       // services server that handles SASL
     pub webirc: Vec<(String, String)>,             // trusted web gateways: (password, name)
-    pub event_tx: Sender<Event>,                   // self-inject events (DNS results)
+    // labeled-response: while Some((uid, buf)), that client's own responses are
+    // diverted into `buf` instead of the socket, so `on_line` can wrap them with
+    // the command's `label` (single tag, BATCH, or ACK). RefCell because the
+    // output primitives are `&self`.
+    pub label_capture: RefCell<Option<(Uid, Vec<String>)>>,
+    pub event_tx: Sender<Event>, // self-inject events (DNS results)
 }
 
 impl Server {
@@ -146,6 +152,7 @@ impl Server {
             dnsbl_reason: cfg.dnsbl_reason,
             sasl_server: cfg.sasl_server,
             webirc: cfg.webirc,
+            label_capture: RefCell::new(None),
             event_tx,
         }
     }
@@ -399,6 +406,22 @@ impl Server {
             } else {
                 line
             };
+            self.emit_to(uid, line);
+        }
+    }
+
+    /// Final hop for one line to a client: diverted into the labeled-response
+    /// capture buffer when one is active for `uid`, otherwise written to the wire.
+    fn emit_to(&self, uid: Uid, line: String) {
+        if let Ok(mut cap) = self.label_capture.try_borrow_mut() {
+            if let Some((cuid, buf)) = cap.as_mut() {
+                if *cuid == uid {
+                    buf.push(line);
+                    return;
+                }
+            }
+        }
+        if let Some(u) = self.users.get(&uid) {
             u.out.send(line);
         }
     }
@@ -536,7 +559,7 @@ impl Server {
             } else {
                 format!("@{} {body}", tags.join(";"))
             };
-            u.out.send(line);
+            self.emit_to(uid, line);
         }
     }
 

src/users.rs

@@ -95,6 +95,8 @@ pub const SUPPORTED_CAPS: &[&str] = &[
     "extended-monitor",
     "account-tag",
     "standard-replies",
+    "labeled-response",
+    "batch",
     "cap-notify",
 ];
 
@@ -118,6 +120,8 @@ pub struct Caps {
     pub extended_monitor: bool, // route away/account/chghost/setname for MONITOR targets
     pub account_tag: bool,      // prepend account=<name> tag on messages from logged-in users
     pub standard_replies: bool, // understands FAIL/WARN/NOTE structured replies
+    pub labeled_response: bool, // tag responses to a labeled command with its label
+    pub batch: bool,            // understands BATCH framing
     pub cap_notify: bool,
 }
 
@@ -163,6 +167,8 @@ impl Caps {
             "extended-monitor" => self.extended_monitor,
             "account-tag" => self.account_tag,
             "standard-replies" => self.standard_replies,
+            "labeled-response" => self.labeled_response,
+            "batch" => self.batch,
             "cap-notify" => self.cap_notify,
             _ => false,
         }
@@ -186,6 +192,8 @@ impl Caps {
             "extended-monitor" => &mut self.extended_monitor,
             "account-tag" => &mut self.account_tag,
             "standard-replies" => &mut self.standard_replies,
+            "labeled-response" => &mut self.labeled_response,
+            "batch" => &mut self.batch,
             "cap-notify" => &mut self.cap_notify,
             _ => return false,
         };