Implement VERSION, ISON, and CHGHOST

  - VERSION: emit 351 with version + server name, followed by
    the same three-line 005 ISUPPORT burst we send on welcome.

  - ISON: reply with 303, listing only those of the requested
    targets that have a live client entry.

  - CHGHOST (oper-only): introduce a per-client :host field
    (defaulting to 'localhost' when unset) and update both
    client-prefix and nuh-for-nick to use it.  CHGHOST <target>
    <newuser> <newhost> mutates the target's :user :username
    and :host, replies 396 to the target itself, and broadcasts
    ':oldprefix CHGHOST newuser newhost' to peers in shared
    channels that negotiated the chghost cap.  Non-opers get
    481; missing params get 461; bad chars get 501.

  Was previously surfaced as gaps by the chat.papo.im
  integration suite; all three commands now respond with the
  RFC-mandated numerics.

1 files changed, 129 insertions, 4 deletions

diff --git a/src/papod.clj b/src/papod.clj
index 35b9b49..e89f7cc 100644
--- a/src/papod.clj
+++ b/src/papod.clj
@@ -765,8 +765,9 @@
   [client]
   (let [nick (or (:nick @client) "*")
         u    (:user @client)
-        user (or (:username u) nick)]
-    (str nick "!" user "@localhost")))
+        user (or (:username u) nick)
+        host (or (:host @client) "localhost")]
+    (str nick "!" user "@" host)))
 
 (defn- numeric-reply
   [client code & parts]
@@ -2578,8 +2579,9 @@
         (when-let [m (get @clients nick)]
           (when-let [c (some-> (:client-atom m) deref)]
             (let [u (:user c)
-                  ident (or (:username u) nick)]
-              (str nick "!" ident "@localhost")))))
+                  ident (or (:username u) nick)
+                  host  (or (:host c) "localhost")]
+              (str nick "!" ident "@" host)))))
       (str nick "!" nick "@localhost")))
 
 (defn- nick-mask-match?
@@ -5880,6 +5882,51 @@
         [(numeric-reply client "391"
            (str +server-name+ " :" (iso-time)))]
 
+        (= command "VERSION")
+        [(numeric-reply client "351"
+           (str +version+ " " +server-name+ " :papod"))
+         (numeric-reply client "005"
+           (str "ACCOUNTEXTBAN=a"
+                " AWAYLEN=200 BOT=B"
+                " CASEMAPPING=ascii"
+                " CHANLIMIT=#:100"
+                " CHANMODES=beI,k,l,Cnt"
+                " CHANNELLEN=64 CHANTYPES=#"
+                " ELIST= EXCEPTS=e"
+                " EXTBAN=~,am HOSTLEN=64"
+                " :are supported by this server"))
+         (numeric-reply client "005"
+           (str "INVEX=I KICKLEN=300"
+                " MAXLIST=b:50,e:50,I:50"
+                " MAXTARGETS=4 MODES=4"
+                " MONITOR=100 NETWORK=papod"
+                " NICKLEN=30 PREFIX=(ov)@+"
+                " STATUSMSG=@+"
+                " :are supported by this server"))
+         (numeric-reply client "005"
+           (str "TARGMAX=KICK:1,LIST:,WHOIS:1,PRIVMSG:4,NAMES:"
+                " TOPICLEN=390 USERLEN=18"
+                " UTF8ONLY WHOX"
+                " :are supported by this server"))]
+
+        (= command "ISON")
+        (let [{:keys [clients]} components
+              online (when clients
+                       (for [target params
+                             :when (and (string? target)
+                                        (seq target))
+                             :let [low (string/lower-case target)
+                                   m   (some
+                                        (fn [[k m]]
+                                          (when (= (string/lower-case k)
+                                                   low)
+                                            m))
+                                        @clients)]
+                             :when m]
+                         target))]
+          [(numeric-reply client "303"
+             (str ":" (string/join " " (or online []))))])
+
         (= command "OPER")
         (cond
           (< (count params) 2)
@@ -5962,6 +6009,84 @@
                   (deliver-to-client! (:w m) line)))
               [])))
 
+        ;; CHGHOST: oper-only, mutates target's user@host and
+        ;; broadcasts ":old-prefix CHGHOST newuser newhost" to
+        ;; peers in shared chans that negotiated the chghost cap.
+        (= command "CHGHOST")
+        (let [{:keys [clients channels]} components
+              target  (first params)
+              newuser (second params)
+              newhost (when (>= (count params) 3)
+                        (let [h (nth params 2)]
+                          (cond-> h
+                            (string/starts-with? h ":")
+                            (subs 1))))
+              nick    (client-target client)]
+          (cond
+            (< (count params) 3)
+            [(numeric-reply client "461"
+               "CHGHOST :Not enough parameters")]
+
+            (not (:oper? @client))
+            [(numeric-reply client "481"
+               (str ":Permission Denied- You're not"
+                    " an IRC operator"))]
+
+            (or (string/blank? newuser)
+                (string/blank? newhost)
+                (string/includes? newuser " ")
+                (string/includes? newhost " "))
+            [(numeric-reply client "501"
+               ":Invalid CHGHOST parameters")]
+
+            :else
+            (let [m (and clients (get @clients target))
+                  ca (when m (:client-atom m))]
+              (cond
+                (not ca)
+                [(numeric-reply client "401"
+                   (str target " :No such nick"))]
+
+                :else
+                (let [old-prefix
+                      (let [c     @ca
+                            tnick (or (:nick c) target)
+                            u     (:user c)
+                            ident (or (:username u) tnick)
+                            host  (or (:host c) "localhost")]
+                        (str tnick "!" ident "@" host))
+                      line (str ":" old-prefix
+                                " CHGHOST " newuser
+                                " " newhost)]
+                  (swap! ca (fn [s]
+                              (-> s
+                                  (assoc-in [:user :username]
+                                            newuser)
+                                  (assoc :host newhost))))
+                  ;; Notify the target itself.
+                  (deliver-to-client! (:w m) line)
+                  ;; Notify peers in shared channels that
+                  ;; negotiated chghost.
+                  (when (and clients channels)
+                    (let [seen (atom #{target})]
+                      (doseq [[ch members] @channels
+                              :when (contains? members target)
+                              mn members
+                              :when (not (contains? @seen mn))
+                              :let [pm (get @clients mn)
+                                    pca (:client-atom pm)
+                                    pcaps (or (some-> pca
+                                               deref :caps)
+                                              #{})]
+                              :when (and pm
+                                         (contains?
+                                          pcaps "chghost"))]
+                        (deliver-to-client! (:w pm) line)
+                        (swap! seen conj mn))))
+                  [(numeric-reply client "396"
+                     (str newuser "@" newhost
+                          " :is now your visible host"))])))))
+
         (or (= command "HELP") (= command "HELPOP"))
         (let [subject (or (first params) "*")
               nick    (client-target client)]