add cringe USERHOST command

lib/server/connection.ml

@@ -61,7 +61,8 @@ let reply t (num, params) =
     | None -> "*"
   in
   let always_trailing = match num with
-    | "256" | "301" | "311" | "312" | "314" | "319" | "332" | "353" -> true
+    | "256" | "301" | "302" | "311" | "312" | "314" | "319" | "332"
+    | "353" -> true
     | _ -> false
   in
   Outbox.send t.outbox
@@ -660,6 +661,28 @@ let on_msg_whowas t nick count =
   list_whowas t nick limit;
   Ok ()
 
+let on_msg_userhost t nicks =
+  let* _me = require_registered t in
+  let results =
+    List.filter_map
+      (fun nick ->
+         try
+           let user = match name_type nick with
+             | `nick -> Router.find_user t.router nick
+             | `chan | `invalid -> raise Not_found
+           in
+           let isaway = match User.away user with
+             | Some _ -> '-'
+             | None -> '+'
+           in
+           Some (Fmt.str "%s=%c%s" (User.nick user) isaway user.userinfo.hostname)
+         with Not_found ->
+           None)
+      nicks
+  in
+  reply t ("302", [String.concat " " results]);
+  Ok ()
+
 
 (* welcome and quit *)
 
@@ -916,12 +939,12 @@ let dispatch t = function
   | "WHOWAS", ([] | "" :: _) -> Error nonicknamegiven
   | "WHOWAS", [nick] -> on_msg_whowas t nick ""
   | "WHOWAS", nick :: count :: _ -> on_msg_whowas t nick count
+  | "USERHOST", nicks -> on_msg_userhost t nicks
   | ("USER" | "JOIN" | "NAMES" | "PART" | "KICK" | "MODE" | "WHO") as cmd, _ ->
     Error (needmoreparams cmd)
   | ("CONNECT" | "KILL" | "REHASH" | "RESTART" | "STATS" | "SQUIT" | "WALLOPS"), _ ->
     Error noprivileges
   (* TODO: "LIST" *)
-  (* TODO: "USERHOST" *)
   | cmd, _ ->
     Error (unknowncommand cmd)