diff --git a/lib/server/connection.ml b/lib/server/connection.ml
index ab4f589..e403c53 100644
--- a/lib/server/connection.ml
+++ b/lib/server/connection.ml
@@ -88,6 +88,7 @@ let on_msg_user t username modestr realname =
 (* > messages and channels *)
 
 let on_msg_privmsg t tgt txt _ =
+  (* TODO: comma-separated list of targets *)
   let msg = Irc.Msg.make "PRIVMSG" [tgt; txt] ~always_trailing:true in
   let dst =
     try
@@ -100,7 +101,10 @@ let on_msg_privmsg t tgt txt _ =
   match dst with
   | `not_found -> `nosuchnick tgt
   | (`to_user _ | `to_chan _) as dst ->
-    (* TODO: check if allowed to send to channel *)
+    (* TODO: check if user is away *)
+    (* TODO: check if channel is +n and user is not a member *)
+    (* TODO: check if channel is +m and user is not priviledged *)
+    (* TODO: check if channel is +b <user> *)
     Router.relay msg ~from:t.user dst;
     `ok
 
@@ -113,6 +117,7 @@ let list_names chan =
   `names ("@", Chan.name chan, names)
 
 let on_msg_names t name _ =
+  (* TODO: comma-separated list of channels *)
   match Irc.name_type name with
   | `nick | `invalid ->
     if name = "" then `needmoreparams else `nosuchchannel name
@@ -120,12 +125,15 @@ let on_msg_names t name _ =
     let chan = try Some (Router.find_chan t.router name)
       with Not_found -> None
     in
-    (* TODO: check if allowed to list names *)
+    (* TODO: check if channel is +s and user is not a member *)
+    (* TODO: check if user in channel is +i and user is not a member *)
     match chan with
     | None -> `nosuchchannel name
     | Some chan -> list_names chan
 
 let on_msg_join t name _ =
+  (* TODO: comma-separated list of channels *)
+  (* TODO: "0" parameter means part from all channels *)
   match Irc.name_type name with
   | `nick | `invalid ->
     if name = "" then `needmoreparams else `nosuchchannel name
@@ -134,13 +142,14 @@ let on_msg_join t name _ =
       with Not_found ->
         Logs.debug (fun m -> m "making new channel %S" name);
         let chan = Chan.make ~name in
-        (* TODO: op user after joining *)
+        (* TODO: make user +o *)
         Chan.register chan ~router:t.router;
         chan
     in
     if Chan.is_member chan t.user then
       `ok
     else begin
+      (* TODO: check if channel is +k, get associated key from parameters *)
       Chan.join chan t.user;
       let msg = Irc.Msg.make "JOIN" [name] in
       Router.relay msg ~from:t.user `to_self;
@@ -149,6 +158,8 @@ let on_msg_join t name _ =
     end
 
 let on_msg_part t name _ =
+  (* TODO: comma-separated list of channels *)
+  (* TODO: part reason *)
   match Irc.name_type name with
   | `nick | `invalid ->
     if name = "" then `needmoreparams else `nosuchchannel name
@@ -179,6 +190,9 @@ let on_msg_part t name = require_registered t (on_msg_part t name)
 (* > misc *)
 
 let on_msg_quit t reason =
+  (* TODO: '''When connections are terminated by a client-sent QUIT command, servers
+     SHOULD prepend <reason> with the ASCII string "Quit: " when sending QUIT messages to
+     other clients''' *)
   let reason = String.concat " " reason in
   shutdown t ~reason;
   `ok