From 696980367dd5e07bad1006fed4f4703520d1c17c Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Mon, 29 Jun 2020 15:41:29 -0400
Subject: [PATCH] fix #1161

---
 irc/channel.go  |  7 +++++++
 irc/handlers.go | 11 +++++++++--
 irc/server.go   | 20 --------------------
 3 files changed, 16 insertions(+), 22 deletions(-)

diff --git a/irc/channel.go b/irc/channel.go
index 99e1960c..f1057e1f 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -1460,3 +1460,10 @@ func (channel *Channel) Invite(invitee *Client, inviter *Client, rb *ResponseBuf
 		rb.Add(nil, inviter.server.name, RPL_AWAY, cnick, tnick, invitee.AwayMessage())
 	}
 }
+
+// data for RPL_LIST
+func (channel *Channel) listData() (memberCount int, name, topic string) {
+	channel.stateMutex.RLock()
+	defer channel.stateMutex.RUnlock()
+	return len(channel.members), channel.name, channel.topic
+}
diff --git a/irc/handlers.go b/irc/handlers.go
index 64b271f6..fc8d0d3d 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -1530,6 +1530,13 @@ func listHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 		}
 	}
 
+	nick := client.Nick()
+	rplList := func(channel *Channel) {
+		if members, name, topic := channel.listData(); members != 0 {
+			rb.Add(nil, client.server.name, RPL_LIST, nick, name, strconv.Itoa(members), topic)
+		}
+	}
+
 	clientIsOp := client.HasMode(modes.Operator)
 	if len(channels) == 0 {
 		for _, channel := range server.channels.Channels() {
@@ -1537,7 +1544,7 @@ func listHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 				continue
 			}
 			if matcher.Matches(channel) {
-				client.RplList(channel, rb)
+				rplList(channel)
 			}
 		}
 	} else {
@@ -1555,7 +1562,7 @@ func listHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Resp
 				continue
 			}
 			if matcher.Matches(channel) {
-				client.RplList(channel, rb)
+				rplList(channel)
 			}
 		}
 	}
diff --git a/irc/server.go b/irc/server.go
index 98725553..577959e1 100644
--- a/irc/server.go
+++ b/irc/server.go
@@ -967,26 +967,6 @@ func (matcher *elistMatcher) Matches(channel *Channel) bool {
 	return true
 }
 
-// RplList returns the RPL_LIST numeric for the given channel.
-func (target *Client) RplList(channel *Channel, rb *ResponseBuffer) {
-	// get the correct number of channel members
-	var memberCount int
-	if target.HasMode(modes.Operator) || channel.hasClient(target) {
-		memberCount = len(channel.Members())
-	} else {
-		for _, member := range channel.Members() {
-			if !member.HasMode(modes.Invisible) {
-				memberCount++
-			}
-		}
-	}
-
-	// #704: some channels are kept around even with no members
-	if memberCount != 0 {
-		rb.Add(nil, target.server.name, RPL_LIST, target.nick, channel.name, strconv.Itoa(memberCount), channel.topic)
-	}
-}
-
 var (
 	infoString1 = strings.Split(`      ▄▄▄   ▄▄▄·  ▄▄ •        ▐ ▄
 ▪     ▀▄ █·▐█ ▀█ ▐█ ▀ ▪▪     •█▌▐█▪