From e84793d7ee397b5ceb0cbaae7e8ddd36700bd327 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Mon, 22 May 2023 12:29:55 -0400
Subject: [PATCH] fix #2063

In #2058 we introduced two bugs:

* A nil dereference when an outside user attempts to speak
* Ordinary copy of a modes.ModeSet (which should only be accessed via atomics)

This fixes both issues.
---
 irc/channel.go | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/irc/channel.go b/irc/channel.go
index 258d3568..d8c5606f 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -1228,20 +1228,26 @@ func (channel *Channel) CanSpeak(client *Client) (bool, modes.Mode) {
 	channel.stateMutex.RLock()
 	memberData, hasClient := channel.members[client]
 	channel.stateMutex.RUnlock()
-	clientModes := memberData.modes
+
+	highestMode := func() modes.Mode {
+		if !hasClient {
+			return modes.Mode(0)
+		}
+		return memberData.modes.HighestChannelUserMode()
+	}
 
 	if !hasClient && channel.flags.HasMode(modes.NoOutside) {
 		// TODO: enforce regular +b bans on -n channels?
 		return false, modes.NoOutside
 	}
-	if channel.isMuted(client) && clientModes.HighestChannelUserMode() == modes.Mode(0) {
+	if channel.isMuted(client) && highestMode() == modes.Mode(0) {
 		return false, modes.BanMask
 	}
-	if channel.flags.HasMode(modes.Moderated) && clientModes.HighestChannelUserMode() == modes.Mode(0) {
+	if channel.flags.HasMode(modes.Moderated) && highestMode() == modes.Mode(0) {
 		return false, modes.Moderated
 	}
 	if channel.flags.HasMode(modes.RegisteredOnlySpeak) && client.Account() == "" &&
-		clientModes.HighestChannelUserMode() == modes.Mode(0) {
+		highestMode() == modes.Mode(0) {
 		return false, modes.RegisteredOnlySpeak
 	}
 	return true, modes.Mode('?')