From e447c61c7381dd5dc2f08f33e0ae84b4c1f3ac52 Mon Sep 17 00:00:00 2001
From: Shivaram Lingamneni <slingamn@cs.stanford.edu>
Date: Thu, 18 Mar 2021 03:49:12 -0400
Subject: [PATCH] fix #1596

All truncation must be made UTF8-safe.
---
 irc/channel.go  | 12 ++++--------
 irc/handlers.go |  9 ++++-----
 2 files changed, 8 insertions(+), 13 deletions(-)

diff --git a/irc/channel.go b/irc/channel.go
index 21326977..4b341e3e 100644
--- a/irc/channel.go
+++ b/irc/channel.go
@@ -13,6 +13,8 @@ import (
 
 	"sync"
 
+	"github.com/goshuirc/irc-go/ircutils"
+
 	"github.com/oragono/oragono/irc/caps"
 	"github.com/oragono/oragono/irc/history"
 	"github.com/oragono/oragono/irc/modes"
@@ -1259,10 +1261,7 @@ func (channel *Channel) SetTopic(client *Client, topic string, rb *ResponseBuffe
 		return
 	}
 
-	topicLimit := client.server.Config().Limits.TopicLen
-	if len(topic) > topicLimit {
-		topic = topic[:topicLimit]
-	}
+	topic = ircutils.TruncateUTF8Safe(topic, client.server.Config().Limits.TopicLen)
 
 	channel.stateMutex.Lock()
 	chname := channel.name
@@ -1520,10 +1519,7 @@ func (channel *Channel) Kick(client *Client, target *Client, comment string, rb
 		return
 	}
 
-	kicklimit := channel.server.Config().Limits.KickLen
-	if len(comment) > kicklimit {
-		comment = comment[:kicklimit]
-	}
+	comment = ircutils.TruncateUTF8Safe(comment, channel.server.Config().Limits.KickLen)
 
 	message := utils.MakeMessage(comment)
 	details := client.Details()
diff --git a/irc/handlers.go b/irc/handlers.go
index b910e1f1..95a99a1a 100644
--- a/irc/handlers.go
+++ b/irc/handlers.go
@@ -22,6 +22,9 @@ import (
 
 	"github.com/goshuirc/irc-go/ircfmt"
 	"github.com/goshuirc/irc-go/ircmsg"
+	"github.com/goshuirc/irc-go/ircutils"
+	"golang.org/x/crypto/bcrypt"
+
 	"github.com/oragono/oragono/irc/caps"
 	"github.com/oragono/oragono/irc/custime"
 	"github.com/oragono/oragono/irc/flatip"
@@ -30,7 +33,6 @@ import (
 	"github.com/oragono/oragono/irc/modes"
 	"github.com/oragono/oragono/irc/sno"
 	"github.com/oragono/oragono/irc/utils"
-	"golang.org/x/crypto/bcrypt"
 )
 
 // helper function to parse ACC callbacks, e.g., mailto:person@example.com, tel:16505551234
@@ -346,10 +348,7 @@ func awayHandler(server *Server, client *Client, msg ircmsg.Message, rb *Respons
 	if len(msg.Params) > 0 {
 		isAway = true
 		awayMessage = msg.Params[0]
-		awayLen := server.Config().Limits.AwayLen
-		if len(awayMessage) > awayLen {
-			awayMessage = awayMessage[:awayLen]
-		}
+		awayMessage = ircutils.TruncateUTF8Safe(awayMessage, server.Config().Limits.AwayLen)
 	}
 
 	rb.session.SetAway(awayMessage)