@@ -212,25 +212,9 @@ func FmtWebsocketCloseMsg(format string, vars ...any) string {
212212// Cap msg length at 123 bytes. nhooyr/websocket only allows close messages
213213// of this length.
214214if len (msg )> websocketCloseMaxLen {
215- // truncateString safely truncates a string to a maximum size of byteLen. It
216- // writes whole runes until a single rune would increase the string size above
217- // byteLen.
218- truncateString := func (str string ,byteLen int )string {
219- builder := strings.Builder {}
220- builder .Grow (byteLen )
221-
222- for _ ,char := range str {
223- if builder .Len ()+ len (string (char ))> byteLen {
224- break
225- }
226-
227- _ ,_ = builder .WriteRune (char )
228- }
229-
230- return builder .String ()
231- }
232-
233- return truncateString (msg ,websocketCloseMaxLen )
215+ // Trim the string to 123 bytes. If we accidentally cut in the middle of
216+ // a UTF-8 character, remove it from the string.
217+ return strings .ToValidUTF8 (string (msg [123 ]),"" )
234218}
235219
236220return msg