Limit chat message size to 8192 bytes

diff --git a/hotline/transaction_handlers.go b/hotline/transaction_handlers.go
index 718dd599bea8cb6997dbd857214030c1fc9141ce..271f3085d07b683f2225fe88c992beda028b03d9 100644 (file)
--- a/hotline/transaction_handlers.go
+++ b/hotline/transaction_handlers.go
@@ -67,14 +67,18 @@ var TransactionHandlers = map[TranType]HandlerFunc{
        TranDownloadBanner:     HandleDownloadBanner,
 }
 
+// The total size of a chat message data field is 8192 bytes.
+const chatMsgLimit = 8192
+
 func HandleChatSend(cc *ClientConn, t *Transaction) (res []Transaction) {
        if !cc.Authorize(accessSendChat) {
                return cc.NewErrReply(t, "You are not allowed to participate in chat.")
        }
 
        // Truncate long usernames
-       trunc := fmt.Sprintf("%13s", cc.UserName)
-       formattedMsg := fmt.Sprintf("\r%.14s:  %s", trunc, t.GetField(FieldData).Data)
+       // %13.13s: This means a string that is right-aligned in a field of 13 characters.
+       // If the string is longer than 13 characters, it will be truncated to 13 characters.
+       formattedMsg := fmt.Sprintf("\r%13.13s:  %s", cc.UserName, t.GetField(FieldData).Data)
 
        // By holding the option key, Hotline chat allows users to send /me formatted messages like:
        // *** Halcyon does stuff
@@ -84,6 +88,9 @@ func HandleChatSend(cc *ClientConn, t *Transaction) (res []Transaction) {
                formattedMsg = fmt.Sprintf("\r*** %s %s", cc.UserName, t.GetField(FieldData).Data)
        }
 
+       // Truncate the message to the limit.  This does not handle the edge case of a string ending on multibyte character.
+       formattedMsg = formattedMsg[:min(len(formattedMsg), chatMsgLimit)]
+
        // The ChatID field is used to identify messages as belonging to a private chat.
        // All clients *except* Frogblast omit this field for public chat, but Frogblast sends a value of 00 00 00 00.
        chatID := t.GetField(FieldChatID).Data