From d111fce37b97bf6b1d24d1a444efe0371dbafe2e Mon Sep 17 00:00:00 2001
From: Vankka <vankka.main@gmail.com>
Date: Thu, 7 Sep 2023 17:41:50 +0300
Subject: [PATCH] Add filtering for which control characters can be sent to
 Minecraft, add removal of line break spam to default config

---
 .../config/main/channels/DiscordToMinecraftChatConfig.java  | 4 +++-
 .../messageforwarding/discord/DiscordChatMessageModule.java | 6 ++++++
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/common/src/main/java/com/discordsrv/common/config/main/channels/DiscordToMinecraftChatConfig.java b/common/src/main/java/com/discordsrv/common/config/main/channels/DiscordToMinecraftChatConfig.java
index 916bd2e9..d49cf39d 100644
--- a/common/src/main/java/com/discordsrv/common/config/main/channels/DiscordToMinecraftChatConfig.java
+++ b/common/src/main/java/com/discordsrv/common/config/main/channels/DiscordToMinecraftChatConfig.java
@@ -51,7 +51,9 @@ public class DiscordToMinecraftChatConfig {
     // TODO: more info on regex pairs (String#replaceAll)
     @Comment("Regex filters for Discord message contents (this is the %message% part of the \"format\" option)")
     @Untranslated(Untranslated.Type.VALUE)
-    public Map<Pattern, String> contentRegexFilters = new LinkedHashMap<>();
+    public Map<Pattern, String> contentRegexFilters = new LinkedHashMap<Pattern, String>() {{
+        put(Pattern.compile("\\n{2,}"), "\n");
+    }};
 
     @Comment("Users, bots, roles and webhooks to ignore")
     public DiscordIgnoresConfig ignores = new DiscordIgnoresConfig();
diff --git a/common/src/main/java/com/discordsrv/common/messageforwarding/discord/DiscordChatMessageModule.java b/common/src/main/java/com/discordsrv/common/messageforwarding/discord/DiscordChatMessageModule.java
index eeaaa80c..46cfc7b5 100644
--- a/common/src/main/java/com/discordsrv/common/messageforwarding/discord/DiscordChatMessageModule.java
+++ b/common/src/main/java/com/discordsrv/common/messageforwarding/discord/DiscordChatMessageModule.java
@@ -52,9 +52,14 @@ import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ScheduledFuture;
+import java.util.regex.Pattern;
 
 public class DiscordChatMessageModule extends AbstractModule<DiscordSRV> {
 
+    // Filter for ASCII control characters which have no use being displayed, but might be misinterpreted somewhere
+    // Notably this excludes, 0x09 HT (\t), 0x0A LF (\n), 0x0B VT (\v) and 0x0D CR (\r) (which may be used for text formatting)
+    private static final Pattern ASCII_CONTROL_FILTER = Pattern.compile("[\\u0000-\\u0008\\u000C\\u000E-\\u001F\\u007F]");
+
     private final Map<String, MessageSend> sends = new ConcurrentHashMap<>();
 
     public DiscordChatMessageModule(DiscordSRV discordSRV) {
@@ -182,6 +187,7 @@ public class DiscordChatMessageModule extends AbstractModule<DiscordSRV> {
         }
 
         Placeholders message = new Placeholders(event.getContent());
+        message.replaceAll(ASCII_CONTROL_FILTER, "");
         chatConfig.contentRegexFilters.forEach(message::replaceAll);
 
         Component messageComponent = DiscordSRVMinecraftRenderer.getWithContext(guild, chatConfig, () ->