Add method to send fake sign updates to players. Adds BUKKIT-2300

By: Patrick Seidel <psycowithespn1@aim.com>

paper-server/src/main/java/org/bukkit/craftbukkit/block/CraftSign.java

@@ -35,16 +35,24 @@ public class CraftSign extends CraftBlockState implements Sign {
         boolean result = super.update(force, applyPhysics);
 
         if (result) {
-            for(int i = 0; i < 4; i++) {
-                if(lines[i] != null) {
-                    sign.lines[i] = lines[i];
-                } else {
-                    sign.lines[i] = "";
-                }
-            }
+            sign.lines = sanitizeLines(lines);
             sign.update();
         }
 
         return result;
     }
+
+    public static String[] sanitizeLines(String[] lines) {
+        String[] astring = new String[4];
+
+        for (int i = 0; i < 4; i++) {
+            if (i < lines.length && lines[i] != null) {
+                astring[i] = lines[i];
+            } else {
+                astring[i] = "";
+            }
+        }
+
+        return TileEntitySign.sanitizeLines(astring);
+    }
 }

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -31,6 +31,7 @@ import org.bukkit.configuration.serialization.DelegateDeserialization;
 import org.bukkit.conversations.Conversation;
 import org.bukkit.conversations.ConversationAbandonedEvent;
 import org.bukkit.conversations.ManuallyAbandonedConversationCanceller;
+import org.bukkit.craftbukkit.block.CraftSign;
 import org.bukkit.craftbukkit.conversations.ConversationTracker;
 import org.bukkit.craftbukkit.CraftEffect;
 import org.bukkit.craftbukkit.CraftOfflinePlayer;
@@ -368,6 +369,27 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         getHandle().playerConnection.sendPacket(packet);
     }
 
+    @Override
+    public void sendSignChange(Location loc, String[] lines) {
+        if (getHandle().playerConnection == null) {
+            return;
+        }
+
+        if (lines == null) {
+            lines = new String[4];
+        }
+
+        Validate.notNull(loc, "Location can not be null");
+        if (lines.length < 4) {
+            throw new IllegalArgumentException("Must have at least 4 lines");
+        }
+
+        // Limit to 15 chars per line and set null lines to blank
+        String[] astring = CraftSign.sanitizeLines(lines);
+
+        getHandle().playerConnection.sendPacket(new PacketPlayOutUpdateSign(loc.getBlockX(), loc.getBlockY(), loc.getBlockZ(), astring));
+    }
+
     @Override
     public boolean sendChunkChange(Location loc, int sx, int sy, int sz, byte[] data) {
         if (getHandle().playerConnection == null) return false;