Book Size Limits

Puts some limits on the size of books.

Spigot-Server-Patches/0410-Book-Size-Limits.patch

@@ -0,0 +1,59 @@
+From aa0ed5b528231c1be6efb064fbc79d4a4f5524c4 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Fri, 16 Nov 2018 23:08:50 -0500
+Subject: [PATCH] Book Size Limits
+
+Puts some limits on the size of books.
+
+diff --git a/src/main/java/com/destroystokyo/paper/PaperConfig.java b/src/main/java/com/destroystokyo/paper/PaperConfig.java
+index bc74ea2f09..ea18ba5880 100644
+--- a/src/main/java/com/destroystokyo/paper/PaperConfig.java
++++ b/src/main/java/com/destroystokyo/paper/PaperConfig.java
+@@ -458,4 +458,11 @@ public class PaperConfig {
+             velocitySecretKey = secret.getBytes(StandardCharsets.UTF_8);
+         }
+     }
++
++    public static int maxBookPageSize = 640;
++    public static double maxBookTotalSizeMultiplier = 0.9D;
++    private static void maxBookSize() {
++        maxBookPageSize = getInt("settings.book-size.page-max", maxBookPageSize);
++        maxBookTotalSizeMultiplier = getDouble("settings.book-size.total-multiplier", maxBookTotalSizeMultiplier);
++    }
+ }
+diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
+index 3427e95e60..c4136640d2 100644
+--- a/src/main/java/net/minecraft/server/PlayerConnection.java
++++ b/src/main/java/net/minecraft/server/PlayerConnection.java
+@@ -750,6 +750,28 @@ public class PlayerConnection implements PacketListenerPlayIn, ITickable {
+     }
+ 
+     public void a(PacketPlayInBEdit packetplayinbedit) {
++        // Paper start
++        ItemStack testStack = packetplayinbedit.b();
++        if (!server.isPrimaryThread() && !testStack.isEmpty() && testStack.getTag() != null) {
++            NBTTagList pageList = testStack.getTag().getList("pages", 8);
++            long byteTotal = 0;
++            int maxBookPageSize = com.destroystokyo.paper.PaperConfig.maxBookPageSize;
++            double multiplier = Math.max(0.3D, Math.min(1D, com.destroystokyo.paper.PaperConfig.maxBookTotalSizeMultiplier));
++            long byteAllowed = maxBookPageSize;
++            for (int i = 0; i < pageList.size(); ++i) {
++                String testString = pageList.getString(i);
++                int byteLength = testString.getBytes().length;
++                byteTotal += byteLength;
++                if (byteTotal > byteAllowed) {
++                    PlayerConnection.LOGGER.warn(this.player.getName() + " tried to send too large of a book. Book Size: " + byteTotal + " - Allowed:  "+ byteAllowed + " - Pages: " + pageList.size());
++                    minecraftServer.postToMainThread(() -> this.disconnect("Book too large!"));
++                    return;
++                }
++                byteAllowed += (maxBookPageSize * multiplier);
++                multiplier *= multiplier;
++            }
++        }
++        // Paper end
+         // CraftBukkit start
+         PlayerConnectionUtils.ensureMainThread(packetplayinbedit, this, this.player.getWorldServer());
+         if (this.lastBookTick + 20 > MinecraftServer.currentTick) {
+-- 
+2.19.1
+