Fix getShareTag replacing data on the server (#3776) Closes #3682

src/main/java/net/minecraftforge/common/util/PacketUtil.java

@@ -0,0 +1,58 @@
+/*
+ * Minecraft Forge
+ * Copyright (c) 2016.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation version 2.1
+ * of the License.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+package net.minecraftforge.common.util;
+
+import net.minecraft.item.Item;
+import net.minecraft.item.ItemStack;
+import net.minecraft.nbt.NBTTagCompound;
+import net.minecraft.network.PacketBuffer;
+
+public class PacketUtil
+{
+    private PacketUtil() {}
+
+    /**
+     * Most ItemStack serialization is Server to Client, and must go through PacketBuffer.writeItemStack which uses Item.getNBTShareTag.
+     * One exception is items from the creative menu, which must be sent from Client to Server with their full NBT.
+     * <br/>
+     * This method matches PacketBuffer.writeItemStack but without the Item.getNBTShareTag patch.
+     * It is compatible with PacketBuffer.readItemStack.
+     */
+    public static void writeItemStackFromClientToServer(PacketBuffer buffer, ItemStack stack)
+    {
+        if (stack.isEmpty())
+        {
+            buffer.writeShort(-1);
+        }
+        else
+        {
+            buffer.writeShort(Item.getIdFromItem(stack.getItem()));
+            buffer.writeByte(stack.getCount());
+            buffer.writeShort(stack.getMetadata());
+            NBTTagCompound nbttagcompound = null;
+
+            if (stack.getItem().isDamageable() || stack.getItem().getShareTag())
+            {
+                nbttagcompound = stack.getTagCompound();
+            }
+
+            buffer.writeCompoundTag(nbttagcompound);
+        }
+    }
+}