FML expands S3F to support payloads up to 2 megs in size. Should be transparent

fml/patches/minecraft/net/minecraft/network/play/server/S3FPacketCustomPayload.java.patch

@@ -0,0 +1,37 @@
+--- ../src-base/minecraft/net/minecraft/network/play/server/S3FPacketCustomPayload.java
++++ ../src-work/minecraft/net/minecraft/network/play/server/S3FPacketCustomPayload.java
+@@ -1,5 +1,6 @@
+ package net.minecraft.network.play.server;
+ 
++import cpw.mods.fml.common.network.ByteBufUtils;
+ import cpw.mods.fml.relauncher.Side;
+ import cpw.mods.fml.relauncher.SideOnly;
+ import io.netty.buffer.ByteBuf;
+@@ -27,23 +28,23 @@
+         this.field_149172_a = p_i45190_1_;
+         this.field_149171_b = p_i45190_2_;
+ 
+-        if (p_i45190_2_.length >= 32767)
++        if (p_i45190_2_.length > 0x1ffff0)
+         {
+-            throw new IllegalArgumentException("Payload may not be larger than 32767 bytes");
++            throw new IllegalArgumentException("Payload may not be larger than 2097136 (0x1ffff0) bytes");
+         }
+     }
+ 
+     public void func_148837_a(PacketBuffer p_148837_1_) throws IOException
+     {
+         this.field_149172_a = p_148837_1_.func_150789_c(20);
+-        this.field_149171_b = new byte[p_148837_1_.readUnsignedShort()];
++        this.field_149171_b = new byte[ByteBufUtils.readVarShort(p_148837_1_)];
+         p_148837_1_.readBytes(this.field_149171_b);
+     }
+ 
+     public void func_148840_b(PacketBuffer p_148840_1_) throws IOException
+     {
+         p_148840_1_.func_150785_a(this.field_149172_a);
+-        p_148840_1_.writeShort(this.field_149171_b.length);
++        ByteBufUtils.writeVarShort(p_148840_1_, this.field_149171_b.length);
+         p_148840_1_.writeBytes(this.field_149171_b);
+     }
+ 

fml/src/main/java/cpw/mods/fml/common/network/ByteBufUtils.java

@@ -55,7 +55,38 @@ public class ByteBufUtils {
 
         return i;
     }
+    /**
+     * An extended length short. Used by custom payload packets to extend size.
+     *
+     * @param buf
+     * @return
+     */
+    public static int readVarShort(ByteBuf buf)
+    {
+        int low = buf.readUnsignedShort();
+        int high = 0;
+        if ((low & 0x8000) != 0)
+        {
+            low = low & 0x7FFF;
+            high = buf.readUnsignedByte();
+        }
+        return ((high & 0xFF) << 15) | low;
+    }
 
+    public static void writeVarShort(ByteBuf buf, int toWrite)
+    {
+        int low = toWrite & 0x7FFF;
+        int high = ( toWrite & 0x7F8000 ) >> 15;
+        if (high != 0)
+        {
+            low = low | 0x8000;
+        }
+        buf.writeShort(low);
+        if (high != 0)
+        {
+            buf.writeByte(high);
+        }
+    }
     /**
      * Write an integer to the buffer using variable length encoding. The maxSize constrains
      * how many bytes (and therefore the maximum number) that will be written.

fml/src/test/java/cpw/mods/fml/test/TestNetStuff.java

@@ -120,4 +120,55 @@ public class TestNetStuff {
         assertArrayEquals("String repeat bytes", new byte[] {-112, 3, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 116, 101, 115, 116, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, buf.array());
     }
 
+
+    @Test
+    public void testVarShort()
+    {
+        ByteBuf buf = Unpooled.buffer(3,3);
+        ByteBufUtils.writeVarShort(buf, 32766);
+        assertArrayEquals("Two byte short written", new byte[] { 127, -2, 0}, buf.array());
+        assertEquals("Two byte short written", 2, buf.readableBytes());
+
+        buf.clear();
+        buf.writeZero(3);
+        buf.clear();
+
+        buf.writeShort(32766);
+        assertArrayEquals("Two byte short written", new byte[] { 127, -2, 0}, buf.array());
+        int val = ByteBufUtils.readVarShort(buf);
+
+        assertEquals("Two byte short read correctly", 32766, val);
+
+        buf.clear();
+        buf.writeZero(3);
+        buf.clear();
+
+        ByteBufUtils.writeVarShort(buf, 32768);
+        assertArrayEquals("Three byte short written", new byte[] { -128, 0, 1}, buf.array());
+        assertEquals("Three byte short written", 3, buf.readableBytes());
+
+        buf.clear();
+        buf.writeZero(3);
+        buf.clear();
+        buf.writeShort(-32768);
+        buf.writeByte(1);
+        val = ByteBufUtils.readVarShort(buf);
+        assertEquals("Three byte short read correctly", 32768, val);
+
+        buf.clear();
+        buf.writeZero(3);
+        buf.clear();
+
+        ByteBufUtils.writeVarShort(buf, 8388607);
+        assertArrayEquals("Three byte short written", new byte[] { -1, -1, -1}, buf.array());
+        assertEquals("Three byte short written", 3, buf.readableBytes());
+
+        buf.clear();
+        buf.writeZero(3);
+        buf.clear();
+        buf.writeShort(-1);
+        buf.writeByte(-1);
+        val = ByteBufUtils.readVarShort(buf);
+        assertEquals("Three byte short read correctly", 8388607, val);
+    }
 }