Attempt to build some protocol negotiation, and fix packet1login so that the dimension is a short, matching packet9respawn

client/cpw/mods/fml/client/FMLClientHandler.java

@@ -411,8 +411,16 @@ public class FMLClientHandler implements IFMLSidedHandler
     }
 
     @Override
-    public void setCompatibilityLevel(NetHandler netHandler, byte compatibilityLevel)
+    public void setClientCompatibilityLevel(byte compatibilityLevel)
     {
-        ((NetClientHandler)netHandler).setConnectionCompatibilityLevel(compatibilityLevel);
+        NetClientHandler.setConnectionCompatibilityLevel(compatibilityLevel);
+    }
+
+    @Override
+    public byte getClientCompatibilityLevel()
+    {
+        System.out.printf("Client Compatibility %d\n", NetClientHandler.getConnectionCompatibilityLevel());
+        Thread.dumpStack();
+        return NetClientHandler.getConnectionCompatibilityLevel();
     }
 }

common/cpw/mods/fml/common/IFMLSidedHandler.java

@@ -38,5 +38,7 @@ public interface IFMLSidedHandler
 
     void handleTinyPacket(NetHandler handler, Packet131MapData mapData);
 
-    void setCompatibilityLevel(NetHandler netHandler, byte compatibilityLevel);
+    void setClientCompatibilityLevel(byte compatibilityLevel);
+
+    byte getClientCompatibilityLevel();
 }

common/cpw/mods/fml/common/network/FMLNetworkHandler.java

@@ -218,6 +218,8 @@ public class FMLNetworkHandler
 
     public static Packet1Login getFMLFakeLoginPacket()
     {
+        // Always reset compat to zero before sending our fake packet
+        FMLCommonHandler.instance().getSidedDelegate().setClientCompatibilityLevel((byte) 0);
         Packet1Login fake = new Packet1Login();
         // Hash FML using a simple function
         fake.field_73561_a = FML_HASH;
@@ -412,4 +414,9 @@ public class FMLNetworkHandler
     {
         return PROTOCOL_VERSION;
     }
+
+    public static boolean vanillaLoginPacketCompatibility()
+    {
+        return FMLCommonHandler.instance().getSidedDelegate().getClientCompatibilityLevel() == 0;
+    }
 }

common/cpw/mods/fml/common/network/ModListRequestPacket.java

@@ -61,7 +61,7 @@ public class ModListRequestPacket extends FMLPacket
         {
             compatibilityLevel = in.readByte();
         }
-        catch (IllegalArgumentException e)
+        catch (IllegalStateException e)
         {
             FMLLog.fine("No compatibility byte found - the server is too old");
         }
@@ -110,16 +110,9 @@ public class ModListRequestPacket extends FMLPacket
             }
         }
 
-        if (compatibilityLevel != 0)
-        {
-            FMLLog.fine("The server has compatibility level %d", compatibilityLevel);
-            FMLCommonHandler.instance().getSidedDelegate().setCompatibilityLevel(netHandler, compatibilityLevel);
-        }
-        Packet250CustomPayload pkt = new Packet250CustomPayload();
-        pkt.field_73630_a = "FML";
-        pkt.field_73629_c = FMLPacket.makePacket(MOD_LIST_RESPONSE, modVersions, missingMods);
-        pkt.field_73628_b = pkt.field_73629_c.length;
+        FMLLog.fine("The server has compatibility level %d", compatibilityLevel);
+        FMLCommonHandler.instance().getSidedDelegate().setClientCompatibilityLevel(compatibilityLevel);
 
-        mgr.func_74429_a(pkt);
+        mgr.func_74429_a(PacketDispatcher.getPacket("FML", FMLPacket.makePacket(MOD_LIST_RESPONSE, modVersions, missingMods)));
     }
 }

common/cpw/mods/fml/server/FMLServerHandler.java

@@ -16,6 +16,7 @@ import java.util.List;
 
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.src.Entity;
+import net.minecraft.src.NetClientHandler;
 import net.minecraft.src.NetHandler;
 import net.minecraft.src.Packet;
 import net.minecraft.src.Packet131MapData;
@@ -164,8 +165,15 @@ public class FMLServerHandler implements IFMLSidedHandler
         // NOOP on server
     }
     @Override
-    public void setCompatibilityLevel(NetHandler netHandler, byte compatibilityLevel)
+    public void setClientCompatibilityLevel(byte compatibilityLevel)
     {
         // NOOP on server
     }
+    @Override
+    public byte getClientCompatibilityLevel()
+    {
+        System.out.printf("Server Compatibility %d\n", 0);
+        Thread.dumpStack();
+        return 0;
+    }
 }

patches/common/net/minecraft/src/Packet1Login.java.patch

@@ -0,0 +1,72 @@
+--- ../src-base/common/net/minecraft/src/Packet1Login.java
++++ ../src-work/common/net/minecraft/src/Packet1Login.java
+@@ -3,6 +3,8 @@
+ import java.io.DataInputStream;
+ import java.io.DataOutputStream;
+ import java.io.IOException;
++
++import cpw.mods.fml.common.network.FMLNetworkHandler;
+ 
+ public class Packet1Login extends Packet
+ {
+@@ -15,7 +17,11 @@
+     public byte field_73556_g;
+     public byte field_73562_h;
+ 
+-    public Packet1Login() {}
++    private boolean vanillaCompatible;
++
++    public Packet1Login() {
++        this.vanillaCompatible = FMLNetworkHandler.vanillaLoginPacketCompatibility();
++    }
+ 
+     public Packet1Login(int p_i3327_1_, WorldType p_i3327_2_, EnumGameType p_i3327_3_, boolean p_i3327_4_, int p_i3327_5_, int p_i3327_6_, int p_i3327_7_, int p_i3327_8_)
+     {
+@@ -27,6 +33,7 @@
+         this.field_73556_g = (byte)p_i3327_7_;
+         this.field_73562_h = (byte)p_i3327_8_;
+         this.field_73560_c = p_i3327_4_;
++        this.vanillaCompatible = false;
+     }
+ 
+     public void func_73267_a(DataInputStream p_73267_1_) throws IOException
+@@ -44,7 +51,14 @@
+         this.field_73560_c = (var3 & 8) == 8;
+         int var4 = var3 & -9;
+         this.field_73557_d = EnumGameType.func_77146_a(var4);
+-        this.field_73558_e = p_73267_1_.readByte();
++        if (vanillaCompatible)
++        {
++            this.field_73558_e = p_73267_1_.readByte();
++        }
++        else
++        {
++            this.field_73558_e = p_73267_1_.readShort();
++        }
+         this.field_73555_f = p_73267_1_.readByte();
+         this.field_73556_g = p_73267_1_.readByte();
+         this.field_73562_h = p_73267_1_.readByte();
+@@ -62,7 +76,14 @@
+         }
+ 
+         p_73273_1_.writeByte(var2);
+-        p_73273_1_.writeByte(this.field_73558_e);
++        if (vanillaCompatible)
++        {
++            p_73273_1_.writeByte(this.field_73558_e);
++        }
++        else
++        {
++            p_73273_1_.writeShort(this.field_73558_e);
++        }
+         p_73273_1_.writeByte(this.field_73555_f);
+         p_73273_1_.writeByte(this.field_73556_g);
+         p_73273_1_.writeByte(this.field_73562_h);
+@@ -82,6 +103,6 @@
+             var1 = this.field_73559_b.func_77127_a().length();
+         }
+ 
+-        return 6 + 2 * var1 + 4 + 4 + 1 + 1 + 1;
++        return 6 + 2 * var1 + 4 + 4 + 1 + 1 + 1 + (vanillaCompatible ? 0 : 1);
+     }
+ }

patches/minecraft/net/minecraft/src/NetClientHandler.java.patch

@@ -13,7 +13,7 @@
      public int field_72556_d = 20;
      Random field_72557_e = new Random();
  
-+    public int connectionCompatibilityLevel;
++    private static byte connectionCompatibilityLevel;
 +
      public NetClientHandler(Minecraft p_i3103_1_, String p_i3103_2_, int p_i3103_3_) throws IOException
      {
@@ -91,12 +91,12 @@
 +        return field_72563_h.field_71439_g;
 +    }
 +
-+    public void setConnectionCompatibilityLevel(int connectionCompatibilityLevel)
++    public static void setConnectionCompatibilityLevel(byte connectionCompatibilityLevel)
 +    {
-+        this.connectionCompatibilityLevel = connectionCompatibilityLevel;
++        NetClientHandler.connectionCompatibilityLevel = connectionCompatibilityLevel;
 +    }
 +
-+    public int getConnectionCompatibilityLevel()
++    public static byte getConnectionCompatibilityLevel()
 +    {
 +        return connectionCompatibilityLevel;
 +    }