Rsge

That's why I'm trying to update it so it does work. I don't think Vazkii will disable these checks as they have their security reasons. Also, it seems to be different on different servers/modpacks, as another 1.12.2-modpack I played didn't have this issue - at least not as bad as in the other pack. So I don't think this is necessarily a bug in Psi itself... - I'll report it regardless, if he still does 1.12.2-fixes...

Hi. I am trying to write a small coremod for my 1.12.2 private server to disable the "Moved wrongly" and maybe the "Moved too quickly" checks in NetHandlerPlayServer, as it is very buggy with Psi's Blink-spell, just teleports you back constantly. First of all, I know this is a security risk because of hacking, but as I said, it's a private server so I don't care about that. Second, I sadly don't have much experience in modding Minecraft and especially not in bytecode and that sort of stuff in Java. So I got most of the code from this post and just tried to update it for 1.12.2. But according to the printlns I added in analyzeClass the methods I need to patch (processVehicleMove and processPlayer) aren't even scanned through. So I don't know if I'm doing the scanning wrong or if there is something else. Everything else seems to work, the mod is loaded and is shown in the Mods-section as expected, so the error must be in this class. Any help would be appreciated. Thanks : ) package rsge.mods.blinkfixer.asm; import org.objectweb.asm.ClassReader; import org.objectweb.asm.ClassWriter; import org.objectweb.asm.Opcodes; import org.objectweb.asm.tree.AbstractInsnNode; import org.objectweb.asm.tree.ClassNode; import org.objectweb.asm.tree.InsnList; import org.objectweb.asm.tree.JumpInsnNode; import org.objectweb.asm.tree.LabelNode; import org.objectweb.asm.tree.LdcInsnNode; import org.objectweb.asm.tree.MethodNode; import net.minecraft.launchwrapper.IClassTransformer; /** * Removes the "Moved Wrongly" checks from {@link net.minecraft.network.NetHandlerPlayServer} * * @author Rsge */ public class NetHandlerPlayServerTransformer implements IClassTransformer { private static enum MovedWronglyState { FIND_LDC, FIND_DCMPL, FIND_IFLE, DONE } /** * Before: LDC2_W 0.0625 DCMPL IFLE <label> (code to execute if the value was greater) After: LDC2_W 0.0625 DCMPL IFLE <label> GOTO <same label> (code that * no longer ever gets executed) I leave the IFLE in just so the DCMPL result gets popped off the stack */ private boolean disableMovedWrongly(MethodNode node) { MovedWronglyState state = MovedWronglyState.FIND_LDC; InsnList insnList = node.instructions; AbstractInsnNode insn = insnList.getFirst(); AbstractInsnNode patchTarget = null; LabelNode gotoLabel = null; while (insn != null && state != MovedWronglyState.DONE) { switch (state) { case FIND_LDC: if (insn.getOpcode() == Opcodes.LDC) { Object value = ((LdcInsnNode) insn).cst; // 0.0625 is 1/16, which can be perfectly represented by a float (power of two denominator) if (value instanceof Double && ((Double) value).doubleValue() == 0.0625) { state = MovedWronglyState.FIND_DCMPL; } } break; case FIND_DCMPL: if (insn.getOpcode() == Opcodes.DCMPL) { state = MovedWronglyState.FIND_IFLE; } else { state = MovedWronglyState.FIND_LDC; } break; case FIND_IFLE: if (insn.getOpcode() == Opcodes.IFLE) { state = MovedWronglyState.DONE; gotoLabel = ((JumpInsnNode) insn).label; patchTarget = insn; } else { state = MovedWronglyState.FIND_LDC; } break; case DONE: break; default: break; } insn = insn.getNext(); } if (state == MovedWronglyState.DONE) { applyGotoPatch(insnList, gotoLabel, patchTarget); return true; } else { return false; } } /* ————————————————————————————————————————————————————— */ private static enum MovedTooQuicklyState { FIND_LDC, FIND_DCMPL, FIND_IFLE, DONE } /** * Before: LDC2_W 100.0 DCMPL IFLE <label> (code to execute if the value was greater) After: LDC2_W 100.0 DCMPL IFLE <label> GOTO <same label> (code that no * longer ever gets executed) As above, I leave the IFLE in so the DCMPL result gets popped off the stack */ private boolean disableMovedTooQuickly(MethodNode node) { MovedTooQuicklyState state = MovedTooQuicklyState.FIND_LDC; InsnList insnList = node.instructions; AbstractInsnNode insn = insnList.getFirst(); AbstractInsnNode patchTarget = null; LabelNode gotoLabel = null; while (insn != null && state != MovedTooQuicklyState.DONE) { switch (state) { case FIND_LDC: if (insn.getOpcode() == Opcodes.LDC) { Object value = ((LdcInsnNode) insn).cst; if (value instanceof Double && ((Double) value).doubleValue() == 100.0) { state = MovedTooQuicklyState.FIND_DCMPL; } } break; case FIND_DCMPL: if (insn.getOpcode() == Opcodes.DCMPL) { state = MovedTooQuicklyState.FIND_IFLE; } else { state = MovedTooQuicklyState.FIND_LDC; } break; case FIND_IFLE: if (insn.getOpcode() == Opcodes.IFLE) { state = MovedTooQuicklyState.DONE; gotoLabel = ((JumpInsnNode) insn).label; patchTarget = insn; } else { state = MovedTooQuicklyState.FIND_LDC; } break; case DONE: break; default: break; } insn = insn.getNext(); } if (state == MovedTooQuicklyState.DONE) { applyGotoPatch(insnList, gotoLabel, patchTarget); return true; } else { return false; } } /* ————————————————————————————————————————————————————— */ private void applyGotoPatch(InsnList instr, LabelNode lbl, AbstractInsnNode trg) { instr.insert(trg, generatePatch(lbl)); } private InsnList generatePatch(LabelNode lbl) { InsnList list = new InsnList(); list.add(new JumpInsnNode(Opcodes.GOTO, lbl)); return list; } /* ————————————————————————————————————————————————————— */ private boolean analyzeClass(ClassNode node) { boolean successVehicleMove = false; boolean successProcessPlayer = false; for (MethodNode method : node.methods) { System.out.println("Method: " + method.name); // Method processVehicleMove if (method.name.equals("a") && method.desc.equals("(Lll;)V")) { successVehicleMove = disableMovedTooQuickly(method) && disableMovedWrongly(method); } // Method processPlayer if (method.name.equals("a") && method.desc.equals("(Llk;)V")) { successProcessPlayer = disableMovedTooQuickly(method) && disableMovedWrongly(method); } } if (!(successVehicleMove && successProcessPlayer)) System.out.println("Unabled to find method to patch"); return successVehicleMove && successProcessPlayer; } @Override public byte[] transform(String name, String transname, byte[] bytes) { if (transname.contains("net.minecraft.network")) System.out.println(name + "; " + transname); if (transname.contains("net.minecraft.network.NetHandlerPlayServer")) { System.out.println("Class to transform: " + transname); ClassReader reader = new ClassReader(bytes); ClassNode node = new ClassNode(); reader.accept(node, 0); if (analyzeClass(node)) { ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS | ClassWriter.COMPUTE_FRAMES); node.accept(writer); bytes = writer.toByteArray(); } else { System.out.println("Failed to patch methods"); } } return bytes; } }