add PacketOrderN

src/main/java/ac/grim/grimac/checks/impl/packetorder/PacketOrderN.java

@@ -0,0 +1,69 @@
+package ac.grim.grimac.checks.impl.packetorder;
+
+import ac.grim.grimac.checks.CheckData;
+import ac.grim.grimac.checks.type.BlockPlaceCheck;
+import ac.grim.grimac.player.GrimPlayer;
+import ac.grim.grimac.utils.anticheat.update.BlockPlace;
+import ac.grim.grimac.utils.anticheat.update.PredictionComplete;
+import com.github.retrooper.packetevents.event.PacketReceiveEvent;
+import com.github.retrooper.packetevents.protocol.packettype.PacketType;
+import com.github.retrooper.packetevents.protocol.player.ClientVersion;
+import com.github.retrooper.packetevents.protocol.world.BlockFace;
+import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientPlayerBlockPlacement;
+import com.github.retrooper.packetevents.wrapper.play.client.WrapperPlayClientPlayerFlying;
+
+@CheckData(name = "PacketOrderN", experimental = true)
+public class PacketOrderN extends BlockPlaceCheck {
+    public PacketOrderN(final GrimPlayer player) {
+        super(player);
+    }
+
+    private int invalid;
+    private boolean usingWithoutPlacing, placing;
+
+    @Override
+    public void onBlockPlace(BlockPlace place) {
+        placing = true;
+        if (usingWithoutPlacing) {
+            if (player.getClientVersion().isOlderThanOrEquals(ClientVersion.V_1_8)) {
+                if (flagAndAlert() && shouldModifyPackets() && shouldCancel()) {
+                    place.resync();
+                }
+            } else {
+                invalid++;
+            }
+        }
+    }
+
+    @Override
+    public void onPacketReceive(PacketReceiveEvent event) {
+        if (event.getPacketType() == PacketType.Play.Client.USE_ITEM
+                || event.getPacketType() == PacketType.Play.Client.PLAYER_BLOCK_PLACEMENT
+                && new WrapperPlayClientPlayerBlockPlacement(event).getFace() == BlockFace.OTHER) {
+            if (!placing) {
+                usingWithoutPlacing = true;
+            }
+
+            placing = false;
+        }
+
+        if (WrapperPlayClientPlayerFlying.isFlying(event.getPacketType()) && player.getClientVersion().isOlderThanOrEquals(ClientVersion.V_1_8) && !player.packetStateData.lastPacketWasTeleport) {
+            usingWithoutPlacing = placing = false;
+        }
+    }
+
+    @Override
+    public void onPredictionComplete(PredictionComplete predictionComplete) {
+        // we don't need to check pre-1.9 players here (no tick skipping)
+        if (player.getClientVersion().isOlderThanOrEquals(ClientVersion.V_1_8)) return;
+
+        if (!player.skippedTickInActualMovement) {
+            for (; invalid >= 1; invalid--) {
+                flagAndAlert();
+            }
+        }
+
+        invalid = 0;
+        usingWithoutPlacing = placing = false;
+    }
+}

src/main/java/ac/grim/grimac/manager/CheckManager.java

@@ -163,6 +163,7 @@ public CheckManager(GrimPlayer player) {
                 .put(FabricatedPlace.class, new FabricatedPlace(player))
                 .put(PositionPlace.class, new PositionPlace(player))
                 .put(RotationPlace.class, new RotationPlace(player))
+                .put(PacketOrderN.class, new PacketOrderN(player))
                 .put(DuplicateRotPlace.class, new DuplicateRotPlace(player))
                 .put(GhostBlockMitigation.class, new GhostBlockMitigation(player))
                 .build();