Check Line of Sight of Player Before Block Placements and Opening Containers

src/main/java/ac/grim/grimac/checks/impl/scaffolding/LineOfSightPlace.java

@@ -0,0 +1,199 @@
+package ac.grim.grimac.checks.impl.scaffolding;
+
+import ac.grim.grimac.checks.CheckData;
+import ac.grim.grimac.checks.type.BlockPlaceCheck;
+import ac.grim.grimac.events.packets.CheckManagerListener;
+import ac.grim.grimac.player.GrimPlayer;
+import ac.grim.grimac.utils.anticheat.update.BlockPlace;
+import ac.grim.grimac.utils.collisions.datatypes.SimpleCollisionBox;
+import ac.grim.grimac.utils.data.HitData;
+import ac.grim.grimac.utils.data.Pair;
+import ac.grim.grimac.utils.nmsutil.Ray;
+import com.github.retrooper.packetevents.protocol.attribute.Attributes;
+import com.github.retrooper.packetevents.protocol.player.ClientVersion;
+import com.github.retrooper.packetevents.protocol.player.GameMode;
+import com.github.retrooper.packetevents.protocol.world.BlockFace;
+import com.github.retrooper.packetevents.protocol.world.states.type.StateType;
+import com.github.retrooper.packetevents.protocol.world.states.type.StateTypes;
+import com.github.retrooper.packetevents.util.Vector3f;
+import com.github.retrooper.packetevents.util.Vector3i;
+import org.bukkit.util.Vector;
+
+import java.util.*;
+
+@CheckData(name = "LineOfSightPlace")
+public class LineOfSightPlace extends BlockPlaceCheck {
+
+    private double flagBuffer = 0; // If the player flags once, force them to play legit, or we will cancel the tick before.
+    private boolean ignorePost = false;
+    private boolean useBlockWhitelist;
+    private HashSet<StateType> blockWhitelist;
+
+    public LineOfSightPlace(GrimPlayer player) {
+        super(player);
+    }
+
+    @Override
+    public void onBlockPlace(final BlockPlace place) {
+        if (checkIfShouldSkip(place)) return;
+
+        if (flagBuffer > 0 && !didRayTraceHit(place)) {
+            ignorePost = true;
+            // If the player hit and has flagged this check recently
+            if (flagAndAlert("pre-flying: " + player.compensatedWorld.getWrappedBlockStateAt(place.getPlacedAgainstBlockLocation()).getType()) && shouldModifyPackets() && shouldCancel()) {
+                place.resync();  // Deny the block placement.
+            }
+        }
+    }
+
+    // Use post flying because it has the correct rotation, and can't false easily.
+    @Override
+    public void onPostFlyingBlockPlace(BlockPlace place) {
+        if (checkIfShouldSkip(place)) return;
+
+        // Don't flag twice
+        if (ignorePost) {
+            ignorePost = false;
+            return;
+        }
+
+        // Ray trace to try and hit the target block.
+        boolean hit = didRayTraceHit(place);
+        // This can false with rapidly moving yaw in 1.8+ clients
+        if (!hit) {
+            flagBuffer = 1;
+            flagAndAlert("post-flying: " + player.compensatedWorld.getWrappedBlockStateAt(place.getPlacedAgainstBlockLocation()).getType());
+        } else {
+            flagBuffer = Math.max(0, flagBuffer - 0.1);
+        }
+    }
+
+    private boolean checkIfShouldSkip(BlockPlace place) {
+        StateType targetBlockStateType = player.compensatedWorld.getWrappedBlockStateAt(place.getPlacedAgainstBlockLocation()).getType();
+        if (place.getMaterial() == StateTypes.SCAFFOLDING) return true; // Scaffolding
+        if (player.gamemode == GameMode.SPECTATOR) return true; // A waste to check creative mode players
+        if (targetBlockStateType == StateTypes.REDSTONE_WIRE) return true; // Redstone too buggy
+        if (player.compensatedWorld.isNearHardEntity(player.boundingBox.copy().expand(4))) return true; // Shulkers and Pistons are too buggy
+
+        if (useBlockWhitelist) {
+            if (!isBlockTypeWhitelisted(targetBlockStateType)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean didRayTraceHit(BlockPlace place) {
+        double[] possibleEyeHeights = player.getPossibleEyeHeightsArray();
+
+        // Start checking if player is in the block
+        double minEyeHeight = Double.MAX_VALUE;
+        double maxEyeHeight = Double.MIN_VALUE;
+        for (double height : possibleEyeHeights) {
+            minEyeHeight = Math.min(minEyeHeight, height);
+            maxEyeHeight = Math.max(maxEyeHeight, height);
+        }
+
+        double movementThreshold = player.getMovementThreshold();
+
+        SimpleCollisionBox eyePositions = new SimpleCollisionBox(player.x, player.y + minEyeHeight, player.z, player.x, player.y + maxEyeHeight, player.z);
+        eyePositions.expand(movementThreshold);
+
+        Vector3i interactBlockVec = place.getPlacedAgainstBlockLocation();
+        BlockFace expectedBlockFace = place.getDirection();
+
+        // If the player is inside a block, then they can ray trace through the block and hit the other side of the block
+        // This may potentially be exploitable as a minor bypass
+        if (eyePositions.isIntersected(new SimpleCollisionBox(interactBlockVec))) {
+            return true;
+        }
+        // End checking if the player is in the block
+        double[][] possibleLookDirs;
+
+        // 1.9+ players could be a tick behind because we don't get skipped ticks
+        if (player.getClientVersion().isNewerThanOrEquals(ClientVersion.V_1_9)) {
+            possibleLookDirs = new double[][]{
+                    {player.lastXRot, player.yRot, 0},
+                    {player.xRot, player.yRot, 0},
+                    {player.lastXRot, player.lastYRot, 0}
+            };
+        } else if (player.getClientVersion().isOlderThan(ClientVersion.V_1_8)) {
+            // 1.7 players do not have any of these issues! They are always on the latest look vector
+            possibleLookDirs = new double[][]{{player.xRot, player.yRot, 0}};
+        } else {
+            possibleLookDirs = new double[][]{
+                    {player.lastXRot, player.yRot, 0},
+                    {player.xRot, player.yRot, 0}
+            };
+        }
+
+        // We do not need to add 0.03/0.0002 to maxDistance to ensure our raytrace hits blocks
+        // Since we expand the hitboxes of the expectedTargetBlock by 0.03/0.002 already later
+        double maxDistance = player.compensatedEntities.getSelf().getAttributeValue(Attributes.PLAYER_BLOCK_INTERACTION_RANGE);
+
+        // Define possible offsets
+        // TODO, vectorize this with SIMD or AVX for performance
+        double[][] offsets = {
+                {0, 0, 0},
+                {movementThreshold, 0, 0},
+                {-movementThreshold, 0, 0},
+                {0, movementThreshold, 0},
+                {0, -movementThreshold, 0},
+                {0, 0, movementThreshold},
+                {0, 0, -movementThreshold}
+        };
+
+        double[] eyePosition = new double[3];
+        double[] eyeLookDir = new double[3];
+
+        for (double eyeHeight : possibleEyeHeights) {
+            for (double[] lookDir : possibleLookDirs) {
+                for (double[] offset : offsets) {
+                    eyePosition[0] = player.x + offset[0];
+                    eyePosition[1] = player.y + eyeHeight + offset[1];
+                    eyePosition[2] = player.z + offset[2];
+
+                    calculateDirection(eyeLookDir, lookDir[0], lookDir[1]);
+
+                    if (getTargetBlock(eyePosition, eyeLookDir, maxDistance, interactBlockVec, expectedBlockFace)) {
+                        return true; // If any possible face matches the client-side placement, assume it's legitimate
+                    }
+                }
+            }
+        }
+
+        return false; // No matching face found
+    }
+
+    // Helper method to calculate direction (replace the Ray class method)
+    private void calculateDirection(double[] result, double xRot, double yRot) {
+        float rotX = (float) Math.toRadians(xRot);
+        float rotY = (float) Math.toRadians(yRot);
+        result[1] = -player.trigHandler.sin(rotY);
+        double xz = player.trigHandler.cos(rotY);
+        result[0] = -xz * player.trigHandler.sin(rotX);
+        result[2] = xz * player.trigHandler.cos(rotX);
+    }
+
+    private boolean getTargetBlock(double[] eyePosition, double[] eyeDirection, double maxDistance, Vector3i targetBlockVec, BlockFace expectedBlockFace) {
+        HitData hitData = CheckManagerListener.getNearestReachHitResult(player, eyePosition, eyeDirection, maxDistance, maxDistance, targetBlockVec, expectedBlockFace);
+        return hitData != null  // Player is inside the block, from expanded hitbox, do we still need this?
+                && targetBlockVec.equals(hitData.getPosition());
+    }
+
+    private boolean isBlockTypeWhitelisted(StateType type) {
+        return blockWhitelist.contains(type);
+    }
+
+    @Override
+    public void reload() {
+        super.reload();
+
+        useBlockWhitelist = getConfig().getBooleanElse("LineOfSightPlace.use-block-whitelist", false);
+        blockWhitelist = new HashSet<>();
+        List<String> blocks = getConfig().getList("LineOfSightPlace.block-whitelist");
+        for (String block : blocks) {
+            blockWhitelist.add(StateTypes.getByName(block));
+        }
+    }
+}

src/main/java/ac/grim/grimac/events/packets/CheckManagerListener.java

@@ -36,6 +36,7 @@
 import com.github.retrooper.packetevents.protocol.world.BlockFace;
 import com.github.retrooper.packetevents.protocol.world.Location;
 import com.github.retrooper.packetevents.protocol.world.states.WrappedBlockState;
+import com.github.retrooper.packetevents.protocol.world.states.defaulttags.BlockTags;
 import com.github.retrooper.packetevents.protocol.world.states.type.StateType;
 import com.github.retrooper.packetevents.protocol.world.states.type.StateTypes;
 import com.github.retrooper.packetevents.protocol.world.states.type.StateValue;
@@ -778,6 +779,62 @@ private static void placeLilypad(GrimPlayer player, InteractionHand hand) {
         }
     }
 
+    public static HitData getNearestReachHitResult(GrimPlayer player, double[] eyePos, double[] lookVec, double currentDistance, double maxDistance, Vector3i targetBlockVec, BlockFace expectedBlockFace) {
+        Vector3d startingPos = new Vector3d(eyePos[0], eyePos[1], eyePos[2]);
+        Vector startingVec = new Vector(startingPos.getX(), startingPos.getY(), startingPos.getZ());
+
+        // Convert double[] to Vector for Ray constructor
+        Vector eyePosVector = new Vector(eyePos[0], eyePos[1], eyePos[2]);
+        Vector lookVecVector = new Vector(lookVec[0], lookVec[1], lookVec[2]);
+        Ray trace = new Ray(eyePosVector, lookVecVector);
+        Vector endVec = trace.getPointAtDistance(maxDistance);
+        Vector3d endPos = new Vector3d(endVec.getX(), endVec.getY(), endVec.getZ());
+
+        StateType heldItem = null;
+        boolean checkInside = true;
+
+        return traverseBlocks(player, startingPos, endPos, (block, vector3i) -> {
+            ClientVersion clientVersion = player.getClientVersion();
+            CollisionBox data = HitboxData.getBlockHitbox(player, heldItem, clientVersion, block, vector3i.getX(), vector3i.getY(), vector3i.getZ());
+            List<SimpleCollisionBox> boxes = new ArrayList<>();
+            data.downCast(boxes);
+
+            double bestHitResult = Double.MAX_VALUE;
+            Vector bestHitLoc = null;
+            BlockFace bestFace = null;
+
+            // BEWARE OF https://bugs.mojang.com/browse/MC-85109 FOR 1.8 PLAYERS
+            // 1.8 Brewing Stand hitbox is a fullblock until it is hit sometimes, can be caused be restarting client and joining server
+            if (vector3i.equals(targetBlockVec) && clientVersion.isNewerThan(ClientVersion.V_1_7_10) && clientVersion.isOlderThan(ClientVersion.V_1_9) && block.getType() == StateTypes.BREWING_STAND) {
+                boxes.add(new SimpleCollisionBox(0, 0, 0, 1, 1, 1, true));
+            }
+
+            for (SimpleCollisionBox box : boxes) {
+                Pair<Vector, BlockFace> intercept = ReachUtils.calculateIntercept(box, trace.getOrigin(), trace.getPointAtDistance(currentDistance));
+                if (intercept.getFirst() == null || intercept.getSecond() != expectedBlockFace) continue; // No intercept or wrong blockFace
+
+                Vector hitLoc = intercept.getFirst();
+
+                // If inside a block, return empty result for reach check
+                if (checkInside && ReachUtils.isVecInside(box, trace.getOrigin())) {
+                    return null;
+                }
+
+                if (hitLoc.distanceSquared(startingVec) < bestHitResult) {
+                    bestHitResult = hitLoc.distanceSquared(startingVec);
+                    bestHitLoc = hitLoc;
+                    bestFace = intercept.getSecond();
+                }
+            }
+
+            if (bestHitLoc != null) {
+                return new HitData(vector3i, bestHitLoc, bestFace, block);
+            }
+
+            return null;
+        });
+    }
+
     private static HitData getNearestHitResult(GrimPlayer player, StateType heldItem, boolean sourcesHaveHitbox) {
         Vector3d startingPos = new Vector3d(player.x, player.y + player.getEyeHeight(), player.z);
         Vector startingVec = new Vector(startingPos.getX(), startingPos.getY(), startingPos.getZ());
@@ -836,4 +893,8 @@ public void onPacketSend(PacketSendEvent event) {
 
         player.checkManager.onPacketSend(event);
     }
+
+    private static boolean isFence(StateType state) {
+        return BlockTags.FENCES.contains(state);
+    }
 }