Clean up anti-fly mitigation and patch elytra fireworks

gradle.properties

@@ -9,7 +9,7 @@ loader_version=0.15.9
 fabric_kotlin_version=1.10.19+kotlin.1.9.23
 access_widener=puffy-anti-exploit.accesswidener
 # Mod Properties
-mod_version=0.2.6
+mod_version=0.2.7
 maven_group=com.puffy
 archives_base_name=puffy-anti-exploit
 # Dependencies

src/main/kotlin/com/puffy/mitigations/AntiFlyMitigation.kt

@@ -3,27 +3,24 @@ package com.puffy.mitigations
 import com.puffy.events.DetectionEventEmitter
 import com.puffy.events.DetectionInfo
 import com.puffy.events.PacketEventEmitter
+import com.puffy.util.isAllowedFlight
+import com.puffy.util.isInAir
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerTickEvents.EndTick
-import net.minecraft.entity.effect.StatusEffect
 import net.minecraft.network.packet.c2s.play.PlayerMoveC2SPacket
 import net.minecraft.server.network.ServerPlayerEntity
 
 const val MAXIMUM_TICKS_SPENT_FLOATING = 85
 const val MAXIMUM_TICKS_SPENT_ASCENDING = 20
 private const val FLOATING_Y_TOLERANCE = 1
 private const val MITIGATION_NAME = "Flight"
-// https://minecraft.fandom.com/wiki/Levitation
-private const val LEVITATION_STATUS_ID = 25
-// Likely, once the player's velocity reaches this threshold it's probably from a tnt jump or mod
-private const val FLIGHT_SPEED_THRESHOLD = 5
 
 class AntiFlyMitigation(val player: ServerPlayerEntity) {
     private var ticksSpentFloating = 0
     private var ticksSpentAscending = 0
     private var lastY = 0.0
 
-    private var isAllowedToFly = false
+    private var lastTickFlightPermission = false
 
     init {
         PacketEventEmitter.addListener(player, PlayerMoveC2SPacket::class) { _ ->
@@ -37,37 +34,26 @@ class AntiFlyMitigation(val player: ServerPlayerEntity) {
                 updateTicksFloating()
                 updateTicksAscending()
                 resetCountersWhenFlightRemoved()
-                isAllowedToFly = isFlightAllowedAtCurrentTick()
+                lastTickFlightPermission = player.isAllowedFlight()
             }
         )
     }
 
     private fun isFlyHacking(): Boolean {
         return (ticksSpentFloating >= MAXIMUM_TICKS_SPENT_FLOATING ||
-            ticksSpentAscending >= MAXIMUM_TICKS_SPENT_ASCENDING) && !isAllowedToFly
+            ticksSpentAscending >= MAXIMUM_TICKS_SPENT_ASCENDING) && !player.isAllowedFlight()
     }
 
     private fun updateTicksFloating() {
-        val world = player.entityWorld
-        val boundingBox = player.boundingBox.expand(0.0, 0.2, 0.0)
-
-        val collidingBlocks = world.getBlockCollisions(player, boundingBox)
-        val collidingEntities =
-            world.getOtherEntities(player, boundingBox) { entity -> !entity.equals(player) }
-
-        if (
-            !collidingBlocks.any() &&
-                !collidingEntities.any() &&
-                player.y - lastY <= FLOATING_Y_TOLERANCE
-        ) {
+        if (player.isInAir() && player.y - lastY <= FLOATING_Y_TOLERANCE) {
             ticksSpentFloating++
         } else {
             ticksSpentFloating = 0
         }
     }
 
     private fun updateTicksAscending() {
-        if (player.y > lastY && !isFlightAllowedAtCurrentTick()) {
+        if (player.y > lastY && !player.isAllowedFlight()) {
             ticksSpentAscending++
         } else {
             ticksSpentAscending = 0
@@ -76,19 +62,8 @@ class AntiFlyMitigation(val player: ServerPlayerEntity) {
         lastY = player.y
     }
 
-    private fun isFlightAllowedAtCurrentTick(): Boolean {
-        return (player.abilities.flying || player.abilities.allowFlying) ||
-            player.isTouchingWater ||
-            player.isSubmergedInWater ||
-            player.isSwimming ||
-            player.isFallFlying ||
-            player.hasStatusEffect(StatusEffect.byRawId(LEVITATION_STATUS_ID)) ||
-            player.velocity.length() >= FLIGHT_SPEED_THRESHOLD ||
-            player.fallDistance > 0
-    }
-
     private fun resetCountersWhenFlightRemoved() {
-        if (isAllowedToFly != isFlightAllowedAtCurrentTick()) {
+        if (lastTickFlightPermission != player.isAllowedFlight()) {
             ticksSpentFloating = 0
             ticksSpentAscending = 0
         }

src/main/kotlin/com/puffy/mitigations/antispeed/MagnitudeWeighter.kt

@@ -1,6 +1,7 @@
 package com.puffy.mitigations.antispeed
 
 import java.util.function.BiPredicate
+import net.minecraft.item.Items
 import net.minecraft.server.network.ServerPlayerEntity
 import org.slf4j.LoggerFactory
 
@@ -32,6 +33,10 @@ object MagnitudeWeighter {
             },
             Weight("Server-permitted Velocity Bias", 0.25) { player, _ ->
                 player.velocity.length() > SERVER_VELOCITY_THRESHOLD
+            },
+            Weight("Server-permitted Firework Bias", 0.10) { player, _ ->
+                player.isFallFlying &&
+                    player.inventory.main.any { stack -> stack.isOf(Items.FIREWORK_ROCKET) }
             }
         )
 
@@ -49,7 +54,7 @@ object MagnitudeWeighter {
         val activeWeights = getActiveWeightsForPlayer(player, lastY)
 
         activeWeights.forEach { weight ->
-            logger.debug("Weight '${weight.title}' is active for player ${player.name.string}")
+            logger.info("Weight '${weight.title}' is active for player ${player.name.string}")
         }
 
         return initialMagnitude * getTotalWeightedMultiplier(activeWeights)

src/main/kotlin/com/puffy/util/IsAllowedFlight.kt

@@ -0,0 +1,23 @@
+package com.puffy.util
+
+import net.minecraft.entity.effect.StatusEffect
+import net.minecraft.server.network.ServerPlayerEntity
+
+// https://minecraft.fandom.com/wiki/Levitation
+private const val LEVITATION_STATUS_ID = 25
+// Likely, once the player's velocity reaches this threshold it's probably from a tnt jump or mod
+private const val FLIGHT_SPEED_THRESHOLD = 5
+
+fun ServerPlayerEntity.isAllowedFlight(): Boolean {
+    // Water internally is implemented as an alternative movement style which isn't walking or
+    // flight, but a little in between. So this returns true for water to be safe
+
+    return (this.abilities.flying || this.abilities.allowFlying) ||
+        this.isTouchingWater ||
+        this.isSubmergedInWater ||
+        this.isSwimming ||
+        this.isFallFlying ||
+        this.hasStatusEffect(StatusEffect.byRawId(LEVITATION_STATUS_ID)) ||
+        this.velocity.length() >= FLIGHT_SPEED_THRESHOLD ||
+        this.fallDistance > 0
+}

src/main/kotlin/com/puffy/util/IsInAir.kt

@@ -0,0 +1,16 @@
+package com.puffy.util
+
+import net.minecraft.server.network.ServerPlayerEntity
+
+private const val Y_BIAS = 0.2
+
+fun ServerPlayerEntity.isInAir(): Boolean {
+    val world = this.entityWorld
+    val boundingBox = this.boundingBox.expand(0.0, Y_BIAS, 0.0)
+
+    val collidingBlocks = world.getBlockCollisions(this, boundingBox)
+    val collidingEntities =
+        world.getOtherEntities(this, boundingBox) { entity -> !entity.equals(this) }
+
+    return !collidingBlocks.any() && !collidingEntities.any()
+}

src/main/resources/fabric.mod.json

@@ -1,7 +1,7 @@
 {
   "schemaVersion": 1,
   "id": "puffy-anti-exploit",
-  "version": "0.2.6",
+  "version": "0.2.7",
   "name": "puffy-anti-exploit",
   "description": "A server-side anti exploit which aims to reduce the possible amount of advantages a player can obtain with a hacked client. This mod does not attempt to ban such players, it only aims to fix certain parts of the server and gently counter these players.",
   "authors": [