FieldAccessException
Astralchroma opened this issue · 4 comments
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- You're using the latest build for your server version
- This isn't an issue caused by another plugin
- You've checked for duplicate issues
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Describe the question
Attempting to use ProtocolLib to fake the render distance sent to the client on login results in a FieldAccessException.
[10:32:48 ERROR]: [ion] Unhandled exception occured in onPacketSending(PacketEvent) for ion
com.comphenix.protocol.reflect.FieldAccessException: Cannot read field due to a security limitation.
at com.comphenix.protocol.reflect.StructureModifier.writeInternal(StructureModifier.java:377) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.reflect.StructureModifier.write(StructureModifier.java:345) ~[ProtocolLib.jar:?]
at net.horizonsend.ion.server.PacketTweaks.onPacketSending(PacketTweaks.kt:13) ~[IonServer.jar:?]
at com.comphenix.protocol.injector.SortedPacketListenerList.invokeSendingListener(SortedPacketListenerList.java:195) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.SortedPacketListenerList.invokePacketSending(SortedPacketListenerList.java:149) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.PacketFilterManager.handlePacket(PacketFilterManager.java:535) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.PacketFilterManager.invokePacketSending(PacketFilterManager.java:516) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ProtocolInjector.packetQueued(ProtocolInjector.java:346) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ProtocolInjector.onPacketSending(ProtocolInjector.java:308) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ChannelInjector.processSending(ChannelInjector.java:433) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ChannelInjector.access$800(ChannelInjector.java:70) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ChannelInjector$3.handleScheduled(ChannelInjector.java:373) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ChannelInjector$3.onMessageScheduled(ChannelInjector.java:343) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.ChannelProxy$2.schedulingRunnable(ChannelProxy.java:127) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.injector.netty.EventLoopProxy.execute(EventLoopProxy.java:95) ~[ProtocolLib.jar:?]
at net.minecraft.network.Connection.writePacket(Connection.java:401) ~[?:?]
at net.minecraft.network.Connection.send(Connection.java:348) ~[?:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.send(ServerGamePacketListenerImpl.java:2006) ~[?:?]
at net.minecraft.server.network.ServerGamePacketListenerImpl.send(ServerGamePacketListenerImpl.java:1992) ~[?:?]
at net.minecraft.server.players.PlayerList.placeNewPlayer(PlayerList.java:270) ~[paper-1.18.1.jar:git-Paper-110]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.placeNewPlayer(ServerLoginPacketListenerImpl.java:218) ~[?:?]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.handleAcceptedLogin(ServerLoginPacketListenerImpl.java:199) ~[?:?]
at net.minecraft.server.network.ServerLoginPacketListenerImpl.tick(ServerLoginPacketListenerImpl.java:87) ~[?:?]
at net.minecraft.network.Connection.tick(Connection.java:517) ~[?:?]
at net.minecraft.server.network.ServerConnectionListener.tick(ServerConnectionListener.java:201) ~[?:?]
at net.minecraft.server.MinecraftServer.tickChildren(MinecraftServer.java:1636) ~[paper-1.18.1.jar:git-Paper-110]
at net.minecraft.server.dedicated.DedicatedServer.tickChildren(DedicatedServer.java:480) ~[paper-1.18.1.jar:git-Paper-110]
at net.minecraft.server.MinecraftServer.tickServer(MinecraftServer.java:1470) ~[paper-1.18.1.jar:git-Paper-110]
at net.minecraft.server.MinecraftServer.runServer(MinecraftServer.java:1264) ~[paper-1.18.1.jar:git-Paper-110]
at net.minecraft.server.MinecraftServer.lambda$spin$0(MinecraftServer.java:317) ~[paper-1.18.1.jar:git-Paper-110]
at java.lang.Thread.run(Thread.java:833) ~[?:?]
Caused by: java.lang.IllegalAccessException: Can not set final int field net.minecraft.network.protocol.game.PacketPlayOutLogin.a to java.lang.Integer
at jdk.internal.reflect.UnsafeFieldAccessorImpl.throwFinalFieldIllegalAccessException(UnsafeFieldAccessorImpl.java:76) ~[?:?]
at jdk.internal.reflect.UnsafeFieldAccessorImpl.throwFinalFieldIllegalAccessException(UnsafeFieldAccessorImpl.java:80) ~[?:?]
at jdk.internal.reflect.UnsafeQualifiedIntegerFieldAccessorImpl.set(UnsafeQualifiedIntegerFieldAccessorImpl.java:79) ~[?:?]
at java.lang.reflect.Field.set(Field.java:799) ~[?:?]
at com.comphenix.protocol.reflect.FieldUtils.writeField(FieldUtils.java:450) ~[ProtocolLib.jar:?]
at com.comphenix.protocol.reflect.StructureModifier.writeInternal(StructureModifier.java:375) ~[ProtocolLib.jar:?]
... 30 more
[10:32:48 ERROR]: Parameters:
net.minecraft.network.protocol.game.PacketPlayOutLogin@664cbae1[
a=42
b=false
c=CREATIVE
d=SURVIVAL
e=[ResourceKey[minecraft:dimension / minecraft:overworld], ResourceKey[minecraft:dimension / minecraft:the_nether], ResourceKey[minecraft:dimension / minecraft:the_end]]
f=net.minecraft.core.IRegistryCustom$Dimension@35ec5c3e
g=net.minecraft.world.level.dimension.DimensionManager@141adc36
h=ResourceKey[minecraft:dimension / minecraft:overworld]
i=-5878948435060608077
j=20
k=10
l=10
m=false
n=true
o=false
p=false
]
API method(s) used
Altering of sent packets
Expected behavior
A render distance of 32 is sent to the client.
Code
PacketTweaks.kt
object PacketTweaks: PacketAdapter(ionInstance, ListenerPriority.HIGHEST, PacketType.Play.Server.LOGIN) {
override fun onPacketSending(event: PacketEvent) {
if (event.packetType == PacketType.Play.Server.LOGIN) {
// Set the render distance to 32
event.packet.integers.write(2, 32)
}
}
}Additional context
Minecraft 1.18.1 (Paper)
Please use 4.8.0 for 1.18. See the readme for the link to the development builds.