From 3351f9d5df7eb93566c74939c5863d74dbf42022 Mon Sep 17 00:00:00 2001
From: Spottedleaf <Spottedleaf@users.noreply.github.com>
Date: Mon, 29 Jul 2024 05:53:06 -0700
Subject: [PATCH] Skip reverse DNS lookup when connecting/pinging servers

The rDNS is not cheap and is not necessary. We skip the
rDNS by providing the input address as the host name when
the input address is a plain ipv4/ipv6 address.
---
 .../ServerAddressResolverMixin.java           | 37 +++++++++++++++++++
 src/main/resources/moonrise.mixins.json       |  1 +
 2 files changed, 38 insertions(+)
 create mode 100644 src/main/java/ca/spottedleaf/moonrise/mixin/serverlist/ServerAddressResolverMixin.java

diff --git a/src/main/java/ca/spottedleaf/moonrise/mixin/serverlist/ServerAddressResolverMixin.java b/src/main/java/ca/spottedleaf/moonrise/mixin/serverlist/ServerAddressResolverMixin.java
new file mode 100644
index 0000000..fa630ba
--- /dev/null
+++ b/src/main/java/ca/spottedleaf/moonrise/mixin/serverlist/ServerAddressResolverMixin.java
@@ -0,0 +1,37 @@
+package ca.spottedleaf.moonrise.mixin.serverlist;
+
+import net.minecraft.client.multiplayer.resolver.ServerAddressResolver;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+import java.net.Inet4Address;
+import java.net.Inet6Address;
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+@Mixin(ServerAddressResolver.class)
+public interface ServerAddressResolverMixin {
+
+    /**
+     * @reason Avoid rDNS lookups for plain IP addresses
+     * @author Spottedleaf
+     */
+    @Redirect(
+            method = "method_36903",
+            at = @At(
+                    value = "INVOKE",
+                    target = "Ljava/net/InetAddress;getByName(Ljava/lang/String;)Ljava/net/InetAddress;"
+            )
+    )
+    private static InetAddress eliminateRDNS(final String name) throws UnknownHostException {
+        final InetAddress ret = InetAddress.getByName(name);
+
+        if (ret instanceof Inet4Address || ret instanceof Inet6Address) {
+            // pass name to prevent rDNS
+            return InetAddress.getByAddress(name, ret.getAddress());
+        }
+
+        return ret;
+    }
+}
diff --git a/src/main/resources/moonrise.mixins.json b/src/main/resources/moonrise.mixins.json
index c8b73d3..d34979b 100644
--- a/src/main/resources/moonrise.mixins.json
+++ b/src/main/resources/moonrise.mixins.json
@@ -116,6 +116,7 @@
     "collisions.ParticleMixin",
     "render.SectionRenderDispatcherMixin",
     "serverlist.ClientConnectionMixin",
+    "serverlist.ServerAddressResolverMixin",
     "serverlist.ServerSelectionListMixin",
     "starlight.multiplayer.ClientPacketListenerMixin"
   ],