Paper/patches/server/0648-Add-Unix-domain-socket-support.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Andrew Steinborn <git@steinborn.me>
Date: Tue, 11 May 2021 17:39:22 -0400
Subject: [PATCH] Add Unix domain socket support

For Windows and ARM support, JEP-380 is required:
https://inside.java/2021/02/03/jep380-unix-domain-sockets-channels/
This will be possible as of the Minecraft 1.17 Java version bump.

Tested-by: Mariell Hoversholm <proximyst@proximyst.com>
Reviewed-by: Mariell Hoversholm <proximyst@proximyst.com>

diff --git a/src/main/java/net/minecraft/network/Connection.java b/src/main/java/net/minecraft/network/Connection.java
index 91556b52edaa1d5c4dc73a825c77b9a66b002c61..00abdd5bba02b7cdf8dbdc423594f0fde890dd84 100644
--- a/src/main/java/net/minecraft/network/Connection.java
+++ b/src/main/java/net/minecraft/network/Connection.java
@@ -627,6 +627,11 @@ public class Connection extends SimpleChannelInboundHandler<Packet<?>> {
     // Spigot Start
     public SocketAddress getRawAddress()
     {
+        // Paper start - this can be nullable in the case of a Unix domain socket, so if it is, fake something
+        if (this.channel.remoteAddress() == null) {
+            return new java.net.InetSocketAddress(java.net.InetAddress.getLoopbackAddress(), 0);
+        }
+        // Paper end
         return this.channel.remoteAddress();
     }
     // Spigot End
diff --git a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
index c6f70d057b7626b6b5bae0b2760f564f55af17a7..3fc342502ca24165ea5dcf0cc6e9867d0378d69f 100644
--- a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
+++ b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
@@ -223,6 +223,20 @@ public class DedicatedServer extends MinecraftServer implements ServerInterface
         this.setEnforceWhitelist(dedicatedserverproperties.enforceWhitelist);
         // this.worldData.setGameType(dedicatedserverproperties.gamemode); // CraftBukkit - moved to world loading
         DedicatedServer.LOGGER.info("Default game type: {}", dedicatedserverproperties.gamemode);
+        // Paper start - Unix domain socket support
+        java.net.SocketAddress bindAddress;
+        if (this.getLocalIp().startsWith("unix:")) {
+            if (!io.netty.channel.epoll.Epoll.isAvailable()) {
+                DedicatedServer.LOGGER.error("**** INVALID CONFIGURATION!");
+                DedicatedServer.LOGGER.error("You are trying to use a Unix domain socket but you're not on a supported OS.");
+                return false;
+            } else if (!io.papermc.paper.configuration.GlobalConfiguration.get().proxies.velocity.enabled && !org.spigotmc.SpigotConfig.bungee) {
+                DedicatedServer.LOGGER.error("**** INVALID CONFIGURATION!");
+                DedicatedServer.LOGGER.error("Unix domain sockets require IPs to be forwarded from a proxy.");
+                return false;
+            }
+            bindAddress = new io.netty.channel.unix.DomainSocketAddress(this.getLocalIp().substring("unix:".length()));
+        } else {
         InetAddress inetaddress = null;
 
         if (!this.getLocalIp().isEmpty()) {
@@ -232,12 +246,15 @@ public class DedicatedServer extends MinecraftServer implements ServerInterface
         if (this.getPort() < 0) {
             this.setPort(dedicatedserverproperties.serverPort);
         }
+        bindAddress = new java.net.InetSocketAddress(inetaddress, this.getPort());
+        }
+        // Paper end
 
         this.initializeKeyPair();
         DedicatedServer.LOGGER.info("Starting Minecraft server on {}:{}", this.getLocalIp().isEmpty() ? "*" : this.getLocalIp(), this.getPort());
 
         try {
-            this.getConnection().startTcpServerListener(inetaddress, this.getPort());
+            this.getConnection().bind(bindAddress); // Paper - Unix domain socket support
         } catch (IOException ioexception) {
             DedicatedServer.LOGGER.warn("**** FAILED TO BIND TO PORT!");
             DedicatedServer.LOGGER.warn("The exception was: {}", ioexception.toString());
diff --git a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
index 076c1d5fb69a4a30b3e412e85b17db09fd9a1def..9e7154c9df96d5a0577886d43a98a73626a8f189 100644
--- a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
+++ b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
@@ -79,7 +79,12 @@ public class ServerConnectionListener {
         this.running = true;
     }
 
+    // Paper start
     public void startTcpServerListener(@Nullable InetAddress address, int port) throws IOException {
+        bind(new java.net.InetSocketAddress(address, port));
+    }
+    public void bind(java.net.SocketAddress address) throws IOException {
+    // Paper end
         List list = this.channels;
 
         synchronized (this.channels) {
@@ -87,7 +92,11 @@ public class ServerConnectionListener {
             LazyLoadedValue lazyinitvar;
 
             if (Epoll.isAvailable() && this.server.isEpollEnabled()) {
+                if (address instanceof io.netty.channel.unix.DomainSocketAddress) {
+                    oclass = io.netty.channel.epoll.EpollServerDomainSocketChannel.class;
+                } else {
                 oclass = EpollServerSocketChannel.class;
+                }
                 lazyinitvar = ServerConnectionListener.SERVER_EPOLL_EVENT_GROUP;
                 ServerConnectionListener.LOGGER.info("Using epoll channel type");
             } else {
@@ -115,7 +124,7 @@ public class ServerConnectionListener {
                     ((Connection) object).setListener(new ServerHandshakePacketListenerImpl(ServerConnectionListener.this.server, (Connection) object));
                     io.papermc.paper.network.ChannelInitializeListenerHolder.callListeners(channel); // Paper
                 }
-            }).group((EventLoopGroup) lazyinitvar.get()).localAddress(address, port)).option(ChannelOption.AUTO_READ, false).bind().syncUninterruptibly()); // CraftBukkit
+            }).group((EventLoopGroup) lazyinitvar.get()).localAddress(address)).option(ChannelOption.AUTO_READ, false).bind().syncUninterruptibly()); // CraftBukkit // Paper
         }
     }
 
diff --git a/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java
index 142737266a2afcbbd70556615f56730d44e862f9..c7ac8193b7f4b29d0d85891de0eca67912c8811c 100644
--- a/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java
@@ -43,6 +43,7 @@ public class ServerHandshakePacketListenerImpl implements ServerHandshakePacketL
                 this.connection.setProtocol(ConnectionProtocol.LOGIN);
                 // CraftBukkit start - Connection throttle
                 try {
+                    if (!(this.connection.channel.localAddress() instanceof io.netty.channel.unix.DomainSocketAddress)) { // Paper - the connection throttle is useless when you have a Unix domain socket
                     long currentTime = System.currentTimeMillis();
                     long connectionThrottle = this.server.server.getConnectionThrottle();
                     InetAddress address = ((java.net.InetSocketAddress) this.connection.getRemoteAddress()).getAddress();
@@ -71,6 +72,7 @@ public class ServerHandshakePacketListenerImpl implements ServerHandshakePacketL
                             }
                         }
                     }
+                    } // Paper - add closing bracket for if check above
                 } catch (Throwable t) {
                     org.apache.logging.log4j.LogManager.getLogger().debug("Failed to check connection throttle", t);
                 }
@@ -119,8 +121,11 @@ public class ServerHandshakePacketListenerImpl implements ServerHandshakePacketL
                         // Paper end
                     // if (org.spigotmc.SpigotConfig.bungee) { // Paper - comment out, we check above!
                         if ( ( split.length == 3 || split.length == 4 ) && ( ServerHandshakePacketListenerImpl.BYPASS_HOSTCHECK || ServerHandshakePacketListenerImpl.HOST_PATTERN.matcher( split[1] ).matches() ) ) { // Paper
+                            // Paper start - Unix domain socket support
+                            java.net.SocketAddress socketAddress = connection.getRemoteAddress();
                             packet.hostName = split[0];
-                            connection.address = new java.net.InetSocketAddress(split[1], ((java.net.InetSocketAddress) this.connection.getRemoteAddress()).getPort());
+                            connection.address = new java.net.InetSocketAddress(split[1], socketAddress instanceof java.net.InetSocketAddress ? ((java.net.InetSocketAddress) socketAddress).getPort() : 0);
+                            // Paper end
                             connection.spoofedUUID = com.mojang.util.UUIDTypeAdapter.fromString( split[2] );
                         } else
                         {