Paper/patches/server/0685-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 bdd4f4db9849d9107b5c62d5e83b1277621f49f1..9d09ec3b127e3440bef6b248578dec109407f9ff 100644
--- a/src/main/java/net/minecraft/network/Connection.java
+++ b/src/main/java/net/minecraft/network/Connection.java
@@ -614,6 +614,11 @@ 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 9b5430bae4a863004aaa0fc41e7b75a7d5797b92..db0110120f88bc06954fa8c44b2a45f0c8229574 100644
--- a/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
+++ b/src/main/java/net/minecraft/server/dedicated/DedicatedServer.java
@@ -231,6 +231,20 @@ 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.fatal("**** INVALID CONFIGURATION!");
+                DedicatedServer.LOGGER.fatal("You are trying to use a Unix domain socket but you're not on a supported OS.");
+                return false;
+            } else if (!com.destroystokyo.paper.PaperConfig.velocitySupport && !org.spigotmc.SpigotConfig.bungee) {
+                DedicatedServer.LOGGER.fatal("**** INVALID CONFIGURATION!");
+                DedicatedServer.LOGGER.fatal("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()) {
@@ -240,12 +254,15 @@ 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 5baf51571398d6af626dfa6be3b2e42d6dd29059..961660f6f9e00b93252519e38b74c66c53388ed2 100644
--- a/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
+++ b/src/main/java/net/minecraft/server/network/ServerConnectionListener.java
@@ -78,7 +78,12 @@ 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) {
@@ -86,7 +91,11 @@ 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 {
@@ -114,7 +123,7 @@ 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 4c44f06ba18cfa2d889d0dd57fdd7eb79971c8c6..e0cd786f130e34b3401d40663e1548fc0076f74a 100644
--- a/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java
+++ b/src/main/java/net/minecraft/server/network/ServerHandshakePacketListenerImpl.java
@@ -44,6 +44,7 @@ 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();
@@ -72,6 +73,7 @@ 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);
                 }
@@ -120,8 +122,11 @@ public class ServerHandshakePacketListenerImpl implements ServerHandshakePacketL
                 //if (org.spigotmc.SpigotConfig.bungee) { // Paper - comment out, we check above!
                         String[] split = packet.hostName.split("\00");
                         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
                         {