Improve server version API

api/src/main/java/us/myles/ViaVersion/api/ViaAPI.java

@@ -26,6 +26,7 @@ import io.netty.buffer.ByteBuf;
 import us.myles.ViaVersion.api.boss.BossBar;
 import us.myles.ViaVersion.api.boss.BossColor;
 import us.myles.ViaVersion.api.boss.BossStyle;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersion;
 
 import java.util.SortedSet;
 import java.util.UUID;
@@ -38,12 +39,11 @@ import java.util.UUID;
 public interface ViaAPI<T> {
 
     /**
-     * Returns the server's protocol version.
+     * Returns the server's protocol version info.
-     * In the case of a proxy, this is the lowest supported version.
      *
-     * @return the server's protocol version
+     * @return the server's protocol version info
      */
-    int getServerVersion();
+    ServerProtocolVersion getServerVersion();
 
     /**
      * Get protocol version number from a player.

api/src/main/java/us/myles/ViaVersion/api/platform/ViaInjector.java

@@ -23,8 +23,11 @@
 package us.myles.ViaVersion.api.platform;
 
 import com.google.gson.JsonObject;
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
+import it.unimi.dsi.fastutil.ints.IntSortedSets;
 
 public interface ViaInjector {
+
     /**
      * Inject into the current Platform
      *
@@ -40,13 +43,36 @@ public interface ViaInjector {
     void uninject() throws Exception;
 
     /**
-     * Get the server protocol version
+     * Returns true if the protocol version cannot be used in the early init.
+     * Namely, this returns true for forks of Vanilla without extra API to get the protocol version.
      *
-     * @return The server protocol integer
+     * @return true if the protocol version cannot be used in the early init
-     * @throws Exception If there is an error with getting this info, eg. not binded.
+     */
+    default boolean lateProtocolVersionSetting() {
+        return false;
+    }
+
+    /**
+     * Returns the server protocol version.
+     * For proxies, this returns the lowest supported protocol version.
+     *
+     * @return server protocol version
+     * @throws Exception if there is an error with getting this info, eg. not binded
+     * @see ViaPlatform#isProxy()
      */
     int getServerProtocolVersion() throws Exception;
 
+    /**
+     * Returns the supported server protocol versions.
+     *
+     * @return server protocol versions
+     * @throws Exception if there is an error with getting this info, eg. not binded
+     * @see ViaPlatform#isProxy()
+     */
+    default IntSortedSet getServerProtocolVersions() throws Exception {
+        return IntSortedSets.singleton(getServerProtocolVersion());
+    }
+
     /**
      * Get the name of the encoder for then netty pipeline for this platform.
      *

api/src/main/java/us/myles/ViaVersion/api/protocol/ProtocolManager.java

@@ -32,12 +32,11 @@ import java.util.concurrent.CompletableFuture;
 public interface ProtocolManager {
 
     /**
-     * Returns the server protocol version, or -1 if not set.
+     * Returns the server protocol version. Its methods will return -1 if not set yet.
-     * In the case of proxies, this returns the lowest supported protocol version.
      *
-     * @return server protocol version, or -1 if not set
+     * @return server protocol version
      */
-    int getServerProtocol();
+    ServerProtocolVersion getServerProtocolVersion();
 
     /**
      * Returns a protocol instance by its class.

api/src/main/java/us/myles/ViaVersion/api/protocol/ServerProtocolVersion.java

@@ -0,0 +1,57 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2021 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package us.myles.ViaVersion.api.protocol;
+
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
+
+public interface ServerProtocolVersion {
+
+    /**
+     * Returns the lowest supported protocol version by this server.
+     * This and {@link #highestSupportedVersion()} should only differ on proxy servers supporting multiple versions.
+     *
+     * @return lowest supported protocol version
+     */
+    int lowestSupportedVersion();
+
+    /**
+     * Returns the lowest supported protocol version by this server.
+     * This and {@link #lowestSupportedVersion()} should only differ on proxy servers supporting multiple versions.
+     *
+     * @return highest supported protocol version
+     */
+    int highestSupportedVersion();
+
+    /**
+     * Returns a sorted set of all supported protocol version by this server.
+     * For non-proxy servers, this should return a singleton set.
+     *
+     * @return sorted set of supported protocol versions
+     */
+    IntSortedSet supportedVersions();
+
+    /**
+     * Returns true if the actual protocol version has not yet been identified.
+     * In that case, all methods above will returns -1.
+     *
+     * @return true if unset
+     */
+    default boolean isKnown() {
+        return lowestSupportedVersion() != -1 && highestSupportedVersion() != -1;
+    }
+}

api/src/main/java/us/myles/ViaVersion/protocols/base/VersionProvider.java

@@ -27,5 +27,11 @@ import us.myles.ViaVersion.api.platform.providers.Provider;
 
 public interface VersionProvider extends Provider {
 
+    /**
+     * Returns the closest server protocol version to the user's protocol version.
+     *
+     * @param connection connection
+     * @return closest server protocol version to the user's protocol version
+     */
     int getServerProtocol(UserConnection connection) throws Exception;
 }

buildSrc/src/main/kotlin/extensions.kt

@@ -70,8 +70,6 @@ private fun ShadowJar.configureExcludes() {
     exclude("it/unimi/dsi/fastutil/*/*Char*")
     // Map types
     exclude("it/unimi/dsi/fastutil/*/*Custom*")
-    exclude("it/unimi/dsi/fastutil/*/*Linked*")
-    exclude("it/unimi/dsi/fastutil/*/*Sorted*")
     exclude("it/unimi/dsi/fastutil/*/*Tree*")
     exclude("it/unimi/dsi/fastutil/*/*Heap*")
     exclude("it/unimi/dsi/fastutil/*/*Queue*")

bukkit/src/main/java/us/myles/ViaVersion/bukkit/listeners/multiversion/PlayerSneakListener.java

@@ -68,7 +68,7 @@ public class PlayerSneakListener extends ViaBukkitListener {
 
 
         // From 1.9 upwards the server hitbox is set in every entity tick, so we have to reset it everytime
-        if (Via.getAPI().getServerVersion() >= ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() >= ProtocolVersion.v1_9.getVersion()) {
             sneaking = new WeakHashMap<>();
             useCache = true;
             plugin.getServer().getScheduler().runTaskTimer(plugin, new Runnable() {

bukkit/src/main/java/us/myles/ViaVersion/bukkit/platform/BukkitViaInjector.java

@@ -179,6 +179,11 @@ public class BukkitViaInjector implements ViaInjector {
         injectedLists.clear();
     }
 
+    @Override
+    public boolean lateProtocolVersionSetting() {
+        return true;
+    }
+
     @Override
     public int getServerProtocolVersion() throws Exception {
         try {

bukkit/src/main/java/us/myles/ViaVersion/bukkit/platform/BukkitViaLoader.java

@@ -85,9 +85,10 @@ public class BukkitViaLoader implements ViaPlatformLoader {
 
         // Add ProtocolSupport ConnectListener if necessary.
         ClassGenerator.registerPSConnectListener(plugin);
+        int serverProtocolVersion = Via.getAPI().getServerVersion().lowestSupportedVersion();
 
         /* 1.9 client to 1.8 server */
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_9.getVersion()) {
             storeListener(new ArmorListener(plugin)).register();
             storeListener(new DeathListener(plugin)).register();
             storeListener(new BlockListener(plugin)).register();
@@ -98,8 +99,8 @@ public class BukkitViaLoader implements ViaPlatformLoader {
             }
         }
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_14.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_14.getVersion()) {
-            boolean use1_9Fix = plugin.getConf().is1_9HitboxFix() && Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion();
+            boolean use1_9Fix = plugin.getConf().is1_9HitboxFix() && serverProtocolVersion < ProtocolVersion.v1_9.getVersion();
             if (use1_9Fix || plugin.getConf().is1_14HitboxFix()) {
                 try {
                     storeListener(new PlayerSneakListener(plugin, use1_9Fix, plugin.getConf().is1_14HitboxFix())).register();
@@ -110,7 +111,7 @@ public class BukkitViaLoader implements ViaPlatformLoader {
             }
         }
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_15.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_15.getVersion()) {
             try {
                 Class.forName("org.bukkit.event.entity.EntityToggleGlideEvent");
                 storeListener(new EntityToggleGlideListener(plugin)).register();
@@ -121,13 +122,13 @@ public class BukkitViaLoader implements ViaPlatformLoader {
         if ((Bukkit.getVersion().toLowerCase(Locale.ROOT).contains("paper")
                 || Bukkit.getVersion().toLowerCase(Locale.ROOT).contains("taco")
                 || Bukkit.getVersion().toLowerCase(Locale.ROOT).contains("torch"))
-                && Via.getAPI().getServerVersion() < ProtocolVersion.v1_12.getVersion()) {
+                && serverProtocolVersion < ProtocolVersion.v1_12.getVersion()) {
             plugin.getLogger().info("Enabling Paper/TacoSpigot/Torch patch: Fixes block placement.");
             storeListener(new PaperPatch(plugin)).register();
         }
 
         /* Providers */
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_9.getVersion()) {
             Via.getManager().getProviders().use(BulkChunkTranslatorProvider.class, new BukkitViaBulkChunkTranslator());
             Via.getManager().getProviders().use(MovementTransmitterProvider.class, new BukkitViaMovementTransmitter());
 
@@ -156,12 +157,12 @@ public class BukkitViaLoader implements ViaPlatformLoader {
             });
         }
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_12.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_12.getVersion()) {
             if (plugin.getConf().is1_12QuickMoveActionFix()) {
                 Via.getManager().getProviders().use(InventoryQuickMoveProvider.class, new BukkitInventoryQuickMoveProvider());
             }
         }
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_13.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_13.getVersion()) {
             if (Via.getConfig().getBlockConnectionMethod().equalsIgnoreCase("world")) {
                 BukkitBlockConnectionProvider blockConnectionProvider = new BukkitBlockConnectionProvider();
                 Via.getManager().getProviders().use(BlockConnectionProvider.class, blockConnectionProvider);

bukkit/src/main/java/us/myles/ViaVersion/bukkit/providers/BukkitInventoryQuickMoveProvider.java

@@ -70,7 +70,7 @@ public class BukkitInventoryQuickMoveProvider extends InventoryQuickMoveProvider
             // windowId is always 0 for player inventory.
             // This has almost definitely something to do with the offhand slot.
             if (slotId >= 36 && slotId <= 44) {
-                int protocolId = Via.getAPI().getServerVersion();
+                int protocolId = Via.getAPI().getServerVersion().lowestSupportedVersion();
                 // this seems to be working just fine.
                 if (protocolId == ProtocolVersion.v1_8.getVersion()) {
                     return false;
@@ -102,7 +102,7 @@ public class BukkitInventoryQuickMoveProvider extends InventoryQuickMoveProvider
         Inventory tinv = inv.getTopInventory();
         InventoryType tinvtype = tinv == null ? null : tinv.getType(); // can this even be null?
         if (tinvtype != null) {
-            int protocolId = Via.getAPI().getServerVersion();
+            int protocolId = Via.getAPI().getServerVersion().lowestSupportedVersion();
             if (protocolId == ProtocolVersion.v1_8.getVersion()) {
                 if (tinvtype == InventoryType.BREWING) {
                     // 1.9 added the blaze powder slot to brewing stand fix for 1.8 servers
@@ -131,7 +131,7 @@ public class BukkitInventoryQuickMoveProvider extends InventoryQuickMoveProvider
             ReflectionUtil.set(packet, "button", 0); // shift + left mouse click
             ReflectionUtil.set(packet, "d", storage.getActionId());
             ReflectionUtil.set(packet, "item", nmsItem);
-            int protocolId = Via.getAPI().getServerVersion();
+            int protocolId = Via.getAPI().getServerVersion().lowestSupportedVersion();
             if (protocolId == ProtocolVersion.v1_8.getVersion()) {
                 ReflectionUtil.set(packet, "shift", 1);
             } else if (protocolId >= ProtocolVersion.v1_9.getVersion()) { // 1.9+
@@ -170,7 +170,7 @@ public class BukkitInventoryQuickMoveProvider extends InventoryQuickMoveProvider
         }
         try {
             this.windowClickPacketClass = NMSUtil.nms("PacketPlayInWindowClick");
-            int protocolId = Via.getAPI().getServerVersion();
+            int protocolId = Via.getAPI().getServerVersion().lowestSupportedVersion();
             if (protocolId >= ProtocolVersion.v1_9.getVersion()) {
                 Class<?> eclassz = NMSUtil.nms("InventoryClickType");
                 Object[] constants = eclassz.getEnumConstants();
@@ -199,7 +199,7 @@ public class BukkitInventoryQuickMoveProvider extends InventoryQuickMoveProvider
     }
 
     private boolean isSupported() {
-        int protocolId = Via.getAPI().getServerVersion();
+        int protocolId = Via.getAPI().getServerVersion().lowestSupportedVersion();
         if (protocolId >= ProtocolVersion.v1_8.getVersion() && protocolId <= ProtocolVersion.v1_11_1.getVersion()) {
             return true; // 1.8-1.11.2
         }

bungee/src/main/java/us/myles/ViaVersion/BungeePlugin.java

@@ -56,7 +56,7 @@ public class BungeePlugin extends Plugin implements ViaPlatform<ProxiedPlayer>,
     @Override
     public void onLoad() {
         try {
-            ProtocolConstants.class.getField("MINECRAFT_1_16_3");
+            ProtocolConstants.class.getField("MINECRAFT_1_16_4");
         } catch (NoSuchFieldException e) {
             getLogger().warning("      / \\");
             getLogger().warning("     /   \\");

bungee/src/main/java/us/myles/ViaVersion/bungee/platform/BungeeViaInjector.java

@@ -20,6 +20,8 @@ package us.myles.ViaVersion.bungee.platform;
 import com.google.gson.JsonObject;
 import io.netty.channel.Channel;
 import io.netty.channel.ChannelInitializer;
+import it.unimi.dsi.fastutil.ints.IntLinkedOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.ViaInjector;
 import us.myles.ViaVersion.bungee.handlers.BungeeChannelInitializer;
@@ -77,7 +79,16 @@ public class BungeeViaInjector implements ViaInjector {
 
     @Override
     public int getServerProtocolVersion() throws Exception {
-        return (int) ReflectionUtil.getStatic(Class.forName("net.md_5.bungee.protocol.ProtocolConstants"), "SUPPORTED_VERSION_IDS", List.class).get(0);
+        return getBungeeSupportedVersions().get(0);
+    }
+
+    @Override
+    public IntSortedSet getServerProtocolVersions() throws Exception {
+        return new IntLinkedOpenHashSet(getBungeeSupportedVersions());
+    }
+
+    private List<Integer> getBungeeSupportedVersions() throws Exception {
+        return ReflectionUtil.getStatic(Class.forName("net.md_5.bungee.protocol.ProtocolConstants"), "SUPPORTED_VERSION_IDS", List.class);
     }
 
     @Override

bungee/src/main/java/us/myles/ViaVersion/bungee/platform/BungeeViaLoader.java

@@ -65,7 +65,7 @@ public class BungeeViaLoader implements ViaPlatformLoader {
         registerListener(new UpdateListener());
         registerListener(new BungeeServerHandler());
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() < ProtocolVersion.v1_9.getVersion()) {
             registerListener(new ElytraPatch());
         }
 
@@ -73,7 +73,7 @@ public class BungeeViaLoader implements ViaPlatformLoader {
         Via.getManager().getProviders().use(VersionProvider.class, new BungeeVersionProvider());
         Via.getManager().getProviders().use(EntityIdProvider.class, new BungeeEntityIdProvider());
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() < ProtocolVersion.v1_9.getVersion()) {
             Via.getManager().getProviders().use(MovementTransmitterProvider.class, new BungeeMovementTransmitter());
             Via.getManager().getProviders().use(BossBarProvider.class, new BungeeBossBarProvider());
             Via.getManager().getProviders().use(MainHandProvider.class, new BungeeMainHandProvider());

common/src/main/java/us/myles/ViaVersion/ViaManagerImpl.java

@@ -17,6 +17,7 @@
  */
 package us.myles.ViaVersion;
 
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.TaskId;
 import us.myles.ViaVersion.api.platform.ViaConnectionManager;
@@ -27,12 +28,16 @@ import us.myles.ViaVersion.api.platform.providers.ViaProviders;
 import us.myles.ViaVersion.api.protocol.ProtocolManager;
 import us.myles.ViaVersion.api.protocol.ProtocolManagerImpl;
 import us.myles.ViaVersion.api.protocol.ProtocolVersion;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersion;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersionRange;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersionSingleton;
 import us.myles.ViaVersion.commands.ViaCommandHandler;
 import us.myles.ViaVersion.protocols.protocol1_13to1_12_2.TabCompleteThread;
 import us.myles.ViaVersion.protocols.protocol1_9to1_8.ViaIdleThread;
 import us.myles.ViaVersion.update.UpdateUtil;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -71,6 +76,11 @@ public class ViaManagerImpl implements ViaManager {
             UpdateUtil.sendUpdateMessage();
         }
 
+        // Load supported protocol versions if we can
+        if (!injector.lateProtocolVersionSetting()) {
+            loadServerProtocol();
+        }
+
         // Register protocols
         protocolManager.registerProtocols();
 
@@ -96,24 +106,33 @@ public class ViaManagerImpl implements ViaManager {
     }
 
     public void onServerLoaded() {
-        // Load Server Protocol
+        if (!protocolManager.getServerProtocolVersion().isKnown()) {
-        try {
+            // Try again
-            protocolManager.setServerProtocol(ProtocolVersion.getProtocol(injector.getServerProtocolVersion()).getVersion());
+            loadServerProtocol();
-        } catch (Exception e) {
-            platform.getLogger().severe("ViaVersion failed to get the server protocol!");
-            e.printStackTrace();
         }
 
         // Check if there are any pipes to this version
-        if (protocolManager.getServerProtocol() != -1) {
+        ServerProtocolVersion protocolVersion = protocolManager.getServerProtocolVersion();
-            platform.getLogger().info("ViaVersion detected server version: " + ProtocolVersion.getProtocol(protocolManager.getServerProtocol()));
+        if (protocolVersion.isKnown()) {
-            if (!protocolManager.isWorkingPipe() && !platform.isProxy()) {
+            if (platform.isProxy()) {
+                platform.getLogger().info("ViaVersion detected lowest supported versions by the proxy: "
+                        + ProtocolVersion.getProtocol(protocolVersion.lowestSupportedVersion())
+                        + "\nHighest supported version by the proxy: "
+                        + ProtocolVersion.getProtocol(protocolVersion.highestSupportedVersion()));
+                if (debug) {
+                    platform.getLogger().info("Supported version range: " + Arrays.toString(protocolVersion.supportedVersions().toArray(new int[0])));
+                }
+            } else {
+                platform.getLogger().info("ViaVersion detected server version: " + ProtocolVersion.getProtocol(protocolVersion.highestSupportedVersion()));
+            }
+
+            if (!protocolManager.isWorkingPipe()) {
                 platform.getLogger().warning("ViaVersion does not have any compatible versions for this server version!");
                 platform.getLogger().warning("Please remember that ViaVersion only adds support for versions newer than the server version.");
                 platform.getLogger().warning("If you need support for older versions you may need to use one or more ViaVersion addons too.");
                 platform.getLogger().warning("In that case please read the ViaVersion resource page carefully or use https://jo0001.github.io/ViaSetup");
                 platform.getLogger().warning("and if you're still unsure, feel free to join our Discord-Server for further assistance.");
-            } else if (protocolManager.getServerProtocol() <= ProtocolVersion.v1_12_2.getVersion() && !platform.isProxy()) {
+            } else if (protocolVersion.highestSupportedVersion() <= ProtocolVersion.v1_12_2.getVersion()) {
                 platform.getLogger().warning("This version of Minecraft is extremely outdated and support for it has reached its end of life. "
                         + "You will still be able to run Via on this version, but we are unlikely to provide any further fixes or help with problems specific to legacy versions. "
                         + "Please consider updating to give your players a better experience and to avoid issues that have long been fixed.");
@@ -132,12 +151,14 @@ public class ViaManagerImpl implements ViaManager {
                 mappingLoadingTask = null;
             }
         }, 10L);
-        if (protocolManager.getServerProtocol() < ProtocolVersion.v1_9.getVersion()) {
+
+        int serverProtocolVersion = protocolManager.getServerProtocolVersion().lowestSupportedVersion();
+        if (serverProtocolVersion < ProtocolVersion.v1_9.getVersion()) {
             if (Via.getConfig().isSimulatePlayerTick()) {
                 Via.getPlatform().runRepeatingSync(new ViaIdleThread(), 1L);
             }
         }
-        if (protocolManager.getServerProtocol() < ProtocolVersion.v1_13.getVersion()) {
+        if (serverProtocolVersion < ProtocolVersion.v1_13.getVersion()) {
             if (Via.getConfig().get1_13TabCompleteDelay() > 0) {
                 Via.getPlatform().runRepeatingSync(new TabCompleteThread(), 1L);
             }
@@ -147,6 +168,24 @@ public class ViaManagerImpl implements ViaManager {
         protocolManager.refreshVersions();
     }
 
+    private void loadServerProtocol() {
+        try {
+            ProtocolVersion serverProtocolVersion = ProtocolVersion.getProtocol(injector.getServerProtocolVersion());
+            ServerProtocolVersion versionInfo;
+            if (platform.isProxy()) {
+                IntSortedSet supportedVersions = injector.getServerProtocolVersions();
+                versionInfo = new ServerProtocolVersionRange(supportedVersions.firstInt(), supportedVersions.lastInt(), supportedVersions);
+            } else {
+                versionInfo = new ServerProtocolVersionSingleton(serverProtocolVersion.getVersion());
+            }
+
+            protocolManager.setServerProtocol(versionInfo);
+        } catch (Exception e) {
+            platform.getLogger().severe("ViaVersion failed to get the server protocol!");
+            e.printStackTrace();
+        }
+    }
+
     public void destroy() {
         // Uninject
         platform.getLogger().info("ViaVersion is disabling, if this is a reload and you experience issues consider rebooting.");

common/src/main/java/us/myles/ViaVersion/api/ViaAPIBase.java

@@ -19,6 +19,7 @@ package us.myles.ViaVersion.api;
 
 import io.netty.buffer.ByteBuf;
 import us.myles.ViaVersion.api.data.UserConnection;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersion;
 
 import java.util.SortedSet;
 import java.util.TreeSet;
@@ -27,8 +28,8 @@ import java.util.UUID;
 public abstract class ViaAPIBase<T> implements ViaAPI<T> {
 
     @Override
-    public int getServerVersion() {
+    public ServerProtocolVersion getServerVersion() {
-        return Via.getManager().getProtocolManager().getServerProtocol();
+        return Via.getManager().getProtocolManager().getServerProtocolVersion();
     }
 
     @Override

common/src/main/java/us/myles/ViaVersion/api/protocol/ProtocolManagerImpl.java

@@ -95,8 +95,8 @@ public class ProtocolManagerImpl implements ProtocolManager {
     private ThreadPoolExecutor mappingLoaderExecutor;
     private boolean mappingsLoaded;
 
+    private ServerProtocolVersion serverProtocolVersion = new ServerProtocolVersionSingleton(-1);
     private int maxProtocolPathSize = 50;
-    private int serverProtocol = -1;
 
     public ProtocolManagerImpl() {
         ThreadFactory threadFactory = new ThreadFactoryBuilder().setNameFormat("Via-Mappingloader-%d").build();
@@ -199,9 +199,9 @@ public class ProtocolManagerImpl implements ProtocolManager {
     public void refreshVersions() {
         supportedVersions.clear();
 
-        supportedVersions.add(serverProtocol);
+        supportedVersions.add(serverProtocolVersion.lowestSupportedVersion());
         for (ProtocolVersion versions : ProtocolVersion.getProtocols()) {
-            List<ProtocolPathEntry> paths = getProtocolPath(versions.getVersion(), serverProtocol);
+            List<ProtocolPathEntry> paths = getProtocolPath(versions.getVersion(), serverProtocolVersion.lowestSupportedVersion());
             if (paths == null) continue;
             supportedVersions.add(versions.getVersion());
             for (ProtocolPathEntry path : paths) {
@@ -309,19 +309,23 @@ public class ProtocolManagerImpl implements ProtocolManager {
     }
 
     @Override
-    public int getServerProtocol() {
+    public ServerProtocolVersion getServerProtocolVersion() {
-        return serverProtocol;
+        return serverProtocolVersion;
     }
 
-    public void setServerProtocol(int serverProtocol) {
+    public void setServerProtocol(ServerProtocolVersion serverProtocolVersion) {
-        this.serverProtocol = serverProtocol;
+        this.serverProtocolVersion = serverProtocolVersion;
-        ProtocolRegistry.SERVER_PROTOCOL = serverProtocol;
+        ProtocolRegistry.SERVER_PROTOCOL = serverProtocolVersion.lowestSupportedVersion();
     }
 
     @Override
     public boolean isWorkingPipe() {
         for (Int2ObjectMap<Protocol> map : registryMap.values()) {
-            if (map.containsKey(serverProtocol)) return true;
+            for (int protocolVersion : serverProtocolVersion.supportedVersions()) {
+                if (map.containsKey(protocolVersion)) {
+                    return true;
+                }
+            }
         }
         return false; // No destination for protocol
     }

common/src/main/java/us/myles/ViaVersion/api/protocol/ServerProtocolVersionRange.java

@@ -0,0 +1,47 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2021 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package us.myles.ViaVersion.api.protocol;
+
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
+
+public class ServerProtocolVersionRange implements ServerProtocolVersion {
+    private final int lowestSupportedVersion;
+    private final int highestSupportedVersion;
+    private final IntSortedSet supportedVersions;
+
+    public ServerProtocolVersionRange(int lowestSupportedVersion, int highestSupportedVersion, IntSortedSet supportedVersions) {
+        this.lowestSupportedVersion = lowestSupportedVersion;
+        this.highestSupportedVersion = highestSupportedVersion;
+        this.supportedVersions = supportedVersions;
+    }
+
+    @Override
+    public int lowestSupportedVersion() {
+        return lowestSupportedVersion;
+    }
+
+    @Override
+    public int highestSupportedVersion() {
+        return highestSupportedVersion;
+    }
+
+    @Override
+    public IntSortedSet supportedVersions() {
+        return supportedVersions;
+    }
+}

common/src/main/java/us/myles/ViaVersion/api/protocol/ServerProtocolVersionSingleton.java

@@ -0,0 +1,44 @@
+/*
+ * This file is part of ViaVersion - https://github.com/ViaVersion/ViaVersion
+ * Copyright (C) 2016-2021 ViaVersion and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+package us.myles.ViaVersion.api.protocol;
+
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
+import it.unimi.dsi.fastutil.ints.IntSortedSets;
+
+public class ServerProtocolVersionSingleton implements ServerProtocolVersion {
+    private final int protocolVersion;
+
+    public ServerProtocolVersionSingleton(int protocolVersion) {
+        this.protocolVersion = protocolVersion;
+    }
+
+    @Override
+    public int lowestSupportedVersion() {
+        return protocolVersion;
+    }
+
+    @Override
+    public int highestSupportedVersion() {
+        return protocolVersion;
+    }
+
+    @Override
+    public IntSortedSet supportedVersions() {
+        return IntSortedSets.singleton(protocolVersion);
+    }
+}

common/src/main/java/us/myles/ViaVersion/commands/defaultsubs/DumpSubCmd.java

@@ -53,7 +53,7 @@ public class DumpSubCmd extends ViaSubCommand {
         VersionInfo version = new VersionInfo(
                 System.getProperty("java.version"),
                 System.getProperty("os.name"),
-                Via.getAPI().getServerVersion(),
+                Via.getAPI().getServerVersion().lowestSupportedVersion(),
                 Via.getManager().getProtocolManager().getSupportedVersions(),
                 Via.getPlatform().getPlatformName(),
                 Via.getPlatform().getPlatformVersion(),

common/src/main/java/us/myles/ViaVersion/protocols/base/BaseProtocol1_7.java

@@ -27,6 +27,7 @@ import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.protocol.ProtocolManagerImpl;
 import us.myles.ViaVersion.api.protocol.ProtocolPathEntry;
 import us.myles.ViaVersion.api.protocol.ProtocolVersion;
+import us.myles.ViaVersion.api.protocol.ServerProtocolVersionSingleton;
 import us.myles.ViaVersion.api.protocol.SimpleProtocol;
 import us.myles.ViaVersion.api.remapper.PacketHandler;
 import us.myles.ViaVersion.api.remapper.PacketRemapper;
@@ -80,9 +81,9 @@ public class BaseProtocol1_7 extends SimpleProtocol {
                                 version.add("supportedVersions", GsonUtil.getGson().toJsonTree(Via.getAPI().getSupportedVersions()));
                             }
 
-                            if (Via.getAPI().getServerVersion() == -1) { // Set the Server protocol if the detection on startup failed
+                            if (!Via.getAPI().getServerVersion().isKnown()) { // Set the Server protocol if the detection on startup failed
                                 ProtocolManagerImpl protocolManager = (ProtocolManagerImpl) Via.getManager().getProtocolManager();
-                                protocolManager.setServerProtocol(ProtocolVersion.getProtocol(protocolVersion).getVersion());
+                                protocolManager.setServerProtocol(new ServerProtocolVersionSingleton(ProtocolVersion.getProtocol(protocolVersion).getVersion()));
                             }
 
                             // Ensure the server has a version provider
@@ -92,16 +93,14 @@ public class BaseProtocol1_7 extends SimpleProtocol {
                                 return;
                             }
 
-                            int protocol = versionProvider.getServerProtocol(wrapper.user());
+                            int closestServerProtocol = versionProvider.getServerProtocol(wrapper.user());
                             List<ProtocolPathEntry> protocols = null;
-
+                            if (info.getProtocolVersion() >= closestServerProtocol || Via.getPlatform().isOldClientsAllowed()) {
-                            // Only allow newer clients or (1.9.2 on 1.9.4 server if the server supports it)
+                                protocols = Via.getManager().getProtocolManager().getProtocolPath(info.getProtocolVersion(), closestServerProtocol);
-                            if (info.getProtocolVersion() >= protocol || Via.getPlatform().isOldClientsAllowed()) {
-                                protocols = Via.getManager().getProtocolManager().getProtocolPath(info.getProtocolVersion(), protocol);
                             }
 
                             if (protocols != null) {
-                                if (protocolVersion == protocol || protocolVersion == 0) { // Fix ServerListPlus
+                                if (protocolVersion == closestServerProtocol || protocolVersion == 0) { // Fix ServerListPlus
                                     ProtocolVersion prot = ProtocolVersion.getProtocol(info.getProtocolVersion());
                                     version.addProperty("protocol", prot.getOriginalVersion());
                                 }

common/src/main/java/us/myles/ViaVersion/protocols/base/BaseVersionProvider.java

@@ -23,6 +23,6 @@ import us.myles.ViaVersion.api.data.UserConnection;
 public class BaseVersionProvider implements VersionProvider {
 
     public int getServerProtocol(UserConnection connection) throws Exception {
-        return Via.getAPI().getServerVersion();
+        return Via.getAPI().getServerVersion().lowestSupportedVersion();
     }
 }

sponge/src/main/java/us/myles/ViaVersion/sponge/handlers/SpongeChannelInitializer.java

@@ -47,7 +47,7 @@ public class SpongeChannelInitializer extends ChannelInitializer<Channel> {
     @Override
     protected void initChannel(Channel channel) throws Exception {
         // Ensure ViaVersion is loaded
-        if (Via.getAPI().getServerVersion() != -1
+        if (Via.getAPI().getServerVersion().isKnown()
                 && channel instanceof SocketChannel) { // channel can be LocalChannel on internal server
             UserConnection info = new UserConnection((SocketChannel) channel);
             // init protocol

sponge/src/main/java/us/myles/ViaVersion/sponge/platform/SpongeViaInjector.java

@@ -120,6 +120,11 @@ public class SpongeViaInjector implements ViaInjector {
         }
     }
 
+    @Override
+    public boolean lateProtocolVersionSetting() {
+        return true;
+    }
+
     @Override
     public void uninject() {
         // TODO: Uninject from players currently online

sponge/src/main/java/us/myles/ViaVersion/sponge/platform/SpongeViaLoader.java

@@ -66,7 +66,7 @@ public class SpongeViaLoader implements ViaPlatformLoader {
         registerListener(new UpdateListener());
 
         /* 1.9 client to 1.8 server */
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() < ProtocolVersion.v1_9.getVersion()) {
             try {
                 Class.forName("org.spongepowered.api.event.entity.DisplaceEntityEvent");
                 storeListener(new Sponge4ArmorListener()).register();
@@ -83,7 +83,7 @@ public class SpongeViaLoader implements ViaPlatformLoader {
         }
 
         /* Providers */
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() < ProtocolVersion.v1_9.getVersion()) {
             Via.getManager().getProviders().use(BulkChunkTranslatorProvider.class, new SpongeViaBulkChunkTranslator());
             Via.getManager().getProviders().use(MovementTransmitterProvider.class, new SpongeViaMovementTransmitter());
 

velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaInjector.java

@@ -19,6 +19,8 @@ package us.myles.ViaVersion.velocity.platform;
 
 import com.google.gson.JsonObject;
 import io.netty.channel.ChannelInitializer;
+import it.unimi.dsi.fastutil.ints.IntLinkedOpenHashSet;
+import it.unimi.dsi.fastutil.ints.IntSortedSet;
 import us.myles.ViaVersion.VelocityPlugin;
 import us.myles.ViaVersion.api.Via;
 import us.myles.ViaVersion.api.platform.ViaInjector;
@@ -79,11 +81,26 @@ public class VelocityViaInjector implements ViaInjector {
         return getLowestSupportedProtocolVersion();
     }
 
+    @Override
+    public IntSortedSet getServerProtocolVersions() throws Exception {
+        int lowestSupportedProtocolVersion = getLowestSupportedProtocolVersion();
+
+        IntSortedSet set = new IntLinkedOpenHashSet();
+        for (com.velocitypowered.api.network.ProtocolVersion version : com.velocitypowered.api.network.ProtocolVersion.SUPPORTED_VERSIONS) {
+            if (version.getProtocol() >= lowestSupportedProtocolVersion) {
+                set.add(version.getProtocol());
+            }
+        }
+        return set;
+    }
+
     public static int getLowestSupportedProtocolVersion() {
         try {
             if (getPlayerInfoForwardingMode != null
                     && ((Enum<?>) getPlayerInfoForwardingMode.invoke(VelocityPlugin.PROXY.getConfiguration()))
-                    .name().equals("MODERN")) return ProtocolVersion.v1_13.getVersion();
+                    .name().equals("MODERN")) {
+                return ProtocolVersion.v1_13.getVersion();
+            }
         } catch (IllegalAccessException | InvocationTargetException ignored) {
         }
         return com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION.getProtocol();

velocity/src/main/java/us/myles/ViaVersion/velocity/platform/VelocityViaLoader.java

@@ -37,7 +37,7 @@ public class VelocityViaLoader implements ViaPlatformLoader {
         Object plugin = VelocityPlugin.PROXY.getPluginManager()
                 .getPlugin("viaversion").flatMap(PluginContainer::getInstance).get();
 
-        if (Via.getAPI().getServerVersion() < ProtocolVersion.v1_9.getVersion()) {
+        if (Via.getAPI().getServerVersion().lowestSupportedVersion() < ProtocolVersion.v1_9.getVersion()) {
             Via.getManager().getProviders().use(MovementTransmitterProvider.class, new VelocityMovementTransmitter());
             Via.getManager().getProviders().use(BossBarProvider.class, new VelocityBossBarProvider());
         }