Snapshot 21w15a

api/src/main/java/com/velocitypowered/api/event/player/PlayerResourcePackStatusEvent.java

@@ -8,7 +8,11 @@
 package com.velocitypowered.api.event.player;
 
 import com.google.common.base.Preconditions;
+import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.Player;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * This event is fired when the status of a resource pack sent to the player by the server is
@@ -18,10 +22,29 @@ public class PlayerResourcePackStatusEvent {
 
   private final Player player;
   private final Status status;
+  private final @MonotonicNonNull ResourcePackInfo packInfo;
+  private boolean overwriteKick;
 
+
+  /**
+   * Instates this event.
+   * @deprecated Use {@link PlayerResourcePackStatusEvent#PlayerResourcePackStatusEvent
+   *             (Player, Status, ResourcePackInfo)} instead.
+   */
+  @Deprecated
   public PlayerResourcePackStatusEvent(Player player, Status status) {
     this.player = Preconditions.checkNotNull(player, "player");
     this.status = Preconditions.checkNotNull(status, "status");
+    this.packInfo = null;
+  }
+
+  /**
+   * Instates this event.
+   */
+  public PlayerResourcePackStatusEvent(Player player, Status status, ResourcePackInfo packInfo) {
+    this.player = Preconditions.checkNotNull(player, "player");
+    this.status = Preconditions.checkNotNull(status, "status");
+    this.packInfo = packInfo;
   }
 
   /**
@@ -42,11 +65,49 @@ public class PlayerResourcePackStatusEvent {
     return status;
   }
 
+  /**
+   * Returns the {@link ResourcePackInfo} this response is for.
+   *
+   * @return the resource-pack info or null if no request was recorded
+   */
+  @Nullable
+  public ResourcePackInfo getPackInfo() {
+    return packInfo;
+  }
+
+  /**
+   * Gets whether or not to override the kick resulting from
+   * {@link ResourcePackInfo#getShouldForce()} being true.
+   *
+   * @return whether or not to overwrite the result
+   */
+  public boolean isOverwriteKick() {
+    return overwriteKick;
+  }
+
+  /**
+   * Set to true to prevent {@link ResourcePackInfo#getShouldForce()}
+   * from kicking the player.
+   * Overwriting this kick is only possible on versions older than 1.17,
+   * as the client or server will enforce this regardless. Cancelling the resulting
+   * kick-events will not prevent the player from disconnecting from the proxy.
+   *
+   * @param overwriteKick whether or not to cancel the kick
+   * @throws IllegalArgumentException if the player version is 1.17 or newer
+   */
+  public void setOverwriteKick(boolean overwriteKick) {
+    Preconditions.checkArgument(player.getProtocolVersion()
+            .compareTo(ProtocolVersion.MINECRAFT_1_17) < 0,
+            "overwriteKick is not supported on 1.17 or newer");
+    this.overwriteKick = overwriteKick;
+  }
+
   @Override
   public String toString() {
     return "PlayerResourcePackStatusEvent{"
         + "player=" + player
         + ", status=" + status
+        + ", packInfo=" + packInfo
         + '}';
   }
 

api/src/main/java/com/velocitypowered/api/network/ProtocolVersion.java

@@ -54,7 +54,7 @@ public enum ProtocolVersion {
   MINECRAFT_1_16_2(751, "1.16.2"),
   MINECRAFT_1_16_3(753, "1.16.3"),
   MINECRAFT_1_16_4(754, "1.16.4", "1.16.5"),
-  MINECRAFT_1_17(-1, 21, "1.17"); // Snapshot: 21w14a, future protocol: 755
+  MINECRAFT_1_17(-1, 22, "1.17"); // Snapshot: 21w15a, future protocol: 755
 
   private static final int SNAPSHOT_BIT = 30;
 

api/src/main/java/com/velocitypowered/api/proxy/Player.java

@@ -13,6 +13,7 @@ import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSink;
 import com.velocitypowered.api.proxy.messages.ChannelMessageSource;
 import com.velocitypowered.api.proxy.player.PlayerSettings;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.api.proxy.player.TabList;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
@@ -25,6 +26,7 @@ import java.util.UUID;
 import net.kyori.adventure.identity.Identified;
 import net.kyori.adventure.identity.Identity;
 import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
  * Represents a player who is connected to the proxy.
@@ -215,7 +217,9 @@ public interface Player extends CommandSource, Identified, InboundConnection,
    * sent resource pack, subscribe to {@link PlayerResourcePackStatusEvent}.
    *
    * @param url the URL for the resource pack
+   * @deprecated Use {@link #sendResourcePackOffer(ResourcePackInfo)} instead
    */
+  @Deprecated
   void sendResourcePack(String url);
 
   /**
@@ -225,10 +229,37 @@ public interface Player extends CommandSource, Identified, InboundConnection,
    *
    * @param url the URL for the resource pack
    * @param hash the SHA-1 hash value for the resource pack
+   * @deprecated Use {@link #sendResourcePackOffer(ResourcePackInfo)} instead
    */
-  default void sendResourcePack(String url, byte[] hash) {
-    sendResourcePack(url, hash, false);
-  }
+  @Deprecated
+  void sendResourcePack(String url, byte[] hash);
+
+  /**
+   * Queues and sends a new Resource-pack offer to the player.
+   * To monitor the status of the sent resource pack, subscribe to
+   * {@link PlayerResourcePackStatusEvent}.
+   *
+   * @param packInfo the resource-pack in question
+   */
+  void sendResourcePackOffer(ResourcePackInfo packInfo);
+
+  /**
+   * Gets the {@link ResourcePackInfo} of the currently applied
+   * resource-pack or null if none.
+   *
+   * @return the applied resource pack
+   */
+  @Nullable
+  ResourcePackInfo getAppliedResourcePack();
+
+  /**
+   * Gets the {@link ResourcePackInfo} of the currently accepted
+   * and currently downloading resource-pack or null if none.
+   *
+   * @return the pending resource pack
+   */
+  @Nullable
+  ResourcePackInfo getPendingResourcePack();
 
   /**
    * <strong>Note that this method does not send a plugin message to the server the player
@@ -241,21 +272,4 @@ public interface Player extends CommandSource, Identified, InboundConnection,
    */
   @Override
   boolean sendPluginMessage(ChannelIdentifier identifier, byte[] data);
-
-  /**
-   * Sends the specified resource pack from {@code url} to the user, using the specified 20-byte
-   * SHA-1 hash. To monitor the status of the sent resource pack, subscribe to
-   * {@link PlayerResourcePackStatusEvent}.
-   * In 1.17 and newer you can additionally specify
-   * whether the resource pack is required or not. Setting this for an older client will have
-   * no effect.
-   *
-   * @param url the URL for the resource pack
-   * @param hash the SHA-1 hash value for the resource pack
-   * @param isRequired Only in 1.17+ or newer: If true shows the pack as required to play,
-   *     and removes the decline option. Declining it anyway will disconnect the user.
-   */
-  void sendResourcePack(String url, byte[] hash, boolean isRequired);
- 
 }
-

api/src/main/java/com/velocitypowered/api/proxy/ProxyServer.java

@@ -13,6 +13,7 @@ import com.velocitypowered.api.event.EventManager;
 import com.velocitypowered.api.plugin.PluginManager;
 import com.velocitypowered.api.proxy.config.ProxyConfig;
 import com.velocitypowered.api.proxy.messages.ChannelRegistrar;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.api.scheduler.Scheduler;
@@ -217,4 +218,24 @@ public interface ProxyServer extends Audience {
   @NonNull
   BossBar createBossBar(net.kyori.text.Component title, @NonNull BossBarColor color,
       @NonNull BossBarOverlay overlay, float progress);
+
+  /**
+   * Creates a builder to build a {@link ResourcePackInfo} instance for use with
+   * {@link com.velocitypowered.api.proxy.Player#sendResourcePackOffer(ResourcePackInfo)}.
+   *
+   * <p>Note: The resource-pack location should always:
+   * - Use HTTPS with a valid certificate.
+   * - Be in a crawler-accessible location. Having it behind Cloudflare or Cloudfront
+   *   may cause issues in downloading.
+   * - Be in location with appropriate bandwidth so the download does not time out or fail.</p>
+   *
+   * <p>Do also make sure that the resource pack is in the correct format for the version
+   * of the client. It is also highly recommended to always provide the resource-pack SHA-1 hash
+   * of the resource pack with {@link ResourcePackInfo.Builder#setHash(byte[])}
+   * whenever possible to save bandwidth.</p>
+   *
+   * @param url The url where the resource pack can be found
+   * @return a ResourcePackInfo builder
+   */
+  ResourcePackInfo.Builder createResourcePackBuilder(String url);
 }

api/src/main/java/com/velocitypowered/api/proxy/player/ResourcePackInfo.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2018 Velocity Contributors
+ *
+ * The Velocity API is licensed under the terms of the MIT License. For more details,
+ * reference the LICENSE file in the api top-level directory.
+ */
+
+package com.velocitypowered.api.proxy.player;
+
+import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public interface ResourcePackInfo {
+
+  /**
+   * Gets the link the resource-pack can be found at.
+   *
+   * @return the location of the resource-pack
+   */
+  String getUrl();
+
+  /**
+   * Gets the {@link Component} that is displayed on the resource-pack prompt.
+   * This is only displayed if the client version is 1.17 or newer.
+   *
+   * @return the prompt if present or null otherwise
+   */
+  @Nullable
+  Component getPrompt();
+
+  /**
+   * Gets whether or not the acceptance of the resource-pack is enforced.
+   * See {@link Builder#setShouldForce(boolean)} for more information.
+   *
+   * @return whether or not to force usage of this resource-pack
+   */
+  boolean getShouldForce();
+
+  /**
+   * Gets the SHA-1 hash of the resource-pack
+   * See {@link Builder#setHash(byte[])} for more information.
+   *
+   * @return the hash if present or null otherwise
+   */
+  @Nullable
+  byte[] getHash();
+
+  /**
+   * Gets the {@link Origin} of the resource-pack.
+   *
+   * @return the origin of the resource pack
+   */
+  Origin getOrigin();
+
+  interface Builder {
+
+    /**
+     * Sets the resource-pack as required to play on the network.
+     * This feature was introduced in 1.17.
+     * Setting this to true has one of two effects:
+     * If the client is on 1.17 or newer:
+     *  - The resource-pack prompt will display without a decline button
+     *  - Accept or disconnect are the only available options but players may still press escape.
+     *  - Forces the resource-pack offer prompt to display even if the player has
+     *    previously declined or disabled resource packs
+     *  - The player will be disconnected from the network if they close/skip the prompt.
+     * If the client is on a version older than 1.17:
+     *  - If the player accepts the resource pack or has previously accepted a resource-pack
+     *    then nothing else will happen.
+     *  - If the player declines the resource pack or has previously declined a resource-pack
+     *    the player will be disconnected from the network
+     *
+     * @param shouldForce whether or not to force the client to accept the resource pack
+     */
+    Builder setShouldForce(boolean shouldForce);
+
+    /**
+     * Sets the SHA-1 hash of the provided resource pack.
+     * Note: It is recommended to always set this hash.
+     * If this hash is not set/ not present then the client will always download
+     * the resource pack even if it may still be cached. By having this hash present,
+     * the client will check first whether or not a resource pack by this hash is cached
+     * before downloading.
+     *
+     * @param hash the SHA-1 hash of the resource-pack
+     */
+    Builder setHash(@Nullable byte[] hash);
+
+    /**
+     * Sets a {@link Component} to display on the download prompt.
+     * This will only display if the client version is 1.17 or newer.
+     *
+     * @param prompt the component to display
+     */
+    Builder setPrompt(@Nullable Component prompt);
+
+    /**
+     * Builds the {@link ResourcePackInfo} from the provided info for use with
+     * {@link com.velocitypowered.api.proxy.Player#sendResourcePackOffer(ResourcePackInfo)}.
+     * Note: Some features may be version-dependent. Check before use.
+     *
+     * @return a ResourcePackInfo instance from the provided information
+     */
+    ResourcePackInfo build();
+  }
+
+  /**
+   * Represents the origin of the resource-pack.
+   */
+  enum Origin {
+    /**
+     * Resource-pack originated from the downstream server.
+     */
+    DOWNSTREAM_SERVER,
+    /**
+     * The player declined to download the resource pack.
+     */
+    PLUGIN_ON_PROXY
+  }
+}

proxy/src/main/java/com/velocitypowered/proxy/VelocityServer.java

@@ -30,6 +30,7 @@ import com.velocitypowered.api.plugin.PluginContainer;
 import com.velocitypowered.api.plugin.PluginManager;
 import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ProxyServer;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.proxy.server.ServerInfo;
 import com.velocitypowered.api.util.Favicon;
@@ -45,6 +46,7 @@ import com.velocitypowered.proxy.command.builtin.ShutdownCommand;
 import com.velocitypowered.proxy.command.builtin.VelocityCommand;
 import com.velocitypowered.proxy.config.VelocityConfiguration;
 import com.velocitypowered.proxy.connection.client.ConnectedPlayer;
+import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.console.VelocityConsole;
 import com.velocitypowered.proxy.network.ConnectionManager;
 import com.velocitypowered.proxy.plugin.VelocityEventManager;
@@ -682,4 +684,9 @@ public class VelocityServer implements ProxyServer, ForwardingAudience {
     return version.compareTo(ProtocolVersion.MINECRAFT_1_16) >= 0 ? POST_1_16_PING_SERIALIZER
         : PRE_1_16_PING_SERIALIZER;
   }
+
+  @Override
+  public ResourcePackInfo.Builder createResourcePackBuilder(String url) {
+    return new VelocityResourcePackInfo.BuilderImpl(url);
+  }
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/backend/BackendPlaySessionHandler.java

@@ -19,6 +19,7 @@ package com.velocitypowered.proxy.connection.backend;
 
 import static com.velocitypowered.proxy.connection.backend.BungeeCordMessageResponder.getBungeeCordChannel;
 
+import com.google.common.base.Preconditions;
 import com.google.common.collect.ImmutableList;
 import com.mojang.brigadier.builder.ArgumentBuilder;
 import com.mojang.brigadier.tree.CommandNode;
@@ -28,10 +29,12 @@ import com.velocitypowered.api.event.command.PlayerAvailableCommandsEvent;
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
 import com.velocitypowered.proxy.connection.client.ClientPlaySessionHandler;
+import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommands;
@@ -40,6 +43,7 @@ import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.KeepAlive;
 import com.velocitypowered.proxy.protocol.packet.PlayerListItem;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
+import com.velocitypowered.proxy.protocol.packet.ResourcePackRequest;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
 import com.velocitypowered.proxy.protocol.util.PluginMessageUtil;
 import io.netty.buffer.ByteBuf;
@@ -128,6 +132,21 @@ public class BackendPlaySessionHandler implements MinecraftSessionHandler {
     return false; // forward
   }
 
+  @Override
+  public boolean handle(ResourcePackRequest packet) {
+    ResourcePackInfo.Builder builder = new VelocityResourcePackInfo.BuilderImpl(
+        Preconditions.checkNotNull(packet.getUrl()))
+        .setPrompt(packet.getPrompt())
+        .setShouldForce(packet.isRequired());
+    // Why SpotBugs decides that this is unsafe I have no idea;
+    if (packet.getHash() != null && !Preconditions.checkNotNull(packet.getHash()).isEmpty()) {
+      builder.setHash(ByteBufUtil.decodeHexDump(packet.getHash()));
+    }
+
+    serverConn.getPlayer().queueResourcePack(builder.build());
+    return true;
+  }
+
   @Override
   public boolean handle(PluginMessage packet) {
     if (bungeecordMessageResponder.process(packet)) {

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ClientPlaySessionHandler.java

@@ -33,6 +33,7 @@ import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.LegacyChannelIdentifier;
 import com.velocitypowered.api.proxy.messages.MinecraftChannelIdentifier;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.proxy.VelocityServer;
 import com.velocitypowered.proxy.connection.ConnectionTypes;
 import com.velocitypowered.proxy.connection.MinecraftConnection;
@@ -72,6 +73,7 @@ import net.kyori.adventure.text.Component;
 import net.kyori.adventure.text.format.NamedTextColor;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
 /**
@@ -283,9 +285,8 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
 
   @Override
   public boolean handle(ResourcePackResponse packet) {
-    server.getEventManager().fireAndForget(new PlayerResourcePackStatusEvent(player,
-        packet.getStatus()));
-    return false;
+    return player.onResourcePackResponse(packet.getStatus(),
+            ByteBufUtil.decodeHexDump(packet.getHash()));
   }
 
   @Override

proxy/src/main/java/com/velocitypowered/proxy/connection/client/ConnectedPlayer.java

@@ -31,6 +31,7 @@ import com.velocitypowered.api.event.player.KickedFromServerEvent.Notify;
 import com.velocitypowered.api.event.player.KickedFromServerEvent.RedirectPlayer;
 import com.velocitypowered.api.event.player.KickedFromServerEvent.ServerKickResult;
 import com.velocitypowered.api.event.player.PlayerModInfoEvent;
+import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
 import com.velocitypowered.api.event.player.PlayerSettingsChangedEvent;
 import com.velocitypowered.api.event.player.ServerPreConnectEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
@@ -42,6 +43,7 @@ import com.velocitypowered.api.proxy.Player;
 import com.velocitypowered.api.proxy.ServerConnection;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.api.proxy.player.PlayerSettings;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
 import com.velocitypowered.api.proxy.server.RegisteredServer;
 import com.velocitypowered.api.util.GameProfile;
 import com.velocitypowered.api.util.MessagePosition;
@@ -55,6 +57,7 @@ import com.velocitypowered.proxy.connection.MinecraftConnection;
 import com.velocitypowered.proxy.connection.MinecraftConnectionAssociation;
 import com.velocitypowered.proxy.connection.backend.VelocityServerConnection;
 import com.velocitypowered.proxy.connection.forge.legacy.LegacyForgeConstants;
+import com.velocitypowered.proxy.connection.player.VelocityResourcePackInfo;
 import com.velocitypowered.proxy.connection.util.ConnectionMessages;
 import com.velocitypowered.proxy.connection.util.ConnectionRequestResults.Impl;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
@@ -76,12 +79,14 @@ import com.velocitypowered.proxy.util.collect.CappedSet;
 import io.netty.buffer.ByteBufUtil;
 import io.netty.buffer.Unpooled;
 import java.net.InetSocketAddress;
+import java.util.ArrayDeque;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 import java.util.Locale;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.Queue;
 import java.util.UUID;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.CompletionException;
@@ -133,6 +138,10 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   private final Collection<String> knownChannels;
   private final CompletableFuture<Void> teardownFuture = new CompletableFuture<>();
   private @MonotonicNonNull List<String> serversToTry = null;
+  private @MonotonicNonNull Boolean previousResourceResponse;
+  private final Queue<ResourcePackInfo> outstandingResourcePacks = new ArrayDeque<>();
+  private @Nullable ResourcePackInfo pendingResourcePack;
+  private @Nullable ResourcePackInfo appliedResourcePack;
 
   ConnectedPlayer(VelocityServer server, GameProfile profile, MinecraftConnection connection,
       @Nullable InetSocketAddress virtualHost, boolean onlineMode) {
@@ -871,31 +880,133 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
   }
 
   @Override
+  @Deprecated
   public void sendResourcePack(String url) {
-    Preconditions.checkNotNull(url, "url");
+    sendResourcePackOffer(new VelocityResourcePackInfo.BuilderImpl(url).build());
+  }
 
+  @Override
+  @Deprecated
+  public void sendResourcePack(String url, byte[] hash) {
+    sendResourcePackOffer(new VelocityResourcePackInfo.BuilderImpl(url).setHash(hash).build());
+  }
+
+  @Override
+  public void sendResourcePackOffer(ResourcePackInfo packInfo) {
     if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
+      Preconditions.checkNotNull(packInfo, "packInfo");
+      queueResourcePack(packInfo);
+    }
+  }
+
+  /**
+   * Queues a resource-pack for sending to the player and sends it
+   * immediately if the queue is empty.
+   */
+  public void queueResourcePack(ResourcePackInfo info) {
+    outstandingResourcePacks.add(info);
+    if (outstandingResourcePacks.size() == 1) {
+      tickResourcePackQueue();
+    }
+  }
+
+  private void tickResourcePackQueue() {
+    ResourcePackInfo queued = outstandingResourcePacks.peek();
+
+    if (queued != null) {
+      // Check if the player declined a resource pack once already
+      if (previousResourceResponse != null && !previousResourceResponse) {
+        // If that happened we can flush the queue right away.
+        // Unless its 1.17+ and forced it will come back denied anyway
+        while (!outstandingResourcePacks.isEmpty()) {
+          queued = outstandingResourcePacks.peek();
+          if (queued.getShouldForce() && getProtocolVersion()
+                  .compareTo(ProtocolVersion.MINECRAFT_1_17) >= 0) {
+            break;
+          }
+          onResourcePackResponse(PlayerResourcePackStatusEvent.Status.DECLINED, new byte[0]);
+          queued = null;
+        }
+        if (queued == null) {
+          // Exit as the queue was cleared
+          return;
+        }
+      }
+
       ResourcePackRequest request = new ResourcePackRequest();
-      request.setUrl(url);
+      request.setUrl(queued.getUrl());
+      if (queued.getHash() != null) {
+        request.setHash(ByteBufUtil.hexDump(queued.getHash()));
+      } else {
         request.setHash("");
-      request.setRequired(false);
+      }
+      request.setRequired(queued.getShouldForce());
+      request.setPrompt(queued.getPrompt());
+
       connection.write(request);
     }
   }
 
   @Override
-  public void sendResourcePack(String url, byte[] hash, boolean isRequired) {
-    Preconditions.checkNotNull(url, "url");
-    Preconditions.checkNotNull(hash, "hash");
-    Preconditions.checkArgument(hash.length == 20, "Hash length is not 20");
-
-    if (this.getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_8) >= 0) {
-      ResourcePackRequest request = new ResourcePackRequest();
-      request.setUrl(url);
-      request.setHash(ByteBufUtil.hexDump(hash));
-      request.setRequired(isRequired);
-      connection.write(request);
+  public @Nullable ResourcePackInfo getAppliedResourcePack() {
+    return appliedResourcePack;
   }
+
+  @Override
+  public @Nullable ResourcePackInfo getPendingResourcePack() {
+    return pendingResourcePack;
+  }
+
+  /**
+   * Processes a client response to a sent resource-pack.
+   */
+  public boolean onResourcePackResponse(PlayerResourcePackStatusEvent.Status status,
+                                        @Nullable byte[] hash) {
+
+    final boolean peek = status == PlayerResourcePackStatusEvent.Status.ACCEPTED;
+    final ResourcePackInfo queued = peek
+            ? outstandingResourcePacks.peek() : outstandingResourcePacks.poll();
+
+    server.getEventManager().fire(new PlayerResourcePackStatusEvent(this, status, queued))
+            .thenAcceptAsync(event -> {
+              if (event.getStatus() == PlayerResourcePackStatusEvent.Status.DECLINED
+                      && event.getPackInfo() != null && event.getPackInfo().getShouldForce()
+                      && (!event.isOverwriteKick() || event.getPlayer()
+                              .getProtocolVersion().compareTo(ProtocolVersion.MINECRAFT_1_17) >= 0)
+              ) {
+                event.getPlayer().disconnect(Component
+                        .translatable("multiplayer.requiredTexturePrompt.disconnect"));
+              }
+            });
+
+
+    switch (status) {
+      case ACCEPTED:
+        previousResourceResponse = true;
+        pendingResourcePack = queued;
+        break;
+      case DECLINED:
+        previousResourceResponse = false;
+        break;
+      case SUCCESSFUL:
+        appliedResourcePack = queued;
+        pendingResourcePack = null;
+        break;
+      case FAILED_DOWNLOAD:
+        pendingResourcePack = null;
+        break;
+      default:
+        break;
+    }
+
+    if (!peek) {
+      CompletableFuture.supplyAsync(() -> {
+        tickResourcePackQueue();
+        return true;
+      });
+    }
+
+    return queued != null && queued.getOrigin() == ResourcePackInfo.Origin.DOWNSTREAM_SERVER;
   }
 
   /**

proxy/src/main/java/com/velocitypowered/proxy/connection/player/VelocityResourcePackInfo.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright (C) 2018 Velocity 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 <https://www.gnu.org/licenses/>.
+ */
+
+package com.velocitypowered.proxy.connection.player;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.player.ResourcePackInfo;
+import net.kyori.adventure.text.Component;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public final class VelocityResourcePackInfo implements ResourcePackInfo {
+  private final String url;
+  private final @Nullable byte[] hash;
+  private final boolean shouldForce;
+  private final @Nullable Component prompt; // 1.17+ only
+  private final Origin origin;
+
+  private VelocityResourcePackInfo(String url, @Nullable byte[] hash, boolean shouldForce,
+                                  @Nullable Component prompt, Origin origin) {
+    this.url = url;
+    this.hash = hash;
+    this.shouldForce = shouldForce;
+    this.prompt = prompt;
+    this.origin = origin;
+  }
+
+  @Override
+  public String getUrl() {
+    return url;
+  }
+
+  @Override
+  public @Nullable Component getPrompt() {
+    return prompt;
+  }
+
+  @Override
+  public boolean getShouldForce() {
+    return shouldForce;
+  }
+
+  @Override
+  public @Nullable byte[] getHash() {
+    return hash == null ? null : hash.clone(); // Thanks spotbugs, very helpful.
+  }
+
+  @Override
+  public Origin getOrigin() {
+    return origin;
+  }
+
+  public static final class BuilderImpl implements ResourcePackInfo.Builder {
+    private final String url;
+    private boolean shouldForce;
+    private @Nullable byte[] hash;
+    private @Nullable Component prompt;
+    private Origin origin = Origin.PLUGIN_ON_PROXY;
+
+    public BuilderImpl(String url) {
+      this.url = Preconditions.checkNotNull(url, "url");
+    }
+
+    @Override
+    public BuilderImpl setShouldForce(boolean shouldForce) {
+      this.shouldForce = shouldForce;
+      return this;
+    }
+
+    @Override
+    public BuilderImpl setHash(@Nullable byte[] hash) {
+      if (hash != null) {
+        Preconditions.checkArgument(hash.length == 20, "Hash length is not 20");
+        this.hash = hash.clone(); // Thanks spotbugs, very helpful.
+      } else {
+        this.hash = null;
+      }
+      return this;
+    }
+
+    @Override
+    public BuilderImpl setPrompt(@Nullable Component prompt) {
+      this.prompt = prompt;
+      return this;
+    }
+
+    @Override
+    public ResourcePackInfo build() {
+      return new VelocityResourcePackInfo(url, hash, shouldForce, prompt, origin);
+    }
+
+    public void setOrigin(Origin origin) {
+      this.origin = origin;
+    }
+  }
+
+}

proxy/src/main/java/com/velocitypowered/proxy/protocol/StateRegistry.java

@@ -226,16 +226,16 @@ public enum StateRegistry {
           map(0x39, MINECRAFT_1_16_2, true),
           map(0x3C, MINECRAFT_1_17, true));
       clientbound.register(ResourcePackRequest.class, ResourcePackRequest::new,
-          map(0x48, MINECRAFT_1_8, true),
-          map(0x32, MINECRAFT_1_9, true),
-          map(0x33, MINECRAFT_1_12, true),
-          map(0x34, MINECRAFT_1_12_1, true),
-          map(0x37, MINECRAFT_1_13, true),
-          map(0x39, MINECRAFT_1_14, true),
-          map(0x3A, MINECRAFT_1_15, true),
-          map(0x39, MINECRAFT_1_16, true),
-          map(0x38, MINECRAFT_1_16_2, true),
-          map(0x3B, MINECRAFT_1_17, true));
+          map(0x48, MINECRAFT_1_8, false),
+          map(0x32, MINECRAFT_1_9, false),
+          map(0x33, MINECRAFT_1_12, false),
+          map(0x34, MINECRAFT_1_12_1, false),
+          map(0x37, MINECRAFT_1_13, false),
+          map(0x39, MINECRAFT_1_14, false),
+          map(0x3A, MINECRAFT_1_15, false),
+          map(0x39, MINECRAFT_1_16, false),
+          map(0x38, MINECRAFT_1_16_2, false),
+          map(0x3B, MINECRAFT_1_17, false));
       clientbound.register(HeaderAndFooter.class, HeaderAndFooter::new,
           map(0x47, MINECRAFT_1_8, true),
           map(0x48, MINECRAFT_1_9, true),

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/ResourcePackRequest.java

@@ -23,6 +23,8 @@ import com.velocitypowered.proxy.protocol.MinecraftPacket;
 import com.velocitypowered.proxy.protocol.ProtocolUtils;
 import com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
 import io.netty.buffer.ByteBuf;
+import net.kyori.adventure.text.Component;
+import net.kyori.adventure.text.serializer.gson.GsonComponentSerializer;
 import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
@@ -31,6 +33,7 @@ public class ResourcePackRequest implements MinecraftPacket {
   private @MonotonicNonNull String url;
   private @MonotonicNonNull String hash;
   private boolean isRequired; // 1.17+
+  private @Nullable Component prompt; // 1.17+
 
   public @Nullable String getUrl() {
     return url;
@@ -56,12 +59,25 @@ public class ResourcePackRequest implements MinecraftPacket {
     isRequired = required;
   }
 
+  public @Nullable Component getPrompt() {
+    return prompt;
+  }
+
+  public void setPrompt(Component prompt) {
+    this.prompt = prompt;
+  }
+
   @Override
   public void decode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
     this.url = ProtocolUtils.readString(buf);
     this.hash = ProtocolUtils.readString(buf);
     if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_17) >= 0) {
       this.isRequired = buf.readBoolean();
+      if (buf.readBoolean()) {
+        this.prompt = GsonComponentSerializer.gson().deserialize(ProtocolUtils.readString(buf));
+      } else {
+        this.prompt = null;
+      }
     }
   }
 
@@ -74,6 +90,12 @@ public class ResourcePackRequest implements MinecraftPacket {
     ProtocolUtils.writeString(buf, hash);
     if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_17) >= 0) {
       buf.writeBoolean(isRequired);
+      if (prompt != null) {
+        buf.writeBoolean(true);
+        ProtocolUtils.writeString(buf, GsonComponentSerializer.gson().serialize(prompt));
+      } else {
+        buf.writeBoolean(false);
+      }
     }
   }
 
@@ -87,6 +109,8 @@ public class ResourcePackRequest implements MinecraftPacket {
     return "ResourcePackRequest{"
         + "url='" + url + '\''
         + ", hash='" + hash + '\''
+        + ", isRequired=" + isRequired
+        + ", prompt='" + prompt + '\''
         + '}';
   }
 }

proxy/src/main/java/com/velocitypowered/proxy/protocol/packet/ResourcePackResponse.java

@@ -38,6 +38,10 @@ public class ResourcePackResponse implements MinecraftPacket {
     return status;
   }
 
+  public String getHash() {
+    return hash;
+  }
+
   @Override
   public void decode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
     if (protocolVersion.compareTo(ProtocolVersion.MINECRAFT_1_9_4) <= 0) {