Resource pack API

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

@@ -0,0 +1,49 @@
+package com.velocitypowered.api.event.player;
+
+import com.google.common.base.Preconditions;
+import com.velocitypowered.api.proxy.Player;
+
+public class PlayerResourcePackStatusEvent {
+  private final Player player;
+  private final Status result;
+
+  public PlayerResourcePackStatusEvent(Player player, Status result) {
+    this.player = Preconditions.checkNotNull(player, "player");
+    this.result = Preconditions.checkNotNull(result, "result");
+  }
+
+  public Player getPlayer() {
+    return player;
+  }
+
+  public Status getResult() {
+    return result;
+  }
+
+  @Override
+  public String toString() {
+    return "PlayerResourcePackStatusEvent{"
+        + "player=" + player
+        + ", result=" + result
+        + '}';
+  }
+
+  public enum Status {
+    /**
+     * The resource pack was applied successfully.
+     */
+    SUCCESSFUL,
+    /**
+     * The player declined to download the resource pack.
+     */
+    DECLINED,
+    /**
+     * The player could not download the resource pack.
+     */
+    FAILED_DOWNLOAD,
+    /**
+     * The player has accepted the resource pack and is now downloading it.
+     */
+    ACCEPTED
+  }
+}

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

@@ -151,4 +151,20 @@ public interface Player extends CommandSource, InboundConnection, ChannelMessage
    * @param input the chat input to send
    */
   void spoofChatInput(String input);
+
+  /**
+   * Sends the specified resource pack from {@code url} to the user. If at all possible, send the
+   * resource pack using {@link #sendResourcePack(String, byte[])}.
+   *
+   * @param url the URL for the resource pack
+   */
+  void sendResourcePack(String url);
+
+  /**
+   * Sends the specified resource pack from {@code url} to the user.
+   *
+   * @param url the URL for the resource pack
+   * @param hash the SHA-1 hash value for the resource pack
+   */
+  void sendResourcePack(String url, byte[] hash);
 }

proxy/src/main/java/com/velocitypowered/proxy/connection/MinecraftSessionHandler.java

@@ -18,6 +18,8 @@ import com.velocitypowered.proxy.protocol.packet.LoginPluginMessage;
 import com.velocitypowered.proxy.protocol.packet.LoginPluginResponse;
 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.ResourcePackResponse;
 import com.velocitypowered.proxy.protocol.packet.Respawn;
 import com.velocitypowered.proxy.protocol.packet.ServerLogin;
 import com.velocitypowered.proxy.protocol.packet.ServerLoginSuccess;
@@ -175,4 +177,12 @@ public interface MinecraftSessionHandler {
   default boolean handle(PlayerListItem packet) {
     return false;
   }
+
+  default boolean handle(ResourcePackRequest packet) {
+    return false;
+  }
+
+  default boolean handle(ResourcePackResponse packet) {
+    return false;
+  }
 }

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

@@ -4,6 +4,7 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_13;
 
 import com.velocitypowered.api.event.connection.PluginMessageEvent;
 import com.velocitypowered.api.event.player.PlayerChatEvent;
+import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.api.proxy.messages.ChannelIdentifier;
 import com.velocitypowered.proxy.VelocityServer;
@@ -18,6 +19,7 @@ import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.JoinGame;
 import com.velocitypowered.proxy.protocol.packet.KeepAlive;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
+import com.velocitypowered.proxy.protocol.packet.ResourcePackResponse;
 import com.velocitypowered.proxy.protocol.packet.Respawn;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteRequest;
 import com.velocitypowered.proxy.protocol.packet.TabCompleteResponse;
@@ -235,6 +237,13 @@ public class ClientPlaySessionHandler implements MinecraftSessionHandler {
     return true;
   }
 
+  @Override
+  public boolean handle(ResourcePackResponse packet) {
+    server.getEventManager().fireAndForget(new PlayerResourcePackStatusEvent(player,
+        packet.getStatus()));
+    return false;
+  }
+
   @Override
   public void handleGeneric(MinecraftPacket packet) {
     VelocityServerConnection serverConnection = player.getConnectedServer();

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

@@ -38,9 +38,11 @@ import com.velocitypowered.proxy.protocol.packet.ClientSettings;
 import com.velocitypowered.proxy.protocol.packet.Disconnect;
 import com.velocitypowered.proxy.protocol.packet.KeepAlive;
 import com.velocitypowered.proxy.protocol.packet.PluginMessage;
+import com.velocitypowered.proxy.protocol.packet.ResourcePackRequest;
 import com.velocitypowered.proxy.protocol.packet.TitlePacket;
 import com.velocitypowered.proxy.server.VelocityRegisteredServer;
 import com.velocitypowered.proxy.tablist.VelocityTabList;
+import io.netty.buffer.ByteBufUtil;
 import java.net.InetSocketAddress;
 import java.util.Collections;
 import java.util.List;
@@ -467,6 +469,28 @@ public class ConnectedPlayer implements MinecraftConnectionAssociation, Player {
     ensureBackendConnection().write(Chat.createServerbound(input));
   }
 
+  @Override
+  public void sendResourcePack(String url) {
+    Preconditions.checkNotNull(url, "url");
+
+    ResourcePackRequest request = new ResourcePackRequest();
+    request.setUrl(url);
+    request.setHash("");
+    connection.write(request);
+  }
+
+  @Override
+  public void sendResourcePack(String url, byte[] hash) {
+    Preconditions.checkNotNull(url, "url");
+    Preconditions.checkNotNull(hash, "hash");
+    Preconditions.checkArgument(hash.length == 20, "Hash length is not 20");
+
+    ResourcePackRequest request = new ResourcePackRequest();
+    request.setUrl(url);
+    request.setHash(ByteBufUtil.hexDump(hash));
+    connection.write(request);
+  }
+
   /**
    * Sends a {@link KeepAlive} packet to the player with a random ID.
    * The response will be ignored by Velocity as it will not match the

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

@@ -17,7 +17,6 @@ import static com.velocitypowered.api.network.ProtocolVersion.MINECRAFT_1_9_4;
 import static com.velocitypowered.api.network.ProtocolVersion.MINIMUM_VERSION;
 import static com.velocitypowered.proxy.protocol.ProtocolUtils.Direction;
 
-import com.google.common.collect.ImmutableList;
 import com.velocitypowered.api.network.ProtocolVersion;
 import com.velocitypowered.proxy.protocol.packet.AvailableCommands;
 import com.velocitypowered.proxy.protocol.packet.BossBar;
@@ -34,6 +33,8 @@ import com.velocitypowered.proxy.protocol.packet.LoginPluginMessage;
 import com.velocitypowered.proxy.protocol.packet.LoginPluginResponse;
 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.ResourcePackResponse;
 import com.velocitypowered.proxy.protocol.packet.Respawn;
 import com.velocitypowered.proxy.protocol.packet.ServerLogin;
 import com.velocitypowered.proxy.protocol.packet.ServerLoginSuccess;
@@ -110,6 +111,11 @@ public enum StateRegistry {
           map(0x0C, MINECRAFT_1_12, false),
           map(0x0B, MINECRAFT_1_12_1, false),
           map(0x0E, MINECRAFT_1_13, false));
+      serverbound.register(ResourcePackResponse.class, ResourcePackResponse::new,
+          map(0x19, MINECRAFT_1_8, false),
+          map(0x16, MINECRAFT_1_9, false),
+          map(0x18, MINECRAFT_1_12, false),
+          map(0x1D, MINECRAFT_1_13, false));
 
       clientbound.register(BossBar.class, BossBar::new,
           map(0x0C, MINECRAFT_1_9, false),
@@ -153,6 +159,12 @@ public enum StateRegistry {
           map(0x34, MINECRAFT_1_12, true),
           map(0x35, MINECRAFT_1_12_2, true),
           map(0x38, MINECRAFT_1_13, 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));
       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

@@ -0,0 +1,64 @@
+package com.velocitypowered.proxy.protocol.packet;
+
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+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 org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+public class ResourcePackRequest implements MinecraftPacket {
+
+  @MonotonicNonNull
+  private String url;
+  @MonotonicNonNull
+  private String hash;
+
+  @Nullable
+  public String getUrl() {
+    return url;
+  }
+
+  public void setUrl(String url) {
+    this.url = url;
+  }
+
+  @Nullable
+  public String getHash() {
+    return hash;
+  }
+
+  public void setHash(String hash) {
+    this.hash = hash;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
+    this.url = ProtocolUtils.readString(buf);
+    this.hash = ProtocolUtils.readString(buf);
+  }
+
+  @Override
+  public void encode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
+    if (url == null || hash == null) {
+      throw new IllegalStateException("Packet not fully filled in yet!");
+    }
+    ProtocolUtils.writeString(buf, url);
+    ProtocolUtils.writeString(buf, hash);
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+
+  @Override
+  public String toString() {
+    return "ResourcePackRequest{"
+        + "url='" + url + '\''
+        + ", hash='" + hash + '\''
+        + '}';
+  }
+}

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

@@ -0,0 +1,45 @@
+package com.velocitypowered.proxy.protocol.packet;
+
+import com.velocitypowered.api.event.player.PlayerResourcePackStatusEvent.Status;
+import com.velocitypowered.api.network.ProtocolVersion;
+import com.velocitypowered.proxy.connection.MinecraftSessionHandler;
+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 org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+
+public class ResourcePackResponse implements MinecraftPacket {
+
+  @MonotonicNonNull
+  private Status status;
+
+  public Status getStatus() {
+    if (status == null) {
+      throw new IllegalStateException("Packet not yet deserialized");
+    }
+    return status;
+  }
+
+  @Override
+  public void decode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
+    this.status = Status.values()[ProtocolUtils.readVarInt(buf)];
+  }
+
+  @Override
+  public void encode(ByteBuf buf, Direction direction, ProtocolVersion protocolVersion) {
+    ProtocolUtils.writeVarInt(buf, status.ordinal());
+  }
+
+  @Override
+  public boolean handle(MinecraftSessionHandler handler) {
+    return handler.handle(this);
+  }
+
+  @Override
+  public String toString() {
+    return "ResourcePackResponse{"
+        + "status=" + status
+        + '}';
+  }
+}