HAProxy PROXY protocol support for downstream connections (#1688)

* Implement downstream PROXY protocol support

* Clarify the configuration version updating procedure

* Bump netty-resolver-dns to 4.1.56.Final

* Update Netty to .56

* Don't increase jar size by 2MB

Co-authored-by: Camotoy <20743703+Camotoy@users.noreply.github.com>

connector/pom.xml

@@ -124,14 +124,26 @@
             <version>26201a4</version>
             <scope>compile</scope>
             <exclusions>
-                <exclusion>
-                    <groupId>io.netty</groupId>
-                    <artifactId>netty-all</artifactId>
-                </exclusion>
                 <exclusion>
                     <groupId>net.kyori</groupId>
                     <artifactId>adventure-text-serializer-gson</artifactId>
                 </exclusion>
+                <exclusion>
+                    <groupId>com.github.steveice10</groupId>
+                    <artifactId>packetlib</artifactId>
+                </exclusion>
+            </exclusions>
+        </dependency>
+        <dependency>
+            <groupId>com.github.steveice10</groupId>
+            <artifactId>PacketLib</artifactId>
+            <version>54f761c</version>
+            <scope>compile</scope>
+            <exclusions>
+                <exclusion> <!-- Move this exclusion back to MCProtocolLib it gets the latest PacketLib -->
+                    <groupId>io.netty</groupId>
+                    <artifactId>netty-all</artifactId>
+                </exclusion>
             </exclusions>
         </dependency>
         <dependency>

connector/src/main/java/org/geysermc/connector/configuration/GeyserConfiguration.java

@@ -34,7 +34,7 @@ import java.util.Map;
 
 public interface GeyserConfiguration {
 
-    // Modify this when you update the config
+    // Modify this when you introduce breaking changes into the config
     int CURRENT_CONFIG_VERSION = 4;
 
     IBedrockConfiguration getBedrock();
@@ -117,6 +117,8 @@ public interface GeyserConfiguration {
         void setPort(int port);
 
         String getAuthType();
+
+        boolean isUseProxyProtocol();
     }
 
     interface IUserAuthenticationInfo {

connector/src/main/java/org/geysermc/connector/configuration/GeyserJacksonConfiguration.java

@@ -148,6 +148,9 @@ public abstract class GeyserJacksonConfiguration implements GeyserConfiguration
         @Setter
         @JsonProperty("auth-type")
         private String authType = "online";
+
+        @JsonProperty("use-proxy-protocol")
+        private boolean useProxyProtocol = false;
     }
 
     @Getter

connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java

@@ -39,6 +39,7 @@ import com.github.steveice10.mc.protocol.packet.ingame.client.player.ClientPlaye
 import com.github.steveice10.mc.protocol.packet.ingame.client.world.ClientTeleportConfirmPacket;
 import com.github.steveice10.mc.protocol.packet.ingame.server.ServerRespawnPacket;
 import com.github.steveice10.mc.protocol.packet.login.server.LoginSuccessPacket;
+import com.github.steveice10.packetlib.BuiltinFlags;
 import com.github.steveice10.packetlib.Client;
 import com.github.steveice10.packetlib.event.session.*;
 import com.github.steveice10.packetlib.packet.Packet;
@@ -459,6 +460,10 @@ public class GeyserSession implements CommandSender {
                 }
 
                 downstream = new Client(remoteServer.getAddress(), remoteServer.getPort(), protocol, new TcpSessionFactory());
+                if (connector.getConfig().getRemote().isUseProxyProtocol()) {
+                    downstream.getSession().setFlag(BuiltinFlags.ENABLE_CLIENT_PROXY_PROTOCOL, true);
+                    downstream.getSession().setFlag(BuiltinFlags.CLIENT_PROXIED_ADDRESS, upstream.getAddress());
+                }
                 // Let Geyser handle sending the keep alive
                 downstream.getSession().setFlag(MinecraftConstants.AUTOMATIC_KEEP_ALIVE_MANAGEMENT, false);
                 downstream.getSession().addListener(new SessionAdapter() {

connector/src/main/resources/config.yml

@@ -32,6 +32,11 @@ remote:
   port: 25565
   # Authentication type. Can be offline, online, or floodgate (see https://github.com/GeyserMC/Geyser/wiki/Floodgate).
   auth-type: online
+  # Whether to enable PROXY protocol or not while connecting to the server.
+  # This is useful only when:
+  # 1) Your server supports PROXY protocol (it probably doesn't)
+  # 2) You run Velocity or BungeeCord with respective option enabled.
+  use-proxy-protocol: false
 
 # Floodgate uses encryption to ensure use from authorised sources.
 # This should point to the public key generated by Floodgate (Bungee or CraftBukkit)