Add option to forward the connection hostname over to the remote server (#2149)

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

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

@@ -138,6 +138,8 @@ public interface GeyserConfiguration {
         boolean isPasswordAuthentication();
 
         boolean isUseProxyProtocol();
+
+        boolean isForwardHost();
     }
 
     interface IUserAuthenticationInfo {

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

@@ -197,6 +197,9 @@ public abstract class GeyserJacksonConfiguration implements GeyserConfiguration
 
         @JsonProperty("use-proxy-protocol")
         private boolean useProxyProtocol = false;
+
+        @JsonProperty("forward-hostname")
+        private boolean forwardHost = false;
     }
 
     @Getter

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

@@ -693,7 +693,9 @@ public class GeyserSession implements CommandSender {
             @Override
             public void packetSending(PacketSendingEvent event) {
                 //todo move this somewhere else
-                if (event.getPacket() instanceof HandshakePacket && floodgate) {
+                if (event.getPacket() instanceof HandshakePacket) {
+                    String addressSuffix;
+                    if (floodgate) {
                         String encrypted = "";
                         try {
                             encrypted = EncryptionUtil.encryptBedrockData(publicKey, new BedrockData(
@@ -709,10 +711,23 @@ public class GeyserSession implements CommandSender {
                             connector.getLogger().error(LanguageUtils.getLocaleStringLog("geyser.auth.floodgate.encrypt_fail"), e);
                         }
 
+                        addressSuffix = '\0' + BedrockData.FLOODGATE_IDENTIFIER + '\0' + encrypted;
+                    } else {
+                        addressSuffix = "";
+                    }
+
                     HandshakePacket handshakePacket = event.getPacket();
+
+                    String address;
+                    if (connector.getConfig().getRemote().isForwardHost()) {
+                        address = clientData.getServerAddress().split(":")[0];
+                    } else {
+                        address = handshakePacket.getHostname();
+                    }
+
                     event.setPacket(new HandshakePacket(
                             handshakePacket.getProtocolVersion(),
-                            handshakePacket.getHostname() + '\0' + BedrockData.FLOODGATE_IDENTIFIER + '\0' + encrypted,
+                            address + addressSuffix,
                             handshakePacket.getPort(),
                             handshakePacket.getIntent()
                     ));

connector/src/main/resources/config.yml

@@ -53,6 +53,9 @@ remote:
   # 2) You run Velocity or BungeeCord with the option enabled in the proxy's main config.
   # IF YOU DON'T KNOW WHAT THIS IS, DON'T TOUCH IT!
   use-proxy-protocol: false
+  # Forward the hostname that the Bedrock client used to connect over to the Java server
+  # This is designed to be used for forced hosts on proxies
+  forward-hostname: false
 
 # Floodgate uses encryption to ensure use from authorised sources.
 # This should point to the public key generated by Floodgate (Bungee or CraftBukkit)