Expose client protocol version and virtual host

paper-server/src/main/java/com/destroystokyo/paper/network/PaperNetworkClient.java

@@ -0,0 +1,49 @@
+package com.destroystokyo.paper.network;
+
+import java.net.InetSocketAddress;
+
+import javax.annotation.Nullable;
+import net.minecraft.network.Connection;
+
+public class PaperNetworkClient implements NetworkClient {
+
+    private final Connection networkManager;
+
+    PaperNetworkClient(Connection networkManager) {
+        this.networkManager = networkManager;
+    }
+
+    @Override
+    public InetSocketAddress getAddress() {
+        return (InetSocketAddress) this.networkManager.getRemoteAddress();
+    }
+
+    @Override
+    public int getProtocolVersion() {
+        return this.networkManager.protocolVersion;
+    }
+
+    @Nullable
+    @Override
+    public InetSocketAddress getVirtualHost() {
+        return this.networkManager.virtualHost;
+    }
+
+    public static InetSocketAddress prepareVirtualHost(String host, int port) {
+        int len = host.length();
+
+        // FML appends a marker to the host to recognize FML clients (\0FML\0)
+        int pos = host.indexOf('\0');
+        if (pos >= 0) {
+            len = pos;
+        }
+
+        // When clients connect with a SRV record, their host contains a trailing '.'
+        if (len > 0 && host.charAt(len -  1) == '.') {
+            len--;
+        }
+
+        return InetSocketAddress.createUnresolved(host.substring(0, len), port);
+    }
+
+}

paper-server/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java

@@ -341,6 +341,20 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         this.getHandle().transferCookieConnection.sendPacket(new ClientboundTransferPacket(host, port));
     }
 
+    // Paper start - Implement NetworkClient
+    @Override
+    public int getProtocolVersion() {
+        if (getHandle().connection == null) return -1;
+        return getHandle().connection.connection.protocolVersion;
+    }
+
+    @Override
+    public InetSocketAddress getVirtualHost() {
+        if (getHandle().connection == null) return null;
+        return getHandle().connection.connection.virtualHost;
+    }
+    // Paper end
+
     @Override
     public double getEyeHeight(boolean ignorePose) {
         if (ignorePose) {