Added config option to disable handshake address rewriting

Fixes #482

Author: RaphiMC

src/main/java/net/raphimc/viaproxy/protocoltranslator/viaproxy/ViaProxyConfig.java

@@ -155,6 +155,13 @@ public class ViaProxyConfig {
     })
     private boolean bungeecordPlayerInfoPassthrough = false;
 
+    @Option("rewrite-handshake-packet")
+    @Description({
+            "Enabling this will rewrite the address in the handshake packet to a value the vanilla client would have sent when connecting directly to the target server.",
+            "This should be left enabled unless you are a server owner and you need the original address on the backend server."
+    })
+    private boolean rewriteHandshakePacket = true;
+
     @Option("rewrite-transfer-packets")
     @Description({
             "Enabling this will rewrite transfer packets to point back to ViaProxy. This allows ViaProxy to perform protocol translation when forwarding the player to the actual server from the transfer packet.",
@@ -473,6 +480,15 @@ public void setPassthroughBungeecordPlayerInfo(final boolean bungeecordPlayerInf
         this.save();
     }
 
+    public boolean shouldRewriteHandshakePacket() {
+        return this.rewriteHandshakePacket;
+    }
+
+    public void setRewriteHandshakePacket(final boolean rewriteHandshakePacket) {
+        this.rewriteHandshakePacket = rewriteHandshakePacket;
+        this.save();
+    }
+
     public boolean shouldRewriteTransferPackets() {
         return this.rewriteTransferPackets;
     }

src/main/java/net/raphimc/viaproxy/proxy/client2proxy/Client2ProxyHandler.java

@@ -267,26 +267,27 @@ private void connect(final SocketAddress serverAddress, final ProtocolVersion se
         }
         ViaProxy.EVENT_MANAGER.call(new ConnectEvent(this.proxyConnection));
 
+        final int handshakePort;
+        if (ViaProxy.getConfig().shouldRewriteHandshakePacket()) {
+            if (serverAddress instanceof InetSocketAddress inetSocketAddress) {
+                handshakeParts[0] = inetSocketAddress.getHostString();
+                handshakePort = inetSocketAddress.getPort();
+            } else {
+                handshakeParts[0] = AddressUtil.toString(serverAddress);
+                handshakePort = 25565;
+            }
+        } else {
+            handshakePort = clientHandshakeAddress.getPort();
+        }
+
         this.proxyConnection.connectToServer(serverAddress, serverVersion).addListeners((ThrowingChannelFutureListener) f -> {
             if (f.isSuccess()) {
                 f.channel().eventLoop().submit(() -> { // Reschedule so the packets get sent after the channel is fully initialized and active
                     if (ViaProxy.getConfig().useBackendHaProxy()) {
                         this.proxyConnection.getChannel().writeAndFlush(HAProxyUtil.createMessage(this.proxyConnection.getC2P(), this.proxyConnection.getChannel(), clientVersion)).addListener(ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE);
                     }
 
-                    final String address;
-                    final int port;
-                    if (serverAddress instanceof InetSocketAddress inetSocketAddress) {
-                        address = inetSocketAddress.getHostString();
-                        port = inetSocketAddress.getPort();
-                    } else {
-                        address = AddressUtil.toString(serverAddress);
-                        port = 25565;
-                    }
-
-                    handshakeParts[0] = address;
-                    final C2SHandshakingClientIntentionPacket newHandshakePacket = new C2SHandshakingClientIntentionPacket(clientVersion.getOriginalVersion(), String.join("\0", handshakeParts), port, intendedState);
-
+                    final C2SHandshakingClientIntentionPacket newHandshakePacket = new C2SHandshakingClientIntentionPacket(clientVersion.getOriginalVersion(), String.join("\0", handshakeParts), handshakePort, intendedState);
                     this.proxyConnection.getChannel().writeAndFlush(newHandshakePacket).addListeners(ChannelFutureListener.FIRE_EXCEPTION_ON_FAILURE, (ChannelFutureListener) f2 -> {
                         if (f2.isSuccess()) {
                             final UserConnection userConnection = this.proxyConnection.getUserConnection();