From dda082c29b8813b0d8c0619737f83015ea2ec86d Mon Sep 17 00:00:00 2001
From: mckaygerhard <mckaygerhard@gmail.com>
Date: Sun, 17 Sep 2023 20:26:34 -0400
Subject: [PATCH] Check property duplicate login names

* Check for duplicate login in TOSERVER_INIT handler
  backported https://github.com/minetest/minetest/commit/492110a640dd8d01838e95aba00f650b37b7ed11
  i.e. checks for duplicate logins before sending all media data to the client
---
 src/network/serverpackethandler.cpp | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/network/serverpackethandler.cpp b/src/network/serverpackethandler.cpp
index 768cdb734..f3134821b 100644
--- a/src/network/serverpackethandler.cpp
+++ b/src/network/serverpackethandler.cpp
@@ -175,6 +175,16 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
 		return;
 	}
 
+	RemotePlayer *player = m_env->getPlayer(playername);
+
+	// If player is already connected, cancel
+	if (player && player->getPeerId() != PEER_ID_INEXISTENT) {
+		actionstream << "Server: Player with name \"" << playername <<
+			"\" tried to connect, but player with same name is already connected" << std::endl;
+		DenyAccess(peer_id, SERVER_ACCESSDENIED_ALREADY_CONNECTED);
+		return;
+	}
+
 	m_clients.setPlayerName(peer_id, playername);
 	//TODO (later) case insensitivity