src/network/serverpackethandler.cpp

@@ -95,6 +95,9 @@ void Server::handleCommand_Init(NetworkPacket* pkt)
 		return;
 	}
 
+	if (denyIfBanned(peer_id))
+		return;
+
 	// First byte after command is maximum supported
 	// serialization version
 	u8 client_max;

src/server.cpp

@@ -1160,31 +1160,6 @@ void Server::ProcessData(NetworkPacket *pkt)
 	ScopeProfiler sp(g_profiler, "Server: Process network packet (sum)");
 	u32 peer_id = pkt->getPeerId();
 
-	try {
-		Address address = getPeerAddress(peer_id);
-		std::string addr_s = address.serializeString();
-
-		// FIXME: Isn't it a bit excessive to check this for every packet?
-		if (m_banmanager->isIpBanned(addr_s)) {
-			std::string ban_name = m_banmanager->getBanName(addr_s);
-			infostream << "Server: A banned client tried to connect from "
-					<< addr_s << "; banned name was " << ban_name << std::endl;
-			DenyAccess(peer_id, SERVER_ACCESSDENIED_CUSTOM_STRING,
-				"Your IP is banned. Banned name was " + ban_name);
-			return;
-		}
-	} catch (con::PeerNotFoundException &e) {
-		/*
-		 * no peer for this packet found
-		 * most common reason is peer timeout, e.g. peer didn't
-		 * respond for some time, your server was overloaded or
-		 * things like that.
-		 */
-		infostream << "Server::ProcessData(): Canceling: peer "
-				<< peer_id << " not found" << std::endl;
-		return;
-	}
-
 	try {
 		ToServerCommand command = (ToServerCommand) pkt->getCommand();
 
@@ -3287,6 +3262,11 @@ void Server::reportFormspecPrependModified(const std::string &name)
 void Server::setIpBanned(const std::string &ip, const std::string &name)
 {
 	m_banmanager->add(ip, name);
+
+	auto clients = m_clients.getClientIDs(CS_Created);
+	for (const auto peer_id : clients) {
+		denyIfBanned(peer_id);
+	}
 }
 
 void Server::unsetIpBanned(const std::string &ip_or_name)
@@ -3299,6 +3279,22 @@ std::string Server::getBanDescription(const std::string &ip_or_name)
 	return m_banmanager->getBanDescription(ip_or_name);
 }
 
+bool Server::denyIfBanned(session_t peer_id)
+{
+	Address address = getPeerAddress(peer_id);
+	std::string addr_s = address.serializeString();
+
+	if (m_banmanager->isIpBanned(addr_s)) {
+		std::string ban_name = m_banmanager->getBanName(addr_s);
+		actionstream << "Server: A banned client tried to connect from "
+			<< addr_s << "; banned name was " << ban_name << std::endl;
+		DenyAccess(peer_id, SERVER_ACCESSDENIED_CUSTOM_STRING,
+			"Your IP is banned. Banned name was " + ban_name);
+		return true;
+	}
+	return false;
+}
+
 void Server::notifyPlayer(const char *name, const std::wstring &msg)
 {
 	// m_env will be NULL if the server is initializing

src/server.h

@@ -245,6 +245,7 @@ public:
 	void setIpBanned(const std::string &ip, const std::string &name);
 	void unsetIpBanned(const std::string &ip_or_name);
 	std::string getBanDescription(const std::string &ip_or_name);
+	bool denyIfBanned(session_t peer_id);
 
 	void notifyPlayer(const char *name, const std::wstring &msg);
 	void notifyPlayers(const std::wstring &msg);