(svn r14897) -Codechange: don't allow a few command flags to be sent over the network as it's bogus information anyway; e.g. the "do not send over network" flag as it will be set whenever the command is received from the server/client.

-Codechange: test earlier whether the command (send from the server) is actually valid.

src/network/network_client.cpp

@@ -685,6 +685,24 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_COMMAND)
 	cp->my_cmd   = p->Recv_bool();
 	cp->next     = NULL;
 
+	if (!IsValidCommand(cp->cmd)) {
+		IConsolePrintF(CC_ERROR, "WARNING: invalid command from server, dropping...");
+		free(cp);
+		return NETWORK_RECV_STATUS_MALFORMED_PACKET;
+	}
+
+	if (GetCommandFlags(cp->cmd) & CMD_OFFLINE) {
+		IConsolePrintF(CC_ERROR, "WARNING: offline only command from server, dropping...");
+		free(cp);
+		return NETWORK_RECV_STATUS_MALFORMED_PACKET;
+	}
+
+	if ((cp->cmd & CMD_FLAGS_MASK) != 0) {
+		IConsolePrintF(CC_ERROR, "WARNING: invalid command flag from server, dropping...");
+		free(cp);
+		return NETWORK_RECV_STATUS_MALFORMED_PACKET;
+	}
+
 	// The server did send us this command..
 	//  queue it in our own queue, so we can handle it in the upcoming frame!
 

src/network/network_data.cpp

@@ -34,6 +34,8 @@ void NetworkAddCommandQueue(NetworkClientSocket *cs, CommandPacket *cp)
 // Prepare a DoCommand to be send over the network
 void NetworkSend_Command(TileIndex tile, uint32 p1, uint32 p2, uint32 cmd, CommandCallback *callback, const char *text)
 {
+	assert((cmd & CMD_FLAG_MASK) == 0);
+
 	CommandPacket c;
 
 	c.company = _local_company;

src/network/network_server.cpp

@@ -839,6 +839,11 @@ static bool CheckCommandFlags(const CommandPacket *cp, const NetworkClientInfo *
 		return false;
 	}
 
+	if ((cp->cmd & CMD_FLAGS_MASK) != 0) {
+		IConsolePrintF(CC_ERROR, "WARNING: invalid command flag from client %d (IP: %s), kicking...", ci->client_id, GetClientIP(ci));
+		return false;
+	}
+
 	return true;
 }