Starterware/AM3351: I am using lwip lib and building a ftp server. but TCP_CONNECT() call back function problem

Tool/software: Starterware

I am using lwip lib and building a ftp server. But, TCP_CONNECT() call back function is never called, as of that, I am not able to do tcp_connect() post tasks. I read few articles in which people have mentioned that i need to call sys_check_timeouts() function periodically. So the problem is  sys_check_timeouts() function is calling sys_now() which is not yet implemented. 

Here sys_now() is giving current time or equivalent to that. My question is how to implement this function which returns current time ?