try SNTP.LIB written by Hans Van Ingelgom (was posted on Zworld's old BB), it's a simple an robust library that can be used to synchronize the on-board RTC. See the description below to decide whether this library is suitable for your application.
/* SNTP.LIB V0.8
* This library provides a very very simple SNTP (Simple Network
* Time Protocol, RFC1769) interface.
* sntp_gettime() returns the time, measured in seconds since
* Jan 01, 1980, 00:00 GMT. To do so, it sends an empty NTP request
* to the server and retreives the time from the reply. THIS MEANS
* THERE IS NO ROUDTRIP DELAY CALCULATION! (read the RFC if you wish
* to implement this feature).
* This software is freeware. You can use it in your own programs,
* as long as this copyright notice is not changed. No warranties
* implied. If you make changes to the code, please send them to
along with a short description of your changes.