(Note: although related, this challenge is not a duplicate of this one because it requires determining leap seconds automatically rather than hardcoding their times, and is not a duplicate of this one because most of the difficulty comes from determining the time without leap second skewing, something that most time APIs don't do by default. As such, a solution is likely to look different from a solution to either of those challenges.)
We're coming to the end of 2016, but it's going to take slightly longer than most people expect. So here's a challenge celebrating our extra second this year.
Output the current time in UTC, as hours, minutes, seconds. (For example, legitimate output formats for midday would include
[12,0,0]; the formatting isn't massively important here.)
However, there's a twist: your program must handle leap seconds appropriately, both past and future. This means that your program will have to obtain a list of leap seconds from some online or automatically updated/updatable source. You may connect to the Internet to obtain this if you wish. However, you may only connect to a URL that predates this challenge (i.e. no downloading parts of your program from elsewhere), and you may not use the connection to determine the current time (specifically: your program must function even if any attempt to access the Internet returns a page that's up to 24 hours stale).
Most operating systems' default APIs for the current time will skew time around leap seconds in order to hide them from programs that might otherwise be confused. As such, the main difficulty of this challenge is to find a method or an API to undo that, and work out the true unmodified current time in UTC.
In theory, your program should be perfectly accurate if it ran on an infinitely fast computer, and must not intentionally take more than zero time to run. (Of course, in practice, your program will run on an imperfect computer, and so will probably not run instantaneously. You don't have to worry about this invalidating the results, but must not depend on it for the correctness of your program.)
Your program must function regardless of which timezone the system clock is set to. (However, it may request information from the operating system or environment as to what timezone is being used, and may assume that the reply is accurate.)
As a code-golf, the shortest program wins. Good luck!