Can skip the download by checksum ?

[Mapaler]

Due to network issues, I always can't update to end.
There are always files to get the header timed out.

Whether the file needs to be updated is determined by checksum, just like the game client. This also does not require additional storage of Cache. Of course, I didn't find the algorithm.

Or can also modify the file as if it were a game client. I found the rule for (lastUpdate + 16305120) * 60 * 1000
LastUpdate is the minute difference from 2001-01-01T00:00:00.000Z

Change the modification time when save. And next time, determines whether the time for modification of the file has changed.