Recover corrupted archive

[Sooda]

http://opensourcepack.blogspot.com/2010/05/recover-corrupted-archive-download-with.html

That post sums up my situation, I am with 3.2 gb 3ds Max 2010 archive (genuine from their download site) and some parts ( up to 450 mb) is bad which needs redownload. For my suprise that is not so easy task.
Thought to toss the question into air why archive programs (winrar, winzip) does not have feature to scan archive and when found unreadable part redownload only that part paste it into full archive and try again to scan until archive is good?

 

[GetTriggerUnit-]

If you are able to get the unreadable part offset and length, it will be easy to fix. I can make a little program that does it. In other case there's not much you can do...

Note: the offsets and length are byte positions.

 

[Sooda]

The thing is not so dramatical, I am able to extract archive. It gives for 4 files crc errors. I can't open archive remotely (Autodesk server) to download only specific files, though server allows resume. Converting corrupted file position to archive offset and length would be solution like you suggested.

There are actually tutorials around web which teach how to manually fix such errors, you do not need to do anything.
I understand with great connection speeds it is not important, but what if your download speed would be 20 MB/ s and file size 9999999999999999999999 TB, it still would matter.

Came up with idea, there would be tool to scan download which makes blueprint of that file (it could divide file to nth parts each having its own checksum) that info is hosted on such server or even put up next to download. Now when you download you can compare your parts against blueprint values and redownload if needed.
That would eliminate greatest problem of putting genuine software to torrent network, instead checksum info is shared and still software itself can be downloaded only from genuine distributer.

EDIT:
Though each data transmission has byte (or) data comparison but still download managers are able to corrupt download (how it is possible to send corrupt byte back to server and get valid result back is mystery to me).