On 2010-08-29 22:14, Peter Pöml wrote:
On Sat, Aug 28, 2010 at 04:35:04AM +0200, Carlos E. R. wrote:
On 2010-08-27 09:58, Basil Chupin wrote:
Notice that this doesn't guarantee a correct download, the http or ftp protocols don't allow that. You need something else for verification of the download, and then retry. This can be automated, but you need a verification method.
DownThemAll! verifies the download (provided that a metalink contains hashes). However, it doesn't verify chunks of the file - only the end result.
He did not say he was using a metalink. Things change a lot. We were talking of plain old html/ftp.
Even though this doesn't guarantee that you get a correct result, it guarantess that you don't get an incorrect one.
(HTTP/FTP themselves have no provision for this, that's true. That's why there are metalinks. Okay, HTTP does have a special header that has recently been updated to support modern hashes (RFC5843), but it's not used yet. And for FTP people are working on a standard. But it's not ready or even used anywhere.
Ah, that's nice. Too late, but nice. Perhaps they though that the checksum in tcp packets were enough security.
Metalinks are ready, actively used and standardized in RFC 5854.)
I know. Although... I was surprised the other day when Yast got three corrupt rpms and I had to tell it to retry, manually. I though that aria2c was already the default or enabled (11.2). I still have to review the logs, I forgot.
For example, if the download manager knows the expected crc, it can insist downloading chunks until the result is good. But blindly, because it can not know what section of the file has the error.
Yes. The download manager aria2c (which has been mentioned before) uses all the hashes and verifies chunks of the file (which it is in transit) and re-downloads pieces from other mirrors if an error happens.
But they are not using aria2c, that is the problem.
Chunked hashes are all available with openSUSE downloads. Hopefully, the number of download clients that actually use them will increase in the future.
Not many people are aware of its existence. -- Cheers / Saludos, Carlos E. R. (from 11.2 x86_64 "Emerald" GM (Elessar))