[Kget] [Bug 158816] New: Use chunk checksums in Metalinks to repair downloads

[Ant Bryan]

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http://bugs.kde.org/show_bug.cgi?id=158816         
           Summary: Use chunk checksums in Metalinks to repair downloads
           Product: kget
           Version: unspecified
          Platform: SuSE RPMs
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: wishlist
          Priority: NOR
         Component: metalink
        AssignedTo: kget kde org
        ReportedBy: anthonybryan gmail com


Version:            (using KDE 4.0.1)
Installed from:    SuSE RPMs
OS:                Linux

Metalinks contain mirror, checksum, & other information for downloads in an XML format. Most Metalinks also include chunk checksums (aka partial file checksums, as opposed to full file checksums) for segments of a file. These chunk checksums can be used to determine if a segment of the download is corrupted. If so, the corrupted chunk can be requested again.

For large downloads, where Metalinks are frequently used, this can save users considerable time and hassle, along with saved bandwidth.

This is one of the most important Metalink features, I hope KGet can support it.

Example Metalinks with chunk checksums can be found at http://download.packages.ro/metalink/openoffice/

The <pieces> section here contains an example of chunk checksums, some of which have been excised (...) to save space.

    <verification>
     <hash type="md5">74c20c8c4f5df40958278a148feec93b</hash>
     <hash type="sha1">0145902fe029c6b6e98ceb4d70715367f0bf462a</hash>
     <hash type="ed2k">af9ae7c710d769abee63d273429a40d7</hash>
    
     <pieces length="1048576" type="sha1">
      <hash piece="0">4a183d5f17bc8db275f7ad8be821432275d34d9e</hash>
      <hash piece="1">7dcc2812b6f3422f3bf5ec9a4bbd76444b1d072c</hash>
      <hash piece="2">a1e4b602c151a464a77f81ac27d41712cfa6ba3f</hash>
      ...
      <hash piece="136">b7c9cb2306c42b825d0bae212ae89ebd1f25fa44</hash>
      <hash piece="137">58c5a413f32702e5b3ad75568f60d608e287406e</hash>
     </pieces>   

    </verification>