Bug #1228

CRC Errors on download

Added by drbits over 10 years ago. Updated about 9 years ago.

Status:ClosedStart date:01/30/2010
Priority:NormalDue date:
Assignee:-% Done:


Category:GeneralEstimated time:0.50 hour
Target version:010 - Next Major Public Release 1.xxx
Resolution:Can't reproduce


Several users are reporting frequent CRC errors on downloads (either identified by the MD5 from the Host or by unrar). Redownload eliminates the problem. I have excluded the known problems. One user reported that he did a binary comparison and only the last byte was different. These users had Max.Con.=1 and in some cases were only downloading one file at a time.

I do not have the evidence yet, but I suspect that the problem is downloading chunks that do not start at a word boundary (4 or 8 bytes, depending on the OS and version).

When a TCP time-out occurs (but the host is keeping the session open), JD performs a new HTTP connection beginning at the next byte. I believe we should round down the beginning byte of each chunk request to a multiple of 8 bytes (AND the start byte with (-8)).

I do not know the architecture of the host plugins well enough to estimate work hours. If the reconnections are in the plugins, this is a big job (on an as changed basis, except for the top sites). If the reconnections are in JD, this should take at most 1/2 hour to fix.

Relates to http://board.jdownloader.org/showthread.php?t=12562

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