[Bug-wget] [bug #51840] Local file corruption using default retry mechanism when retry returns no data

[anonymous]

URL:
  <http://savannah.gnu.org/bugs/?51840>

                 Summary: Local file corruption using default retry mechanism
when retry returns no data
                 Project: GNU Wget
            Submitted by: None
            Submitted on: Thu 24 Aug 2017 03:13:30 PM UTC
                Category: Program Logic
                Severity: 3 - Normal
                Priority: 5 - Normal
                  Status: None
                 Privacy: Public
             Assigned to: None
         Originator Name: Andrew Caruth
        Originator Email: address@hidden
             Open/Closed: Open
         Discussion Lock: Any
                 Release: 1.18
        Operating System: GNU/Linux
         Reproducibility: Every Time
           Fixed Release: None
         Planned Release: None
              Regression: None
           Work Required: None
          Patch Included: None

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Details:

The following server behaviour results in a corrupt local download:

1: Accept TCP connection from wget
2: Return all of the HTTP response header and N bytes of the content
3: Close the connection
(wget retry attempt 1 begins from offset N using the range header)
4: Accept TCP connection from wget
5: Close the connection
(wget retry attempt 2 begins with no byte range)
6: Return all of the HTTP response header and all of the content
7: Close the connection

The local file will now contain the bytes received in step 2 as well as all of
the bytes received in step 6.

I believe that if a 'ranged' retry receives no data, further retries should
continue to make ranged requests. Alternatively the offset in the partial file
should be reset to 0 so the next non-ranged request starts from the correct
place.

I've attached a tcpdump capture and wget debug output. The file requested is
12 bytes ("hello world!") and the resulting file is 17 bytes ("hellohello
world!").

I have also reproduced this with wget 1.13.



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File Attachments:


-------------------------------------------------------
Date: Thu 24 Aug 2017 03:13:30 PM UTC  Name: wget118_corruption.pcap  Size:
3KiB   By: None

<http://savannah.gnu.org/bugs/download.php?file_id=41642>
-------------------------------------------------------
Date: Thu 24 Aug 2017 03:13:30 PM UTC  Name: wget_debug.log  Size: 3KiB   By:
None

<http://savannah.gnu.org/bugs/download.php?file_id=41643>

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