Issue resuming an upload (WinSCP)

Discussion of open issues, suggestions and bugs regarding network security and data protection solution - SecureBridge
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mbillig02
Posts: 19
Joined: Sat 09 Feb 2019 23:16

Issue resuming an upload (WinSCP)

Post by mbillig02 » Fri 11 Feb 2022 20:20

I am not sure where the problem is but when interrupting an upload and then resuming with WinSCP it fails. It looks like WinSCP causes SimpleSSHServer (10.0.1) to allocate the full size of the file being uploaded. When interrupted and resumed it immediately thinks it is complete.

I tried uploading with FileZilla and did not have the issue. I then tried using WinSCP to upload to Bitvise SSH server and did not have the issue. Any ideas?

YanishevskiyVI
Devart Team
Posts: 70
Joined: Wed 02 Jun 2021 09:30

Re: Issue resuming an upload (WinSCP)

Post by YanishevskiyVI » Mon 21 Feb 2022 12:16

Hi there,

The issue occurs because according to the SFTP protocol, at the beginning of the upload file on the server, allocate exact same size file, so there is no way to determine on which part of the file the connection is broken.

We have successfully reproduced this error and started researching ways to solve it.

We will notify you as soon as we receive the necessary information.

stlcours
Posts: 33
Joined: Wed 14 Sep 2011 20:22

Re: Issue resuming an upload (WinSCP)

Post by stlcours » Mon 28 Feb 2022 04:57

You can create another temp file (maybe it should be hidden) to note where the connection is broken. When the whole file is uploaded, SB will aotomatically delete this temp file!

But I have a question, does SB use serveral chunnels to upload the same file? If yes, SB should note serveral places broken.
Wait for your anwser, Thanks.

dzhanhira
Devart Team
Posts: 239
Joined: Mon 26 Oct 2020 13:49

Re: Issue resuming an upload (WinSCP)

Post by dzhanhira » Mon 04 Apr 2022 12:49

Kindly be informed that the answer to your question depends on the situation.

If the file is uploaded from one application - the SFTP client opens the handle of the file and then uploads data using this handle in different streams, then this method should work correctly.

If the file upload occurs in such a way that many accesses to one file are opened at the same time and writing is performed to the same file from different handles, then this method is not provided.

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