Ubuntu
zsync package

"https" address causes zsync download to fail with error 'could not read control file from URL'

Bug #1927807 reported by Sai Vinoba
62
This bug affects 15 people
Affects Status Importance Assigned to Milestone
Ubuntu CD Images
Invalid
Undecided
Unassigned
zsync (Debian)
New
Unknown
zsync (Ubuntu)
Triaged
High
Unassigned

Bug Description

How to reproduce:
1. Go to cdimage.ubuntu.com, choose any flavor and navigate to release or daily-live folder.
2. Copy (link address of) the .zsync file.
3. Open a terminal and try to perform zsync download with the copied zsync URL.

Expected:
Zsync download happens normally.

Actual:
Zsync download fails with error '...could not read control file from URL'.

Below is an example error (for Ubuntu 21.10 20210507 daily build iso):

```
zsync https://cdimage.ubuntu.com/ubuntu/daily-live/20210507/impish-desktop-amd64.iso.zsync
failed on url https://cdimage.ubuntu.com/ubuntu/daily-live/20210507/impish-desktop-amd64.iso.zsync
could not read control file from URL https://cdimage.ubuntu.com/ubuntu/daily-live/20210507/impish-desktop-amd64.iso.zsync
```

If we change the protocol to `http` instead of `https` the zsync function works.

This is happening for all flavors.

Suggested solution: Change/keep all zsync file's address to use `http` till (if) zsync software supports `https` protocol.

Revision history for this message
Bryan Quigley (bryanquigley) wrote :

Apparently this has been known for a while: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=459706

Sai Vinoba (saivinob)
tags: added: impish
tags: added: iso-testing
Revision history for this message
Steve Langasek (vorlon) wrote :

Reassigning to the zsync package then, since this is not an error in the infrastructure.

affects: ubuntu-cdimage → zsync (Ubuntu)
Revision history for this message
Bryan Quigley (bryanquigley) wrote :

zsync is no longer maintained.
https://github.com/cph6/zsync/issues/15#issuecomment-835307920 - but zsync2 exists..

Revision history for this message
Sai Vinoba (saivinob) wrote :

@vorlon, while it may not be an *error* on infrastructure side, the infrastructure team *can* provide solution i.e., by changing the link address of zsync files from 'https' to 'http'.

If we check the linked debian bug report, they are not interested in implementing 'https' feature in zsync for 'overload' concerns. If infrastructure team passes the issue to package, it will be open forever.

Revision history for this message
Matthew Fearnley (matthew-w-fearnley) wrote :

I've been wondering if it's worth making a small patch to zsync so it at least rejects HTTPS with a clear error message? (I was confused by this for a while..)

If I did, where would be the best place to submit it?

Revision history for this message
Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in zsync (Ubuntu):
status: New → Confirmed
Norbert (nrbrtx)
tags: added: jammy
tags: added: bionic focal
Revision history for this message
Norbert (nrbrtx) wrote (last edit ):

I'm using Ubuntu 18.04.6 LTS.

Here

```
zsync https://cdimage.ubuntu.com/daily-canary/current/jammy-desktop-canary-amd64.iso.zsync
```

fails with

```
failed on url https://cdimage.ubuntu.com/daily-canary/current/jammy-desktop-canary-amd64.iso.zsync
could not read control file from URL https://cdimage.ubuntu.com/daily-canary/current/jammy-desktop-canary-amd64.iso.zsync
```

Also it should be noted that pages https://cdimage.ubuntu.com/daily-canary/current/ like has a link to http://zsync.moria.org.uk/ which works normally, so still available.

Jeremy Bícha (jbicha)
Changed in zsync (Ubuntu):
importance: Undecided → High
status: Confirmed → Triaged
Bug Watch Updater (bug-watch-updater)
Changed in zsync (Debian):
status: Unknown → New
corrado venturini (corradoventu)
tags: added: kinetic
Gre0 (gre0)
tags: added: lunar
Revision history for this message
wontfix (wontfix) wrote :

The concerns from the Debian and Fedora bug reports from over a decade ago, shouldn't exist in 2023.
https://istlsfastyet.com/

tags: added: mantic tls
Steve Langasek (vorlon)
Changed in ubuntu-cdimage:
status: New → Invalid
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