Firefox synthesizes A-records for ipv6-only subdomains under some circumstances
Categories
(Core :: Networking, defect, P3)
Tracking
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People
(Reporter: laura, Unassigned)
Details
(Whiteboard: [necko-triaged])
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36
Steps to reproduce:
Go to https://mozbug.zotan.services with an ipv4-only connection
Actual results:
The request to v6.mozbug.zotan.services should fail, as there are no A records on that subdomain
Expected results:
It connects anyways, with the ipv4 address of the root domain
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Reporter | |
Comment 1•3 years ago
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Reporter | |
Comment 2•3 years ago
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It appears that the actual and expected results are the wrong way around in the issue, sorry about that
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Reporter | |
Comment 3•3 years ago
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It appears to poison the cache, the issue is not reproducible without ajax requests (potentially even in the order any->v4only->v6only) at first, but after it triggers you can open the v6 only subdomain directly and it works perfectly fine (while connecting over ipv4)
about:networking#dns does not show anything that should cause that, however, which is interesting
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Comment 4•3 years ago
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The Bugbug bot thinks this bug should belong to the 'Core::Networking' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.
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Comment 5•3 years ago
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Valentin, we may want to fix this at some point.
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Comment 6•3 years ago
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Hi, I was able to reproduce this issue as well In our latest Firefox Release, Beta and Nightly builds, I will update the flags accordingly.
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Comment 7•3 years ago
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This is caused by the connection coalescing issue in bug 1420777.
I confirmed by looking at the logs that resolving v6.mozbug.zotan.services does not produce an IPv4 addr. And disabling http2 makes the issue go away.
Description
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