1885801 - Secure DNS causes delayed website loading at startup

Status: RESOLVED FIXED

(Core :: Networking: DNS, defect, P1)

Description

[georges]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:123.0) Gecko/20100101 Firefox/123.0

Steps to reproduce:

Enable DNS over HTTPS, turn session restore ON. Quit firefox with a tab open then reopen.

I tried this in safe mode, and confirmed it still happens unles DNA over HTTPS (set to always) is changed.

Actual results:

Firefox starts promptly and the UI is resposnive, tabs are restored however the websites do not load for anywhere between 5-10 seconds.

Expected results:

Firefox starts promptly, websites load promtply.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Networking: DNS' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.

Comment 2

[Kershaw Chang [:kershaw]]

Hi Reporter,

Could you try to record a http log? Since this happens during startup, please set the correct environment variables (MOZ_LOG and MOZ_LOG_FILE) before starting Firefox. Then, please send the log file to [e-mail].

Thanks.

Comment 3

[georges]

Hello, this has been. Thank you.

Comment 4

[georges]

(In reply to georges from comment #3)

Hello, this has been. Thank you.

Typo, it has been sent.

Comment 5

[edgul]

NI for log review

Comment 6

[Kershaw Chang [:kershaw]]

Thanks for the log.

It shows that the delay by the following things:

1. Firefox tried to load the PAC URL (http://wpad/wpad.dat).
2. Firefox tried to resolve wpad via TRR.
3. The TRR mode was TRR_ONLY_MODE, so the TRR request timeouted after 30s.
4. All HTTP requests were delayed for 30s.

I think we should not try to resolve wpad vis TRR, since it's not resolvable.

Comment 7

[Kershaw Chang [:kershaw]]

Attachment: Bug 1885801 - Disable TRR for PAC channel, r=#necko

Comment 8

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/55e08b64e59d
Disable TRR for PAC channel, r=necko-reviewers,jesup,valentin

Comment 9

[Norisz Fay [:noriszfay]]

https://hg.mozilla.org/mozilla-central/rev/55e08b64e59d