1888513 - DoH region switch takes 2 weeks of roaming to trigger

Status: RESOLVED FIXED

(Core :: Networking: DNS, defect, P2)

Description

[Ted Campbell [:tcampbell]]

In Bug 1859608, we tried to have DoH switch regions in response to the REGION_TOPIC observer. Unfortunately, the REGION_TOPIC is intended for long-term switching rather than travel/roaming. The default time interval the observer waits is 2 weeks.

As a result, when roaming (eg from Canada to US) the DoH region sticks as home (CIRA is default) which then has timeout or simply traffic throttling behaviour. This ends up with very frequent DoH issues when roaming. In "Increased Protection" or above, there is a lot of network problems experienced.

https://searchfox.org/mozilla-central/rev/28cc363411d2029aed04c969c8f98785cae110db/toolkit/modules/Region.sys.mjs#96-99

Comment 1

[Valentin Gosu [:valentin] (he/him)]

Thanks for reporting this, Ted. We were wondering why telemetry didn't immediately change after bug 1859608.
Do you happen to know a better way to immediately detect region changes?
Thanks!

Comment 2

[Valentin Gosu [:valentin] (he/him)]

From our discussion last week, we should force a region check on the daily-idle event or when a timezone change is detected.

Comment 3

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1888513 - Refactor DoHConfig.sys.mjs to make kRegionPrefBranch into a function r=#necko

This is not a constant, so it should defer to the pref as a source of truth.

Comment 4

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1888513 - Default DoHConfig to current region instead of home region r=#necko

Comment 5

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1888513 - use idle-daily event instead of region change event r=#necko

The region change event is emitted after 2 weeks of being in a region.
Using the idle-daily event and checking if the current region has changed
should allow users to move to the correct DoH provider sooner.

Comment 6

[Valentin Gosu [:valentin] (he/him)]

Attachment: Bug 1888513 - Perform a region check when the timezone changes r=#necko

A timezone change indicates that the user has just changed location.
This is the most relevant signal that we should change DoH region,
so we immediately do a region fetch and check if it matches the current
DoH region.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/04bd60cbb83f
Refactor DoHConfig.sys.mjs to make kRegionPrefBranch into a function r=necko-reviewers,jesup
https://hg.mozilla.org/integration/autoland/rev/d9d9a6bb63d6
Default DoHConfig to current region instead of home region r=necko-reviewers,jesup
https://hg.mozilla.org/integration/autoland/rev/b2bc9b3dff39
use idle-daily event instead of region change event r=necko-reviewers,jesup
https://hg.mozilla.org/integration/autoland/rev/c6e3a646b7d4
Perform a region check when the timezone changes r=necko-reviewers,jesup

Comment 8

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/04bd60cbb83f
https://hg.mozilla.org/mozilla-central/rev/d9d9a6bb63d6
https://hg.mozilla.org/mozilla-central/rev/b2bc9b3dff39
https://hg.mozilla.org/mozilla-central/rev/c6e3a646b7d4

Comment 9

[Hsin-Yi Tsai (she/her) | away [:hsinyi]]

Clearing old pending NI. The bug was resolved.