1693057 - Requests are being handled via TRR while connected to a PPTP VPN server

Status: RESOLVED INVALID

(Core :: Networking: DNS, defect)

Description

[Alexandru Trif, Desktop Test Engineering [:atrif]]

Attachment: trr_true_00.gif

Affected versions

• 87.0a1 (20210210215051)
• 86.0 (20210215141125)
• 85.0.2 (20210216094005)

Preconditions

• Connect to a VPN server:
  Steps to configure VPN server: https://www.impactcomputing.co.uk/help-centre/how-to-setup-a-vpn-connection-in-windows-10-(pptp)
  Free VPN servers: https://www.vpnbook.com/

Affected platforms

• Windows 10x64

Steps to reproduce

1. Open Firefox and about:config.
2. Set network.trr.mode:2.
3. Restart Firefox.
4. Acces a random domain.

Expected result

• A VPN connection is detected and the request is not being handled via TRR.

Actual result

• The request is being handled via TRR.

Regression range

• I will search for one ASAP.

Notes

• Attached a screen recording.

Comment 1

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

We intentionally converted this into a doh-rollout heuristic.
Could you check that TRR isn't used when enabling TRR via doh-rollout.enabled ?

Comment 2

[Alexandru Trif, Desktop Test Engineering [:atrif]]

(In reply to Valentin Gosu [:valentin] (he/him) from comment #1)

We intentionally converted this into a doh-rollout heuristic.
Could you check that TRR isn't used when enabling TRR via doh-rollout.enabled ?

Hi Valentin!
If I open Firefox while connected to a PPTP VPN server and set doh-rollout.enabled:true, restart the browser, then access a random domain, the TRR for the accessed domain is set on false in about:networking#dns.

Comment 3

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

That's great! It means the heuristic is working as expected.