Using adblock DNS can cause blank pages

Mifuru

Hello!

I have been using Vivaldi for over a year, mixed with DNS servers that block requests to ad servers.

I noticed that if the DNS server processes the request for a long enough time (about 500 ms), then the browser will freeze.

How it works:

We connect a DNS server to our router, for example, AdGuard
We start using the browser
If the site is open for a very long time, then the browser window starts to freeze
Buttons "Page refresh", "Back", "Forward" do not work
We see a blank page, the browser cannot be closed without the task manager

Pathduck

@mifuru Hi - does this happen in other browsers as well?

First I'd like to state that using a DNS solution for adblocking is a Bad Idea - you have no control over what is blocked, no way to fix it if a site breaks because of this blocking, and very difficult to troubleshoot.

It also means that the browser still has to make the request (to IP 0.0.0.0), instead of using a local adblocker like uBO or the Vivaldi blocker, where the request is blocked before it even attempts a connection.

If you set the primary DNS in router, is your OS set to use the router as primary?

I notice the Adguard DNS sets known trackers to IP 0.0.0.0:

$ nslookup doubleclick.net 94.140.14.14
Server:  dns.adguard.com
Address:  94.140.14.14

Non-authoritative answer:
Name:    doubleclick.net
Addresses:  ::
          0.0.0.0

Every time the browser has to make a connection to this IP it takes a couple of seconds to give an error for each request:

$ time nc -v 0.0.0.0 443
nc: connect to 0.0.0.0 port 443 (tcp) failed: Connection refused

real    0m2.079s
user    0m0.000s
sys     0m0.015s

Mifuru

@Pathduck, hi!

Yes, I use DNS blockers and I understand the consequences of my choice. In my case, I describe a problem in which if 0.0.0.0 is returned to the browser, it starts to work very badly, returning an empty page instead of an error page and deliberately makes the browser freeze very wildly.

Pathduck

@mifuru Yes, but does this also happen in other browsers?

Do you have an example site where this happens often?

Mifuru

@pathduck, no. Only in Vivaldi. For example: variety[.]com.

We connect a DNS server to our router, for example, AdGuard
We start using the browser
If the site is open for a very long time, then the browser window starts to freeze
Buttons "Page refresh", "Back", "Forward" do not work
We see a blank page, the browser cannot be closed without the task manager

Pathduck

@mifuru How are you so sure this is caused by the adblocking DNS and not some other issue?

Have you tried the troubleshooting steps, including testing in a clean profile/disabling extensions?
https://help.vivaldi.com/desktop/troubleshoot/troubleshooting-issues/

Mifuru

@Pathduck, no. This bug working only with adblock DNS.

Pathduck

@Mifuru Hi, out of curiousity I tried this on my system. I did not set DNS server in my router, since that would require me to reboot my router and I don't want that. But setting local DNS should do the same.

Went into the local machine DNS settings and set Adguard DNS servers from
https://kb.adguard.com/en/general/dns-providers
Verified with ipconfig /all that DNS servers were set:

DNS Servers . . . . . . . . . . . : 94.140.14.14
                                    94.140.15.15

Opened Vivaldi 5.0 Stable, clean profile
Opened variety.com in a tab
Using Wireshark, verified that IP lookups were going to Adguard and returning 0.0.0.0 for ad-servers like Doubleclick:
1974 22:59:40,446640 dns.adguard.com 53 192.168.0.10 54130 DNS 91 Standard query response 0x0002 A doubleclick.net A 0.0.0.0
Opened Vivaldi Devtools (F12), Network tab
Reloaded Variety tab, in Devtools verified requests failing (because they were going to IP 0.0.0.0)
Surfed around on Variety a bit and keeping tab open
Opened another tab for a site with a lot of trackers:
https://www.vgtv.no/video/231392/oppdal-aldri-opplevd-saa-brutal-vind
and watched some videos
Let tabs opened 20 mins.
No problems recorded, no freeze, buttons still working

I think you first need to define "for a very long time", what does it mean, 30 minutes, an hour, many hours?

You also need to investigate your router and how it replies to DNS requests, while looking at the Network tab in devtools, see if you get timeouts/hangs and similar.

If you feel absolutely certain this is a bug in Vivaldi, you are of course free to report a bug, but I wouldn't bet on it being reproducible, and if so will likely be closed.

Please read:

carefully and report the bug to Vivaldi bugtracker