1616252 - Maybe add a /etc/hosts parser

Status: RESOLVED FIXED

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

Description

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

We've been avoiding this for a while, mostly because the system resolver already checks this file. But lately we've encountered some issues that seem to require us parsing the file.

Comment 1

[Michal Novotny [:michal]]

We should make sure we can handle very large hosts files. We can test the parser on file generated by AdAway. The generated hosts file on my phone has 48000 lines.

Comment 2

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

Thanks for the info, Michal.
I've been thinking that we probably don't want to enable it on Android at the moment, considering TRR isn't enabled there.
However, Android is a great testcase for parsing a big file with limited hardware resources, so I'll make sure to test it before we ship it.

Comment 3

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

Attachment: Bug 1616252 - Exclude domains in /etc/hosts from using TRR

Comment 4

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/2b1366e8c8ee
Exclude domains in /etc/hosts from using TRR r=necko-reviewers,dragana

Comment 5

[Atila Butkovits]

https://hg.mozilla.org/mozilla-central/rev/2b1366e8c8ee

Comment 7

[nicoenkarin]

I know this issue is resolved, but I want to mention that Firefox fails to parse a large hosts file (mine has 42000 entries a.t.m).
Happens in a fresh profile as well.

FWIW, Chromium-dev 95.0.4624.0 with DoH enabled (same provider, Quad9) does parse the large file.

A hosts file with only 1 entry is parsed, however it takes some time to display the error message.

Linux Mint 19.3; Firefox 91.0.2

Modified preferences:

network.trr.blocklist_cleanup_done ---> true  
network.trr.custom_uri --- > https://dns.quad9.net/dns-query  
network.trr.mode --- > 2  
network.trr.request_timeout_ms --- > 4000  
network.trr.uri --- > https://dns.quad9.net/dns-query