1567201 - Support mDNS queries in mdns_service

Status: RESOLVED FIXED

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

Description

[Dan Minor [:dminor]]

Bug 1554976 is adding a Rust mdns_service to respond to mDNS queries. We'll need to expand that service to also support generating queries as some versions of Windows do not support mDNS and the necko DNS code relies upon the operating system to handle queries.

Comment 1

[Michael Froman [:mjf]]

Marking this P2 for now to match the meta bug.

Comment 2

[Dan Minor [:dminor]]

Try job with green test runs on desktop platforms: https://treeherder.mozilla.org/#/jobs?repo=try&revision=d7100a10b8abfe4a4e40f2a5ff895789d41c8a07

Comment 3

[Dan Minor [:dminor]]

Another try run hitting a wider range of builds: https://treeherder.mozilla.org/#/jobs?repo=try&revision=0571b42eb329ca12d8275bbe011ddca7a74ad9ab

The build fails on mingw opt builds. Part of this change is adding an extern "C" callback from Rust back to C++. The mingw builds are --disable-webrtc and on the opt builds, it is complaining that the callback is undefined. I'm guessing the callback implementation in C++ is being optimized away as the debug builds are working. It would be nice to not build mdns_service for --disable-webrtc builds, but I'm not sure if that is possible. Nathan, do you have any suggestions on how to handle this? Thanks!

Comment 4

[Nathan Froyd [:froydnj]]

Only building mdns_service for --enable-webrtc builds should be pretty straightforward; you need to set up some feature hereabouts:

https://searchfox.org/mozilla-central/source/toolkit/library/rust/gkrust-features.mozbuild

something like:

if CONFIG['MOZ_WEBRTC']:
    gkrust_features += ['mdns']

(or webrtc, or whatever you want to call the feature). You'll need to add it to:

https://searchfox.org/mozilla-central/source/toolkit/library/rust/Cargo.toml
https://searchfox.org/mozilla-central/source/toolkit/library/gtest/rust/Cargo.toml

as well and propagate the feature down into:

https://searchfox.org/mozilla-central/source/toolkit/library/rust/shared/Cargo.toml

where mdns would enable the mdns_service dependency (mdns_service would also become optional at that point). You'd also need to modify:

https://searchfox.org/mozilla-central/source/toolkit/library/rust/shared/lib.rs#53

to be guarded with the appropriate #[cfg(feature = "mdns")]

And that should be all you need.

Comment 5

[Dan Minor [:dminor]]

Thanks! that worked: https://treeherder.mozilla.org/#/jobs?repo=try&revision=5c485f0c7963b6cc69688c671445f2c4ea489224

Comment 6

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Enable hostname obfuscation on Linux, OS X, and Windows; r=mjf!

Comment 7

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Add query support to mdns_service; r=mjf!

This adds basic query support to the mdns_service. Support for limiting
the number of pending queries, timeouts and retries is added in
another commit in this series.

Depends on D46974

Comment 8

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Add mDNS query support to StunAddrsRequest; r=mjf!

Depends on D46975

Comment 9

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Use mdns_service to handle mDNS queries; r=mjf!

Depends on D46976

Comment 10

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Validate hostname prior to registration and querying; r=ng!

We don't want web content to use mDNS to map out the local network, so
we only support registering and querying hostnames that are valid
UUIDs (followed by .local).

Depends on D46977

Comment 11

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Limit pending mDNS queries; r=ng!

This limits the number of pending mDNS queries to 50, adds support for
retrying queries if they timeout, and support for reporting failure if a query
times out twice in a row.

Depends on D46978

Comment 12

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Add unit tests for mdns_service; r=ng!

This adds Rust unit tests for some of the edge cases in handling queries
like limits and retries.

Depends on D46979

Comment 13

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Join multicast group on all interfaces; r=mjf!

We need to join the multicast group on all network interfaces or we may end up
missing packets. There is a limit on the number of groups joinable by a single
socket (20 on my Linux system) but it doesn't seem worth worrying about
hitting that limit at the moment as it seems unlikely that many users would
have more than 20 network interfaces on a system on which they are running
Firefox.

Depends on D46980

Comment 14

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Obfuscate server reflex candidates if necessary; r=ng!

According to https://tools.ietf.org/html/draft-ietf-rtcweb-mdns-ice-candidates-03#section-3.1.2.1
we need to hide the rel-addr and rel-port attributes for server reflex
candidates in order to avoid leaking local addresses.

Depends on D46981

Comment 15

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Support multiple queries in a single packet; r=ng!

If there are multiple pending queries, this allows up to five of them to be
sent in a single packet. This also adds a check to ensure we don't already have
a pending query for a hostname prior to sending a new query.

Depends on D46982

Comment 16

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Don't build mdns_service on --disable-webrtc builds

Depends on D46983

Comment 17

[Dan Minor [:dminor]]

Attachment: Bug 1567201 - Use Maybe rather than empty string for timedout queries; r=ng!

Depends on D46984

Comment 18

[Dan Minor [:dminor]]

Because this missed the deadline for QA for Firefox 71, I'm going to land this preffed off in 71 and flip the pref early in 72.

Comment 19

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/be237496f41e
Add query support to mdns_service; r=mjf
https://hg.mozilla.org/integration/autoland/rev/2afa8a8a0445
Add mDNS query support to StunAddrsRequest; r=mjf
https://hg.mozilla.org/integration/autoland/rev/b2f61006436d
Use mdns_service to handle mDNS queries; r=mjf
https://hg.mozilla.org/integration/autoland/rev/6f29bc4ed952
Validate hostname prior to registration and querying; r=ng
https://hg.mozilla.org/integration/autoland/rev/fc0a313fa8e2
Limit pending mDNS queries; r=ng
https://hg.mozilla.org/integration/autoland/rev/9f849d55a360
Add unit tests for mdns_service; r=ng
https://hg.mozilla.org/integration/autoland/rev/87443564bb2a
Join multicast group on all interfaces; r=mjf
https://hg.mozilla.org/integration/autoland/rev/ddc6931cddec
Obfuscate server reflex candidates if necessary; r=ng
https://hg.mozilla.org/integration/autoland/rev/c45a8001b0a1
Support multiple queries in a single packet; r=ng
https://hg.mozilla.org/integration/autoland/rev/570b2370189e
Don't build mdns_service on --disable-webrtc builds r=froydnj
https://hg.mozilla.org/integration/autoland/rev/d93156659b1b
Use Maybe rather than empty string for timedout queries; r=ng

Comment 20

[Stefan Hindli [:stefan_hindli]]

https://hg.mozilla.org/mozilla-central/rev/be237496f41e
https://hg.mozilla.org/mozilla-central/rev/2afa8a8a0445
https://hg.mozilla.org/mozilla-central/rev/b2f61006436d
https://hg.mozilla.org/mozilla-central/rev/6f29bc4ed952
https://hg.mozilla.org/mozilla-central/rev/fc0a313fa8e2
https://hg.mozilla.org/mozilla-central/rev/9f849d55a360
https://hg.mozilla.org/mozilla-central/rev/87443564bb2a
https://hg.mozilla.org/mozilla-central/rev/ddc6931cddec
https://hg.mozilla.org/mozilla-central/rev/c45a8001b0a1
https://hg.mozilla.org/mozilla-central/rev/570b2370189e
https://hg.mozilla.org/mozilla-central/rev/d93156659b1b