Guest/Host P2P setup failure in Firefox on Android

[dozingpip]

Firefox app version is 102.2.1, Android version 12, it's a Pixel 3 XL, can give more info if relevant.

Not sure if it's an issue specific to my device, but I can't select all the text to join as a guest/ host in Firefox on Android. It basically doesn't let me expand my text selection and the menu that usually would let me select from Cut/Paste/Select All, etc, does not show up... I tried it in Chrome app and it works fine as expected. (It's also fine in desktop Firefox)
Probably that specific type of text box just works differently in Firefox for mobile?
Such a weirdly specific issue, I know, sorry :/

[PrimalZed]

Looks like the text-area click event works differently in Firefox.

Try tapping on the "Offer Code" or "Answer Code" label rather than the code text underneath. This should display the confirmation "Copied!" notification, and copy the text to your clipboard.

Please let me know whether that works.

[dozingpip]

I think that worked, thanks! Hard to tell when it actually did it, didn't get any feedback saying when it actually copied it... Also there's no feedback about whether the connection was successful when I hit the checkmark? Should there be any? I feel like there should be something?

[PrimalZed]

When entering the host code's into the guest's prompt and hitting the green checkmark, the guest's form should switch to a "Copy Answer Code to Send to Host" prompt with a new code.

After entering the guest's answer code into the host's prompt and hitting the green checkmark, both the host and guest forms should switch to a "Connected" confirmation.

The host can continue adding new guests.

If you're using mobile devices, the QR Code option might be easier.

[PrimalZed]

If you still can't get it to work, DM me on reddit and we'll see if we can get a discord call or something going.

[dozingpip]

Still nope, sent you a DM.

[PrimalZed]

I think I've narrowed the issue down to two things:

1. In firefox, the datachannel is already open before I can add an event listener to it.
2. Firefox does not support the connectionState event on RTCPeerConnection: https://developer.mozilla.org/en-US/docs/Web/API/RTCPeerConnection/connectionState

I'm addressing these by:

1. Checking current datachannel readystate when adding event listener
2. using iceConnectionState instead of connectionState

Also added Copy buttons to the p2p text boxes.

[PrimalZed]

I haven't been able to get it to work on Android Firefox. The short version is I think I need to have a TURN server, which I'd rather not do. I'm hoping mDNS support improves on browsers so this can work without STUN or TURN servers.

mDNS issues?

While working on this, I noticed issues in chromium as well. While running locally without PWA (npm run ng serve), it works. While running locally with PWA (npm run pwa), it wouldn't seem to do anything after setting the answer description in the host connection. (The event it waits for is dataChannel 'open', but the logs on other events don't capture anything either.)

I think this is due to WebRTC not working right with mDNS. When running as a PWA, the answer code will have mDNS address <guid>.local. When running without PWA, the answer code will the intranet IP address 192.168.1.5, and the connection worked. (For both with and without PWA, the offer code from the host uses mDNS address <guid>.local.) I have no idea why the answer code will use mDNS address when running as a PWA and intranet IP address when not running as PWA. I also have no idea why an answer code with an mDNS address doesn't work (especially considering the offer code uses an mDNS address in both scenarios).

It seems that mDNS support started to get added to WebRTC around 2019, which is well before I started work on this application. I don't know if there was some update to WebRTC or mDNS in chromium after I initially worked on this, or if it never worked while running as PWA and I never tried it out.

I addressed this for now by adding a Google-hosted STUN server to get external IP address rather than intranet address. That means it won't work without an Internet connection, which I was hoping to not need. I'll try checking back periodically to see if it works with an mDNS address in future browser updates, which would allow me to drop the STUN server.

Android Firefox

Even with a STUN server to use Internet addresses - which works in desktop chromium, desktop Firefox, and Android chromium - it still wouldn't work with Android Firefox. The console receives an error suggesting I use a TURN server.

TURN servers are used for handling data in difficult network scenarios (meaning it's not even strictly "p2p" anymore). Unlike STUN servers, there are not publicly available TURN servers. The STUN server is just used to determine the external IP address of the device (very low bandwidth), while a TURN server is used for the ongoing communication between devices in difficult network scenarios (potentially lots of bandwidth).

I'd rather not go through setting up my own TURN server. Configuring it is pretty involved, and I would need to set up hosting for it.

I'm going to have to say that Android Firefox is not supported for now. If it works with all other browsers - including desktop Firefox - it seems like there is something wrong with the Android Firefox implementation of WebRTC. I'll try checking back every so often to see if this gets addressed in an update of Android Firefox.

[dozingpip]

Okay, thank you! Good to know I'm not crazy and it's not more super specific to my personal setup. I'm fine with using chrome for now anyway, I think I'd be the only one in my board game group who'd care, thankfully. Maybe someday Android Firefox will fix its WebRTC implementation someday... Do you think it's worth me looking into sending a bug report to Mozilla for this? I'm not exactly sure how to explain all the details other than give my version info and mostly copy paste what you said^. I tried looking for similar bugs in https://bugzilla.mozilla.org/buglist.cgi?quicksearch=stun+server , but most of those seem fairly old or irrelevant? I tried filtering by Android as platform + "stun" in summary, got nothing....

[PrimalZed]

I'm pretty sure trying to use WebRTC for intranet-only data channel is pretty unusual. I'll have to try to set up minimal reproductions of each issue (chromium with mDNS and android firefox needing a TURN server) to post bugs for them.