Identifying QR linked users

[chonymony]

Hi,

When linking a new device through a QR code with /v1/qrcodelink, the account appears in the list of added accounts(/v1/accounts). However, I'm unsure how to specifically identify the account just linked, especially if multiple accounts are being registered simultaneously. Is there a way to return the newly linked account's details, possibly using the UUID from the QR code, to avoid collisions or errors?

Thanks!

[chonymony]

Checking the logs i found out that there's actually a way to do this as there's a relationship between the link deviceLinkUri > [account ID? MAster's device ID?] > [Phone Number!] as the logs suggest:
`
| GET "/v1/qrcodelink?device_name=signal-api"

| time="2025-01-26T22:32:59Z" level=debug msg="json-rpc command: {"jsonrpc":"2.0","method":"finishLink","id":"[account ID? Master's device ID?]","params":{"deviceLinkUri":"sgnl://linkdevice?uuid=---------------pub_key=---------------","deviceName":"signal-api"}}"

| time="2025-01-26T22:33:10Z" level=debug msg="json-rpc received data: {"jsonrpc":"2.0","result":{"number":"[Phone Number!]"},"id":"[account ID? Master's device ID?]"}\n"
`

So I was wondering if I need to fork the project or this could be implemented as a Plugin. The idea is to receive (Maybe through Web Socket?) the data from the account that used the 'deviceLinkUri' (QR link).

[bbernhard]

Ah, I think I got it. So, you basically would like a way to get your hands on the deviceLinkUri without decoding the QR code, right? So another endpoint for that (similar to the qrcodelink) which returns the data as a JSON payload would be fine?

---

I've implemented a first version of the HTTP callback. It's still living on a feature branch and isn't merged into the release branch yet.
If you want to give it a try, you can use the following docker image: bbernhard/signal-cli-rest-api:0.178-dev (the build is still running, but should hopefully finish soon: https://github.com/bbernhard/signal-cli-rest-api/actions/runs/13060753631/job/36442887226)

In order to call the qrcodelink endpoint with an HTTP callback, you can use the callback_url query parameter:

e.g:

http://127.0.0.1:8080/v1/qrcodelink?device_name=a&callback_url=http%3A%2F%2F127.0.0.1%3A8080%2Fv1%2Fplugins%2Fabc

which specifies the HTTP callback as: http://127.0.0.1:8080/v1/plugins/abc

You can either implement the endpoint yourself as a lua plugin (see https://github.com/bbernhard/signal-cli-rest-api/tree/master/plugins for details) or implement another listing webserver which handles the request.

For testing purposes I created a small plugin with the following contents:

abc.def:

endpoint: abc
method: POST

abc.lua:

local json = require("json")

print("hello")
local customEndpointPayload = json.decode(pluginInputData.payload)
print(customEndpointPayload)
print(pluginInputData.payload)

which just prints the data it receives to the console.

So, in the docker logs, you would see something like this {"number":"+xxxxxxx"} after the linking was successful.

This only works in json-rpc mode

[chonymony]

Wow that's fast!, I'll give it a try right away.
Thanks for suggesting creating another endpoint, but I think that could be a burden for you in terms of maintaining it.
Probably just adding it to the response of the QR endpoint as part of the response, or choose the response format on a parameter could be more than enough.

[bbernhard]

Ok, looks like the CI has some connectivity problems. I'll try it later again. If you want build it yourself in the meantime, clone the repository, check out the http_callback branch and build the image with docker.

[chonymony]

Thanks a bunch, I'll wait for the release of the container.

[bbernhard]

the image should now be up