LedgerHQ / LedgerHQ/blue-loader-python

Flakiness connecting to Ledger on Mac OS due to multiple HID devices

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Dominant language
Python
Stars
125
Forks
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Description

We have observed a lot of flakiness with connecting to the Ledger on Mac OS, specifically in this code from the ledgereth library which bottoms out here in ledgerblue.

We found that when the Ethereum app is opened on the Ledger device, another HID entry shows up on the Mac. It is identical to the original HID entry except that usage_page is 61904 instead of 65440. The order of hid.enumerate() is not deterministic, so sometimes you get the original, good device, and sometimes you get the second, bad device. Hence the flakiness.

I'm not knowledgeable about the HID spec but I was wondering if changing the or condition in this line to an and condition would be appropriate. It would fix our problem at least because it would enforce that the device has a usage page of 65440, which would exclude the second, bad device.

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First steps

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start at ledgerblue/comm.py around line 357 and inspect how HID devices from hid.enumerate() are filtered, especially usage_page values 65440 and 61904. Reproduce the connection attempt on Mac OS with the Ethereum app open, then verify that the intended Ledger device is selected consistently and the flaky connection no longer occurs.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
embedded-iot
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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