noble/bleno

Unable to use GATT server with central role

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#326 opened on Jul 6, 2017

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help wanted

Description

I'm trying to use noble and bleno together in a single application to allow linux to be in the central role but also be the GATT server. I actually have this working, but had to remove an if statement in bleno. Namely, I had to remove this if:

BlenoBindings.prototype.onLeConnComplete = function(status, handle, role, addressType, address, interval, latency, supervisionTimeout, masterClockAccuracy) {
  // if (role !== 1) {
  //   // not slave, ignore
  //   return;
  // }
  ...
}

from here.

With that if the AclStream never gets set up and bleno never responds to discover services requests (or any other request).

I understand why that check is there, since a connection callback is valid in both the central and peripheral contexts, however, I believe a GATT server is equally valid in both contexts. Any thoughts on this? Would an environment variable be the right approach to skip that check in cases like mine?

Contributor guide

Tech stack
javascriptnodejs
Domain
backend
Issue type
feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
BLE central and peripheral rolesNode.js event handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
20
Research direction
Analyze the condition in bleno/lib/hci socket/bindings.js at onLeConnComplete where role !== 1 is checked. Evaluate whether GATT server can be valid in both central and peripheral roles. Consider implementing an environment variable to toggle this behavior, and test with dual role devices.