jonas-schievink/rubble

Only reply to LL_VERSION_IND once

Open

#49 opened on Apr 23, 2019

View on GitHub
 (0 comments) (1 reaction) (0 assignees)Rust (403 stars) (58 forks)user submission
area: link layergood first issuestatus: needs codetype: bug

Description

Either master or slave may send the LL_VERSION_IND LL Control PDU, and both will respond to it. According to the spec, you're supposed to keep track of whether you've already sent this and ignore the PDU in that case. We currently rely on the master to implement this correctly, since we'd otherwise end up in an endless loop.

To fix this, we need to add another bool to the real-time LinkLayer state to track whether we've sent this already. Eventually we should collapse all the bool flags into a single byte storing them as bitflags.

Contributor guide

Tech stack
rust
Domain
backend
Issue type
bug
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
Rust programmingBLE protocol basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Locate the LinkLayer struct in the real time state (likely in rubble/src/link/link layer.rs or similar). Add a bool field to track whether LL VERSION IND has been sent. In the handler for LL VERSION IND PDU reception, check this flag and ignore if already sent, otherwise respond and set the flag. Ensure master/slave logic is respected. Consider eventual refactoring of bool flags into bitflags as noted.