platformio/platformio-core

Bug: sin1.contabostorage.com blocked by QUAD9 (DoH) DNS-over-HTTPS leads to DNS flood

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#5,323 opened on Dec 5, 2025

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 (9 comments) (4 reactions) (0 assignees)Python (791 forks)batch import
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Description

I said "Bug" in the title because, while a blocked DNS is not a bug per se, what platformio does try to do here is definitely a bug:

platformio does NOT look for another mirror like it says in the output, instead it floods the DNS with hundreds of requests per second (while loop as fast as the CPU can).

it continiously tries sin1.contabostorage.com repeatedly.

my primary issue filing here is the above mentioned "DNS flood"-type bug.

on a secondary note: you probably want to fix your DNS (you are definitely on the blocklist of QUAD 9).

Contributor guide

Research direction
Investigate the mirror retry logic in the network code. Look for a loop that repeatedly tries 'sin1.contabostorage.com' and implement exponential backoff or a limit on retries. Also consider handling DNS failures gracefully by falling back to other mirrors.
Tech stack
python
Domain
infrastructuretooling
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.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PythonGit
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
75