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Retry a failed WebRTC upgrade (libdatachannel DTLS race) - #25
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The httpeers-conformance tests failed under CPU load (most runs with
every core busy; often in the full parallel suite): members fell back to
the relay link, and calls to them were reset.
Root cause, traced with libdatachannel's own logs: on the OFFERER,
libdatachannel <= 0.24.5 hands the remote answer to the ICE agent before
committing it. ICE can complete at once (the answerer has been sending
checks), DTLS starts, and the fingerprint check finds no remote
description: "DTLS alert: unknown CA", "certificate verify failed", the
peer connection fails and libp2p's dial times out. Fixed upstream by
libdatachannel 0235225 ("start DTLS after remote description"), not yet
in any node-datachannel release (0.33.4 bundles 0.24.5). Browsers
implement WebRTC themselves and are not affected.
dialWebRTC (httpeers-libp2p) tries a WebRTC upgrade up to 3 times; each
attempt is an independent race. reachHub, preDialPeer and the route
ensurer use it. A WebRTC path that cannot come up still fails every
attempt and the relay fallback runs as before. Remove the retry once
node-datachannel ships the upstream fix.
Verified: conformance under full CPU load 8/8 runs green (4/6 failed
before); the full parallel suite 3/3 green (2-3/4 failed before).
httpeers-libp2p 0.1.4, httpeers-member 0.1.5.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DAiZN6XrTAdQpNN3eXEz2U
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Problem
httpeers-conformancefailed under CPU load: in most runs with every core busy, and often in the full parallel suite. Members fell back to their relay link (tests pinningdirectfailed), and calls to such members were reset (PeerStreamResetError), because members do not serve over a circuit.Root cause
Traced through libp2p's and libdatachannel's own logs. Under Node, WebRTC is libdatachannel (
node-datachannel). On the offerer, libdatachannel ≤ 0.24.5 hands the remote answer to the ICE agent before committing it as the remote description. ICE can complete immediately (the answerer has been sending checks), DTLS starts, and the fingerprint check finds no remote description:The peer connection fails and libp2p's dial times out. Fixed upstream in libdatachannel
0235225("fix: start DTLS after remote description", PR #1612), not yet in any node-datachannel release (0.33.4 bundles 0.24.5). Browsers are not affected.Fix
dialWebRTC(httpeers-libp2p) tries a WebRTC upgrade up to 3 times; each attempt is an independent race. Used byreachHub,preDialPeerand the route ensurer. A WebRTC path that cannot come up still fails every attempt, and the relay fallback runs as before. Remove once node-datachannel ships the upstream fix.Verification
pnpm -r run test: 3/3 green (2–3 of 4 failed before).dialWebRTC(retries, then rethrows the last failure).Releases httpeers-libp2p 0.1.4 and httpeers-member 0.1.5 (published to npm before merge).
🤖 Generated with Claude Code
https://claude.ai/code/session_01DAiZN6XrTAdQpNN3eXEz2U