Repository navigation
client: a direct dial reuses a still-handshaking pinned link (mcl-warden#3) - #90
Merged
Merged
Conversation
… dialing a duplicate (mcl-warden#3) (red)
… link link_for_node_id/2 asks each live link's completed handshake first, then its pinned expected_node_id -- a configured seed's pin names the same station identity its handshake will prove, so a link that has not completed HELLO yet is still recognizably THE station. Both the direct-dial reuse path (reuse_by_node_id/3) and the discovery dedup (already_connected_to/2) now go through it. Without the pin fallback, a fresh pool's first direct dial (e.g. a boot claim to the realm's serving station) races the configured seed link's first HELLO: the pool dials a second connection to the same station under the literal address the station_endpoint advertises, the station replaces one of the two (one connection per identity), the replaced one respawns and replaces the other back -- a permanent flap. Seen live 2026-10-10 on a fresh warden box: 761 duplicate_replaced events at the station, proof-rate refusal, /health never healthy (mcl-warden#3). A pin that does not match the station's real identity never matches a caller's verified node_id, so a stale pin still falls through to a fresh dial exactly as before.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
What
A fresh pool's direct dial for a station it already holds a configured seed for must reuse that seed's link even before the link has completed HELLO. Today it can't: the identity fallback (
find_link_by_node_id/2overknown_links/1) only sees links that completed their handshake, so the pool dials a second connection to the same station — and the station's one-connection-per-identity policy turns the two links into a permanent mutual-replacement flap.Found live on a freshly enrolled warden box (mcl-warden#3, 2026-10-10): 761
_macula.peering.duplicate_replacedevents at the station,connect → peer_closedevery ~1.3 s toward both the DNS name and the literal IPv6, session-proof-rate refusal,/healthnever healthy. Old boxes never hit it because their links completed HELLO long ago and the boot claim that triggers the direct dial is long issued — it is a fresh-enrollment bug.Fix
New
link_for_node_id/2: a live link whose completed handshake named the node id wins; otherwise a live link whose pinnedexpected_node_idnames it. A configured seed's pin is the identity its handshake will prove, so a still-handshaking link is recognizably THE station — andcall_when_connected/2/link_when_connected/2already wait for that handshake, so reuse is safe. A pin that does not match the station's real identity never matches a caller's DHT-verified node id, so a stale pin still falls through to a fresh dial exactly as before.Both the direct-dial path (
reuse_by_node_id/3) and the discovery dedup (already_connected_to/2) now go through it — the discovery pass had the same fresh-pool race for a still-handshaking bootstrap seed spelled differently by the directory.Red/green
9e1e4d57test: ... (red):a_direct_dial_for_the_pinned_station_of_a_still_handshaking_seed_reuses_that_seed_testfails on v14.8.0 — the unpatched pool dials a second link (asserted vialinks/1length).25cc82d6the fix: same test passes.Verified locally (v14.8.0 base, Erlang 28.4.2)
rebar3 eunit— 5,369 tests passedrebar3 xref— cleanrebar3 as lint lint— cleanrebar3 as consumer_contracts dialyzer— cleanRollout
Patch release after merge; mcl-warden's
mcl_om "~> 0.39"floats onto it, so the fleet pins the rebuilt warden and the be-bru row goes back into its manifest.Refs mcl-warden#3, macula-fleet#19.