Brad Fitzpatrick 70de111394 wgengine/magicsock: fix three race conditions in TestTwoDevicePing
Fix three independent flake sources, at least as debugged by Claude,
though empirically no longer flaking as it was before:

1. Poll for connection counter data instead of reading immediately.
   The conncount callback fires asynchronously on received WireGuard
   traffic, so after counts.Reset() there is no guarantee the counter
   has been repopulated before checkStats reads it. Use tstest.WaitFor
   with a 5s timeout to retry until a matching connection appears.

2. Replace the *2 symmetry assumption in global metric assertions.
   metricSendUDP and friends are AggregateCounters that sum per-conn
   expvars from both magicsock instances. The old assertion assumed
   both instances had identical packet counts, which breaks under
   asymmetric background WireGuard activity (handshake retries, etc).
   The new assertGlobalMetricsMatchPerConn computes the actual sum of
   both conns' expvars and compares against the AggregateCounter value.

3. Tolerate physical stats being 0 when user metrics are non-zero.
   A rebind event replaces the socket mid-measurement, resetting the
   physical connection counter while user metrics still reflect packets
   processed before the rebind. Log instead of failing in this case.
   Also move counts.Reset() after metric reads and reorder the reset
   sequence (counts before metrics) to minimize the race window.

Fixes tailscale/tailscale#13420

Change-Id: I7b090a4dc229a862c1a52161b3f2547ec1d1f23f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-03-11 07:34:52 -07:00
2026-03-02 08:04:19 -08:00
2026-03-05 13:52:01 -08:00
2026-01-27 16:15:17 -08:00
2026-03-06 11:27:29 -08:00
2026-03-06 11:27:29 -08:00

Tailscale

https://tailscale.com

Private WireGuard® networks made easy

Overview

This repository contains the majority of Tailscale's open source code. Notably, it includes the tailscaled daemon and the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows, macOS, and to varying degrees on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's code, but this repo doesn't contain the mobile GUI code.

Other Tailscale repos of note:

For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.

Using

We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.

Other clients

The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.

Building

We always require the latest Go release, currently Go 1.25. (While we build releases with our Go fork, its use is not required.)

go install tailscale.com/cmd/tailscale{,d}

If you're packaging Tailscale for distribution, use build_dist.sh instead, to burn commit IDs and version info into the binaries:

./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled

If your distro has conventions that preclude the use of build_dist.sh, please do the equivalent of what it does in your distro's way, so that bug reports contain useful version information.

Bugs

Please file any issues about this code or the hosted service on the issue tracker.

Contributing

PRs welcome! But please file bugs. Commit messages should reference bugs.

We require Developer Certificate of Origin Signed-off-by lines in commits.

See commit-messages.md (or skim git log) for our commit message style.

About Us

Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:

WireGuard is a registered trademark of Jason A. Donenfeld.

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