Brad Fitzpatrick
b8dc4061b0
Shutting down a socket's read side after its peer's FIN has arrived does
nothing on the wire and fails with ENOTCONN on macOS (and on Linux once
the socket reaches TIME_WAIT), so every cleanly half-closed connection
was logged as a failure and TestTCPHalfClose failed on macOS. Only
half-close the destination after EOF.
When one direction fails, one of the two sockets is dead. If the failure
was writing to it, the other direction is reading from that dead socket
and finishes on its own once it has drained what arrived before the
failure, so leave it alone rather than truncate the data. If the failure
was reading from it, the other direction may be blocked reading the live
peer, so close both connections to unblock it; nothing deliverable is
lost in that case.
Telling the two apart means wrapping the destination, which disables the
kernel splice fast path when both ends are bare TCP connections (about a
third of relay throughput on Linux loopback). That is accepted here: the
common userspace-networking and proxymux configurations wrap the
connections anyway, so they never had the fast path.
The regression was introduced by 027e249fcf (#21359), merged 2026-09-17.
Tested on Linux and on macOS 27 (arm64): the old test failed 49 of 50
runs on macOS; the new tests pass 200 iterations there and pass under
the race detector on Linux.
Fixes #21522
Updates #20883
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I7c2e4a9d1b8f5e3c6a0d2f4b8e1c9a7d3f5b6e2c
Tailscale
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:
- the Android app is at https://github.com/tailscale/tailscale-android
- the Synology package is at https://github.com/tailscale/tailscale-synology
- the QNAP package is at https://github.com/tailscale/tailscale-qpkg
- the Chocolatey packaging is at https://github.com/tailscale/tailscale-chocolatey
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 1.27. (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:
- https://github.com/tailscale/tailscale/graphs/contributors
- https://github.com/tailscale/tailscale-android/graphs/contributors
Legal
WireGuard is a registered trademark of Jason A. Donenfeld.