221ca20a00
The filch implementation is fairly broken: * When Filch.cur exceeds MaxFileSize, it calls moveContents to copy the entirety of cur into alt (while holding the write lock). By nature, this is the movement of a lot of data in a hot path, meaning that all log calls will be globally blocked! It also means that log uploads will be blocked during the move. * The implementation of moveContents is buggy in that it copies data from cur into the start of alt, but fails to truncate alt to the number of bytes copied. Consequently, there are unrelated lines near the end, leading to out-of-order lines when being read back. * Data filched via stderr do not directly respect MaxFileSize, which is only checked every 100 Filch.Write calls. This means that it is possible that the file grows far beyond the specified max file size before moveContents is called. * If both log files have data when New is called, it also copies the entirety of cur into alt. This can block the startup of a process copying lots of data before the process can do any useful work. * TryReadLine is implemented using bufio.Scanner. Unfortunately, it will choke on any lines longer than bufio.MaxScanTokenSize, rather than gracefully skip over them. The re-implementation avoids a lot of these problems by fundamentally eliminating the need for moveContent. We enforce MaxFileSize by simply rotating the log files whenever the current file exceeds MaxFileSize/2. This is a constant-time operation regardless of file size. To more gracefully handle lines longer than bufio.MaxScanTokenSize, we skip over these lines (without growing the read buffer) and report an error. This allows subsequent lines to be read. In order to improve debugging, we add alot of metrics. Note that the the mechanism of dup2 with stderr is inherently racy with a the two file approach. The order of operations during a rotation is carefully chosen to reduce the race window to be as short as possible. Thus, this is slightly less racy than before. Updates tailscale/corp#21363 Signed-off-by: Joe Tsai <joetsai@digital-static.net>
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 1.25. (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:
- 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.