Brad Fitzpatrick
8e1fbc4740
Previously the DERP handler served each connection for its lifetime on its hijacked connection's net/http handler goroutine. That goroutine's conn.serve stack frame kept the dead HTTP/1 server state reachable for the whole DERP connection: the http.conn and its 4KB bufio.Writer (hijack hands over c.bufw but conn.serve still references it, so derpserver returning it to its flush pool never made it collectable), the 4KB bufio.Reader, the upgrade *http.Request with its parsed headers, and the request context chain. The goroutine also kept the stack growth from the TLS handshake and HTTP request parsing. Instead, hand the connection off to a new goroutine and return from the handler (ala tailscale/corp@dc09e27aef), letting all the HTTP upgrade state be collected. Give Accept a smaller 1KB frame reader, draining and releasing the hijacked reader if it contains buffered bytes from a fast-start client, and a nil bufio.Writer so writes go through pooled buffers held only for the duration of a write instead of a per-connection buffer. Because the handler now returns at handoff time, cmd/derper's gauge_derper_tls_active_version decrement can no longer be deferred to handler return: intercept Hijack in the TLS metrics wrapper and, for hijacked connections (DERP, its WebSocket flavor, and CONNECT), decrement the gauge once when the hijacked connection closes, restoring the gauge's connection-lifetime semantics. Teach derpserver's TCP RTT stats to unwrap the close-hook conn so they still find the underlying *net.TCPConn. Also soften the UntypedHexString deprecation notices in types/key to warnings: the untyped hex string format is the DERP wire protocol's key encoding, so these call sites are legitimate and permanent, and a Deprecated marker just makes them light up in editors and linters. The cautionary text about the format's risks remains. Measured with 100,000 idle TLS DERP connections on linux/amd64: standing memory drops from 55.6KB to 32.6KB per connection (-41%). Updates #21064 Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com> Change-Id: If05a0c6ea79134807e9e8872861db216
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.