Every Go-identifier reference in // and /* */ comments now uses
godoc's [Name] linking syntax so pkg.go.dev and `go doc` render
them as clickable cross-references. No behaviour change.
Pattern applied across the tree:
In-package [Foo], [Foo.Bar]
Cross-package [pkg.Foo], [pkg.Foo.Bar]
Stdlib [netip.Prefix], [errors.Is], [context.Context]
Tailscale [tailcfg.MapResponse], [tailcfg.Node.CapMap],
[tailcfg.NodeAttrSuggestExitNode]
Skip rules:
- File:line refs left as plain text
- HuJSON wire keys inside backtick raw strings untouched
- ACL/policy syntax tokens (tag:foo, autogroup:self, ...) not Go
symbols, left as plain text
- JSON/OIDC wire keys, gorm tags, RFC IPv6 placeholders, markdown
link tags, decorative dividers — all left as-is
Blocked callers waiting on a pingTracker response channel would
hang forever if the server Close()d mid-probe. Drain the pending map on
Close so those goroutines unblock and exit cleanly.
Updates #3157
Implement tailcfg.PingRequest support so the control server can verify
whether a connected node is still reachable. This is the foundation for
faster offline detection (currently ~16min due to Go HTTP/2 TCP retransmit
behavior) and future C2N communication.
The server sends a PingRequest via MapResponse with a unique callback
URL. The Tailscale client responds with a HEAD request to that URL,
proving connectivity. Round-trip latency is measured.
Wire PingRequest through the Change → Batcher → MapResponse pipeline,
add a ping tracker on State for correlating requests with responses,
add ResolveNode for looking up nodes by ID/IP/hostname, and expose a
/debug/ping page (elem-go form UI) and /machine/ping-response endpoint.
Updates #2902
Updates #2129
