Update

vendor/tailscale.com/net/netx/netx.go

@@ -0,0 +1,53 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package netx contains types to describe and abstract over how dialing and
+// listening are performed.
+package netx
+
+import (
+	"context"
+	"fmt"
+	"net"
+)
+
+// DialFunc is a function that dials a network address.
+//
+// It's the type implemented by net.Dialer.DialContext or required
+// by net/http.Transport.DialContext, etc.
+type DialFunc func(ctx context.Context, network, address string) (net.Conn, error)
+
+// Network describes a network that can listen and dial. The two common
+// implementations are [RealNetwork], using the net package to use the real
+// network, or [memnet.Network], using an in-memory network (typically for testing)
+type Network interface {
+	NewLocalTCPListener() net.Listener
+	Listen(network, address string) (net.Listener, error)
+	Dial(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+// RealNetwork returns a Network implementation that uses the real
+// net package.
+func RealNetwork() Network { return realNetwork{} }
+
+// realNetwork implements [Network] using the real net package.
+type realNetwork struct{}
+
+func (realNetwork) Listen(network, address string) (net.Listener, error) {
+	return net.Listen(network, address)
+}
+
+func (realNetwork) Dial(ctx context.Context, network, address string) (net.Conn, error) {
+	var d net.Dialer
+	return d.DialContext(ctx, network, address)
+}
+
+func (realNetwork) NewLocalTCPListener() net.Listener {
+	ln, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		if ln, err = net.Listen("tcp6", "[::1]:0"); err != nil {
+			panic(fmt.Sprintf("failed to listen on either IPv4 or IPv6 localhost port: %v", err))
+		}
+	}
+	return ln
+}