tailscale/net/netns/netns.go

// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package netns contains the common code for using the Go net package
// in a logical "network namespace" to avoid routing loops where
// Tailscale-created packets would otherwise loop back through
// Tailscale routes.
//
// Despite the name netns, the exact mechanism used differs by
// operating system, and perhaps even by version of the OS.
package netns

import (
	"net"

	"tailscale.com/syncs"
)

var skipPrivileged syncs.AtomicBool

// Listener returns a new net.Listener with its Control hook func
// initialized as necessary to run in logical network namespace that
// doesn't route back into Tailscale.
func Listener() *net.ListenConfig {
	return &net.ListenConfig{Control: control}
}

// Dialer returns a new net.Dialer with its Control hook func
// initialized as necessary to run in a logical network namespace that
// doesn't route back into Tailscale.
func Dialer() *net.Dialer {
	return &net.Dialer{Control: control}
}

// TestOnlySkipPrivilegedOps disables any behavior in this package
// that requires root or other elevated privileges. It's used only in
// tests, and using it definitely breaks some Tailscale functionality.
func TestOnlySkipPrivilegedOps() {
	skipPrivileged.Set(true)
}