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// Copyright (c) Tailscale Inc & contributors
// SPDX-License-Identifier: BSD-3-Clause
package netmon
import (
"errors"
"net"
"tailscale.com/syncs"
)
type ifProps struct {
mu syncs.Mutex
name string // interface name, if known/set
index int // interface index, if known/set
}
// tsIfProps tracks the properties (name and index) of the tailscale interface.
// There is only one tailscale interface per tailscaled instance.
var tsIfProps ifProps
func (p *ifProps) tsIfName() string {
p.mu.Lock()
defer p.mu.Unlock()
return p.name
}
func (p *ifProps) tsIfIndex() int {
p.mu.Lock()
defer p.mu.Unlock()
return p.index
}
func (p *ifProps) set(ifName string, ifIndex int) {
p.mu.Lock()
defer p.mu.Unlock()
p.name = ifName
p.index = ifIndex
}
// TODO (barnstar): This doesn't need the Monitor receiver anymore but we're
// keeping it for API compatibility to avoid a breaking change. This can be
// removed when the various clients have switched to SetTailscaleInterfaceProps
func (m *Monitor) SetTailscaleInterfaceName(ifName string) {
SetTailscaleInterfaceProps(ifName, 0)
}
// SetTailscaleInterfaceProps sets the name of the Tailscale interface and
// its index for use by various listeners/dialers. If the index is zero,
// an attempt will be made to look it up by name. This makes no attempt
// to validate that the interface exists at the time of calling.
//
// If this method is called, it is the responsibility of the caller to
// update the interface name and index if they change.
//
// This should be called as early as possible during tailscaled startup.
func SetTailscaleInterfaceProps(ifName string, ifIndex int) {
if ifIndex != 0 {
tsIfProps.set(ifName, ifIndex)
return
}
ifaces, err := net.Interfaces()
if err != nil {
return
}
for _, iface := range ifaces {
if iface.Name == ifName {
ifIndex = iface.Index
break
}
}
tsIfProps.set(ifName, ifIndex)
}
// TailscaleInterfaceName returns the name of the Tailscale interface.
// For example, "tailscale0", "tun0", "utun3", etc or an error if unset.
//
// Callers must handle errors, as the Tailscale interface
// name may not be set in some environments.
func TailscaleInterfaceName() (string, error) {
name := tsIfProps.tsIfName()
if name == "" {
return "", errors.New("Tailscale interface name not set")
}
return name, nil
}
// TailscaleInterfaceIndex returns the index of the Tailscale interface or
// an error if unset.
//
// Callers must handle errors, as the Tailscale interface
// index may not be set in some environments.
func TailscaleInterfaceIndex() (int, error) {
index := tsIfProps.tsIfIndex()
if index == 0 {
return 0, errors.New("Tailscale interface index not set")
}
return index, nil
}
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