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