mirror of
https://git.zx2c4.com/wireguard-go
synced 2024-11-15 01:05:15 +01:00
4369db522b
Peers are currently removed after Device's goroutines are signaled to stop, but without waiting for them to actually do so, which is racy. For example, RoutineHandshake may be in Peer.SendKeepalive when the corresponding peer is removed, which closes its nonce channel. This causes a send on a closed channel, as observed in tailscale/tailscale#487. This patch seems to be the correct synchronizing action: Peer's goroutines are receivers and handle channel closure gracefully, so Device's goroutines are the ones that should be fully stopped first. Signed-Off-By: Dmytro Shynkevych <dmytro@tailscale.com>
548 lines
11 KiB
Go
548 lines
11 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2020 WireGuard LLC. All Rights Reserved.
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*/
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package device
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import (
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"runtime"
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"sync"
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"sync/atomic"
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"time"
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"golang.org/x/net/ipv4"
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"golang.org/x/net/ipv6"
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"golang.zx2c4.com/wireguard/conn"
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"golang.zx2c4.com/wireguard/ratelimiter"
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"golang.zx2c4.com/wireguard/rwcancel"
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"golang.zx2c4.com/wireguard/tun"
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)
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type Device struct {
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isUp AtomicBool // device is (going) up
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isClosed AtomicBool // device is closed? (acting as guard)
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log *Logger
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// synchronized resources (locks acquired in order)
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state struct {
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starting sync.WaitGroup
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stopping sync.WaitGroup
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sync.Mutex
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changing AtomicBool
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current bool
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}
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net struct {
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starting sync.WaitGroup
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stopping sync.WaitGroup
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sync.RWMutex
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bind conn.Bind // bind interface
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netlinkCancel *rwcancel.RWCancel
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port uint16 // listening port
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fwmark uint32 // mark value (0 = disabled)
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}
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staticIdentity struct {
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sync.RWMutex
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privateKey NoisePrivateKey
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publicKey NoisePublicKey
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}
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peers struct {
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sync.RWMutex
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keyMap map[NoisePublicKey]*Peer
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}
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// unprotected / "self-synchronising resources"
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allowedips AllowedIPs
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indexTable IndexTable
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cookieChecker CookieChecker
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rate struct {
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underLoadUntil atomic.Value
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limiter ratelimiter.Ratelimiter
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}
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pool struct {
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messageBufferPool *sync.Pool
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messageBufferReuseChan chan *[MaxMessageSize]byte
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inboundElementPool *sync.Pool
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inboundElementReuseChan chan *QueueInboundElement
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outboundElementPool *sync.Pool
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outboundElementReuseChan chan *QueueOutboundElement
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}
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queue struct {
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encryption chan *QueueOutboundElement
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decryption chan *QueueInboundElement
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handshake chan QueueHandshakeElement
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}
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signals struct {
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stop chan struct{}
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}
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tun struct {
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device tun.Device
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mtu int32
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}
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}
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/* Converts the peer into a "zombie", which remains in the peer map,
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* but processes no packets and does not exists in the routing table.
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*
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* Must hold device.peers.Mutex
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*/
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func unsafeRemovePeer(device *Device, peer *Peer, key NoisePublicKey) {
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// stop routing and processing of packets
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device.allowedips.RemoveByPeer(peer)
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peer.Stop()
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// remove from peer map
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delete(device.peers.keyMap, key)
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}
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func deviceUpdateState(device *Device) {
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// check if state already being updated (guard)
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if device.state.changing.Swap(true) {
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return
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}
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// compare to current state of device
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device.state.Lock()
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newIsUp := device.isUp.Get()
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if newIsUp == device.state.current {
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device.state.changing.Set(false)
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device.state.Unlock()
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return
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}
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// change state of device
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switch newIsUp {
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case true:
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if err := device.BindUpdate(); err != nil {
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device.log.Error.Printf("Unable to update bind: %v\n", err)
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device.isUp.Set(false)
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break
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}
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device.peers.RLock()
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for _, peer := range device.peers.keyMap {
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peer.Start()
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if peer.persistentKeepaliveInterval > 0 {
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peer.SendKeepalive()
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}
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}
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device.peers.RUnlock()
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case false:
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device.BindClose()
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device.peers.RLock()
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for _, peer := range device.peers.keyMap {
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peer.Stop()
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}
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device.peers.RUnlock()
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}
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// update state variables
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device.state.current = newIsUp
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device.state.changing.Set(false)
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device.state.Unlock()
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// check for state change in the mean time
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deviceUpdateState(device)
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}
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func (device *Device) Up() {
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// closed device cannot be brought up
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if device.isClosed.Get() {
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return
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}
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device.isUp.Set(true)
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deviceUpdateState(device)
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}
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func (device *Device) Down() {
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device.isUp.Set(false)
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deviceUpdateState(device)
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}
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func (device *Device) IsUnderLoad() bool {
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// check if currently under load
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now := time.Now()
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underLoad := len(device.queue.handshake) >= UnderLoadQueueSize
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if underLoad {
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device.rate.underLoadUntil.Store(now.Add(UnderLoadAfterTime))
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return true
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}
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// check if recently under load
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until := device.rate.underLoadUntil.Load().(time.Time)
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return until.After(now)
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}
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func (device *Device) SetPrivateKey(sk NoisePrivateKey) error {
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// lock required resources
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device.staticIdentity.Lock()
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defer device.staticIdentity.Unlock()
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if sk.Equals(device.staticIdentity.privateKey) {
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return nil
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}
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device.peers.Lock()
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defer device.peers.Unlock()
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lockedPeers := make([]*Peer, 0, len(device.peers.keyMap))
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for _, peer := range device.peers.keyMap {
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peer.handshake.mutex.RLock()
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lockedPeers = append(lockedPeers, peer)
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}
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// remove peers with matching public keys
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publicKey := sk.publicKey()
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for key, peer := range device.peers.keyMap {
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if peer.handshake.remoteStatic.Equals(publicKey) {
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unsafeRemovePeer(device, peer, key)
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}
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}
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// update key material
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device.staticIdentity.privateKey = sk
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device.staticIdentity.publicKey = publicKey
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device.cookieChecker.Init(publicKey)
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// do static-static DH pre-computations
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expiredPeers := make([]*Peer, 0, len(device.peers.keyMap))
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for _, peer := range device.peers.keyMap {
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handshake := &peer.handshake
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handshake.precomputedStaticStatic = device.staticIdentity.privateKey.sharedSecret(handshake.remoteStatic)
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expiredPeers = append(expiredPeers, peer)
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}
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for _, peer := range lockedPeers {
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peer.handshake.mutex.RUnlock()
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}
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for _, peer := range expiredPeers {
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peer.ExpireCurrentKeypairs()
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}
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return nil
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}
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func NewDevice(tunDevice tun.Device, logger *Logger) *Device {
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device := new(Device)
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device.isUp.Set(false)
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device.isClosed.Set(false)
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device.log = logger
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device.tun.device = tunDevice
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mtu, err := device.tun.device.MTU()
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if err != nil {
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logger.Error.Println("Trouble determining MTU, assuming default:", err)
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mtu = DefaultMTU
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}
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device.tun.mtu = int32(mtu)
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device.peers.keyMap = make(map[NoisePublicKey]*Peer)
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device.rate.limiter.Init()
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device.rate.underLoadUntil.Store(time.Time{})
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device.indexTable.Init()
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device.allowedips.Reset()
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device.PopulatePools()
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// create queues
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device.queue.handshake = make(chan QueueHandshakeElement, QueueHandshakeSize)
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device.queue.encryption = make(chan *QueueOutboundElement, QueueOutboundSize)
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device.queue.decryption = make(chan *QueueInboundElement, QueueInboundSize)
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// prepare signals
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device.signals.stop = make(chan struct{})
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// prepare net
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device.net.port = 0
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device.net.bind = nil
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// start workers
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cpus := runtime.NumCPU()
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device.state.starting.Wait()
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device.state.stopping.Wait()
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for i := 0; i < cpus; i += 1 {
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device.state.starting.Add(3)
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device.state.stopping.Add(3)
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go device.RoutineEncryption()
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go device.RoutineDecryption()
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go device.RoutineHandshake()
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}
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device.state.starting.Add(2)
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device.state.stopping.Add(2)
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go device.RoutineReadFromTUN()
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go device.RoutineTUNEventReader()
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device.state.starting.Wait()
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return device
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}
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func (device *Device) LookupPeer(pk NoisePublicKey) *Peer {
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device.peers.RLock()
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defer device.peers.RUnlock()
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return device.peers.keyMap[pk]
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}
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func (device *Device) RemovePeer(key NoisePublicKey) {
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device.peers.Lock()
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defer device.peers.Unlock()
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// stop peer and remove from routing
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peer, ok := device.peers.keyMap[key]
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if ok {
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unsafeRemovePeer(device, peer, key)
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}
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}
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func (device *Device) RemoveAllPeers() {
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device.peers.Lock()
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defer device.peers.Unlock()
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for key, peer := range device.peers.keyMap {
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unsafeRemovePeer(device, peer, key)
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}
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device.peers.keyMap = make(map[NoisePublicKey]*Peer)
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}
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func (device *Device) FlushPacketQueues() {
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for {
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select {
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case elem, ok := <-device.queue.decryption:
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if ok {
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elem.Drop()
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}
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case elem, ok := <-device.queue.encryption:
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if ok {
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elem.Drop()
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}
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case <-device.queue.handshake:
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default:
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return
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}
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}
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}
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func (device *Device) Close() {
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if device.isClosed.Swap(true) {
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return
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}
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device.state.starting.Wait()
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device.log.Info.Println("Device closing")
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device.state.changing.Set(true)
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device.state.Lock()
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defer device.state.Unlock()
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device.tun.device.Close()
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device.BindClose()
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device.isUp.Set(false)
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close(device.signals.stop)
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device.state.stopping.Wait()
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device.RemoveAllPeers()
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device.FlushPacketQueues()
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device.rate.limiter.Close()
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device.state.changing.Set(false)
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device.log.Info.Println("Interface closed")
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}
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func (device *Device) Wait() chan struct{} {
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return device.signals.stop
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}
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func (device *Device) SendKeepalivesToPeersWithCurrentKeypair() {
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if device.isClosed.Get() {
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return
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}
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device.peers.RLock()
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for _, peer := range device.peers.keyMap {
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peer.keypairs.RLock()
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sendKeepalive := peer.keypairs.current != nil && !peer.keypairs.current.created.Add(RejectAfterTime).Before(time.Now())
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peer.keypairs.RUnlock()
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if sendKeepalive {
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peer.SendKeepalive()
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}
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}
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device.peers.RUnlock()
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}
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func unsafeCloseBind(device *Device) error {
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var err error
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netc := &device.net
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if netc.netlinkCancel != nil {
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netc.netlinkCancel.Cancel()
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}
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if netc.bind != nil {
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err = netc.bind.Close()
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netc.bind = nil
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}
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netc.stopping.Wait()
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return err
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}
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func (device *Device) Bind() conn.Bind {
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device.net.Lock()
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defer device.net.Unlock()
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return device.net.bind
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}
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func (device *Device) BindSetMark(mark uint32) error {
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device.net.Lock()
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defer device.net.Unlock()
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// check if modified
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if device.net.fwmark == mark {
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return nil
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}
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// update fwmark on existing bind
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device.net.fwmark = mark
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if device.isUp.Get() && device.net.bind != nil {
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if err := device.net.bind.SetMark(mark); err != nil {
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return err
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}
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}
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// clear cached source addresses
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device.peers.RLock()
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for _, peer := range device.peers.keyMap {
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peer.Lock()
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defer peer.Unlock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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}
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device.peers.RUnlock()
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return nil
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}
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func (device *Device) BindUpdate() error {
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device.net.Lock()
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defer device.net.Unlock()
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// close existing sockets
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if err := unsafeCloseBind(device); err != nil {
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return err
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}
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// open new sockets
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if device.isUp.Get() {
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// bind to new port
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var err error
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netc := &device.net
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netc.bind, netc.port, err = conn.CreateBind(netc.port)
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if err != nil {
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netc.bind = nil
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netc.port = 0
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return err
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}
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netc.netlinkCancel, err = device.startRouteListener(netc.bind)
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if err != nil {
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netc.bind.Close()
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netc.bind = nil
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netc.port = 0
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return err
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}
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// set fwmark
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if netc.fwmark != 0 {
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err = netc.bind.SetMark(netc.fwmark)
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if err != nil {
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return err
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}
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}
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// clear cached source addresses
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device.peers.RLock()
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for _, peer := range device.peers.keyMap {
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peer.Lock()
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defer peer.Unlock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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}
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device.peers.RUnlock()
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// start receiving routines
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device.net.starting.Add(2)
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device.net.stopping.Add(2)
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go device.RoutineReceiveIncoming(ipv4.Version, netc.bind)
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go device.RoutineReceiveIncoming(ipv6.Version, netc.bind)
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device.net.starting.Wait()
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device.log.Debug.Println("UDP bind has been updated")
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}
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return nil
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}
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func (device *Device) BindClose() error {
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device.net.Lock()
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err := unsafeCloseBind(device)
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device.net.Unlock()
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return err
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}
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