232 lines
6.9 KiB
Go
232 lines
6.9 KiB
Go
/* SPDX-License-Identifier: MIT
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*
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* Copyright (C) 2017-2021 WireGuard LLC. All Rights Reserved.
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*
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* This is based heavily on timers.c from the kernel implementation.
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*/
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package device
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import (
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"sync"
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"sync/atomic"
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"time"
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_ "unsafe"
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)
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//go:linkname fastrandn runtime.fastrandn
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func fastrandn(n uint32) uint32
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// A Timer manages time-based aspects of the WireGuard protocol.
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// Timer roughly copies the interface of the Linux kernel's struct timer_list.
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type Timer struct {
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*time.Timer
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modifyingLock sync.RWMutex
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runningLock sync.Mutex
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isPending bool
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}
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func (peer *Peer) NewTimer(expirationFunction func(*Peer)) *Timer {
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timer := &Timer{}
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timer.Timer = time.AfterFunc(time.Hour, func() {
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timer.runningLock.Lock()
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defer timer.runningLock.Unlock()
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timer.modifyingLock.Lock()
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if !timer.isPending {
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timer.modifyingLock.Unlock()
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return
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}
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timer.isPending = false
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timer.modifyingLock.Unlock()
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expirationFunction(peer)
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})
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timer.Stop()
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return timer
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}
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func (timer *Timer) Mod(d time.Duration) {
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timer.modifyingLock.Lock()
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timer.isPending = true
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timer.Reset(d)
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timer.modifyingLock.Unlock()
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}
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func (timer *Timer) Del() {
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timer.modifyingLock.Lock()
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timer.isPending = false
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timer.Stop()
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timer.modifyingLock.Unlock()
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}
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func (timer *Timer) DelSync() {
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timer.Del()
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timer.runningLock.Lock()
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timer.Del()
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timer.runningLock.Unlock()
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}
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func (timer *Timer) IsPending() bool {
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timer.modifyingLock.RLock()
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defer timer.modifyingLock.RUnlock()
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return timer.isPending
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}
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func (peer *Peer) timersActive() bool {
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return peer.isRunning.Get() && peer.device != nil && peer.device.isUp()
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}
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func expiredRetransmitHandshake(peer *Peer) {
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if atomic.LoadUint32(&peer.timers.handshakeAttempts) > MaxTimerHandshakes {
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peer.device.log.Verbosef("%s - Handshake did not complete after %d attempts, giving up", peer, MaxTimerHandshakes+2)
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if peer.timersActive() {
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peer.timers.sendKeepalive.Del()
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}
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/* We drop all packets without a keypair and don't try again,
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* if we try unsuccessfully for too long to make a handshake.
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*/
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peer.FlushStagedPackets()
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/* We set a timer for destroying any residue that might be left
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* of a partial exchange.
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*/
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if peer.timersActive() && !peer.timers.zeroKeyMaterial.IsPending() {
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peer.timers.zeroKeyMaterial.Mod(RejectAfterTime * 3)
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}
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} else {
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atomic.AddUint32(&peer.timers.handshakeAttempts, 1)
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peer.device.log.Verbosef("%s - Handshake did not complete after %d seconds, retrying (try %d)", peer, int(RekeyTimeout.Seconds()), atomic.LoadUint32(&peer.timers.handshakeAttempts)+1)
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/* We clear the endpoint address src address, in case this is the cause of trouble. */
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peer.Lock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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peer.Unlock()
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peer.SendHandshakeInitiation(true)
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}
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}
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func expiredSendKeepalive(peer *Peer) {
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peer.SendKeepalive()
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if peer.timers.needAnotherKeepalive.Get() {
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peer.timers.needAnotherKeepalive.Set(false)
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if peer.timersActive() {
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peer.timers.sendKeepalive.Mod(KeepaliveTimeout)
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}
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}
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}
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func expiredNewHandshake(peer *Peer) {
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peer.device.log.Verbosef("%s - Retrying handshake because we stopped hearing back after %d seconds", peer, int((KeepaliveTimeout + RekeyTimeout).Seconds()))
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/* We clear the endpoint address src address, in case this is the cause of trouble. */
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peer.Lock()
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if peer.endpoint != nil {
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peer.endpoint.ClearSrc()
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}
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peer.Unlock()
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peer.SendHandshakeInitiation(false)
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}
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func expiredZeroKeyMaterial(peer *Peer) {
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peer.device.log.Verbosef("%s - Removing all keys, since we haven't received a new one in %d seconds", peer, int((RejectAfterTime * 3).Seconds()))
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peer.ZeroAndFlushAll()
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}
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func expiredPersistentKeepalive(peer *Peer) {
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if atomic.LoadUint32(&peer.persistentKeepaliveInterval) > 0 {
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peer.SendKeepalive()
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}
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}
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/* Should be called after an authenticated data packet is sent. */
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func (peer *Peer) timersDataSent() {
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if peer.timersActive() && !peer.timers.newHandshake.IsPending() {
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peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs)))
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}
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}
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/* Should be called after an authenticated data packet is received. */
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func (peer *Peer) timersDataReceived() {
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if peer.timersActive() {
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if !peer.timers.sendKeepalive.IsPending() {
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peer.timers.sendKeepalive.Mod(KeepaliveTimeout)
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} else {
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peer.timers.needAnotherKeepalive.Set(true)
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}
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}
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}
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/* Should be called after any type of authenticated packet is sent -- keepalive, data, or handshake. */
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func (peer *Peer) timersAnyAuthenticatedPacketSent() {
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if peer.timersActive() {
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peer.timers.sendKeepalive.Del()
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}
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}
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/* Should be called after any type of authenticated packet is received -- keepalive, data, or handshake. */
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func (peer *Peer) timersAnyAuthenticatedPacketReceived() {
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if peer.timersActive() {
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peer.timers.newHandshake.Del()
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}
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}
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/* Should be called after a handshake initiation message is sent. */
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func (peer *Peer) timersHandshakeInitiated() {
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if peer.timersActive() {
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peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs)))
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}
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}
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/* Should be called after a handshake response message is received and processed or when getting key confirmation via the first data message. */
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func (peer *Peer) timersHandshakeComplete() {
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if peer.timersActive() {
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peer.timers.retransmitHandshake.Del()
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}
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atomic.StoreUint32(&peer.timers.handshakeAttempts, 0)
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peer.timers.sentLastMinuteHandshake.Set(false)
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atomic.StoreInt64(&peer.stats.lastHandshakeNano, time.Now().UnixNano())
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}
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/* Should be called after an ephemeral key is created, which is before sending a handshake response or after receiving a handshake response. */
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func (peer *Peer) timersSessionDerived() {
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if peer.timersActive() {
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peer.timers.zeroKeyMaterial.Mod(RejectAfterTime * 3)
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}
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}
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/* Should be called before a packet with authentication -- keepalive, data, or handshake -- is sent, or after one is received. */
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func (peer *Peer) timersAnyAuthenticatedPacketTraversal() {
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keepalive := atomic.LoadUint32(&peer.persistentKeepaliveInterval)
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if keepalive > 0 && peer.timersActive() {
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peer.timers.persistentKeepalive.Mod(time.Duration(keepalive) * time.Second)
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}
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}
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func (peer *Peer) timersInit() {
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peer.timers.retransmitHandshake = peer.NewTimer(expiredRetransmitHandshake)
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peer.timers.sendKeepalive = peer.NewTimer(expiredSendKeepalive)
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peer.timers.newHandshake = peer.NewTimer(expiredNewHandshake)
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peer.timers.zeroKeyMaterial = peer.NewTimer(expiredZeroKeyMaterial)
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peer.timers.persistentKeepalive = peer.NewTimer(expiredPersistentKeepalive)
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}
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func (peer *Peer) timersStart() {
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atomic.StoreUint32(&peer.timers.handshakeAttempts, 0)
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peer.timers.sentLastMinuteHandshake.Set(false)
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peer.timers.needAnotherKeepalive.Set(false)
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}
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func (peer *Peer) timersStop() {
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peer.timers.retransmitHandshake.DelSync()
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peer.timers.sendKeepalive.DelSync()
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peer.timers.newHandshake.DelSync()
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peer.timers.zeroKeyMaterial.DelSync()
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peer.timers.persistentKeepalive.DelSync()
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}
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