EtherGuard-VPN/timers.go

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/* SPDX-License-Identifier: GPL-2.0
*
* Copyright (C) 2015-2018 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*
* This is based heavily on timers.c from the kernel implementation.
*/
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package main
import (
"math/rand"
"sync/atomic"
"time"
)
/* This Timer structure and related functions should roughly copy the interface of
* the Linux kernel's struct timer_list.
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*/
type Timer struct {
timer *time.Timer
isPending bool
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}
func (peer *Peer) NewTimer(expirationFunction func(*Peer)) *Timer {
timer := &Timer{}
timer.timer = time.AfterFunc(time.Hour, func() {
timer.isPending = false
expirationFunction(peer)
})
timer.timer.Stop()
return timer
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}
func (timer *Timer) Mod(d time.Duration) {
timer.isPending = true
timer.timer.Reset(d)
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}
func (timer *Timer) Del() {
timer.isPending = false
timer.timer.Stop()
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}
func (peer *Peer) timersActive() bool {
return peer.isRunning.Get() && peer.device != nil && peer.device.isUp.Get() && len(peer.device.peers.keyMap) > 0
}
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func expiredRetransmitHandshake(peer *Peer) {
if peer.timers.handshakeAttempts > MaxTimerHandshakes {
peer.device.log.Debug.Printf("%s: Handshake did not complete after %d attempts, giving up\n", peer, MaxTimerHandshakes+2)
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if peer.timersActive() {
peer.timers.sendKeepalive.Del()
}
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/* We drop all packets without a keypair and don't try again,
* if we try unsuccessfully for too long to make a handshake.
*/
peer.FlushNonceQueue()
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/* We set a timer for destroying any residue that might be left
* of a partial exchange.
*/
if peer.timersActive() && !peer.timers.zeroKeyMaterial.isPending {
peer.timers.zeroKeyMaterial.Mod(RejectAfterTime * 3)
}
} else {
peer.timers.handshakeAttempts++
peer.device.log.Debug.Printf("%s: Handshake did not complete after %d seconds, retrying (try %d)\n", peer, int(RekeyTimeout.Seconds()), peer.timers.handshakeAttempts+1)
/* We clear the endpoint address src address, in case this is the cause of trouble. */
peer.mutex.Lock()
if peer.endpoint != nil {
peer.endpoint.ClearSrc()
}
peer.mutex.Unlock()
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peer.SendHandshakeInitiation(true)
}
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}
func expiredSendKeepalive(peer *Peer) {
peer.SendKeepalive()
if peer.timers.needAnotherKeepalive {
peer.timers.needAnotherKeepalive = false
if peer.timersActive() {
peer.timers.sendKeepalive.Mod(KeepaliveTimeout)
}
}
}
func expiredNewHandshake(peer *Peer) {
peer.device.log.Debug.Printf("%s: Retrying handshake because we stopped hearing back after %d seconds\n", peer, int((KeepaliveTimeout + RekeyTimeout).Seconds()))
/* We clear the endpoint address src address, in case this is the cause of trouble. */
peer.mutex.Lock()
if peer.endpoint != nil {
peer.endpoint.ClearSrc()
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}
peer.mutex.Unlock()
peer.SendHandshakeInitiation(false)
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}
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func expiredZeroKeyMaterial(peer *Peer) {
peer.device.log.Debug.Printf(":%s Removing all keys, since we haven't received a new one in %d seconds\n", peer, int((RejectAfterTime * 3).Seconds()))
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peer.ZeroAndFlushAll()
}
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func expiredPersistentKeepalive(peer *Peer) {
if peer.persistentKeepaliveInterval > 0 {
if peer.timersActive() {
peer.timers.sendKeepalive.Del()
}
peer.SendKeepalive()
}
}
/* Should be called after an authenticated data packet is sent. */
func (peer *Peer) timersDataSent() {
if peer.timersActive() {
peer.timers.sendKeepalive.Del()
}
if peer.timersActive() && !peer.timers.newHandshake.isPending {
peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout)
}
}
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/* Should be called after an authenticated data packet is received. */
func (peer *Peer) timersDataReceived() {
if peer.timersActive() {
if !peer.timers.sendKeepalive.isPending {
peer.timers.sendKeepalive.Mod(KeepaliveTimeout)
} else {
peer.timers.needAnotherKeepalive = true
}
}
}
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/* Should be called after any type of authenticated packet is received -- keepalive or data. */
func (peer *Peer) timersAnyAuthenticatedPacketReceived() {
if peer.timersActive() {
peer.timers.newHandshake.Del()
}
}
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/* Should be called after a handshake initiation message is sent. */
func (peer *Peer) timersHandshakeInitiated() {
if peer.timersActive() {
peer.timers.sendKeepalive.Del()
peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(rand.Int31n(RekeyTimeoutJitterMaxMs)))
}
}
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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. */
func (peer *Peer) timersHandshakeComplete() {
if peer.timersActive() {
peer.timers.retransmitHandshake.Del()
}
peer.timers.handshakeAttempts = 0
peer.timers.sentLastMinuteHandshake = false
atomic.StoreInt64(&peer.stats.lastHandshakeNano, time.Now().UnixNano())
}
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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. */
func (peer *Peer) timersSessionDerived() {
if peer.timersActive() {
peer.timers.zeroKeyMaterial.Mod(RejectAfterTime * 3)
}
}
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/* Should be called before a packet with authentication -- data, keepalive, either handshake -- is sent, or after one is received. */
func (peer *Peer) timersAnyAuthenticatedPacketTraversal() {
if peer.persistentKeepaliveInterval > 0 && peer.timersActive() {
peer.timers.persistentKeepalive.Mod(time.Duration(peer.persistentKeepaliveInterval) * time.Second)
}
}
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func (peer *Peer) timersInit() {
peer.timers.retransmitHandshake = peer.NewTimer(expiredRetransmitHandshake)
peer.timers.sendKeepalive = peer.NewTimer(expiredSendKeepalive)
peer.timers.newHandshake = peer.NewTimer(expiredNewHandshake)
peer.timers.zeroKeyMaterial = peer.NewTimer(expiredZeroKeyMaterial)
peer.timers.persistentKeepalive = peer.NewTimer(expiredPersistentKeepalive)
peer.timers.handshakeAttempts = 0
peer.timers.sentLastMinuteHandshake = false
peer.timers.needAnotherKeepalive = false
}
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func (peer *Peer) timersStop() {
peer.timers.retransmitHandshake.Del()
peer.timers.sendKeepalive.Del()
peer.timers.newHandshake.Del()
peer.timers.zeroKeyMaterial.Del()
peer.timers.persistentKeepalive.Del()
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}