mirror of
https://github.com/KusakabeShi/EtherGuard-VPN.git
synced 2024-11-22 07:13:09 +01:00
a86492a567
Now that we block when enqueueing to the decryption queue, there is only one case in which we "drop" a inbound element, when decryption fails. We can use a simple, obvious, sync-free sentinel for that, elem.packet == nil. Also, we can return the message buffer to the pool slightly later, which further simplifies the code. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
607 lines
13 KiB
Go
607 lines
13 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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"bytes"
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"encoding/binary"
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"errors"
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"net"
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"strconv"
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"sync"
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"sync/atomic"
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"time"
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"golang.org/x/crypto/chacha20poly1305"
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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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)
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type QueueHandshakeElement struct {
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msgType uint32
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packet []byte
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endpoint conn.Endpoint
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buffer *[MaxMessageSize]byte
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}
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type QueueInboundElement struct {
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sync.Mutex
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buffer *[MaxMessageSize]byte
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packet []byte
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counter uint64
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keypair *Keypair
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endpoint conn.Endpoint
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}
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// clearPointers clears elem fields that contain pointers.
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// This makes the garbage collector's life easier and
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// avoids accidentally keeping other objects around unnecessarily.
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// It also reduces the possible collateral damage from use-after-free bugs.
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func (elem *QueueInboundElement) clearPointers() {
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elem.buffer = nil
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elem.packet = nil
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elem.keypair = nil
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elem.endpoint = nil
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}
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func (device *Device) addToHandshakeQueue(queue chan QueueHandshakeElement, elem QueueHandshakeElement) bool {
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select {
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case queue <- elem:
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return true
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default:
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return false
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}
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}
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/* Called when a new authenticated message has been received
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*
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* NOTE: Not thread safe, but called by sequential receiver!
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*/
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func (peer *Peer) keepKeyFreshReceiving() {
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if peer.timers.sentLastMinuteHandshake.Get() {
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return
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}
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keypair := peer.keypairs.Current()
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if keypair != nil && keypair.isInitiator && time.Since(keypair.created) > (RejectAfterTime-KeepaliveTimeout-RekeyTimeout) {
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peer.timers.sentLastMinuteHandshake.Set(true)
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peer.SendHandshakeInitiation(false)
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}
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}
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/* Receives incoming datagrams for the device
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*
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* Every time the bind is updated a new routine is started for
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* IPv4 and IPv6 (separately)
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*/
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func (device *Device) RoutineReceiveIncoming(IP int, bind conn.Bind) {
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logDebug := device.log.Debug
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defer func() {
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logDebug.Println("Routine: receive incoming IPv" + strconv.Itoa(IP) + " - stopped")
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device.queue.decryption.wg.Done()
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device.net.stopping.Done()
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}()
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logDebug.Println("Routine: receive incoming IPv" + strconv.Itoa(IP) + " - started")
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// receive datagrams until conn is closed
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buffer := device.GetMessageBuffer()
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var (
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err error
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size int
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endpoint conn.Endpoint
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deathSpiral int
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)
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for {
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switch IP {
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case ipv4.Version:
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size, endpoint, err = bind.ReceiveIPv4(buffer[:])
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case ipv6.Version:
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size, endpoint, err = bind.ReceiveIPv6(buffer[:])
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default:
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panic("invalid IP version")
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}
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if err != nil {
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device.PutMessageBuffer(buffer)
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if errors.Is(err, net.ErrClosed) {
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return
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}
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device.log.Error.Printf("Failed to receive packet: %v", err)
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if deathSpiral < 10 {
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deathSpiral++
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time.Sleep(time.Second / 3)
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continue
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}
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return
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}
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deathSpiral = 0
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if size < MinMessageSize {
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continue
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}
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// check size of packet
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packet := buffer[:size]
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msgType := binary.LittleEndian.Uint32(packet[:4])
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var okay bool
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switch msgType {
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// check if transport
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case MessageTransportType:
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// check size
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if len(packet) < MessageTransportSize {
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continue
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}
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// lookup key pair
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receiver := binary.LittleEndian.Uint32(
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packet[MessageTransportOffsetReceiver:MessageTransportOffsetCounter],
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)
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value := device.indexTable.Lookup(receiver)
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keypair := value.keypair
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if keypair == nil {
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continue
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}
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// check keypair expiry
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if keypair.created.Add(RejectAfterTime).Before(time.Now()) {
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continue
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}
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// create work element
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peer := value.peer
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elem := device.GetInboundElement()
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elem.packet = packet
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elem.buffer = buffer
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elem.keypair = keypair
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elem.endpoint = endpoint
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elem.counter = 0
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elem.Mutex = sync.Mutex{}
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elem.Lock()
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// add to decryption queues
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peer.queue.RLock()
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if peer.isRunning.Get() {
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peer.queue.inbound <- elem
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device.queue.decryption.c <- elem
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buffer = device.GetMessageBuffer()
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} else {
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device.PutInboundElement(elem)
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}
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peer.queue.RUnlock()
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continue
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// otherwise it is a fixed size & handshake related packet
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case MessageInitiationType:
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okay = len(packet) == MessageInitiationSize
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case MessageResponseType:
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okay = len(packet) == MessageResponseSize
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case MessageCookieReplyType:
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okay = len(packet) == MessageCookieReplySize
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default:
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logDebug.Println("Received message with unknown type")
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}
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if okay {
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if (device.addToHandshakeQueue(
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device.queue.handshake,
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QueueHandshakeElement{
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msgType: msgType,
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buffer: buffer,
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packet: packet,
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endpoint: endpoint,
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},
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)) {
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buffer = device.GetMessageBuffer()
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}
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}
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}
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}
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func (device *Device) RoutineDecryption() {
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var nonce [chacha20poly1305.NonceSize]byte
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logDebug := device.log.Debug
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defer func() {
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logDebug.Println("Routine: decryption worker - stopped")
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device.state.stopping.Done()
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}()
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logDebug.Println("Routine: decryption worker - started")
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for elem := range device.queue.decryption.c {
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// split message into fields
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counter := elem.packet[MessageTransportOffsetCounter:MessageTransportOffsetContent]
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content := elem.packet[MessageTransportOffsetContent:]
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// decrypt and release to consumer
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var err error
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elem.counter = binary.LittleEndian.Uint64(counter)
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// copy counter to nonce
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binary.LittleEndian.PutUint64(nonce[0x4:0xc], elem.counter)
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elem.packet, err = elem.keypair.receive.Open(
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content[:0],
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nonce[:],
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content,
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nil,
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)
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if err != nil {
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elem.packet = nil
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}
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elem.Unlock()
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}
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}
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/* Handles incoming packets related to handshake
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*/
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func (device *Device) RoutineHandshake() {
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logInfo := device.log.Info
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logError := device.log.Error
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logDebug := device.log.Debug
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var elem QueueHandshakeElement
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var ok bool
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defer func() {
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logDebug.Println("Routine: handshake worker - stopped")
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device.state.stopping.Done()
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if elem.buffer != nil {
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device.PutMessageBuffer(elem.buffer)
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}
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}()
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logDebug.Println("Routine: handshake worker - started")
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for {
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if elem.buffer != nil {
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device.PutMessageBuffer(elem.buffer)
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elem.buffer = nil
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}
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select {
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case elem, ok = <-device.queue.handshake:
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case <-device.signals.stop:
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return
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}
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if !ok {
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return
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}
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// handle cookie fields and ratelimiting
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switch elem.msgType {
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case MessageCookieReplyType:
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// unmarshal packet
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var reply MessageCookieReply
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reader := bytes.NewReader(elem.packet)
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err := binary.Read(reader, binary.LittleEndian, &reply)
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if err != nil {
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logDebug.Println("Failed to decode cookie reply")
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return
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}
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// lookup peer from index
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entry := device.indexTable.Lookup(reply.Receiver)
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if entry.peer == nil {
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continue
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}
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// consume reply
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if peer := entry.peer; peer.isRunning.Get() {
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logDebug.Println("Receiving cookie response from ", elem.endpoint.DstToString())
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if !peer.cookieGenerator.ConsumeReply(&reply) {
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logDebug.Println("Could not decrypt invalid cookie response")
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}
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}
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continue
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case MessageInitiationType, MessageResponseType:
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// check mac fields and maybe ratelimit
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if !device.cookieChecker.CheckMAC1(elem.packet) {
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logDebug.Println("Received packet with invalid mac1")
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continue
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}
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// endpoints destination address is the source of the datagram
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if device.IsUnderLoad() {
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// verify MAC2 field
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if !device.cookieChecker.CheckMAC2(elem.packet, elem.endpoint.DstToBytes()) {
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device.SendHandshakeCookie(&elem)
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continue
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}
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// check ratelimiter
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if !device.rate.limiter.Allow(elem.endpoint.DstIP()) {
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continue
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}
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}
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default:
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logError.Println("Invalid packet ended up in the handshake queue")
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continue
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}
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// handle handshake initiation/response content
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switch elem.msgType {
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case MessageInitiationType:
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// unmarshal
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var msg MessageInitiation
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reader := bytes.NewReader(elem.packet)
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err := binary.Read(reader, binary.LittleEndian, &msg)
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if err != nil {
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logError.Println("Failed to decode initiation message")
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continue
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}
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// consume initiation
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peer := device.ConsumeMessageInitiation(&msg)
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if peer == nil {
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logInfo.Println(
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"Received invalid initiation message from",
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elem.endpoint.DstToString(),
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)
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continue
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}
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// update timers
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peer.timersAnyAuthenticatedPacketTraversal()
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peer.timersAnyAuthenticatedPacketReceived()
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// update endpoint
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peer.SetEndpointFromPacket(elem.endpoint)
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logDebug.Println(peer, "- Received handshake initiation")
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atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
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peer.SendHandshakeResponse()
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case MessageResponseType:
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// unmarshal
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var msg MessageResponse
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reader := bytes.NewReader(elem.packet)
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err := binary.Read(reader, binary.LittleEndian, &msg)
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if err != nil {
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logError.Println("Failed to decode response message")
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continue
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}
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// consume response
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peer := device.ConsumeMessageResponse(&msg)
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if peer == nil {
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logInfo.Println(
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"Received invalid response message from",
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elem.endpoint.DstToString(),
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)
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continue
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}
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// update endpoint
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peer.SetEndpointFromPacket(elem.endpoint)
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logDebug.Println(peer, "- Received handshake response")
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atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)))
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// update timers
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peer.timersAnyAuthenticatedPacketTraversal()
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peer.timersAnyAuthenticatedPacketReceived()
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// derive keypair
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err = peer.BeginSymmetricSession()
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if err != nil {
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logError.Println(peer, "- Failed to derive keypair:", err)
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continue
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}
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peer.timersSessionDerived()
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peer.timersHandshakeComplete()
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peer.SendKeepalive()
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select {
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case peer.signals.newKeypairArrived <- struct{}{}:
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default:
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}
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}
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}
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}
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func (peer *Peer) RoutineSequentialReceiver() {
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device := peer.device
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logInfo := device.log.Info
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logError := device.log.Error
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logDebug := device.log.Debug
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var elem *QueueInboundElement
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defer func() {
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logDebug.Println(peer, "- Routine: sequential receiver - stopped")
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peer.routines.stopping.Done()
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if elem != nil {
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device.PutMessageBuffer(elem.buffer)
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device.PutInboundElement(elem)
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}
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}()
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logDebug.Println(peer, "- Routine: sequential receiver - started")
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for {
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if elem != nil {
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device.PutMessageBuffer(elem.buffer)
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device.PutInboundElement(elem)
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elem = nil
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}
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var elemOk bool
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select {
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case <-peer.routines.stop:
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return
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case elem, elemOk = <-peer.queue.inbound:
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if !elemOk {
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return
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}
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}
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// wait for decryption
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elem.Lock()
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if elem.packet == nil {
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// decryption failed
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continue
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}
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// check for replay
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if !elem.keypair.replayFilter.ValidateCounter(elem.counter, RejectAfterMessages) {
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continue
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}
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// update endpoint
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peer.SetEndpointFromPacket(elem.endpoint)
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// check if using new keypair
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if peer.ReceivedWithKeypair(elem.keypair) {
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peer.timersHandshakeComplete()
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select {
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case peer.signals.newKeypairArrived <- struct{}{}:
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default:
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}
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}
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peer.keepKeyFreshReceiving()
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peer.timersAnyAuthenticatedPacketTraversal()
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peer.timersAnyAuthenticatedPacketReceived()
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atomic.AddUint64(&peer.stats.rxBytes, uint64(len(elem.packet)+MinMessageSize))
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// check for keepalive
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if len(elem.packet) == 0 {
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logDebug.Println(peer, "- Receiving keepalive packet")
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continue
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}
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peer.timersDataReceived()
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// verify source and strip padding
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switch elem.packet[0] >> 4 {
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case ipv4.Version:
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// strip padding
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if len(elem.packet) < ipv4.HeaderLen {
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continue
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}
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field := elem.packet[IPv4offsetTotalLength : IPv4offsetTotalLength+2]
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length := binary.BigEndian.Uint16(field)
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if int(length) > len(elem.packet) || int(length) < ipv4.HeaderLen {
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continue
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}
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elem.packet = elem.packet[:length]
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// verify IPv4 source
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src := elem.packet[IPv4offsetSrc : IPv4offsetSrc+net.IPv4len]
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if device.allowedips.LookupIPv4(src) != peer {
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logInfo.Println(
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"IPv4 packet with disallowed source address from",
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peer,
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)
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continue
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}
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case ipv6.Version:
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// strip padding
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if len(elem.packet) < ipv6.HeaderLen {
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continue
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}
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field := elem.packet[IPv6offsetPayloadLength : IPv6offsetPayloadLength+2]
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length := binary.BigEndian.Uint16(field)
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length += ipv6.HeaderLen
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if int(length) > len(elem.packet) {
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continue
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}
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elem.packet = elem.packet[:length]
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// verify IPv6 source
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src := elem.packet[IPv6offsetSrc : IPv6offsetSrc+net.IPv6len]
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if device.allowedips.LookupIPv6(src) != peer {
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logInfo.Println(
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"IPv6 packet with disallowed source address from",
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peer,
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)
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continue
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}
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default:
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logInfo.Println("Packet with invalid IP version from", peer)
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continue
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}
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// write to tun device
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offset := MessageTransportOffsetContent
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_, err := device.tun.device.Write(elem.buffer[:offset+len(elem.packet)], offset)
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if err != nil && !device.isClosed.Get() {
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logError.Println("Failed to write packet to TUN device:", err)
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}
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if len(peer.queue.inbound) == 0 {
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err := device.tun.device.Flush()
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if err != nil {
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peer.device.log.Error.Printf("Unable to flush packets: %v", err)
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}
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}
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}
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}
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