504 lines
10 KiB
Go
504 lines
10 KiB
Go
package mucp
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import (
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"crypto/cipher"
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"encoding/base32"
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"io"
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"sync"
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"time"
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"github.com/micro/go-micro/v3/logger"
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"github.com/micro/go-micro/v3/transport"
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"github.com/micro/go-micro/v3/tunnel"
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)
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// session is our pseudo session for transport.Socket
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type session struct {
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// the tunnel id
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tunnel string
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// the channel name
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channel string
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// the session id based on Micro.Tunnel-Session
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session string
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// token is the session token
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token string
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// closed
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closed chan bool
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// remote addr
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remote string
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// local addr
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local string
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// send chan
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send chan *message
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// recv chan
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recv chan *message
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// if the discovery worked
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discovered bool
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// if the session was accepted
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accepted bool
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// outbound marks the session as outbound dialled connection
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outbound bool
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// lookback marks the session as a loopback on the inbound
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loopback bool
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// mode of the connection
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mode tunnel.Mode
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// the dial timeout
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dialTimeout time.Duration
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// the read timeout
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readTimeout time.Duration
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// the link on which this message was received
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link string
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// the error response
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errChan chan error
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// key for session encryption
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key []byte
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// cipher for session
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gcm cipher.AEAD
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sync.RWMutex
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}
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// message is sent over the send channel
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type message struct {
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// type of message
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typ string
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// tunnel id
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tunnel string
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// channel name
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channel string
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// the session id
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session string
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// outbound marks the message as outbound
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outbound bool
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// loopback marks the message intended for loopback
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loopback bool
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// mode of the connection
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mode tunnel.Mode
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// the link to send the message on
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link string
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// transport data
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data *transport.Message
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// the error channel
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errChan chan error
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}
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func (s *session) Remote() string {
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return s.remote
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}
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func (s *session) Local() string {
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return s.local
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}
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func (s *session) Link() string {
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return s.link
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}
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func (s *session) Id() string {
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return s.session
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}
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func (s *session) Channel() string {
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return s.channel
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}
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// newMessage creates a new message based on the session
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func (s *session) newMessage(typ string) *message {
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return &message{
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typ: typ,
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tunnel: s.tunnel,
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channel: s.channel,
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session: s.session,
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outbound: s.outbound,
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loopback: s.loopback,
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mode: s.mode,
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link: s.link,
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errChan: s.errChan,
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}
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}
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func (s *session) sendMsg(msg *message) error {
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select {
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case <-s.closed:
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return io.EOF
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case s.send <- msg:
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return nil
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}
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}
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func (s *session) wait(msg *message) error {
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// wait for an error response
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select {
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case err := <-msg.errChan:
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if err != nil {
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return err
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}
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case <-s.closed:
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return io.EOF
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}
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return nil
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}
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// waitFor waits for the message type required until the timeout specified
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func (s *session) waitFor(msgType string, timeout time.Duration) (*message, error) {
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now := time.Now()
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after := func(timeout time.Duration) <-chan time.Time {
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if timeout < time.Duration(0) {
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return nil
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}
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// get the delta
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d := time.Since(now)
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// dial timeout minus time since
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wait := timeout - d
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if wait < time.Duration(0) {
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wait = time.Duration(0)
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}
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return time.After(wait)
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}
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// wait for the message type
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for {
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select {
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case msg := <-s.recv:
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// there may be no message type
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if len(msgType) == 0 {
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return msg, nil
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}
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// ignore what we don't want
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if msg.typ != msgType {
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if logger.V(logger.DebugLevel, log) {
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log.Debugf("Tunnel received non %s message in waiting for %s", msg.typ, msgType)
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}
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continue
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}
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// got the message
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return msg, nil
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case <-after(timeout):
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return nil, tunnel.ErrReadTimeout
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case <-s.closed:
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// check pending message queue
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select {
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case msg := <-s.recv:
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// there may be no message type
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if len(msgType) == 0 {
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return msg, nil
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}
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// ignore what we don't want
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if msg.typ != msgType {
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if logger.V(logger.DebugLevel, log) {
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log.Debugf("Tunnel received non %s message in waiting for %s", msg.typ, msgType)
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}
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continue
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}
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// got the message
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return msg, nil
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default:
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// non blocking
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}
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return nil, io.EOF
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}
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}
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}
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// Discover attempts to discover the link for a specific channel.
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// This is only used by the tunnel.Dial when first connecting.
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func (s *session) Discover() error {
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// create a new discovery message for this channel
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msg := s.newMessage("discover")
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// broadcast the message to all links
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msg.mode = tunnel.Broadcast
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// its an outbound connection since we're dialling
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msg.outbound = true
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// don't set the link since we don't know where it is
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msg.link = ""
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// if multicast then set that as session
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if s.mode == tunnel.Multicast {
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msg.session = "multicast"
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}
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// send discover message
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if err := s.sendMsg(msg); err != nil {
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return err
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}
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// set time now
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now := time.Now()
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// after strips down the dial timeout
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after := func() time.Duration {
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d := time.Since(now)
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// dial timeout minus time since
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wait := s.dialTimeout - d
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// make sure its always > 0
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if wait < time.Duration(0) {
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return time.Duration(0)
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}
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return wait
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}
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// the discover message is sent out, now
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// wait to hear back about the sent message
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select {
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case <-time.After(after()):
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return tunnel.ErrDialTimeout
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case err := <-s.errChan:
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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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// bail early if its not unicast
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// we don't need to wait for the announce
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if s.mode != tunnel.Unicast {
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s.discovered = true
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s.accepted = true
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return nil
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}
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// wait for announce
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_, err := s.waitFor("announce", after())
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if err != nil {
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return err
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}
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// set discovered
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s.discovered = true
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return nil
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}
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// Open will fire the open message for the session. This is called by the dialler.
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// This is to indicate that we want to create a new session.
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func (s *session) Open() error {
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// create a new message
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msg := s.newMessage("open")
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// send open message
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if err := s.sendMsg(msg); err != nil {
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return err
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}
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// wait for an error response for send
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if err := s.wait(msg); err != nil {
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return err
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}
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// now wait for the accept message to be returned
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msg, err := s.waitFor("accept", s.dialTimeout)
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if err != nil {
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return err
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}
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// set to accepted
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s.accepted = true
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// set link
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s.link = msg.link
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return nil
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}
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// Accept sends the accept response to an open message from a dialled connection
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func (s *session) Accept() error {
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msg := s.newMessage("accept")
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// send the accept message
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if err := s.sendMsg(msg); err != nil {
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return err
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}
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// wait for send response
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return s.wait(msg)
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}
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// Announce sends an announcement to notify that this session exists.
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// This is primarily used by the listener.
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func (s *session) Announce() error {
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msg := s.newMessage("announce")
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// we don't need an error back
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msg.errChan = nil
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// announce to all
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msg.mode = tunnel.Broadcast
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// we don't need the link
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msg.link = ""
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// send announce message
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return s.sendMsg(msg)
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}
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// Send is used to send a message
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func (s *session) Send(m *transport.Message) error {
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var err error
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s.RLock()
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gcm := s.gcm
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s.RUnlock()
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if gcm == nil {
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gcm, err = newCipher(s.key)
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if err != nil {
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return err
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}
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s.Lock()
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s.gcm = gcm
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s.Unlock()
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}
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// encrypt the transport message payload
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body, err := Encrypt(gcm, m.Body)
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if err != nil {
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log.Debugf("failed to encrypt message body: %v", err)
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return err
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}
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// make copy, without rehash and realloc
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data := &transport.Message{
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Header: make(map[string]string, len(m.Header)),
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Body: body,
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}
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// encrypt all the headers
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for k, v := range m.Header {
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// encrypt the transport message payload
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val, err := Encrypt(s.gcm, []byte(v))
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if err != nil {
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log.Debugf("failed to encrypt message header %s: %v", k, err)
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return err
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}
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// add the encrypted header value
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data.Header[k] = base32.StdEncoding.EncodeToString(val)
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}
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// create a new message
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msg := s.newMessage("session")
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// set the data
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msg.data = data
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// if multicast don't set the link
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if s.mode != tunnel.Unicast {
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msg.link = ""
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}
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if logger.V(logger.TraceLevel, log) {
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log.Tracef("Appending to send backlog: %v", msg)
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}
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// send the actual message
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if err := s.sendMsg(msg); err != nil {
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return err
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}
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// wait for an error response
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return s.wait(msg)
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}
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// Recv is used to receive a message
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func (s *session) Recv(m *transport.Message) error {
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var msg *message
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msg, err := s.waitFor("", s.readTimeout)
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if err != nil {
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return err
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}
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// check the error if one exists
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select {
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case err := <-msg.errChan:
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return err
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default:
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}
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if logger.V(logger.TraceLevel, log) {
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log.Tracef("Received from recv backlog: %v", msg)
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}
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gcm, err := newCipher([]byte(s.token + s.channel + msg.session))
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if err != nil {
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if logger.V(logger.ErrorLevel, log) {
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log.Errorf("unable to create cipher: %v", err)
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}
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return err
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}
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// decrypt the received payload using the token
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// we have to used msg.session because multicast has a shared
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// session id of "multicast" in this session struct on
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// the listener side
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msg.data.Body, err = Decrypt(gcm, msg.data.Body)
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if err != nil {
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if logger.V(logger.DebugLevel, log) {
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log.Debugf("failed to decrypt message body: %v", err)
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}
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return err
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}
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// dencrypt all the headers
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for k, v := range msg.data.Header {
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// decode the header values
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h, err := base32.StdEncoding.DecodeString(v)
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if err != nil {
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if logger.V(logger.DebugLevel, log) {
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log.Debugf("failed to decode message header %s: %v", k, err)
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}
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return err
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}
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// dencrypt the transport message payload
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val, err := Decrypt(gcm, h)
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if err != nil {
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if logger.V(logger.DebugLevel, log) {
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log.Debugf("failed to decrypt message header %s: %v", k, err)
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}
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return err
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}
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// add decrypted header value
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msg.data.Header[k] = string(val)
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}
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// set the link
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// TODO: decruft, this is only for multicast
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// since the session is now a single session
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// likely provide as part of message.Link()
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msg.data.Header["Micro-Link"] = msg.link
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// set message
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*m = *msg.data
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// return nil
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return nil
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}
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// Close closes the session by sending a close message
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func (s *session) Close() error {
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select {
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case <-s.closed:
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// no op
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default:
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close(s.closed)
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// don't send close on multicast or broadcast
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if s.mode != tunnel.Unicast {
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return nil
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}
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// append to backlog
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msg := s.newMessage("close")
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// no error response on close
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msg.errChan = nil
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// send the close message
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select {
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case s.send <- msg:
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case <-time.After(time.Millisecond * 10):
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}
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}
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return nil
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}
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