micro/tunnel/session.go

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package tunnel
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import (
"errors"
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"io"
"time"
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"github.com/micro/go-micro/transport"
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"github.com/micro/go-micro/util/log"
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)
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// session is our pseudo session for transport.Socket
type session struct {
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// the tunnel id
tunnel string
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// the channel name
channel string
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// the session id based on Micro.Tunnel-Session
session string
// closed
closed chan bool
// remote addr
remote string
// local addr
local string
// send chan
send chan *message
// recv chan
recv chan *message
// wait until we have a connection
wait chan bool
// if the discovery worked
discovered bool
// if the session was accepted
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
loopback bool
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// mode of the connection
mode Mode
// the timeout
timeout time.Duration
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// the link on which this message was received
link string
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// the error response
errChan chan error
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}
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// message is sent over the send channel
type message struct {
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// type of message
typ string
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// tunnel id
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tunnel string
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// channel name
channel string
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// the session id
session string
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// outbound marks the message as outbound
outbound bool
// loopback marks the message intended for loopback
loopback bool
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// mode of the connection
mode Mode
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// the link to send the message on
link string
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// transport data
data *transport.Message
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// the error channel
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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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 {
return s.link
}
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func (s *session) Id() string {
return s.session
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}
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func (s *session) Channel() string {
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 {
return &message{
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typ: typ,
tunnel: s.tunnel,
channel: s.channel,
session: s.session,
outbound: s.outbound,
loopback: s.loopback,
mode: s.mode,
link: s.link,
errChan: s.errChan,
}
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}
// waitFor waits for the message type required until the timeout specified
func (s *session) waitFor(msgType string, timeout time.Duration) (*message, error) {
now := time.Now()
after := func(timeout time.Duration) time.Duration {
d := time.Since(now)
// dial timeout minus time since
wait := timeout - d
if wait < time.Duration(0) {
return time.Duration(0)
}
return wait
}
// wait for the message type
for {
select {
case msg := <-s.recv:
// ignore what we don't want
if msg.typ != msgType {
log.Debugf("Tunnel received non %s message in waiting for %s", msg.typ, msgType)
continue
}
// got the message
return msg, nil
case <-time.After(after(timeout)):
return nil, ErrDialTimeout
case <-s.closed:
return nil, io.EOF
}
}
}
// Discover attempts to discover the link for a specific channel
func (s *session) Discover() error {
// create a new discovery message for this channel
msg := s.newMessage("discover")
msg.mode = Broadcast
msg.outbound = true
msg.link = ""
// send the discovery message
s.send <- msg
// set time now
now := time.Now()
after := func() time.Duration {
d := time.Since(now)
// dial timeout minus time since
wait := s.timeout - d
if wait < time.Duration(0) {
return time.Duration(0)
}
return wait
}
// wait to hear back about the sent message
select {
case <-time.After(after()):
return ErrDialTimeout
case err := <-s.errChan:
if err != nil {
return err
}
}
var err error
// set a new dialTimeout
dialTimeout := after()
// set a shorter delay for multicast
if s.mode != Unicast {
// shorten this
dialTimeout = time.Millisecond * 500
}
// wait for announce
_, err = s.waitFor("announce", dialTimeout)
// if its multicast just go ahead because this is best effort
if s.mode != Unicast {
s.discovered = true
s.accepted = true
return nil
}
if err != nil {
return err
}
// set discovered
s.discovered = true
return nil
}
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// Open will fire the open message for the session. This is called by the dialler.
func (s *session) Open() error {
// create a new message
msg := s.newMessage("open")
// send open message
s.send <- msg
// wait for an error response for send
select {
case err := <-msg.errChan:
if err != nil {
return err
}
case <-s.closed:
return io.EOF
}
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// don't wait on multicast/broadcast
if s.mode == Multicast {
s.accepted = true
return nil
}
// now wait for the accept
msg, err := s.waitFor("accept", s.timeout)
if err != nil {
return err
}
// set to accepted
s.accepted = true
// set link
s.link = msg.link
return nil
}
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// Accept sends the accept response to an open message from a dialled connection
func (s *session) Accept() error {
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msg := s.newMessage("accept")
// send the accept message
select {
case <-s.closed:
return io.EOF
case s.send <- msg:
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// no op here
}
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// don't wait on multicast/broadcast
if s.mode == Multicast {
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return nil
}
// wait for send response
select {
case err := <-s.errChan:
if err != nil {
return err
}
case <-s.closed:
return io.EOF
}
return nil
}
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// Announce sends an announcement to notify that this session exists. This is primarily used by the listener.
func (s *session) Announce() error {
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msg := s.newMessage("announce")
// we don't need an error back
msg.errChan = nil
// announce to all
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msg.mode = Broadcast
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// we don't need the link
msg.link = ""
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select {
case s.send <- msg:
return nil
case <-s.closed:
return io.EOF
}
}
// Send is used to send a message
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func (s *session) Send(m *transport.Message) error {
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select {
case <-s.closed:
return io.EOF
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default:
// no op
}
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// make copy
data := &transport.Message{
Header: make(map[string]string),
Body: m.Body,
}
for k, v := range m.Header {
data.Header[k] = v
}
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// create a new message
msg := s.newMessage("session")
// set the data
msg.data = data
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// if multicast don't set the link
if s.mode == Multicast {
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msg.link = ""
}
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log.Tracef("Appending %+v to send backlog", msg)
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// send the actual message
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s.send <- msg
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// wait for an error response
select {
case err := <-msg.errChan:
return err
case <-s.closed:
return io.EOF
}
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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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select {
case <-s.closed:
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return errors.New("session is closed")
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default:
// no op
}
// recv from backlog
msg := <-s.recv
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// check the error if one exists
select {
case err := <-msg.errChan:
return err
default:
}
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log.Tracef("Received %+v from recv backlog", msg)
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// set message
*m = *msg.data
// return nil
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 {
case <-s.closed:
// no op
default:
close(s.closed)
// append to backlog
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msg := s.newMessage("close")
// no error response on close
msg.errChan = nil
// send the close message
select {
case s.send <- msg:
default:
}
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}
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return nil
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}