Cloak/internal/multiplex/session.go
2019-07-28 23:27:59 +01:00

177 lines
4.1 KiB
Go

package multiplex
import (
"errors"
//"log"
"net"
"sync"
"sync/atomic"
"time"
)
const (
acceptBacklog = 1024
)
var ErrBrokenSession = errors.New("broken session")
var errRepeatSessionClosing = errors.New("trying to close a closed session")
type Session struct {
id uint32
// Used in Stream.Write. Add multiplexing headers, encrypt and add TLS header
obfs Obfser
// Remove TLS header, decrypt and unmarshall multiplexing headers
deobfs Deobfser
// This is supposed to read one TLS message, the same as GoQuiet's ReadTillDrain
obfsedRead func(net.Conn, []byte) (int, error)
// atomic
nextStreamID uint32
streamsM sync.Mutex
streams map[uint32]*Stream
// Switchboard manages all connections to remote
sb *switchboard
addrs atomic.Value
// For accepting new streams
acceptCh chan *Stream
closed uint32
terminalMsg atomic.Value
}
func MakeSession(id uint32, valve *Valve, obfs Obfser, deobfs Deobfser, obfsedRead func(net.Conn, []byte) (int, error)) *Session {
sesh := &Session{
id: id,
obfs: obfs,
deobfs: deobfs,
obfsedRead: obfsedRead,
nextStreamID: 1,
streams: make(map[uint32]*Stream),
acceptCh: make(chan *Stream, acceptBacklog),
}
sesh.addrs.Store([]net.Addr{nil, nil})
sesh.sb = makeSwitchboard(sesh, valve)
go sesh.timeoutAfter(30 * time.Second)
return sesh
}
func (sesh *Session) AddConnection(conn net.Conn) {
sesh.sb.addConn(conn)
addrs := []net.Addr{conn.LocalAddr(), conn.RemoteAddr()}
sesh.addrs.Store(addrs)
}
func (sesh *Session) OpenStream() (*Stream, error) {
if sesh.IsClosed() {
return nil, ErrBrokenSession
}
id := atomic.AddUint32(&sesh.nextStreamID, 1) - 1
// Because atomic.AddUint32 returns the value after incrementation
stream := makeStream(id, sesh)
sesh.streamsM.Lock()
sesh.streams[id] = stream
sesh.streamsM.Unlock()
//log.Printf("Opening stream %v\n", id)
return stream, nil
}
func (sesh *Session) Accept() (net.Conn, error) {
if sesh.IsClosed() {
return nil, ErrBrokenSession
}
stream := <-sesh.acceptCh
if stream == nil {
return nil, ErrBrokenSession
}
return stream, nil
}
func (sesh *Session) delStream(id uint32) {
sesh.streamsM.Lock()
delete(sesh.streams, id)
if len(sesh.streams) == 0 {
go sesh.timeoutAfter(30 * time.Second)
}
sesh.streamsM.Unlock()
}
// either fetch an existing stream or instantiate a new stream and put it in the dict, and return it
func (sesh *Session) getStream(id uint32, closingFrame bool) *Stream {
// it would have been neater to use defer Unlock(), however it gives
// non-negligable overhead and this function is performance critical
sesh.streamsM.Lock()
defer sesh.streamsM.Unlock()
stream := sesh.streams[id]
if stream != nil {
return stream
} else {
if closingFrame {
// If the stream has been closed and the current frame is a closing frame,
// we return nil
return nil
} else {
stream = makeStream(id, sesh)
sesh.streams[id] = stream
sesh.acceptCh <- stream
//log.Printf("Adding stream %v\n", id)
return stream
}
}
}
func (sesh *Session) SetTerminalMsg(msg string) {
sesh.terminalMsg.Store(msg)
}
func (sesh *Session) TerminalMsg() string {
msg := sesh.terminalMsg.Load()
if msg != nil {
return msg.(string)
} else {
return ""
}
}
func (sesh *Session) Close() error {
atomic.StoreUint32(&sesh.closed, 1)
sesh.streamsM.Lock()
sesh.acceptCh <- nil
for id, stream := range sesh.streams {
// If we call stream.Close() here, streamsM will result in a deadlock
// because stream.Close calls sesh.delStream, which locks the mutex.
// so we need to implement a method of stream that closes the stream without calling
// sesh.delStream
go stream.closeNoDelMap()
delete(sesh.streams, id)
}
sesh.streamsM.Unlock()
sesh.sb.closeAll()
return nil
}
func (sesh *Session) IsClosed() bool {
return atomic.LoadUint32(&sesh.closed) == 1
}
func (sesh *Session) timeoutAfter(to time.Duration) {
time.Sleep(to)
sesh.streamsM.Lock()
if len(sesh.streams) == 0 && !sesh.IsClosed() {
sesh.streamsM.Unlock()
sesh.SetTerminalMsg("timeout")
sesh.Close()
} else {
sesh.streamsM.Unlock()
}
}
func (sesh *Session) Addr() net.Addr { return sesh.addrs.Load().([]net.Addr)[0] }