mirror of https://github.com/status-im/consul.git
475 lines
13 KiB
Go
475 lines
13 KiB
Go
package proto
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import (
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"fmt"
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"github.com/inconshreveable/muxado/proto/frame"
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"io"
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"net"
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"reflect"
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"sync"
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"sync/atomic"
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"time"
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)
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const (
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defaultWindowSize = 0x10000 // 64KB
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defaultAcceptQueueDepth = 100
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MinExtensionType = 0xFFFFFFFF - 0x100 // 512 extensions
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)
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// private interface for Sessions to call Streams
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type stream interface {
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IStream
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handleStreamData(*frame.RStreamData)
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handleStreamWndInc(*frame.RStreamWndInc)
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handleStreamRst(*frame.RStreamRst)
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closeWith(error)
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}
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// for extensions
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type ExtAccept func() (IStream, error)
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type Extension interface {
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Start(ISession, ExtAccept) frame.StreamType
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}
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type deadReason struct {
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errorCode frame.ErrorCode
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err error
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remoteDebug []byte
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}
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// factory function that creates new streams
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type streamFactory func(id frame.StreamId, priority frame.StreamPriority, streamType frame.StreamType, finLocal bool, finRemote bool, windowSize uint32, sess session) stream
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// checks the parity of a stream id (local vs remote, client vs server)
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type parityFn func(frame.StreamId) bool
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// state for each half of the session (remote and local)
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type halfState struct {
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goneAway int32 // true if that half of the stream has gone away
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lastId uint32 // last id used/seen from one half of the session
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}
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// Session implements a simple streaming session manager. It has the following characteristics:
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//
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// - When closing the Session, it does not linger, all pending write operations will fail immediately.
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// - It completely ignores stream priority when processing and writing frames
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// - It offers no customization of settings like window size/ping time
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type Session struct {
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conn net.Conn // connection the transport is running over
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transport frame.Transport // transport
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streams StreamMap // all active streams
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local halfState // client state
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remote halfState // server state
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syn *frame.WStreamSyn // STREAM_SYN frame for opens
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wr sync.Mutex // synchronization when writing frames
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accept chan stream // new streams opened by the remote
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diebit int32 // true if we're dying
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remoteDebug []byte // debugging data sent in the remote's GoAway frame
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defaultWindowSize uint32 // window size when creating new streams
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newStream streamFactory // factory function to make new streams
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dead chan deadReason // dead
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isLocal parityFn // determines if a stream id is local or remote
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exts map[frame.StreamType]chan stream // map of extension stream type -> accept channel for the extension
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}
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func NewSession(conn net.Conn, newStream streamFactory, isClient bool, exts []Extension) ISession {
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sess := &Session{
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conn: conn,
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transport: frame.NewBasicTransport(conn),
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streams: NewConcurrentStreamMap(),
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local: halfState{lastId: 0},
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remote: halfState{lastId: 0},
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syn: frame.NewWStreamSyn(),
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diebit: 0,
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defaultWindowSize: defaultWindowSize,
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accept: make(chan stream, defaultAcceptQueueDepth),
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newStream: newStream,
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dead: make(chan deadReason, 1), // don't block die() if there is no Wait call
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exts: make(map[frame.StreamType]chan stream),
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}
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if isClient {
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sess.isLocal = sess.isClient
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sess.local.lastId += 1
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} else {
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sess.isLocal = sess.isServer
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sess.remote.lastId += 1
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}
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for _, ext := range exts {
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sess.startExtension(ext)
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}
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go sess.reader()
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return sess
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}
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////////////////////////////////
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// public interface
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////////////////////////////////
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func (s *Session) Open() (IStream, error) {
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return s.OpenStream(0, 0, false)
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}
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func (s *Session) OpenStream(priority frame.StreamPriority, streamType frame.StreamType, fin bool) (ret IStream, err error) {
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// check if the remote has gone away
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if atomic.LoadInt32(&s.remote.goneAway) == 1 {
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return nil, fmt.Errorf("Failed to create stream, remote has gone away.")
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}
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// this lock prevents the following race:
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// goroutine1 goroutine2
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// - inc stream id
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// - inc stream id
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// - send streamsyn
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// - send streamsyn
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s.wr.Lock()
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// get the next id we can use
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nextId := frame.StreamId(atomic.AddUint32(&s.local.lastId, 2))
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// make the stream
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str := s.newStream(nextId, priority, streamType, fin, false, s.defaultWindowSize, s)
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// add to to the stream map
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s.streams.Set(nextId, str)
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// write the frame
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if err = s.syn.Set(nextId, priority, streamType, fin); err != nil {
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s.wr.Unlock()
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s.die(frame.InternalError, err)
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return
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}
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if err = s.transport.WriteFrame(s.syn); err != nil {
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s.wr.Unlock()
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s.die(frame.InternalError, err)
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return
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}
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s.wr.Unlock()
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return str, nil
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}
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func (s *Session) Accept() (str IStream, err error) {
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var ok bool
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if str, ok = <-s.accept; !ok {
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return nil, fmt.Errorf("Session closed")
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}
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return
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}
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func (s *Session) Kill() error {
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return s.transport.Close()
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}
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func (s *Session) Close() error {
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return s.die(frame.NoError, fmt.Errorf("Session Close()"))
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}
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func (s *Session) GoAway(errorCode frame.ErrorCode, debug []byte) (err error) {
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if !atomic.CompareAndSwapInt32(&s.local.goneAway, 0, 1) {
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return fmt.Errorf("Already sent GoAway!")
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}
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s.wr.Lock()
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f := frame.NewWGoAway()
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remoteId := frame.StreamId(atomic.LoadUint32(&s.remote.lastId))
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if err = f.Set(remoteId, errorCode, debug); err != nil {
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s.wr.Unlock()
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s.die(frame.InternalError, err)
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return
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}
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if err = s.transport.WriteFrame(f); err != nil {
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s.wr.Unlock()
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s.die(frame.InternalError, err)
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return
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}
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s.wr.Unlock()
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return
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}
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func (s *Session) LocalAddr() net.Addr {
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return s.conn.LocalAddr()
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}
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func (s *Session) RemoteAddr() net.Addr {
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return s.conn.RemoteAddr()
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}
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func (s *Session) Wait() (frame.ErrorCode, error, []byte) {
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reason := <-s.dead
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return reason.errorCode, reason.err, reason.remoteDebug
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}
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////////////////////////////////
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// private interface for streams
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////////////////////////////////
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// removeStream removes a stream from this session's stream registry
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//
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// It does not error if the stream is not present
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func (s *Session) removeStream(id frame.StreamId) {
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s.streams.Delete(id)
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return
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}
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// writeFrame writes the given frame to the transport and returns the error from the write operation
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func (s *Session) writeFrame(f frame.WFrame, dl time.Time) (err error) {
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s.wr.Lock()
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s.conn.SetWriteDeadline(dl)
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err = s.transport.WriteFrame(f)
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s.wr.Unlock()
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return
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}
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// die closes the session cleanly with the given error and protocol error code
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func (s *Session) die(errorCode frame.ErrorCode, err error) error {
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// only one shutdown ever happens
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if !atomic.CompareAndSwapInt32(&s.diebit, 0, 1) {
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return fmt.Errorf("Shutdown already in progress")
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}
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// send a go away frame
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s.GoAway(errorCode, []byte(err.Error()))
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// now we're safe to stop accepting incoming connections
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close(s.accept)
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// we cleaned up as best as possible, close the transport
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s.transport.Close()
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// notify all of the streams that we're closing
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s.streams.Each(func(id frame.StreamId, str stream) {
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str.closeWith(fmt.Errorf("Session closed"))
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})
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s.dead <- deadReason{errorCode, err, s.remoteDebug}
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return nil
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}
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////////////////////////////////
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// internal methods
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////////////////////////////////
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// reader() reads frames from the underlying transport and handles passes them to handleFrame
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func (s *Session) reader() {
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defer s.recoverPanic("reader()")
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// close all of the extension accept channels when we're done
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// we do this here instead of in die() since otherwise it wouldn't
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// be safe to access s.exts
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defer func() {
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for _, extAccept := range s.exts {
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close(extAccept)
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}
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}()
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for {
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f, err := s.transport.ReadFrame()
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if err != nil {
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// if we fail to read a frame, terminate the session
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_, ok := err.(*frame.FramingError)
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if ok {
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s.die(frame.ProtocolError, err)
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} else {
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s.die(frame.InternalError, err)
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}
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return
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}
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s.handleFrame(f)
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}
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}
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func (s *Session) handleFrame(rf frame.RFrame) {
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switch f := rf.(type) {
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case *frame.RStreamSyn:
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// if we're going away, refuse new streams
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if atomic.LoadInt32(&s.local.goneAway) == 1 {
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rstF := frame.NewWStreamRst()
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rstF.Set(f.StreamId(), frame.RefusedStream)
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go s.writeFrame(rstF, time.Time{})
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return
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}
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if f.StreamId() <= frame.StreamId(atomic.LoadUint32(&s.remote.lastId)) {
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s.die(frame.ProtocolError, fmt.Errorf("Stream id %d is less than last remote id.", f.StreamId()))
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return
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}
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if s.isLocal(f.StreamId()) {
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s.die(frame.ProtocolError, fmt.Errorf("Stream id has wrong parity for remote endpoint: %d", f.StreamId()))
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return
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}
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// update last remote id
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atomic.StoreUint32(&s.remote.lastId, uint32(f.StreamId()))
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// make the new stream
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str := s.newStream(f.StreamId(), f.StreamPriority(), f.StreamType(), false, f.Fin(), s.defaultWindowSize, s)
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// add it to the stream map
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s.streams.Set(f.StreamId(), str)
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// check if this is an extension stream
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if f.StreamType() >= MinExtensionType {
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extAccept, ok := s.exts[f.StreamType()]
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if !ok {
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// Extension type of stream not registered
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fRst := frame.NewWStreamRst()
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if err := fRst.Set(f.StreamId(), frame.StreamClosed); err != nil {
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s.die(frame.InternalError, err)
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}
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s.wr.Lock()
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defer s.wr.Unlock()
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s.transport.WriteFrame(fRst)
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} else {
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extAccept <- str
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}
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return
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}
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// put the new stream on the accept channel
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s.accept <- str
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case *frame.RStreamData:
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if str := s.getStream(f.StreamId()); str != nil {
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str.handleStreamData(f)
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} else {
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// if we get a data frame on a non-existent connection, we still
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// need to read out the frame body so that the stream stays in a
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// good state. read the payload into a throwaway buffer
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discard := make([]byte, f.Length())
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io.ReadFull(f.Reader(), discard)
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// DATA frames on closed connections are just stream-level errors
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fRst := frame.NewWStreamRst()
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if err := fRst.Set(f.StreamId(), frame.StreamClosed); err != nil {
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s.die(frame.InternalError, err)
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}
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s.wr.Lock()
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defer s.wr.Unlock()
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s.transport.WriteFrame(fRst)
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return
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}
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case *frame.RStreamRst:
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// delegate to the stream to handle these frames
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if str := s.getStream(f.StreamId()); str != nil {
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str.handleStreamRst(f)
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}
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case *frame.RStreamWndInc:
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// delegate to the stream to handle these frames
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if str := s.getStream(f.StreamId()); str != nil {
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str.handleStreamWndInc(f)
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}
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case *frame.RGoAway:
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atomic.StoreInt32(&s.remote.goneAway, 1)
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s.remoteDebug = f.Debug()
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lastId := f.LastStreamId()
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s.streams.Each(func(id frame.StreamId, str stream) {
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// close all streams that we opened above the last handled id
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if s.isLocal(str.Id()) && str.Id() > lastId {
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str.closeWith(fmt.Errorf("Remote is going away"))
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}
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})
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default:
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s.die(frame.ProtocolError, fmt.Errorf("Unrecognized frame type: %v", reflect.TypeOf(f)))
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return
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}
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}
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func (s *Session) recoverPanic(prefix string) {
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if r := recover(); r != nil {
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s.die(frame.InternalError, fmt.Errorf("%s panic: %v", prefix, r))
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}
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}
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func (s *Session) getStream(id frame.StreamId) (str stream) {
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// decide if this id is in the "idle" state (i.e. greater than any we've seen for that parity)
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var lastId *uint32
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if s.isLocal(id) {
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lastId = &s.local.lastId
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} else {
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lastId = &s.remote.lastId
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}
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if uint32(id) > atomic.LoadUint32(lastId) {
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s.die(frame.ProtocolError, fmt.Errorf("%d is an invalid, unassigned stream id", id))
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}
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// find the stream in the stream map
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var ok bool
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if str, ok = s.streams.Get(id); !ok {
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return nil
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}
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return
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}
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// check if a stream id is for a client stream. client streams are odd
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func (s *Session) isClient(id frame.StreamId) bool {
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return uint32(id)&1 == 1
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}
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func (s *Session) isServer(id frame.StreamId) bool {
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return !s.isClient(id)
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}
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//////////////////////////////////////////////
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// session extensions
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//////////////////////////////////////////////
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func (s *Session) startExtension(ext Extension) {
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accept := make(chan stream)
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extAccept := func() (IStream, error) {
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s, ok := <-accept
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if !ok {
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return nil, fmt.Errorf("Failed to accept connection, shutting down")
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}
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return s, nil
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}
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extType := ext.Start(s, extAccept)
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s.exts[extType] = accept
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}
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//////////////////////////////////////////////
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// net adaptors
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//////////////////////////////////////////////
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func (s *Session) NetDial(_, _ string) (net.Conn, error) {
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str, err := s.Open()
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return net.Conn(str), err
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}
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func (s *Session) NetListener() net.Listener {
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return &netListenerAdaptor{s}
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}
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type netListenerAdaptor struct {
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*Session
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}
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func (a *netListenerAdaptor) Addr() net.Addr {
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return a.LocalAddr()
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}
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func (a *netListenerAdaptor) Accept() (net.Conn, error) {
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str, err := a.Session.Accept()
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return net.Conn(str), err
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}
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