308 lines
7.2 KiB
Go
308 lines
7.2 KiB
Go
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// Copyright 2016 The CMux Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
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// implied. See the License for the specific language governing
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// permissions and limitations under the License.
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package cmux
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import (
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"errors"
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"fmt"
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"io"
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"net"
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"sync"
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"time"
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)
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// Matcher matches a connection based on its content.
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type Matcher func(io.Reader) bool
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// MatchWriter is a match that can also write response (say to do handshake).
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type MatchWriter func(io.Writer, io.Reader) bool
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// ErrorHandler handles an error and returns whether
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// the mux should continue serving the listener.
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type ErrorHandler func(error) bool
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var _ net.Error = ErrNotMatched{}
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// ErrNotMatched is returned whenever a connection is not matched by any of
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// the matchers registered in the multiplexer.
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type ErrNotMatched struct {
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c net.Conn
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}
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func (e ErrNotMatched) Error() string {
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return fmt.Sprintf("mux: connection %v not matched by an matcher",
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e.c.RemoteAddr())
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}
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// Temporary implements the net.Error interface.
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func (e ErrNotMatched) Temporary() bool { return true }
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// Timeout implements the net.Error interface.
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func (e ErrNotMatched) Timeout() bool { return false }
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type errListenerClosed string
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func (e errListenerClosed) Error() string { return string(e) }
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func (e errListenerClosed) Temporary() bool { return false }
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func (e errListenerClosed) Timeout() bool { return false }
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// ErrListenerClosed is returned from muxListener.Accept when the underlying
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// listener is closed.
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var ErrListenerClosed = errListenerClosed("mux: listener closed")
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// ErrServerClosed is returned from muxListener.Accept when mux server is closed.
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var ErrServerClosed = errors.New("mux: server closed")
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// for readability of readTimeout
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var noTimeout time.Duration
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// New instantiates a new connection multiplexer.
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func New(l net.Listener) CMux {
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return &cMux{
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root: l,
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bufLen: 1024,
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errh: func(_ error) bool { return true },
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donec: make(chan struct{}),
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readTimeout: noTimeout,
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}
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}
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// CMux is a multiplexer for network connections.
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type CMux interface {
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// Match returns a net.Listener that sees (i.e., accepts) only
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// the connections matched by at least one of the matcher.
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//
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// The order used to call Match determines the priority of matchers.
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Match(...Matcher) net.Listener
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// MatchWithWriters returns a net.Listener that accepts only the
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// connections that matched by at least of the matcher writers.
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//
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// Prefer Matchers over MatchWriters, since the latter can write on the
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// connection before the actual handler.
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//
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// The order used to call Match determines the priority of matchers.
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MatchWithWriters(...MatchWriter) net.Listener
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// Serve starts multiplexing the listener. Serve blocks and perhaps
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// should be invoked concurrently within a go routine.
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Serve() error
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// Closes cmux server and stops accepting any connections on listener
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Close()
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// HandleError registers an error handler that handles listener errors.
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HandleError(ErrorHandler)
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// sets a timeout for the read of matchers
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SetReadTimeout(time.Duration)
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}
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type matchersListener struct {
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ss []MatchWriter
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l muxListener
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}
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type cMux struct {
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root net.Listener
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bufLen int
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errh ErrorHandler
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sls []matchersListener
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readTimeout time.Duration
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donec chan struct{}
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mu sync.Mutex
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}
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func matchersToMatchWriters(matchers []Matcher) []MatchWriter {
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mws := make([]MatchWriter, 0, len(matchers))
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for _, m := range matchers {
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cm := m
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mws = append(mws, func(w io.Writer, r io.Reader) bool {
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return cm(r)
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})
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}
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return mws
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}
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func (m *cMux) Match(matchers ...Matcher) net.Listener {
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mws := matchersToMatchWriters(matchers)
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return m.MatchWithWriters(mws...)
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}
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func (m *cMux) MatchWithWriters(matchers ...MatchWriter) net.Listener {
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ml := muxListener{
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Listener: m.root,
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connc: make(chan net.Conn, m.bufLen),
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donec: make(chan struct{}),
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}
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m.sls = append(m.sls, matchersListener{ss: matchers, l: ml})
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return ml
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}
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func (m *cMux) SetReadTimeout(t time.Duration) {
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m.readTimeout = t
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}
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func (m *cMux) Serve() error {
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var wg sync.WaitGroup
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defer func() {
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m.closeDoneChans()
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wg.Wait()
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for _, sl := range m.sls {
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close(sl.l.connc)
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// Drain the connections enqueued for the listener.
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for c := range sl.l.connc {
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_ = c.Close()
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}
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}
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}()
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for {
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c, err := m.root.Accept()
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if err != nil {
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if !m.handleErr(err) {
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return err
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}
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continue
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}
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wg.Add(1)
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go m.serve(c, m.donec, &wg)
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}
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}
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func (m *cMux) serve(c net.Conn, donec <-chan struct{}, wg *sync.WaitGroup) {
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defer wg.Done()
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muc := newMuxConn(c)
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if m.readTimeout > noTimeout {
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_ = c.SetReadDeadline(time.Now().Add(m.readTimeout))
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}
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for _, sl := range m.sls {
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for _, s := range sl.ss {
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matched := s(muc.Conn, muc.startSniffing())
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if matched {
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muc.doneSniffing()
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if m.readTimeout > noTimeout {
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_ = c.SetReadDeadline(time.Time{})
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}
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select {
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case sl.l.connc <- muc:
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case <-donec:
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_ = c.Close()
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}
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return
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}
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}
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}
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_ = c.Close()
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err := ErrNotMatched{c: c}
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if !m.handleErr(err) {
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_ = m.root.Close()
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}
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}
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func (m *cMux) Close() {
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m.closeDoneChans()
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}
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func (m *cMux) closeDoneChans() {
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m.mu.Lock()
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defer m.mu.Unlock()
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select {
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case <-m.donec:
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// Already closed. Don't close again
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default:
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close(m.donec)
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}
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for _, sl := range m.sls {
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select {
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case <-sl.l.donec:
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// Already closed. Don't close again
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default:
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close(sl.l.donec)
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}
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}
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}
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func (m *cMux) HandleError(h ErrorHandler) {
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m.errh = h
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}
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func (m *cMux) handleErr(err error) bool {
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if !m.errh(err) {
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return false
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}
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if ne, ok := err.(net.Error); ok {
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return ne.Temporary()
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}
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return false
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}
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type muxListener struct {
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net.Listener
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connc chan net.Conn
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donec chan struct{}
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}
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func (l muxListener) Accept() (net.Conn, error) {
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select {
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case c, ok := <-l.connc:
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if !ok {
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return nil, ErrListenerClosed
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}
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return c, nil
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case <-l.donec:
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return nil, ErrServerClosed
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}
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}
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// MuxConn wraps a net.Conn and provides transparent sniffing of connection data.
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type MuxConn struct {
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net.Conn
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buf bufferedReader
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}
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func newMuxConn(c net.Conn) *MuxConn {
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return &MuxConn{
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Conn: c,
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buf: bufferedReader{source: c},
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}
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}
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// From the io.Reader documentation:
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//
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// When Read encounters an error or end-of-file condition after
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// successfully reading n > 0 bytes, it returns the number of
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// bytes read. It may return the (non-nil) error from the same call
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// or return the error (and n == 0) from a subsequent call.
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// An instance of this general case is that a Reader returning
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// a non-zero number of bytes at the end of the input stream may
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// return either err == EOF or err == nil. The next Read should
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// return 0, EOF.
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func (m *MuxConn) Read(p []byte) (int, error) {
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return m.buf.Read(p)
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}
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func (m *MuxConn) startSniffing() io.Reader {
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m.buf.reset(true)
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return &m.buf
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}
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func (m *MuxConn) doneSniffing() {
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m.buf.reset(false)
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}
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