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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package tcpproxy
import (
"io"
"net"
"sync"
)
// TargetListener implements both net.Listener and Target.
// Matched Targets become accepted connections.
type TargetListener struct {
Address string // Address is the string reported by TargetListener.Addr().String().
mu sync.Mutex
cond *sync.Cond
closed bool
nextConn net.Conn
}
var (
_ net.Listener = (*TargetListener)(nil)
_ Target = (*TargetListener)(nil)
)
func (tl *TargetListener) lock() {
tl.mu.Lock()
if tl.cond == nil {
tl.cond = sync.NewCond(&tl.mu)
}
}
type tcpAddr string
func (a tcpAddr) Network() string { return "tcp" }
func (a tcpAddr) String() string { return string(a) }
func (tl *TargetListener) Addr() net.Addr { return tcpAddr(tl.Address) }
func (tl *TargetListener) Close() error {
tl.lock()
if tl.closed {
tl.mu.Unlock()
return nil
}
tl.closed = true
tl.mu.Unlock()
tl.cond.Broadcast()
return nil
}
// HandleConn implements the Target interface. It blocks until tl is
// closed or another goroutine has called Accept and received c.
func (tl *TargetListener) HandleConn(c net.Conn) {
tl.lock()
defer tl.mu.Unlock()
for tl.nextConn != nil && !tl.closed {
tl.cond.Wait()
}
if tl.closed {
c.Close()
return
}
tl.nextConn = c
tl.cond.Broadcast() // Signal might be sufficient; verify.
for tl.nextConn == c && !tl.closed {
tl.cond.Wait()
}
if tl.closed {
c.Close()
return
}
}
func (tl *TargetListener) Accept() (net.Conn, error) {
tl.lock()
for tl.nextConn == nil && !tl.closed {
tl.cond.Wait()
}
if tl.closed {
tl.mu.Unlock()
return nil, io.EOF
}
c := tl.nextConn
tl.nextConn = nil
tl.mu.Unlock()
tl.cond.Broadcast() // Signal might be sufficient; verify.
return c, nil
}
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