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dummy-client.go
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dummy-client.go
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// Dummy no-op pluggable transport client. Works only as a managed proxy.
//
// Usage (in torrc):
// UseBridges 1
// Bridge dummy X.X.X.X:YYYY
// ClientTransportPlugin dummy exec dummy-client
//
// Because this transport doesn't do anything to the traffic, you can use any
// ordinary relay's ORPort in the Bridge line; it doesn't have to declare
// support for the dummy transport.
package main
import (
"io"
"net"
"os"
"os/signal"
"sync"
"syscall"
)
import "git.torproject.org/pluggable-transports/goptlib.git"
var ptInfo pt.ClientInfo
// When a connection handler starts, +1 is written to this channel; when it
// ends, -1 is written.
var handlerChan = make(chan int)
func copyLoop(a, b net.Conn) {
var wg sync.WaitGroup
wg.Add(2)
go func() {
io.Copy(b, a)
wg.Done()
}()
go func() {
io.Copy(a, b)
wg.Done()
}()
wg.Wait()
}
func handler(conn *pt.SocksConn) error {
handlerChan <- 1
defer func() {
handlerChan <- -1
}()
defer conn.Close()
remote, err := net.Dial("tcp", conn.Req.Target)
if err != nil {
conn.Reject()
return err
}
defer remote.Close()
err = conn.Grant(remote.RemoteAddr().(*net.TCPAddr))
if err != nil {
return err
}
copyLoop(conn, remote)
return nil
}
func acceptLoop(ln *pt.SocksListener) error {
defer ln.Close()
for {
conn, err := ln.AcceptSocks()
if err != nil {
if e, ok := err.(net.Error); ok && !e.Temporary() {
return err
}
continue
}
go handler(conn)
}
}
func main() {
var err error
ptInfo, err = pt.ClientSetup([]string{"dummy"})
if err != nil {
os.Exit(1)
}
listeners := make([]net.Listener, 0)
for _, methodName := range ptInfo.MethodNames {
switch methodName {
case "dummy":
ln, err := pt.ListenSocks("tcp", "127.0.0.1:0")
if err != nil {
pt.CmethodError(methodName, err.Error())
break
}
go acceptLoop(ln)
pt.Cmethod(methodName, ln.Version(), ln.Addr())
listeners = append(listeners, ln)
default:
pt.CmethodError(methodName, "no such method")
}
}
pt.CmethodsDone()
var numHandlers int = 0
var sig os.Signal
sigChan := make(chan os.Signal, 1)
signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM)
// wait for first signal
sig = nil
for sig == nil {
select {
case n := <-handlerChan:
numHandlers += n
case sig = <-sigChan:
}
}
for _, ln := range listeners {
ln.Close()
}
if sig == syscall.SIGTERM {
return
}
// wait for second signal or no more handlers
sig = nil
for sig == nil && numHandlers != 0 {
select {
case n := <-handlerChan:
numHandlers += n
case sig = <-sigChan:
}
}
}