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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 the
// ORPort of any ordinary bridge (or relay that has DirPort set) in the bridge
// line; it doesn't have to declare support for the dummy transport.
package main
import (
"io"
"io/ioutil"
"net"
"os"
"os/signal"
"sync"
"syscall"
)
import "gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/goptlib"
var ptInfo pt.ClientInfo
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 {
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() {
continue
}
return err
}
go handler(conn)
}
}
func main() {
var err error
ptInfo, err = pt.ClientSetup(nil)
if err != nil {
os.Exit(1)
}
pt.ReportVersion("dummy-client", "0.1")
if ptInfo.ProxyURL != nil {
pt.ProxyError("proxy is not supported")
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()
sigChan := make(chan os.Signal, 1)
signal.Notify(sigChan, syscall.SIGTERM)
if os.Getenv("TOR_PT_EXIT_ON_STDIN_CLOSE") == "1" {
// This environment variable means we should treat EOF on stdin
// just like SIGTERM: https://bugs.torproject.org/15435.
go func() {
io.Copy(ioutil.Discard, os.Stdin)
sigChan <- syscall.SIGTERM
}()
}
// wait for a signal
<-sigChan
// signal received, shut down
for _, ln := range listeners {
ln.Close()
}
}
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