From ef38b844f9989dff25f553b583aeafc411dd100e Mon Sep 17 00:00:00 2001
From: Yawning Angel <yawning@schwanenlied.me>
Date: Fri, 9 May 2014 10:23:58 +0000
Subject: Initial import.

---
 obfs4-client/obfs4-client.go | 183 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 183 insertions(+)
 create mode 100644 obfs4-client/obfs4-client.go

(limited to 'obfs4-client')

diff --git a/obfs4-client/obfs4-client.go b/obfs4-client/obfs4-client.go
new file mode 100644
index 0000000..077fb85
--- /dev/null
+++ b/obfs4-client/obfs4-client.go
@@ -0,0 +1,183 @@
+/*
+ * Copyright (c) 2014, Yawning Angel <yawning at torproject dot org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * This file is based off goptlib's dummy-client.go file.
+ */
+
+// obfs4 pluggable transport client. Works only as a managed proxy.
+//
+// Usage (in torrc):
+// 	UseBridges 1
+// 	Bridge obfs4 X.X.X.X:YYYY public-key=<Base64 Bridge public key> node-id=<Base64 Node ID>
+// 	ClientTransportPlugin obfs4 exec obfs4-client
+//
+// Becuase the pluggable transport requires arguments, using obfs4-client 
+// requires tor 0.2.5.x.
+package main
+
+import (
+	"io"
+	"net"
+	"os"
+	"os/signal"
+	"sync"
+	"syscall"
+
+	"github.com/yawning/obfs4"
+)
+
+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)
+
+	// TODO: Log errors.
+	go func() {
+		io.Copy(b, a)
+		wg.Done()
+	}()
+	go func() {
+		io.Copy(a, b)
+		wg.Done()
+	}()
+
+	wg.Wait()
+}
+
+func handler(conn *pt.SocksConn) error {
+	// Extract the peer's node ID and public key.
+	nodeID, ok := conn.Req.Args.Get("node-id")
+	if !ok {
+		// TODO: Log something here.
+		conn.Reject()
+	}
+	publicKey, ok := conn.Req.Args.Get("public-key")
+	if !ok {
+		// TODO: Log something here.
+		conn.Reject()
+	}
+
+	handlerChan <- 1
+	defer func() {
+		handlerChan <- -1
+	}()
+
+	defer conn.Close()
+	remote, err := obfs4.Dial("tcp", conn.Req.Target, nodeID, publicKey)
+	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{"obfs4"})
+	if err != nil {
+		os.Exit(1)
+	}
+
+	listeners := make([]net.Listener, 0)
+	for _, methodName := range ptInfo.MethodNames {
+		switch methodName {
+		case "obfs4":
+			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:
+		}
+	}
+}
-- 
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