Added STUN-aware UDP proxy mode

1 files changed, 396 insertions, 0 deletions

diff --git a/modes/stun_udp/stun_udp.go b/modes/stun_udp/stun_udp.go
new file mode 100644
index 0000000..52872c3
--- /dev/null
+++ b/modes/stun_udp/stun_udp.go
@@ -0,0 +1,396 @@
+/*
+ * Copyright (c) 2014-2015, 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.
+ */
+
+// Go language Tor Pluggable Transport suite.  Works only as a managed
+// client/server.
+package stun_udp
+
+import (
+	"io"
+	"fmt"
+	golog "log"
+	"net"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"golang.org/x/net/proxy"
+
+	"github.com/willscott/goturn"
+
+	"git.torproject.org/pluggable-transports/goptlib.git"
+	"github.com/OperatorFoundation/obfs4/common/log"
+	"github.com/OperatorFoundation/obfs4/common/termmon"
+	"github.com/OperatorFoundation/obfs4/transports"
+	"github.com/OperatorFoundation/obfs4/transports/base"
+)
+
+const (
+	obfs4proxyVersion = "0.0.7-dev"
+	obfs4proxyLogFile = "obfs4proxy.log"
+	socksAddr         = "127.0.0.1:1234"
+)
+
+var stateDir string
+
+type ConnState struct {
+	Conn *net.Conn
+	Waiting bool
+}
+
+func NewConnState() ConnState {
+	return ConnState{nil, true}
+}
+
+type ConnTracker map[string]ConnState
+
+func ClientSetup(termMon *termmon.TermMonitor, target string) bool {
+	methodNames := [...]string{"obfs2"}
+	var ptClientProxy *url.URL = nil
+
+	// Launch each of the client listeners.
+	for _, name := range methodNames {
+		t := transports.Get(name)
+		if t == nil {
+			log.Errorf("no such transport is supported: %s", name)
+			continue
+		}
+
+		f, err := t.ClientFactory(stateDir)
+		if err != nil {
+			log.Errorf("failed to get ClientFactory: %s", name)
+			continue
+		}
+
+		udpAddr, err := net.ResolveUDPAddr("udp", socksAddr)
+		if err != nil {
+			fmt.Println("Error resolving address", socksAddr)
+		}
+
+		fmt.Println("@@@ Listening ", name, socksAddr)
+		ln, err := net.ListenUDP("udp", udpAddr)
+		if err != nil {
+			log.Errorf("failed to listen %s %s", name, err.Error())
+			continue
+		}
+
+		go clientHandler(target, termMon, f, ln, ptClientProxy)
+
+		log.Infof("%s - registered listener: %s", name, ln)
+	}
+
+	return true
+}
+
+func clientHandler(target string, termMon *termmon.TermMonitor, f base.ClientFactory, conn *net.UDPConn, proxyURI *url.URL) {
+	defer conn.Close()
+	termMon.OnHandlerStart()
+	defer termMon.OnHandlerFinish()
+
+	fmt.Println("@@@ handling...")
+
+  tracker := make(ConnTracker)
+
+	name := f.Transport().Name()
+
+	fmt.Println("Transport is", name)
+
+  buf := make([]byte, 1024)
+
+  // Receive UDP packets and forward them over transport connections forever
+	for {
+		n, addr, err := conn.ReadFromUDP(buf)
+		fmt.Println("Received ",string(buf[0:n]), " from ",addr)
+
+		if err != nil {
+      fmt.Println("Error: ",err)
+		}
+
+    fmt.Println(tracker)
+
+		if state, ok := tracker[addr.String()]; ok {
+			// There is an open transport connection, or a connection attempt is in progress.
+
+			if state.Waiting {
+				// The connection attempt is in progress.
+				// Drop the packet.
+				fmt.Println("recv: waiting")
+			} else {
+				// There is an open transport connection.
+				// Send the packet through the transport.
+				fmt.Println("recv: write")
+				fmt.Println("writing...")
+				(*state.Conn).Write(buf)
+			}
+    } else {
+			// There is not an open transport connection and a connection attempt is not in progress.
+			// Open a transport connection.
+
+      fmt.Println("Opening connection to ", target)
+
+			openConnection(&tracker, addr.String(), target, termMon, f, proxyURI)
+
+			// Drop the packet.
+			fmt.Println("recv: Open")
+		}
+	}
+}
+
+func openConnection(tracker *ConnTracker, addr string, target string, termMon *termmon.TermMonitor, f base.ClientFactory, proxyURI *url.URL) {
+	fmt.Println("Making dialer...")
+
+	newConn := NewConnState()
+	(*tracker)[addr]=newConn
+
+	go dialConn(tracker, addr, target, f, proxyURI)
+}
+
+func dialConn(tracker *ConnTracker, addr string, target string, f base.ClientFactory, proxyURI *url.URL) {
+	// Obtain the proxy dialer if any, and create the outgoing TCP connection.
+	dialFn := proxy.Direct.Dial
+	if proxyURI != nil {
+		dialer, err := proxy.FromURL(proxyURI, proxy.Direct)
+		if err != nil {
+			// This should basically never happen, since config protocol
+			// verifies this.
+			fmt.Println("failed to obtain dialer", proxyURI, proxy.Direct)
+			log.Errorf("(%s) - failed to obtain proxy dialer: %s", target, log.ElideError(err))
+			return
+		}
+		dialFn = dialer.Dial
+	}
+
+	fmt.Println("Dialing....")
+
+	// Deal with arguments.
+	args, err := f.ParseArgs(&pt.Args{})
+	if err != nil {
+		fmt.Println("Invalid arguments")
+		log.Errorf("(%s) - invalid arguments: %s", target, err)
+		delete(*tracker, addr)
+		return
+	}
+
+	fmt.Println("Dialing ", target)
+	remote, err := f.Dial("tcp", target, dialFn, args)
+	if err != nil {
+		fmt.Println("outgoing connection failed", err)
+		log.Errorf("(%s) - outgoing connection failed: %s", target, log.ElideError(err))
+		fmt.Println("Failed")
+		delete(*tracker, addr)
+		return
+	}
+
+	fmt.Println("Success")
+
+	(*tracker)[addr]=ConnState{&remote, false}
+}
+
+func ServerSetup(termMon *termmon.TermMonitor, bindaddrString string, target string) bool {
+	fmt.Println("ServerSetup")
+
+	bindaddrs, _ := getServerBindaddrs(bindaddrString)
+
+	for _, bindaddr := range bindaddrs {
+		name := bindaddr.MethodName
+		fmt.Println("bindaddr", bindaddr)
+		t := transports.Get(name)
+		if t == nil {
+			fmt.Println(name, "no such transport is supported")
+			continue
+		}
+
+		f, err := t.ServerFactory(stateDir, &bindaddr.Options)
+		if err != nil {
+			fmt.Println(name, err.Error())
+			continue
+		}
+
+		ln, err := net.ListenTCP("tcp", bindaddr.Addr)
+		if err != nil {
+			fmt.Println(name, err.Error())
+			continue
+		}
+
+		go serverAcceptLoop(termMon, f, ln, target)
+
+		log.Infof("%s - registered listener: %s", name, log.ElideAddr(ln.Addr().String()))
+	}
+
+	return true
+}
+
+func getServerBindaddrs(serverBindaddr string) ([]pt.Bindaddr, error) {
+	var result []pt.Bindaddr
+
+	for _, spec := range strings.Split(serverBindaddr, ",") {
+		var bindaddr pt.Bindaddr
+
+		parts := strings.SplitN(spec, "-", 2)
+		if len(parts) != 2 {
+			fmt.Println("TOR_PT_SERVER_BINDADDR: doesn't contain \"-\"", spec)
+			return nil, nil
+		}
+		bindaddr.MethodName = parts[0]
+		addr, err := resolveAddr(parts[1])
+		if err != nil {
+			fmt.Println("TOR_PT_SERVER_BINDADDR: ", spec, err.Error())
+			return nil, nil
+		}
+		bindaddr.Addr = addr
+		//		bindaddr.Options = optionsMap[bindaddr.MethodName]
+		result = append(result, bindaddr)
+	}
+
+	return result, nil
+}
+
+// Resolve an address string into a net.TCPAddr. We are a bit more strict than
+// net.ResolveTCPAddr; we don't allow an empty host or port, and the host part
+// must be a literal IP address.
+func resolveAddr(addrStr string) (*net.TCPAddr, error) {
+	ipStr, portStr, err := net.SplitHostPort(addrStr)
+	if err != nil {
+		// Before the fixing of bug #7011, tor doesn't put brackets around IPv6
+		// addresses. Split after the last colon, assuming it is a port
+		// separator, and try adding the brackets.
+		parts := strings.Split(addrStr, ":")
+		if len(parts) <= 2 {
+			return nil, err
+		}
+		addrStr := "[" + strings.Join(parts[:len(parts)-1], ":") + "]:" + parts[len(parts)-1]
+		ipStr, portStr, err = net.SplitHostPort(addrStr)
+	}
+	if err != nil {
+		return nil, err
+	}
+	if ipStr == "" {
+		return nil, net.InvalidAddrError(fmt.Sprintf("address string %q lacks a host part", addrStr))
+	}
+	if portStr == "" {
+		return nil, net.InvalidAddrError(fmt.Sprintf("address string %q lacks a port part", addrStr))
+	}
+	ip := net.ParseIP(ipStr)
+	if ip == nil {
+		return nil, net.InvalidAddrError(fmt.Sprintf("not an IP string: %q", ipStr))
+	}
+	port, err := parsePort(portStr)
+	if err != nil {
+		return nil, err
+	}
+	return &net.TCPAddr{IP: ip, Port: port}, nil
+}
+
+func parsePort(portStr string) (int, error) {
+	port, err := strconv.ParseUint(portStr, 10, 16)
+	return int(port), err
+}
+
+func serverAcceptLoop(termMon *termmon.TermMonitor, f base.ServerFactory, ln net.Listener, target string) error {
+	defer ln.Close()
+	for {
+		conn, err := ln.Accept()
+		fmt.Println("accepted")
+		if err != nil {
+			if e, ok := err.(net.Error); ok && !e.Temporary() {
+				return err
+			}
+			continue
+		}
+		go serverHandler(termMon, f, conn, target)
+	}
+}
+
+func serverHandler(termMon *termmon.TermMonitor, f base.ServerFactory, conn net.Conn, target string) {
+	var header *turn.StunHeader
+
+	defer conn.Close()
+	termMon.OnHandlerStart()
+	defer termMon.OnHandlerFinish()
+
+	name := f.Transport().Name()
+	addrStr := log.ElideAddr(conn.RemoteAddr().String())
+	fmt.Println("### handling", name)
+	log.Infof("%s(%s) - new connection", name, addrStr)
+
+	// Instantiate the server transport method and handshake.
+	remote, err := f.WrapConn(conn)
+	if err != nil {
+		fmt.Println("handshake failed", err)
+		log.Warnf("%s(%s) - handshake failed: %s", name, addrStr, log.ElideError(err))
+		return
+	}
+
+	serverAddr, err := net.ResolveUDPAddr("udp",target)
+	if err != nil {
+		golog.Fatal(err)
+	}
+
+	localAddr, err := net.ResolveUDPAddr("udp", "127.0.0.1:0")
+	if err != nil {
+		golog.Fatal(err)
+	}
+
+	dest, err := net.DialUDP("udp", localAddr, serverAddr)
+	if err != nil {
+		golog.Fatal(err)
+	}
+
+  fmt.Println("pumping")
+
+	defer dest.Close()
+
+	headerBuffer := make([]byte, 20)
+
+	for {
+		fmt.Println("reading...")
+		// Read the incoming connection into the buffer.
+	  _, err := io.ReadFull(remote, headerBuffer)
+		if err != nil {
+			fmt.Println("read error")
+			break
+		}
+
+		header=&turn.StunHeader{}
+		header.Decode(headerBuffer)
+
+		fmt.Println(header.Length)
+
+		fmt.Println("reading data")
+
+		readBuffer := make([]byte, header.Length)
+		_, err = io.ReadFull(remote, readBuffer)
+		if err != nil {
+			fmt.Println("read error")
+			break
+		}
+
+    writeBuffer := append(headerBuffer, readBuffer...)
+
+		dest.Write(writeBuffer)
+  }
+}