Remove net package and refactor

cmd/spoof-dpi/main.go

@@ -11,9 +11,16 @@ import (
 	"github.com/xvzc/SpoofDPI/util"
 )
 
+var VERSION = "v0.0.0(dev)"
 func main() {
 	util.ParseArgs()
 	config := util.GetConfig()
+	if *config.Version {
+		println("spoog-dpi", VERSION)
+		println("\nA simple and fast anti-censorship tool written in Go.")
+		println("https://github.com/xvzc/SpoofDPI")
+		os.Exit(0)
+	}
 
 	pxy := proxy.New(config)
 	if *config.Debug {

net/dial.go

@@ -1,31 +0,0 @@
-package net
-
-import (
-	"net"
-	"strconv"
-)
-
-func ListenTCP(network string, addr *TCPAddr) (Listener, error) {
-	l, err := net.ListenTCP(network, addr.Addr)
-	if err != nil {
-		return Listener{}, err
-	}
-
-	return Listener{listener: l}, nil
-}
-
-func DialTCP(network string, ip string, port string) (*Conn, error) {
-	p, _ := strconv.Atoi(port)
-
-	addr := &net.TCPAddr{
-		IP:   net.ParseIP(ip),
-		Port: p,
-	}
-
-	conn, err := net.DialTCP(network, nil, addr)
-	if err != nil {
-		return &Conn{}, err
-	}
-
-	return &Conn{*conn}, nil
-}

net/listener.go

@@ -1,18 +0,0 @@
-package net
-
-import (
-	"net"
-)
-
-type Listener struct {
-	listener *net.TCPListener
-}
-
-func (l *Listener) Accept() (*Conn, error) {
-	conn, err := l.listener.AcceptTCP()
-	if err != nil {
-		return &Conn{}, err
-	}
-
-	return &Conn{*conn}, nil
-}

net/tcp.go

@@ -1,20 +0,0 @@
-package net
-
-import (
-	"net"
-)
-
-type TCPAddr struct {
-	Addr *net.TCPAddr
-}
-
-func TcpAddr(ip string, port int) *TCPAddr {
-	addr := &net.TCPAddr{
-		IP:   net.ParseIP(ip),
-		Port: port,
-	}
-
-	return &TCPAddr{
-		Addr: addr,
-	}
-}

proxy/http.go

@@ -1,21 +1,28 @@
 package proxy
 
 import (
+	"net"
+	"strconv"
+
 	log "github.com/sirupsen/logrus"
-	"github.com/xvzc/SpoofDPI/net"
+
 	"github.com/xvzc/SpoofDPI/packet"
 )
 
-func (pxy *Proxy) HandleHttp(lConn *net.Conn, pkt *packet.HttpPacket, ip string) {
+func (pxy *Proxy) HandleHttp(lConn *net.TCPConn, pkt *packet.HttpPacket, ip string) {
 	pkt.Tidy()
 
-	// Create connection to server
+	// Create a connection to the requested server
-	var port = "80"
+	var port int = 80
+	var err error
 	if pkt.Port() != "" {
-		port = pkt.Port()
+		port, err = strconv.Atoi(pkt.Port())
+		if err != nil {
+			log.Debug("[HTTPS] Error while parsing port for ", pkt.Domain(), " aborting..")
+		}
 	}
 
-	rConn, err := net.DialTCP("tcp", ip, port)
+	rConn, err := net.DialTCP("tcp", nil, &net.TCPAddr{IP: net.ParseIP(ip), Port: port})
 	if err != nil {
 		lConn.Close()
 		log.Debug("[HTTP] ", err)
@@ -32,7 +39,7 @@ func (pxy *Proxy) HandleHttp(lConn *net.Conn, pkt *packet.HttpPacket, ip string)
 
 	log.Debug("[HTTP] New connection to the server ", pkt.Domain(), " ", rConn.LocalAddr())
 
-	go rConn.Serve(lConn, "[HTTP]", lConn.RemoteAddr().String(), pkt.Domain(), pxy.timeout)
+	go Serve(rConn, lConn, "[HTTP]", lConn.RemoteAddr().String(), pkt.Domain(), pxy.timeout)
 
 	_, err = rConn.Write(pkt.Raw())
 	if err != nil {
@@ -42,5 +49,5 @@ func (pxy *Proxy) HandleHttp(lConn *net.Conn, pkt *packet.HttpPacket, ip string)
 
 	log.Debug("[HTTP] Sent a request to ", pkt.Domain())
 
-	lConn.Serve(rConn, "[HTTP]", lConn.RemoteAddr().String(), pkt.Domain(), pxy.timeout)
+	Serve(lConn, rConn, "[HTTP]", lConn.RemoteAddr().String(), pkt.Domain(), pxy.timeout)
 }

proxy/https.go

@@ -1,19 +1,25 @@
 package proxy
 
 import (
+	"net"
+	"strconv"
+
 	log "github.com/sirupsen/logrus"
-	"github.com/xvzc/SpoofDPI/net"
 	"github.com/xvzc/SpoofDPI/packet"
 )
 
-func (pxy *Proxy) HandleHttps(lConn *net.Conn, initPkt *packet.HttpPacket, ip string) {
+func (pxy *Proxy) HandleHttps(lConn *net.TCPConn, initPkt *packet.HttpPacket, ip string) {
 	// Create a connection to the requested server
-	var port = "443"
+	var port int = 443
+	var err error
 	if initPkt.Port() != "" {
-		port = initPkt.Port()
+		port, err = strconv.Atoi(initPkt.Port())
+		if err != nil {
+			log.Debug("[HTTPS] Error while parsing port for ", initPkt.Domain(), " aborting..")
+		}
 	}
 
-	rConn, err := net.DialTCP("tcp4", ip, port)
+	rConn, err := net.DialTCP("tcp", nil, &net.TCPAddr{IP: net.ParseIP(ip), Port: port})
 	if err != nil {
 		lConn.Close()
 		log.Debug("[HTTPS] ", err)
@@ -39,7 +45,7 @@ func (pxy *Proxy) HandleHttps(lConn *net.Conn, initPkt *packet.HttpPacket, ip st
 	log.Debug("[HTTPS] Sent 200 Connection Estabalished to ", lConn.RemoteAddr())
 
 	// Read client hello
-	clientHello, err := lConn.ReadBytes()
+	clientHello, err := ReadBytes(lConn)
 	if err != nil {
 		log.Debug("[HTTPS] Error reading client hello from the client", err)
 		return
@@ -51,22 +57,27 @@ func (pxy *Proxy) HandleHttps(lConn *net.Conn, initPkt *packet.HttpPacket, ip st
 
 	chPkt := packet.NewHttpsPacket(clientHello)
 
-	go rConn.Serve(lConn, "[HTTPS]", rConn.RemoteAddr().String(), initPkt.Domain(), pxy.timeout)
+	lConn.SetLinger(3)
+	rConn.SetLinger(3)
+
+	go Serve(rConn, lConn, "[HTTPS]", rConn.RemoteAddr().String(), initPkt.Domain(), pxy.timeout)
 
 	if pxy.patternExists() && !pxy.patternMatches([]byte(initPkt.Domain())) {
+		log.Debug("[HTTPS] Writing plain client hello to ", initPkt.Domain())
 		if _, err := rConn.Write(chPkt.Raw()); err != nil {
-      log.Debug("[HTTPS] Error writing client hello to ", initPkt.Domain(), err)
+			log.Debug("[HTTPS] Error writing plain client hello to ", initPkt.Domain(), err)
 			return
 		}
 	} else {
+		log.Debug("[HTTPS] Writing chunked client hello to ", initPkt.Domain())
 		chunks := pxy.splitInChunks(chPkt.Raw(), pxy.windowSize)
-    if _, err := rConn.WriteChunks(chunks); err != nil {
+		if _, err := WriteChunks(rConn, chunks); err != nil {
-      log.Debug("[HTTPS] Error writing client hello to ", initPkt.Domain(), err)
+			log.Debug("[HTTPS] Error writing chunked client hello to ", initPkt.Domain(), err)
 			return
 		}
 	}
 
-	lConn.Serve(rConn, "[HTTPS]", lConn.RemoteAddr().String(), initPkt.Domain(), pxy.timeout)
+	Serve(lConn, rConn, "[HTTPS]", lConn.RemoteAddr().String(), initPkt.Domain(), pxy.timeout)
 }
 
 func (pxy *Proxy) splitInChunks(bytes []byte, size int) [][]byte {

proxy/io.go

@@ -1,4 +1,4 @@
-package net
+package proxy
 
 import (
 	"errors"
@@ -11,11 +11,7 @@ import (
 
 const BUF_SIZE = 1024
 
-type Conn struct {
+func WriteChunks(conn *net.TCPConn, c [][]byte) (n int, err error) {
-	net.TCPConn
-}
-
-func (conn *Conn) WriteChunks(c [][]byte) (n int, err error) {
 	total := 0
 	for i := 0; i < len(c); i++ {
 		b, err := conn.Write(c[i])
@@ -29,7 +25,7 @@ func (conn *Conn) WriteChunks(c [][]byte) (n int, err error) {
 	return total, nil
 }
 
-func (conn *Conn) ReadBytes() ([]byte, error) {
+func ReadBytes(conn *net.TCPConn) ([]byte, error) {
 	ret := make([]byte, 0)
 	buf := make([]byte, BUF_SIZE)
 
@@ -57,7 +53,7 @@ func (conn *Conn) ReadBytes() ([]byte, error) {
 	return ret, nil
 }
 
-func (from *Conn) Serve(to *Conn, proto string, fd string, td string, timeout int) {
+func Serve(from *net.TCPConn, to *net.TCPConn, proto string, fd string, td string, timeout int) {
 	proto += " "
 
 	for {
@@ -65,7 +61,7 @@ func (from *Conn) Serve(to *Conn, proto string, fd string, td string, timeout in
 			time.Now().Add(time.Millisecond * time.Duration(timeout)),
 		)
 
-		buf, err := from.ReadBytes()
+		buf, err := ReadBytes(from)
 		if err != nil {
 			if err == io.EOF {
 				log.Debug(proto, "Finished ", fd)

proxy/proxy.go

@@ -2,12 +2,13 @@ package proxy
 
 import (
 	"fmt"
+	"net"
 	"os"
 	"regexp"
+	"strconv"
 
 	log "github.com/sirupsen/logrus"
 	"github.com/xvzc/SpoofDPI/dns"
-	"github.com/xvzc/SpoofDPI/net"
 	"github.com/xvzc/SpoofDPI/packet"
 	"github.com/xvzc/SpoofDPI/util"
 )
@@ -34,34 +35,26 @@ func New(config *util.Config) *Proxy {
 	}
 }
 
-func (pxy *Proxy) TcpAddr() *net.TCPAddr {
-	return net.TcpAddr(pxy.addr, pxy.port)
-}
-
-func (pxy *Proxy) Port() int {
-	return pxy.port
-}
-
 func (pxy *Proxy) Start() {
-	l, err := net.ListenTCP("tcp4", pxy.TcpAddr())
+	l, err := net.ListenTCP("tcp4", &net.TCPAddr{IP: net.ParseIP(pxy.addr), Port: pxy.port})
 	if err != nil {
-		log.Fatal("Error creating listener: ", err)
+		log.Fatal("[PROXY] Error creating listener: ", err)
 		os.Exit(1)
 	}
 
-	log.Println(fmt.Sprintf("Connection timeout is set to %dms", pxy.timeout))
+	log.Println(fmt.Sprintf("[PROXY] Connection timeout is set to %dms", pxy.timeout))
 
-	log.Println("Created a listener on port", pxy.Port())
+	log.Println("[PROXY] Created a listener on port", pxy.port)
 
 	for {
 		conn, err := l.Accept()
 		if err != nil {
-			log.Fatal("Error accepting connection: ", err)
+			log.Fatal("[PROXY] Error accepting connection: ", err)
 			continue
 		}
 
 		go func() {
-			b, err := conn.ReadBytes()
+			b, err := ReadBytes(conn.(*net.TCPConn))
 			if err != nil {
 				return
 			}
@@ -70,32 +63,68 @@ func (pxy *Proxy) Start() {
 
 			pkt, err := packet.NewHttpPacket(b)
 			if err != nil {
-				log.Debug("Error while parsing request: ", string(b))
+				log.Debug("[PROXY] Error while parsing request: ", string(b))
 				conn.Close()
 				return
 			}
 
 			if !pkt.IsValidMethod() {
-				log.Debug("Unsupported method: ", pkt.Method())
+				log.Debug("[PROXY] Unsupported method: ", pkt.Method())
 				conn.Close()
 				return
 			}
 
 			ip, err := pxy.resolver.Lookup(pkt.Domain())
 			if err != nil {
-				log.Error("[HTTP] Error looking up for domain with ", pkt.Domain(), " ", err)
+				log.Error("[PROXY] Error looking up for domain with ", pkt.Domain(), " ", err)
 				conn.Write([]byte(pkt.Version() + " 502 Bad Gateway\r\n\r\n"))
 				conn.Close()
 				return
 			}
 
+			// Avoid recursively querying self
+			if pkt.Port() == strconv.Itoa(pxy.port) && isLoopedRequest(net.ParseIP(ip)) {
+				log.Error("[HTTP] Invalid request: final target has the same IP and port as our proxy")
+				conn.Close()
+				return
+			}
+
 			if pkt.IsConnectMethod() {
-				log.Debug("[HTTPS] Start")
+				log.Debug("[PROXY] Start HTTPS")
-				pxy.HandleHttps(conn, pkt, ip)
+				pxy.HandleHttps(conn.(*net.TCPConn), pkt, ip)
 			} else {
-				log.Debug("[HTTP] Start")
+				log.Debug("[PROXY] Start HTTP")
-				pxy.HandleHttp(conn, pkt, ip)
+				pxy.HandleHttp(conn.(*net.TCPConn), pkt, ip)
 			}
 		}()
 	}
 }
+
+func isLoopedRequest(ip net.IP) bool {
+	// we don't handle IPv6 at all it seems
+	if ip.To4() == nil {
+		return false
+	}
+
+	if ip.IsLoopback() {
+		return true
+	}
+
+	// Get list of available addresses
+	// See `ip -4 addr show`
+	addr, err := net.InterfaceAddrs() // needs AF_NETLINK on linux
+	if err != nil {
+		log.Error("[PROXY] Error while getting addresses of our network interfaces: ", err)
+		return false
+	}
+
+	for _, addr := range addr {
+		if ipnet, ok := addr.(*net.IPNet); ok {
+			if ipnet.IP.To4() != nil && ipnet.IP.To4().Equal(ip) {
+				return true
+			}
+		}
+	}
+
+	return false
+}

util/config.go

@@ -23,6 +23,7 @@ type Config struct {
 	AllowedPattern *regexp.Regexp
 	AllowedUrls    *regexp.Regexp
 	WindowSize     *int
+	Version        *bool
 }
 
 type ArrayFlags []string
@@ -55,6 +56,7 @@ func ParseArgs() {
 	config.NoBanner = flag.Bool("no-banner", false, "Disable banner")
 	config.Timeout = flag.Int("timeout", 2000, "timeout in milliseconds")
 	config.WindowSize = flag.Int("window-size", 50, "window-size for fragmented client hello")
+	config.Version = flag.Bool("v", false, "print version")
 
 	flag.Var(&allowedHosts, "url", "Bypass DPI only on this url, can be passed multiple times")
 	allowedPattern = flag.String(