Added experimental support (-K) for kcp-go reliable-UDP instead of TCP

github.com/xtaci/kcp-go

** Note: hkexcp appears to hang (client-side) on completion w/complete file copy
   (Note server-side logs on final missed ctrlStatOp msg)

Signed-off-by: Russ Magee <rmagee@gmail.com>

hkexnet/hkexnet.go

@@ -25,6 +25,7 @@ package hkexnet
 import (
 	"bytes"
 	"crypto/cipher"
+	"crypto/sha1"
 	"encoding/binary"
 	"encoding/hex"
 	"errors"
@@ -40,6 +41,9 @@ import (
 	"sync"
 	"time"
 
+	kcp "github.com/xtaci/kcp-go"
+	"golang.org/x/crypto/pbkdf2"
+
 	hkex "blitter.com/go/herradurakex"
 	"blitter.com/go/hkexsh/logger"
 	kyber "git.schwanenlied.me/yawning/kyber.git"
@@ -693,12 +697,21 @@ func Dial(protocol string, ipport string, extensions ...string) (hc Conn, err er
 		Init(false, "client", logger.LOG_DAEMON|logger.LOG_DEBUG)
 	}
 
-	// Open raw Conn c
-	c, err := net.Dial(protocol, ipport)
-	if err != nil {
-		return Conn{}, err
+	var c net.Conn
+	if protocol == "kcp" {
+		kcpKey := pbkdf2.Key([]byte("demo pass"), []byte("demo salt"), 1024, 32, sha1.New)
+		block, _ := kcp.NewNoneBlockCrypt(kcpKey)
+		c, err = kcp.DialWithOptions(ipport, block, 10, 3)
+		if err != nil {
+			return Conn{}, err
+		}
+	} else {
+		// Open raw Conn c
+		c, err = net.Dial(protocol, ipport)
+		if err != nil {
+			return Conn{}, err
+		}
 	}
-
 	// Init hkexnet.Conn hc over net.Conn c
 	ret, err := _new(getkexalgnum(extensions...), &c)
 	if err != nil {
@@ -819,23 +832,35 @@ func (hc *Conn) SetReadDeadline(t time.Time) error {
 //
 // See go doc net.Listener
 type HKExListener struct {
-	l net.Listener
+	l     net.Listener
+	proto string
 }
 
 // Listen for a connection
 //
 // See go doc net.Listen
-func Listen(protocol string, ipport string) (hl HKExListener, e error) {
+func Listen(proto string, ipport string) (hl HKExListener, e error) {
 	if Log == nil {
 		Init(false, "server", logger.LOG_DAEMON|logger.LOG_DEBUG)
 	}
 
-	l, err := net.Listen(protocol, ipport)
-	if err != nil {
-		return HKExListener{nil}, err
+	kcpKey := pbkdf2.Key([]byte("demo pass"), []byte("demo salt"), 1024, 32, sha1.New)
+	//var block kcp.BlockCrypt
+	var lErr error
+	var l net.Listener
+	
+	if proto == "kcp" {
+		block, _ := kcp.NewNoneBlockCrypt(kcpKey)
+		l, lErr = kcp.ListenWithOptions(ipport, block, 10, 3)
+	} else {
+		l, lErr = net.Listen(proto, ipport)
 	}
-	logger.LogDebug(fmt.Sprintf("[Listening on %s]\n", ipport))
+	if lErr != nil {
+		return HKExListener{nil, proto}, lErr
+	}
+	logger.LogDebug(fmt.Sprintf("[Listening (proto '%s') on %s]\n", proto, ipport))
 	hl.l = l
+	hl.proto = proto
 	return
 }
 
@@ -859,13 +884,23 @@ func (hl HKExListener) Addr() net.Addr {
 //
 // See go doc net.Listener.Accept
 func (hl *HKExListener) Accept() (hc Conn, err error) {
-	// Open raw Conn c
-	c, err := hl.l.Accept()
-	if err != nil {
-		return Conn{}, err
-	}
-	logger.LogDebug(fmt.Sprintln("[net.Listener Accepted]"))
+	var c net.Conn
+	if hl.proto == "kcp" {
+		c, err = hl.l.(*kcp.Listener).AcceptKCP()
+		if err != nil {
+			return Conn{}, err
+		}
 
+		logger.LogDebug(fmt.Sprintln("[kcp.Listener Accepted]"))
+	} else {
+		// Open raw Conn c
+		c, err = hl.l.Accept()
+		if err != nil {
+			return Conn{}, err
+		}
+
+		logger.LogDebug(fmt.Sprintln("[net.Listener Accepted]"))
+	}
 	// Read KEx alg proposed by client
 	var kexAlg KEXAlg
 	//! NB. Was using fmt.FScanln() here, but integers with a leading zero

hkexsh/hkexsh.go

@@ -46,6 +46,9 @@ var (
 
 	// wg controls when the goroutines handling client I/O complete
 	wg sync.WaitGroup
+
+	kopt bool // set to use kcp (encrypted reliable UDP) instead of TCP
+
 	// Log defaults to regular syslog output (no -d)
 	Log *logger.Writer
 
@@ -624,6 +627,7 @@ func main() {
 	flag.StringVar(&cipherAlg, "c", "C_AES_256", "`cipher` [\"C_AES_256\" | \"C_TWOFISH_128\" | \"C_BLOWFISH_64\" | \"C_CRYPTMT1\"]")
 	flag.StringVar(&hmacAlg, "m", "H_SHA256", "`hmac` [\"H_SHA256\" | \"H_SHA512\"]")
 	flag.StringVar(&kexAlg, "k", "KEX_HERRADURA512", "`kex` [\"KEX_HERRADURA{256/512/1024/2048}\" | \"KEX_KYBER{512/768/1024}\" | \"KEX_NEWHOPE\" | \"KEX_NEWHOPE_SIMPLE\"]")
+	flag.BoolVar(&kopt, "K", false, "set true to use KCP (github.com/xtaci/kcp-go) reliable UDP instead of TCP")
 	flag.UintVar(&port, "p", 2000, "`port`")
 	//flag.StringVar(&authCookie, "a", "", "auth cookie")
 	flag.BoolVar(&chaffEnabled, "e", true, "enable chaff pkts")
@@ -818,7 +822,11 @@ func main() {
 		}
 	}
 
-	conn, err := hkexnet.Dial("tcp", server, cipherAlg, hmacAlg, kexAlg)
+	proto := "tcp"
+	if kopt {
+		proto = "kcp"
+	}
+	conn, err := hkexnet.Dial(proto, server, cipherAlg, hmacAlg, kexAlg)
 	if err != nil {
 		fmt.Println(err)
 		exitWithStatus(3)

hkexshd/hkexshd.go

@@ -39,6 +39,7 @@ var (
 	gitCommit   string // set in -ldflags by build
 	
 	useSysLogin bool
+	kopt bool // set to use kcp (encrypted reliable UDP) instead of TCP
 	
 	// Log - syslog output (with no -d)
 	Log *logger.Writer
@@ -443,6 +444,7 @@ func main() {
 
 	flag.BoolVar(&vopt, "v", false, "show version")
 	flag.StringVar(&laddr, "l", ":2000", "interface[:port] to listen")
+	flag.BoolVar(&kopt, "K", false, "set true to use KCP (github.com/xtaci/kcp-go) reliable UDP instead of TCP")
 	flag.BoolVar(&useSysLogin, "L", false, "use system login")
 	flag.BoolVar(&chaffEnabled, "e", true, "enable chaff pkts")
 	flag.UintVar(&chaffFreqMin, "f", 100, "chaff pkt freq min (msecs)")
@@ -505,9 +507,11 @@ func main() {
 		}
 	}()
 
-	// Listen on TCP port 2000 on all available unicast and
-	// anycast IP addresses of the local system.
-	l, err := hkexnet.Listen("tcp", laddr)
+	proto := "tcp"
+	if kopt {
+		proto = "kcp"
+	}
+	l, err := hkexnet.Listen(proto, laddr)
 	if err != nil {
 		log.Fatal(err)
 	}