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xs/xsnet/net.go

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// xsnet.go - net.Conn compatible channel setup with encrypted/HMAC
// negotiation
// Copyright (c) 2017-2020 Russell Magee
// Licensed under the terms of the MIT license (see LICENSE.mit in this
// distribution)
//
// golang implementation by Russ Magee (rmagee_at_gmail.com)
package xsnet
// Implementation of HKEx-wrapped versions of the golang standard
// net package interfaces, allowing clients and servers to simply replace
// 'net.Dial' and 'net.Listen' with 'hkex.Dial' and 'hkex.Listen'
// (though some extra methods are implemented and must be used
// for things outside of the scope of plain sockets).
// DESIGN PRINCIPLE: There shall be no protocol features which enable
// downgrade attacks. The server shall have final authority to accept or
// reject any and all proposed KEx and connection parameters proposed by
// clients at setup. Action on denial shall be a simple server disconnect
// with possibly a status code sent so client can determine why connection
// was denied (compare to how failed auth is communicated to client).
import (
"bytes"
"crypto/cipher"
"encoding/binary"
"encoding/hex"
"errors"
"fmt"
"hash"
"io"
"io/ioutil"
"log"
"math/big"
"math/rand"
"net"
"strings"
"sync"
"time"
crand "crypto/rand"
hkex "blitter.com/go/herradurakex"
"blitter.com/go/kyber"
"blitter.com/go/newhope"
"blitter.com/go/xs/logger"
frodo "github.com/kuking/go-frodokem"
)
/*---------------------------------------------------------------------*/
const PAD_SZ = 32 // max size of padding applied to each packet
const HMAC_CHK_SZ = 8 // leading bytes of HMAC to xmit for verification
type (
WinSize struct {
Rows uint16
Cols uint16
}
// chaffconfig captures attributes used to send chaff packets betwixt
// client and server connections, to obscure true traffic timing and
// patterns
// see: https://en.wikipedia.org/wiki/chaff_(countermeasure)
ChaffConfig struct {
shutdown bool //set to inform chaffHelper to shut down
enabled bool
msecsMin uint //msecs min interval
msecsMax uint //msecs max interval
szMax uint // max size in bytes
}
// Conn is a connection wrapping net.Conn with KEX & session state
Conn struct {
kex KEXAlg // KEX/KEM proposal (client -> server)
m *sync.Mutex // (internal)
c *net.Conn // which also implements io.Reader, io.Writer, ...
logCipherText bool // somewhat expensive, for debugging
logPlainText bool // INSECURE and somewhat expensive, for debugging
logTunActivity bool
cipheropts uint32 // post-KEx cipher/hmac options
opts uint32 // post-KEx protocol options (caller-defined)
WinCh chan WinSize
Rows uint16
Cols uint16
chaff ChaffConfig
tuns *map[uint16](*TunEndpoint)
closeStat *CSOType // close status (CSOExitStatus)
r cipher.Stream //read cipherStream
rm hash.Hash
w cipher.Stream //write cipherStream
wm hash.Hash
dBuf *bytes.Buffer //decrypt buffer for Read()
}
)
var (
Log *logger.Writer // reg. syslog output (no -d)
)
// Return string (suitable as map key) for a tunnel endpoint
func (t *TunEndpoint) String() string {
return fmt.Sprintf("[%d:%s:%d]", t.Lport, t.Peer, t.Rport)
}
func (k *KEXAlg) String() string {
switch *k {
case KEX_HERRADURA256:
return "KEX_HERRADURA256"
case KEX_HERRADURA512:
return "KEX_HERRADURA512"
case KEX_HERRADURA1024:
return "KEX_HERRADURA1024"
case KEX_HERRADURA2048:
return "KEX_HERRADURA2048"
case KEX_KYBER512:
return "KEX_KYBER512"
case KEX_KYBER768:
return "KEX_KYBER768"
case KEX_KYBER1024:
return "KEX_KYBER1024"
case KEX_NEWHOPE:
return "KEX_NEWHOPE"
case KEX_NEWHOPE_SIMPLE:
return "KEX_NEWHOPE_SIMPLE"
case KEX_FRODOKEM_1344AES:
return "KEX_FRODOKEM_1344AES"
case KEX_FRODOKEM_1344SHAKE:
return "KEX_FRODOKEM_1344SHAKE"
case KEX_FRODOKEM_976AES:
return "KEX_FRODOKEM_976AES"
case KEX_FRODOKEM_976SHAKE:
return "KEX_FRODOKEM_976SHAKE"
default:
return "KEX_ERR_UNK"
}
}
func (hc *Conn) CAlg() CSCipherAlg {
return CSCipherAlg(hc.cipheropts & 0x0FF)
}
func (c *CSCipherAlg) String() string {
switch *c & 0x0FF {
case CAlgAES256:
return "C_AES_256"
case CAlgTwofish128:
return "C_TWOFISH_128"
case CAlgBlowfish64:
return "C_BLOWFISH_64"
case CAlgCryptMT1:
return "C_CRYPTMT1"
case CAlgHopscotch:
return "C_HOPSCOTCH"
case CAlgChaCha20_12:
return "C_CHACHA20_12"
default:
return "C_ERR_UNK"
}
}
func (hc *Conn) HAlg() CSHmacAlg {
return CSHmacAlg((hc.cipheropts >> 8) & 0x0FF)
}
func (h *CSHmacAlg) String() string {
switch (*h >> 8) & 0x0FF {
case HmacSHA256:
return "H_SHA256"
case HmacSHA512:
return "C_SHA512"
default:
return "H_ERR_UNK"
}
}
func _initLogging(d bool, c string, f logger.Priority) {
if Log == nil {
Log, _ = logger.New(f, fmt.Sprintf("%s:xsnet", c))
}
if d {
log.SetFlags(0) // syslog will have date,time
log.SetOutput(Log)
} else {
log.SetOutput(ioutil.Discard)
}
}
func Init(d bool, c string, f logger.Priority) {
_initLogging(d, c, f)
}
func (hc *Conn) Lock() {
hc.m.Lock()
}
func (hc *Conn) Unlock() {
hc.m.Unlock()
}
func (hc *Conn) KEX() KEXAlg {
return hc.kex
}
func (hc *Conn) GetStatus() CSOType {
return *hc.closeStat
}
func (hc *Conn) SetStatus(stat CSOType) {
*hc.closeStat = stat
log.Println("closeStat:", *hc.closeStat)
}
// ConnOpts returns the cipher/hmac options value, which is sent to the
// peer but is not itself part of the KEx.
//
// (Used for protocol-level negotiations after KEx such as
// cipher/HMAC algorithm options etc.)
func (hc *Conn) ConnOpts() uint32 {
return hc.cipheropts
}
// SetConnOpts sets the cipher/hmac options value, which is sent to the
// peer as part of KEx but not part of the KEx itself.
//
// opts - bitfields for cipher and hmac alg. to use after KEx
func (hc *Conn) SetConnOpts(copts uint32) {
hc.cipheropts = copts
}
// Opts returns the protocol options value, which is sent to the peer
// but is not itself part of the KEx or connection (cipher/hmac) setup.
//
// Consumers of this lib may use this for protocol-level options not part
// of the KEx or encryption info used by the connection.
func (hc Conn) Opts() uint32 {
return hc.opts
}
// SetOpts sets the protocol options value, which is sent to the peer
// but is not itself part of the KEx or connection (cipher/hmac) setup.
//
// Consumers of this lib may use this for protocol-level options not part
// of the KEx of encryption info used by the connection.
//
// opts - a uint32, caller-defined
func (hc *Conn) SetOpts(opts uint32) {
hc.opts = opts
}
// Return a new xsnet.Conn
//
// Note this is internal: use Dial() or Accept()
func _new(kexAlg KEXAlg, conn *net.Conn) (hc *Conn, e error) {
// Set up stuff common to all KEx/KEM types
hc = &Conn{kex: kexAlg,
m: &sync.Mutex{},
c: conn,
closeStat: new(CSOType),
WinCh: make(chan WinSize, 1),
dBuf: new(bytes.Buffer)}
tempMap := make(map[uint16]*TunEndpoint)
hc.tuns = &tempMap
*hc.closeStat = CSEStillOpen // open or prematurely-closed status
// Set up KEx/KEM-specifics
switch kexAlg {
case KEX_HERRADURA256:
fallthrough
case KEX_HERRADURA512:
fallthrough
case KEX_HERRADURA1024:
fallthrough
case KEX_HERRADURA2048:
fallthrough
case KEX_KYBER512:
fallthrough
case KEX_KYBER768:
fallthrough
case KEX_KYBER1024:
fallthrough
case KEX_NEWHOPE:
fallthrough
case KEX_NEWHOPE_SIMPLE:
fallthrough
case KEX_FRODOKEM_1344AES:
fallthrough
case KEX_FRODOKEM_1344SHAKE:
fallthrough
case KEX_FRODOKEM_976AES:
fallthrough
case KEX_FRODOKEM_976SHAKE:
log.Printf("[KEx alg %d accepted]\n", kexAlg)
default:
// UNREACHABLE: _getkexalgnum() guarantees a valid KEX value
hc.kex = KEX_HERRADURA512
log.Printf("[KEx alg %d ?? defaults to %d]\n", kexAlg, hc.kex)
}
//hc.logCipherText = true // !!! DEBUGGING ONLY !!! NEVER DEPLOY this uncommented !!!
return
}
// applyConnExtensions processes optional Dial() negotiation
// parameters. See also getkexalgnum().
//
// Currently defined extension values
//
// KEx algs
//
// KEX_HERRADURA256 KEX_HERRADURA512 KEX_HERRADURA1024 KEX_HERRADURA2048
//
// KEX_KYBER512 KEX_KYBER768 KEX_KYBER1024
//
// KEX_NEWHOPE KEX_NEWHOPE_SIMPLE
//
// Session (symmetric) crypto
//
// C_AES_256 C_TWOFISH_128 C_BLOWFISH_128 C_CRYPTMT1 C_CHACHA20_12 C_HOPSCOTCH
//
// Session HMACs
//
// H_SHA256 H_SHA512
func (hc *Conn) applyConnExtensions(extensions ...string) {
for _, s := range extensions {
switch s {
case "C_AES_256":
log.Println("[extension arg = C_AES_256]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgAES256
case "C_TWOFISH_128":
log.Println("[extension arg = C_TWOFISH_128]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgTwofish128
case "C_BLOWFISH_64":
log.Println("[extension arg = C_BLOWFISH_64]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgBlowfish64
case "C_CRYPTMT1":
log.Println("[extension arg = C_CRYPTMT1]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgCryptMT1
case "C_HOPSCOTCH":
log.Println("[extension arg = C_HOPSCOTCH]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgHopscotch
case "C_CHACHA20_12":
log.Println("[extension arg = C_CHACHA20_12]")
hc.cipheropts &= (0xFFFFFF00)
hc.cipheropts |= CAlgChaCha20_12
case "H_SHA256":
log.Println("[extension arg = H_SHA256]")
hc.cipheropts &= (0xFFFF00FF)
hc.cipheropts |= (HmacSHA256 << 8)
case "H_SHA512":
log.Println("[extension arg = H_SHA512]")
hc.cipheropts &= (0xFFFF00FF)
hc.cipheropts |= (HmacSHA512 << 8)
//default:
// log.Printf("[Dial ext \"%s\" ignored]\n", s)
}
}
}
func getkexalgnum(extensions ...string) (k KEXAlg) {
k = KEX_HERRADURA512 // default
for _, s := range extensions {
switch s {
case "KEX_HERRADURA256":
k = KEX_HERRADURA256
break //out of for
case "KEX_HERRADURA512":
k = KEX_HERRADURA512
break //out of for
case "KEX_HERRADURA1024":
k = KEX_HERRADURA1024
break //out of for
case "KEX_HERRADURA2048":
k = KEX_HERRADURA2048
break //out of for
case "KEX_KYBER512":
k = KEX_KYBER512
break //out of for
case "KEX_KYBER768":
k = KEX_KYBER768
break //out of for
case "KEX_KYBER1024":
k = KEX_KYBER1024
break //out of for
case "KEX_NEWHOPE":
k = KEX_NEWHOPE
break //out of for
case "KEX_NEWHOPE_SIMPLE":
k = KEX_NEWHOPE_SIMPLE
break //out of for
case "KEX_FRODOKEM_1344AES":
k = KEX_FRODOKEM_1344AES
break //out of for
case "KEX_FRODOKEM_1344SHAKE":
k = KEX_FRODOKEM_1344SHAKE
break //out of for
case "KEX_FRODOKEM_976AES":
k = KEX_FRODOKEM_976AES
break //out of for
case "KEX_FRODOKEM_976SHAKE":
k = KEX_FRODOKEM_976SHAKE
break //out of for
}
}
return
}
func FrodoKEMDialSetup(c io.ReadWriter, hc *Conn) (err error) {
// Send xsnet.Conn parameters to remote side
// Alice, step 1: Generate a key pair.
var kem frodo.FrodoKEM
switch hc.kex {
case KEX_FRODOKEM_1344AES:
kem = frodo.Frodo1344AES()
case KEX_FRODOKEM_1344SHAKE:
kem = frodo.Frodo1344SHAKE()
case KEX_FRODOKEM_976AES:
kem = frodo.Frodo976AES()
default:
kem = frodo.Frodo976SHAKE()
}
pubA, secA := kem.Keygen() // pA
// Alice, step 2: Send the public key (na,ea) to Bob
n, err := fmt.Fprintf(c, "0x%x\n", pubA)
if err != nil {
panic(err)
}
if n < len(pubA) {
panic(errors.New("incomplete Fprintf() of pubA"))
}
// (... and send cipher, connection opts)
fmt.Fprintf(c, "0x%x:0x%x\n", hc.cipheropts, hc.opts)
// [Bob does the same and sends use a public key (nb, eb)
pubB_bigint := big.NewInt(0)
_, err = fmt.Fscanf(c, "0x%x\n", pubB_bigint)
pubB := pubB_bigint.Bytes()
// (... and sends us cipher, connection opts)
_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
// Alice, step 3: Create ctAtoB, shareA
ctAtoB, shareA, err := kem.Encapsulate(pubB)
if err != nil {
return err
}
// Alice, step 4: Send ctAtoB to Bob
fmt.Fprintf(c, "0x%x\n", ctAtoB)
// Alice, step 5: Receive ctBtoA from Bob
ctBtoA_bigint := big.NewInt(0)
_, err = fmt.Fscanf(c, "0x%x\n", ctBtoA_bigint)
ctBtoA := ctBtoA_bigint.Bytes()
// Alice, step 6: compute Bob's share
shareB, err := kem.Dencapsulate(secA, ctBtoA)
sessionKey := append(shareA, shareB...)
hc.r, hc.rm, err = hc.getStream(sessionKey)
hc.w, hc.wm, err = hc.getStream(sessionKey)
return
}
func NewHopeDialSetup(c io.ReadWriter, hc *Conn) (err error) {
// Send xsnet.Conn parameters to remote side
// Alice, step 1: Generate a key pair.
privKeyAlice, pubKeyAlice, err := newhope.GenerateKeyPairAlice(crand.Reader)
if err != nil {
panic(err)
}
// Alice, step 2: Send the public key to Bob
fmt.Fprintf(c, "0x%x\n0x%x:0x%x\n", pubKeyAlice.Send,
hc.cipheropts, hc.opts)
// [Bob does step 1-3], from which we read Bob's pubkey
publicKeyBob := big.NewInt(0)
fmt.Fscanf(c, "0x%x\n", publicKeyBob)
var pubKeyBob newhope.PublicKeyBob
for i := range pubKeyBob.Send {
pubKeyBob.Send[i] = publicKeyBob.Bytes()[i]
}
//log.Printf("[Got server pubKey[]:%v]\n", pubKeyBob)
// Read cipheropts, session opts
_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
// Alice, step 3: Derive shared secret
// (NOTE: actual over-wire exchange was already done above. This is
// the math voodoo 'exchange' done after receiving data from Bob.)
aliceSharedSecret, err := newhope.KeyExchangeAlice(&pubKeyBob, privKeyAlice)
if err != nil {
panic(err)
}
hc.r, hc.rm, err = hc.getStream(aliceSharedSecret)
hc.w, hc.wm, err = hc.getStream(aliceSharedSecret)
return
}
func NewHopeSimpleDialSetup(c io.ReadWriter, hc *Conn) (err error) {
// Send xsnet.Conn parameters to remote side
// Alice, step 1: Generate a key pair.
privKeyAlice, pubKeyAlice, err := newhope.GenerateKeyPairSimpleAlice(crand.Reader)
if err != nil {
panic(err)
}
// Alice, step 2: Send the public key to Bob
fmt.Fprintf(c, "0x%x\n0x%x:0x%x\n", pubKeyAlice.Send,
hc.cipheropts, hc.opts)
// [Bob does step 1-3], from which we read Bob's pubkey
publicKeyBob := big.NewInt(0)
fmt.Fscanf(c, "0x%x\n", publicKeyBob)
var pubKeyBob newhope.PublicKeySimpleBob
for i := range pubKeyBob.Send {
pubKeyBob.Send[i] = publicKeyBob.Bytes()[i]
}
//log.Printf("[Got server pubKey[]:%v]\n", pubKeyBob)
// Read cipheropts, session opts
_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
// Alice, step 3: Derive shared secret
// (NOTE: actual over-wire exchange was already done above. This is
// the math voodoo 'exchange' done after receiving data from Bob.)
aliceSharedSecret, err := newhope.KeyExchangeSimpleAlice(&pubKeyBob, privKeyAlice)
if err != nil {
panic(err)
}
hc.r, hc.rm, err = hc.getStream(aliceSharedSecret)
hc.w, hc.wm, err = hc.getStream(aliceSharedSecret)
return
}
func KyberDialSetup(c io.ReadWriter /*net.Conn*/, hc *Conn) (err error) {
// Send xsnet.Conn parameters to remote side
// Alice, step 1: Generate a key pair.
var alicePublicKey *kyber.PublicKey
var alicePrivateKey *kyber.PrivateKey
switch hc.kex {
case KEX_KYBER512:
alicePublicKey, alicePrivateKey, err = kyber.Kyber512.GenerateKeyPair(crand.Reader)
case KEX_KYBER768:
alicePublicKey, alicePrivateKey, err = kyber.Kyber768.GenerateKeyPair(crand.Reader)
case KEX_KYBER1024:
alicePublicKey, alicePrivateKey, err = kyber.Kyber1024.GenerateKeyPair(crand.Reader)
default:
alicePublicKey, alicePrivateKey, err = kyber.Kyber768.GenerateKeyPair(crand.Reader)
}
if err != nil {
panic(err)
}
// Alice, step 2: Send the public key to Bob
fmt.Fprintf(c, "0x%x\n0x%x:0x%x\n", alicePublicKey.Bytes(),
hc.cipheropts, hc.opts)
// [Bob, step 1-3], from which we read cipher text
pubKeyB := make([]byte, 4096)
fmt.Fscanf(c, "0x%x\n", &pubKeyB)
//if err != nil {
// return err
//}
//log.Printf("[Got server pubKeyB[]:%v]\n", pubKeyB)
// Read cipheropts, session opts
_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
// Alice, step 3: Decrypt the KEM cipher text.
aliceSharedSecret := alicePrivateKey.KEMDecrypt(pubKeyB)
hc.r, hc.rm, err = hc.getStream(aliceSharedSecret)
hc.w, hc.wm, err = hc.getStream(aliceSharedSecret)
return
}
func HKExDialSetup(c io.ReadWriter /*net.Conn*/, hc *Conn) (err error) {
var h *hkex.HerraduraKEx
switch hc.kex {
case KEX_HERRADURA256:
h = hkex.New(256, 64)
case KEX_HERRADURA512:
h = hkex.New(512, 128)
case KEX_HERRADURA1024:
h = hkex.New(1024, 256)
case KEX_HERRADURA2048:
h = hkex.New(2048, 512)
default:
h = hkex.New(256, 64)
}
// Send xsnet.Conn parameters to remote side
// d is value for Herradura key exchange
fmt.Fprintf(c, "0x%s\n0x%x:0x%x\n", h.D().Text(16),
hc.cipheropts, hc.opts)
// Read peer D over net.Conn (c)
d := big.NewInt(0)
_, err = fmt.Fscanln(c, d)
if err != nil {
return err
}
_, err = fmt.Fscanf(c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
h.SetPeerD(d)
log.Printf("** local D:%s\n", h.D().Text(16))
log.Printf("**(c)** peer D:%s\n", h.PeerD().Text(16))
h.ComputeFA()
log.Printf("**(c)** FA:%s\n", h.FA())
hc.r, hc.rm, err = hc.getStream(h.FA().Bytes())
hc.w, hc.wm, err = hc.getStream(h.FA().Bytes())
return
}
func FrodoKEMAcceptSetup(c *net.Conn, hc *Conn) (err error) {
// Bob, step 1: Generate a key pair.
var kem frodo.FrodoKEM
switch hc.kex {
case KEX_FRODOKEM_1344AES:
kem = frodo.Frodo1344AES()
case KEX_FRODOKEM_1344SHAKE:
kem = frodo.Frodo1344SHAKE()
case KEX_FRODOKEM_976AES:
kem = frodo.Frodo976AES()
default:
kem = frodo.Frodo976SHAKE()
}
pubB, secB := kem.Keygen()
// [Alice sends use a public key (na, ea)
pubA_bigint := big.NewInt(0)
_, err = fmt.Fscanf(*c, "0x%x\n", pubA_bigint)
pubA := pubA_bigint.Bytes()
// (... and sends us cipher, connection opts)
_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
if err != nil {
return err
}
// Bob, step 2: Send the public key (nb,eb) to Alice
n, err := fmt.Fprintf(*c, "0x%x\n", pubB)
if err != nil {
panic(err)
}
if n < len(pubB) {
panic(errors.New("incomplete Fprintf() of pubB"))
}
// (... and send cipher, connection opts)
fmt.Fprintf(*c, "0x%x:0x%x\n", hc.cipheropts, hc.opts)
// Bob, step 3: Create ctBtoA, shareB
ctBtoA, shareB, err := kem.Encapsulate(pubA)
if err != nil {
return err
}
// Bob, step 4: Send ctBtoA to Alice
fmt.Fprintf(*c, "0x%x\n", ctBtoA)
// Bob, step 5: Receive ctAtoB from Alice
ctAtoB_bigint := big.NewInt(0)
_, err = fmt.Fscanf(*c, "0x%x\n", ctAtoB_bigint)
ctAtoB := ctAtoB_bigint.Bytes()
// Alice, step 6: compute Bob's share
shareA, err := kem.Dencapsulate(secB, ctAtoB)
sessionKey := append(shareA, shareB...)
hc.r, hc.rm, err = hc.getStream(sessionKey)
hc.w, hc.wm, err = hc.getStream(sessionKey)
return
}
func NewHopeAcceptSetup(c *net.Conn, hc *Conn) (err error) {
// Bob, step 1: Deserialize Alice's public key from the binary encoding.
alicePublicKey := big.NewInt(0)
_, err = fmt.Fscanln(*c, alicePublicKey)
//log.Printf("[Got client pubKey:0x%x\n]", alicePublicKey)
if err != nil {
return err
}
var pubKeyAlice newhope.PublicKeyAlice
for i := range pubKeyAlice.Send {
pubKeyAlice.Send[i] = alicePublicKey.Bytes()[i]
}
_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
if err != nil {
return err
}
// Bob, step 2: Generate the KEM cipher text and shared secret.
pubKeyBob, bobSharedSecret, err := newhope.KeyExchangeBob(crand.Reader, &pubKeyAlice)
if err != nil {
panic(err)
}
// Bob, step 3: Send the cipher text to Alice.
fmt.Fprintf(*c, "0x%x\n0x%x:0x%x\n", pubKeyBob.Send,
hc.cipheropts, hc.opts)
hc.r, hc.rm, err = hc.getStream(bobSharedSecret)
hc.w, hc.wm, err = hc.getStream(bobSharedSecret)
return
}
func NewHopeSimpleAcceptSetup(c *net.Conn, hc *Conn) (err error) {
// Bob, step 1: Deserialize Alice's public key from the binary encoding.
alicePublicKey := big.NewInt(0)
_, err = fmt.Fscanln(*c, alicePublicKey)
//log.Printf("[Got client pubKey:0x%x\n]", alicePublicKey)
if err != nil {
return err
}
var pubKeyAlice newhope.PublicKeySimpleAlice
for i := range pubKeyAlice.Send {
pubKeyAlice.Send[i] = alicePublicKey.Bytes()[i]
}
_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
if err != nil {
return err
}
// Bob, step 2: Generate the KEM cipher text and shared secret.
pubKeyBob, bobSharedSecret, err := newhope.KeyExchangeSimpleBob(crand.Reader, &pubKeyAlice)
if err != nil {
panic(err)
}
// Bob, step 3: Send the cipher text to Alice.
fmt.Fprintf(*c, "0x%x\n0x%x:0x%x\n", pubKeyBob.Send,
hc.cipheropts, hc.opts)
hc.r, hc.rm, err = hc.getStream(bobSharedSecret)
hc.w, hc.wm, err = hc.getStream(bobSharedSecret)
return
}
func KyberAcceptSetup(c *net.Conn, hc *Conn) (err error) {
// Bob, step 1: Deserialize Alice's public key from the binary encoding.
alicePublicKey := big.NewInt(0)
_, err = fmt.Fscanln(*c, alicePublicKey)
//log.Printf("[Got client pubKey:0x%x\n]", alicePublicKey)
if err != nil {
return err
}
_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
if err != nil {
return err
}
var peerPublicKey *kyber.PublicKey
switch hc.kex {
case KEX_KYBER512:
peerPublicKey, err = kyber.Kyber512.PublicKeyFromBytes(alicePublicKey.Bytes())
case KEX_KYBER768:
peerPublicKey, err = kyber.Kyber768.PublicKeyFromBytes(alicePublicKey.Bytes())
case KEX_KYBER1024:
peerPublicKey, err = kyber.Kyber1024.PublicKeyFromBytes(alicePublicKey.Bytes())
default:
peerPublicKey, err = kyber.Kyber768.PublicKeyFromBytes(alicePublicKey.Bytes())
}
if err != nil {
panic(err)
}
// Bob, step 2: Generate the KEM cipher text and shared secret.
cipherText, bobSharedSecret, err := peerPublicKey.KEMEncrypt(crand.Reader)
if err != nil {
panic(err)
}
// Bob, step 3: Send the cipher text to Alice.
fmt.Fprintf(*c, "0x%x\n0x%x:0x%x\n", cipherText,
hc.cipheropts, hc.opts)
hc.r, hc.rm, err = hc.getStream(bobSharedSecret)
hc.w, hc.wm, err = hc.getStream(bobSharedSecret)
return
}
func HKExAcceptSetup(c *net.Conn, hc *Conn) (err error) {
var h *hkex.HerraduraKEx
switch hc.kex {
case KEX_HERRADURA256:
h = hkex.New(256, 64)
case KEX_HERRADURA512:
h = hkex.New(512, 128)
case KEX_HERRADURA1024:
h = hkex.New(1024, 256)
case KEX_HERRADURA2048:
h = hkex.New(2048, 512)
default:
h = hkex.New(256, 64)
}
// Read in xsnet.Conn parameters over raw Conn c
// d is value for Herradura key exchange
d := big.NewInt(0)
_, err = fmt.Fscanln(*c, d)
log.Printf("[Got d:%v]", d)
if err != nil {
return err
}
_, err = fmt.Fscanf(*c, "0x%x:0x%x\n",
&hc.cipheropts, &hc.opts)
log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
if err != nil {
return err
}
h.SetPeerD(d)
log.Printf("** D:%s\n", h.D().Text(16))
log.Printf("**(s)** peerD:%s\n", h.PeerD().Text(16))
h.ComputeFA()
log.Printf("**(s)** FA:%s\n", h.FA())
// Send D and cipheropts/conn_opts to peer
fmt.Fprintf(*c, "0x%s\n0x%x:0x%x\n", h.D().Text(16),
hc.cipheropts, hc.opts)
hc.r, hc.rm, err = hc.getStream(h.FA().Bytes())
hc.w, hc.wm, err = hc.getStream(h.FA().Bytes())
return
}
// Dial as net.Dial(), but with implicit key exchange to set up secure
// channel on connect
//
// Can be called like net.Dial(), defaulting to C_AES_256/H_SHA256,
// or additional extensions can be passed amongst the following:
//
// "C_AES_256" | "C_TWOFISH_128" | ...
//
// "H_SHA256" | "H_SHA512" | ...
//
// See go doc -u xsnet.applyConnExtensions
func Dial(protocol string, ipport string, extensions ...string) (hc Conn, err error) {
if Log == nil {
Init(false, "client", logger.LOG_DAEMON|logger.LOG_DEBUG)
}
var c net.Conn
if protocol == "kcp" {
c, err = kcpDial(ipport, extensions)
if err != nil {
return Conn{}, err
}
} else {
// Open raw Conn c
c, err = net.Dial(protocol, ipport)
if err != nil {
return Conn{}, err
}
}
// Init xsnet.Conn hc over net.Conn c
ret, err := _new(getkexalgnum(extensions...), &c)
if err != nil {
return Conn{}, err
}
hc = *ret
// Client has full control over Conn extensions. It's the server's
// responsibility to accept or reject the proposed parameters.
hc.applyConnExtensions(extensions...)
// Perform Key Exchange according to client-request algorithm
fmt.Fprintf(c, "%02x\n", hc.kex)
switch hc.kex {
case KEX_HERRADURA256:
fallthrough
case KEX_HERRADURA512:
fallthrough
case KEX_HERRADURA1024:
fallthrough
case KEX_HERRADURA2048:
log.Printf("[Setting up for KEX_HERRADURA %d]\n", hc.kex)
if HKExDialSetup(c, &hc) != nil {
return Conn{}, nil
}
case KEX_KYBER512:
fallthrough
case KEX_KYBER768:
fallthrough
case KEX_KYBER1024:
log.Printf("[Setting up for KEX_KYBER %d]\n", hc.kex)
if KyberDialSetup(c, &hc) != nil {
return Conn{}, nil
}
case KEX_NEWHOPE:
log.Printf("[Setting up for KEX_NEWHOPE %d]\n", hc.kex)
if NewHopeDialSetup(c, &hc) != nil {
return Conn{}, nil
}
case KEX_NEWHOPE_SIMPLE:
log.Printf("[Setting up for KEX_NEWHOPE_SIMPLE %d]\n", hc.kex)
if NewHopeSimpleDialSetup(c, &hc) != nil {
return Conn{}, nil
}
case KEX_FRODOKEM_1344AES:
fallthrough
case KEX_FRODOKEM_1344SHAKE:
fallthrough
case KEX_FRODOKEM_976AES:
fallthrough
case KEX_FRODOKEM_976SHAKE:
log.Printf("[Setting up for KEX_FRODOKEM %d]\n", hc.kex)
if FrodoKEMDialSetup(c, &hc) != nil {
return Conn{}, nil
}
default:
return Conn{}, err
}
return
}
// Close a hkex.Conn
func (hc *Conn) Close() (err error) {
hc.DisableChaff()
s := make([]byte, 4)
binary.BigEndian.PutUint32(s, uint32(*hc.closeStat))
log.Printf("** Writing closeStat %d at Close()\n", *hc.closeStat)
//(*hc.c).SetWriteDeadline(time.Now().Add(500 * time.Millisecond))
hc.WritePacket(s, CSOExitStatus)
err = (*hc.c).Close()
logger.LogDebug(fmt.Sprintln("[Conn Closing]"))
return
}
// LocalAddr returns the local network address.
func (hc *Conn) LocalAddr() net.Addr {
return (*hc.c).LocalAddr()
}
// RemoteAddr returns the remote network address.
func (hc *Conn) RemoteAddr() net.Addr {
return (*hc.c).RemoteAddr()
}
// SetDeadline sets the read and write deadlines associated
// with the connection. It is equivalent to calling both
// SetReadDeadline and SetWriteDeadline.
//
// A deadline is an absolute time after which I/O operations
// fail with a timeout (see type Error) instead of
// blocking. The deadline applies to all future and pending
// I/O, not just the immediately following call to Read or
// Write. After a deadline has been exceeded, the connection
// can be refreshed by setting a deadline in the future.
//
// An idle timeout can be implemented by repeatedly extending
// the deadline after successful Read or Write calls.
//
// A zero value for t means I/O operations will not time out.
func (hc *Conn) SetDeadline(t time.Time) error {
return (*hc.c).SetDeadline(t)
}
// SetWriteDeadline sets the deadline for future Write calls
// and any currently-blocked Write call.
// Even if write times out, it may return n > 0, indicating that
// some of the data was successfully written.
// A zero value for t means Write will not time out.
func (hc *Conn) SetWriteDeadline(t time.Time) error {
return (*hc.c).SetWriteDeadline(t)
}
// SetReadDeadline sets the deadline for future Read calls
// and any currently-blocked Read call.
// A zero value for t means Read will not time out.
func (hc *Conn) SetReadDeadline(t time.Time) error {
return (*hc.c).SetReadDeadline(t)
}
/*---------------------------------------------------------------------*/
// HKExListener is a Listener conforming to net.Listener
//
// See go doc net.Listener
type HKExListener struct {
l net.Listener
proto string
}
// Listen for a connection
//
// See go doc net.Listen
func Listen(proto string, ipport string, extensions ...string) (hl HKExListener, e error) {
if Log == nil {
Init(false, "server", logger.LOG_DAEMON|logger.LOG_DEBUG)
}
var lErr error
var l net.Listener
if proto == "kcp" {
l, lErr = kcpListen(ipport, extensions)
} else {
l, lErr = net.Listen(proto, 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
}
// Close a hkex Listener - closes the Listener.
// Any blocked Accept operations will be unblocked and return errors.
//
// See go doc net.Listener.Close
func (hl HKExListener) Close() error {
logger.LogDebug(fmt.Sprintln("[Listener Closed]"))
return hl.l.Close()
}
// Addr returns a the listener's network address.
//
// See go doc net.Listener.Addr
func (hl HKExListener) Addr() net.Addr {
return hl.l.Addr()
}
// Accept a client connection, conforming to net.Listener.Accept()
//
// See go doc net.Listener.Accept
func (hl *HKExListener) Accept() (hc Conn, err error) {
var c net.Conn
if hl.proto == "kcp" {
c, err = hl.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
// were being mis-scanned? (is it an octal thing? Investigate.)
_, err = fmt.Fscanf(c, "%02x\n", &kexAlg)
if err != nil {
return Conn{}, err
}
log.Printf("[Client proposed KEx alg: %v]\n", kexAlg)
// --
ret, err := _new(kexAlg, &c)
if err != nil {
return Conn{}, err
}
hc = *ret
switch hc.kex {
case KEX_HERRADURA256:
fallthrough
case KEX_HERRADURA512:
fallthrough
case KEX_HERRADURA1024:
fallthrough
case KEX_HERRADURA2048:
log.Printf("[Setting up for KEX_HERRADURA %d]\n", hc.kex)
if HKExAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_KYBER512:
fallthrough
case KEX_KYBER768:
fallthrough
case KEX_KYBER1024:
log.Printf("[Setting up for KEX_KYBER %d]\n", hc.kex)
if KyberAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_NEWHOPE:
log.Printf("[Setting up for KEX_NEWHOPE %d]\n", hc.kex)
if NewHopeAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_NEWHOPE_SIMPLE:
log.Printf("[Setting up for KEX_NEWHOPE_SIMPLE %d]\n", hc.kex)
if NewHopeSimpleAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_FRODOKEM_1344AES:
log.Printf("[Setting up for KEX_FRODOKEM_1344AES %d]\n", hc.kex)
if FrodoKEMAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_FRODOKEM_1344SHAKE:
log.Printf("[Setting up for KEX_FRODOKEM_1344SHAKE %d]\n", hc.kex)
if FrodoKEMAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_FRODOKEM_976AES:
log.Printf("[Setting up for KEX_FRODOKEM_976AES %d]\n", hc.kex)
if FrodoKEMAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
case KEX_FRODOKEM_976SHAKE:
log.Printf("[Setting up for KEX_FRODOKEM_976SHAKE %d]\n", hc.kex)
if FrodoKEMAcceptSetup(&c, &hc) != nil {
return Conn{}, err
}
default:
return Conn{}, err
}
// Finally, ensure alg proposed by client is allowed by server config
//if hc.kex.String() {
log.Println("[hc.Accept successful]")
return
}
/*---------------------------------------------------------------------*/
// Read into a byte slice
//
// In addition to regular io.Reader behaviour this does demultiplexing of
// secured terminal comms and (if defined) tunnel traffic and session control
// packet processing.
//
// See go doc io.Reader
func (hc Conn) Read(b []byte) (n int, err error) {
for {
if hc.dBuf.Len() > 0 {
break
}
var ctrlStatOp uint8
var hmacIn [HMAC_CHK_SZ]uint8
var payloadLen uint32
// Read ctrl/status opcode (CSOHmacInvalid on hmac mismatch)
err = binary.Read(*hc.c, binary.BigEndian, &ctrlStatOp)
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogDebug(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "ctrlStatOp", err)
logger.LogDebug(etxt)
return 0, errors.New(etxt)
}
log.Printf("[ctrlStatOp: %v]\n", ctrlStatOp)
if ctrlStatOp == CSOHmacInvalid {
// Other side indicated channel tampering, close channel
hc.Close()
return 0, errors.New("** ALERT - remote end detected HMAC mismatch - possible channel tampering **")
}
// Read the hmac and payload len first
err = binary.Read(*hc.c, binary.BigEndian, &hmacIn)
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogDebug(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "HMAC", err)
logger.LogDebug(etxt)
return 0, errors.New(etxt)
}
err = binary.Read(*hc.c, binary.BigEndian, &payloadLen)
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogDebug(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "payloadLen", err)
logger.LogDebug(etxt)
return 0, errors.New(etxt)
}
if payloadLen > MAX_PAYLOAD_LEN {
logger.LogDebug(fmt.Sprintf("[Insane payloadLen:%v]\n", payloadLen))
hc.Close()
return 1, errors.New("Insane payloadLen")
}
var payloadBytes = make([]byte, payloadLen)
n, err = io.ReadFull(*hc.c, payloadBytes)
if err != nil {
if err.Error() == "EOF" {
return 0, io.EOF
}
if strings.HasSuffix(err.Error(), "use of closed network connection") {
logger.LogDebug(fmt.Sprintln("[Client hung up]"))
return 0, io.EOF
}
etxt := fmt.Sprintf("** Failed read:%s (%s) **", "payloadBytes", err)
logger.LogDebug(etxt)
return 0, errors.New(etxt)
}
if hc.logCipherText {
log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
}
//fmt.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
hc.rm.Write(payloadBytes) // Calc hmac on received data
hTmp := hc.rm.Sum(nil)[0:HMAC_CHK_SZ]
//log.Printf("<%04x) HMAC:(i)%s (c)%02x\r\n", decryptN, hex.EncodeToString([]byte(hmacIn[0:])), hTmp)
// Log alert if hmac didn't match, corrupted channel
if !bytes.Equal(hTmp, []byte(hmacIn[0:])) /*|| hmacIn[0] > 0xf8*/ {
logger.LogDebug(fmt.Sprintln("** ALERT - detected HMAC mismatch, possible channel tampering **"))
_, _ = (*hc.c).Write([]byte{CSOHmacInvalid})
}
db := bytes.NewBuffer(payloadBytes[:n]) //copying payloadBytes to db
// The StreamReader acts like a pipe, decrypting
// whatever is available and forwarding the result
// to the parameter of Read() as a normal io.Reader
rs := &cipher.StreamReader{S: hc.r, R: db}
// The caller isn't necessarily reading the full payload so we need
// to decrypt to an intermediate buffer, draining it on demand of caller
decryptN, err := rs.Read(payloadBytes)
if hc.logPlainText {
log.Printf(" <:ptext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
}
if err != nil {
log.Println("xsnet.Read():", err)
//panic(err)
} else {
// Padding: Read padSide, padLen, (padding | d) or (d | padding)
padSide := payloadBytes[0]
padLen := payloadBytes[1]
payloadBytes = payloadBytes[2:]
if padSide == 0 {
payloadBytes = payloadBytes[padLen:]
} else {
payloadBytes = payloadBytes[0 : len(payloadBytes)-int(padLen)]
}
// Throw away pkt if it's chaff (ie., caller to Read() won't see this data)
if ctrlStatOp == CSOChaff {
log.Printf("[Chaff pkt, discarded (len %d)]\n", decryptN)
} else if ctrlStatOp == CSOTermSize {
fmt.Sscanf(string(payloadBytes), "%d %d", &hc.Rows, &hc.Cols)
log.Printf("[TermSize pkt: rows %v cols %v]\n", hc.Rows, hc.Cols)
hc.WinCh <- WinSize{hc.Rows, hc.Cols}
} else if ctrlStatOp == CSOExitStatus {
if len(payloadBytes) > 0 {
hc.SetStatus(CSOType(binary.BigEndian.Uint32(payloadBytes)))
} else {
logger.LogDebug(fmt.Sprintln("[truncated payload, cannot determine CSOExitStatus]"))
hc.SetStatus(CSETruncCSO)
}
hc.Close()
} else if ctrlStatOp == CSOTunSetup {
// server side tunnel setup in response to client
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
if _, ok := (*hc.tuns)[rport]; !ok {
// tunnel first-time open
logger.LogDebug(fmt.Sprintf("[Server] Got Initial CSOTunSetup [%d:%d]", lport, rport))
hc.StartServerTunnel(lport, rport)
} else {
logger.LogDebug(fmt.Sprintf("[Server] Got CSOTunSetup [%d:%d]", lport, rport))
}
(*hc.tuns)[rport].Ctl <- 'd' // Dial() rport
} else if ctrlStatOp == CSOTunSetupAck {
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
if _, ok := (*hc.tuns)[rport]; !ok {
// tunnel first-time open
logger.LogDebug(fmt.Sprintf("[Client] Got Initial CSOTunSetupAck [%d:%d]", lport, rport))
hc.StartClientTunnel(lport, rport)
} else {
logger.LogDebug(fmt.Sprintf("[Client] Got CSOTunSetupAck [%d:%d]", lport, rport))
}
(*hc.tuns)[rport].Ctl <- 'a' // Listen() for lport connection
} else if ctrlStatOp == CSOTunRefused {
// client side receiving CSOTunRefused means the remote side
// could not dial() rport. So we cannot yet listen()
// for client-side on lport.
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
logger.LogDebug(fmt.Sprintf("[Client] Got CSOTunRefused [%d:%d]", lport, rport))
if _, ok := (*hc.tuns)[rport]; ok {
hc.MarkTunDead(rport)
} else {
logger.LogDebug(fmt.Sprintf("[Client] CSOTunRefused on already-closed tun [%d:%d]", lport, rport))
}
} else if ctrlStatOp == CSOTunDisconn {
// server side's rport has disconnected (server lost)
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
logger.LogDebug(fmt.Sprintf("[Client] Got CSOTunDisconn [%d:%d]", lport, rport))
if _, ok := (*hc.tuns)[rport]; ok {
hc.MarkTunDead(rport)
} else {
logger.LogDebug(fmt.Sprintf("[Client] CSOTunDisconn on already-closed tun [%d:%d]", lport, rport))
}
} else if ctrlStatOp == CSOTunHangup {
// client side's lport has hung up
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
logger.LogDebug(fmt.Sprintf("[Server] Got CSOTunHangup [%d:%d]", lport, rport))
if _, ok := (*hc.tuns)[rport]; ok {
hc.MarkTunDead(rport)
} else {
logger.LogDebug(fmt.Sprintf("[Server] CSOTunHangup to already-closed tun [%d:%d]", lport, rport))
}
} else if ctrlStatOp == CSOTunData {
lport := binary.BigEndian.Uint16(payloadBytes[0:2])
rport := binary.BigEndian.Uint16(payloadBytes[2:4])
//fmt.Printf("[Got CSOTunData: [lport %d:rport %d] data:%v\n", lport, rport, payloadBytes[4:])
if _, ok := (*hc.tuns)[rport]; ok {
if hc.logTunActivity {
logger.LogDebug(fmt.Sprintf("[Writing data to rport [%d:%d]", lport, rport))
}
(*hc.tuns)[rport].Data <- payloadBytes[4:]
hc.ResetTunnelAge(rport)
} else {
logger.LogDebug(fmt.Sprintf("[Attempt to write data to closed tun [%d:%d]", lport, rport))
}
} else if ctrlStatOp == CSOTunKeepAlive {
// client side has sent keepalive for tunnels -- if client
// dies or exits unexpectedly the absence of this will
// let the server know to hang up on Dial()ed server rports.
_ = binary.BigEndian.Uint16(payloadBytes[0:2])
//logger.LogDebug(fmt.Sprintf("[Server] Got CSOTunKeepAlive"))
for _, t := range *hc.tuns {
hc.Lock()
t.KeepAlive = 0
hc.Unlock()
}
} else if ctrlStatOp == CSONone {
hc.dBuf.Write(payloadBytes)
} else {
logger.LogDebug(fmt.Sprintf("[Unknown CSOType:%d]", ctrlStatOp))
}
}
}
retN := hc.dBuf.Len()
if retN > len(b) {
retN = len(b)
}
log.Printf("Read() got %d bytes\n", retN)
copy(b, hc.dBuf.Next(retN))
return retN, nil
}
// Write a byte slice
//
// See go doc io.Writer
func (hc Conn) Write(b []byte) (n int, err error) {
n, err = hc.WritePacket(b, CSONone)
return n, err
}
// Write a byte slice with specified ctrlStatOp byte
func (hc *Conn) WritePacket(b []byte, ctrlStatOp byte) (n int, err error) {
//log.Printf("[Encrypting...]\r\n")
var hmacOut []uint8
var payloadLen uint32
if hc.m == nil || hc.wm == nil {
return 0, errors.New("Secure chan not ready for writing")
}
//Padding prior to encryption
padSz := rand.Intn(PAD_SZ-1) + 1 /*(rand.Intn(PAD_SZ) / 2) + (PAD_SZ / 2)*/
padLen := padSz - ((len(b) + padSz) % padSz)
if padLen == padSz {
// No padding required
padLen = 0
}
padBytes := make([]byte, padLen)
rand.Read(padBytes)
// For a little more confusion let's support padding either before
// or after the payload.
padSide := rand.Intn(2)
if padSide == 0 {
b = append([]byte{byte(padSide)}, append([]byte{byte(padLen)}, append(padBytes, b...)...)...)
} else {
b = append([]byte{byte(padSide)}, append([]byte{byte(padLen)}, append(b, padBytes...)...)...)
}
// N.B. Originally this Lock() surrounded only the
// calls to binary.Write(hc.c ..) however there appears
// to be some other unshareable state in the Conn
// struct that must be protected to serialize main and
// chaff data written to it.
//
// Would be nice to determine if the mutex scope
// could be tightened.
hc.Lock()
payloadLen = uint32(len(b))
if hc.logPlainText {
log.Printf(" >:ptext:\r\n%s\r\n", hex.Dump(b[0:payloadLen]))
}
// NOTE releases prior to v0.9 used Authenticate-then-Encrypt,
// which in block modes is insecure; however
// 1) we use exclusively XOR-stream modes with random padding,
// 2) are padding randomly either before or after the real payload, and
// 3) the padding side indicator value itself is part of the ciphertext
// ... thus are not subject to oracle attacks of the type used on SSL
// (described in (Krawczyk 2001/2014,
// https://link.springer.com/content/pdf/10.1007%2F3-540-44647-8_19.pdf)
//
// Nevertheless, to address any future concerns v0.9 onwards switches to
// Encrypt-then-Auth and breaks interop with earlier versions.
// -rlm 2020-12-15
var wb bytes.Buffer
// The StreamWriter acts like a pipe, forwarding whatever is
// written to it through the cipher, encrypting as it goes
ws := &cipher.StreamWriter{S: hc.w, W: &wb}
wN, err := ws.Write(b[0:payloadLen])
if err != nil {
panic(err)
}
if wN < int(payloadLen) {
panic("truncated Write to cipher *****")
}
if hc.logCipherText {
log.Printf(" >:ctext:\r\n%s\r\n", hex.Dump(wb.Bytes()))
}
//fmt.Printf(" >:ctext:\r\n%s\r\n", hex.Dump(wb.Bytes()))
// Calculate hmac on cipher payload
hc.wm.Write(wb.Bytes())
hmacOut = hc.wm.Sum(nil)[0:HMAC_CHK_SZ] //finalize
//log.Printf(" (%08x> HMAC(o):%s\r\n", payloadLen, hex.EncodeToString(hmacOut))
err = binary.Write(*hc.c, binary.BigEndian, &ctrlStatOp)
if err == nil {
// Write hmac LSB, payloadLen followed by payload
err = binary.Write(*hc.c, binary.BigEndian, hmacOut)
if err == nil {
err = binary.Write(*hc.c, binary.BigEndian, payloadLen)
if err == nil {
n, err = (*hc.c).Write(wb.Bytes())
} else {
//fmt.Println("[c]WriteError!")
}
} else {
//fmt.Println("[b]WriteError!")
}
} else {
//fmt.Println("[a]WriteError!")
}
hc.Unlock()
if err != nil {
log.Println(err)
}
// We must 'lie' to caller indicating the length of THEIR
// data written (ie., not including the padding and padding headers)
retN := n - 2 - int(padLen)
if retN <= 0 {
retN = 0
}
return retN, err
}
func (hc *Conn) EnableChaff() {
hc.chaff.shutdown = false
hc.chaff.enabled = true
log.Println("Chaffing ENABLED")
hc.chaffHelper()
}
func (hc *Conn) DisableChaff() {
hc.chaff.enabled = false
log.Println("Chaffing DISABLED")
}
func (hc *Conn) ShutdownChaff() {
hc.chaff.shutdown = true
log.Println("Chaffing SHUTDOWN")
}
func (hc *Conn) SetupChaff(msecsMin uint, msecsMax uint, szMax uint) {
hc.chaff.msecsMin = msecsMin //move these to params of chaffHelper() ?
hc.chaff.msecsMax = msecsMax
hc.chaff.szMax = szMax
}
// Helper routine to spawn a chaffing goroutine for each Conn
func (hc *Conn) chaffHelper() {
go func() {
for {
var nextDuration int
if hc.chaff.enabled {
var bufTmp []byte
bufTmp = make([]byte, rand.Intn(int(hc.chaff.szMax)))
min := int(hc.chaff.msecsMin)
nextDuration = rand.Intn(int(hc.chaff.msecsMax)-min) + min
_, _ = rand.Read(bufTmp)
_, err := hc.WritePacket(bufTmp, CSOChaff)
if err != nil {
log.Println("[ *** error - chaffHelper quitting *** ]")
hc.chaff.enabled = false
break
}
}
time.Sleep(time.Duration(nextDuration) * time.Millisecond)
if hc.chaff.shutdown {
log.Println("*** chaffHelper shutting down")
break
}
}
}()
}
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