mirror of
https://gogs.blitter.com/RLabs/xs
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708 lines
20 KiB
Go
708 lines
20 KiB
Go
// hkexnet.go - net.Conn compatible channel setup with encrypted/HMAC
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// negotiation
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// Copyright (c) 2017-2018 Russell Magee
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// Licensed under the terms of the MIT license (see LICENSE.mit in this
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// distribution)
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//
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// golang implementation by Russ Magee (rmagee_at_gmail.com)
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package hkexnet
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// TODO:
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// If key exchange algs other than the experimental HerraduraKEx are to
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// be supported, the Dial() and Accept() methods should take a kex param,
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// specifying which to use; and the client/server negotiation must then
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// prefix the channel setup with this param over the wire in order to decide
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// which is in use.
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//
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// DESIGN PRINCIPLE: There shall be no protocol features which enable
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// downgrade attacks. The server shall have final authority to accept or
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// reject any and all proposed KEx and connection parameters proposed by
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// clients at setup. Action on denial shall be a simple server disconnect
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// with possibly a status code sent so client can determine why connection
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// was denied (compare to how failed auth is communicated to client).
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// Implementation of HKEx-wrapped versions of the golang standard
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// net package interfaces, allowing clients and servers to simply replace
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// 'net.Dial' and 'net.Listen' with 'hkex.Dial' and 'hkex.Listen'
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// (though some extra methods are implemented and must be used
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// for things outside of the scope of plain sockets).
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import (
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"bytes"
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"crypto/cipher"
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"encoding/binary"
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"encoding/hex"
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"errors"
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"fmt"
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"hash"
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"io"
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"log"
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"math/big"
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"math/rand"
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"net"
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"strings"
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"sync"
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"time"
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"blitter.com/go/hkexsh/herradurakex"
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)
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// KEx type - sent from client to server in order to specify which
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// algo shall be used (eg., HerraduraKEx, [TODO: others...])
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type KEX uint8
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const (
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KEX_HERRADURA = iota // this MUST be first for default if omitted in ctor
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KEX_FOO
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//KEX_DH
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//KEX_ETC
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)
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// const CSExtendedCode - extended (>255 UNIX exit status) codes
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// This indicate channel-related or internal errors
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const (
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CSEBadAuth = 1024 // Failed login password
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CSETruncCSO // No CSOExitStatus in payload
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CSEStillOpen // Channel closed unexpectedly
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CSEExecFail // cmd.Start() (exec) failed
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CSEPtyExecFail // pty.Start() (exec w/pty) failed
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)
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const (
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CSONone = iota // No error, normal packet
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CSOHmacInvalid // HMAC mismatch detected on remote end
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CSOTermSize // set term size (rows:cols)
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CSOExitStatus // Remote cmd exit status
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CSOChaff // Dummy packet, do not pass beyond decryption
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)
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const MAX_PAYLOAD_LEN = 4*1024*1024*1024 - 1
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/*---------------------------------------------------------------------*/
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type (
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WinSize struct {
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Rows uint16
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Cols uint16
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}
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// chaffconfig captures attributes used to send chaff packets betwixt
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// client and server connections, to obscure true traffic timing and
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// patterns
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// see: https://en.wikipedia.org/wiki/chaff_(countermeasure)
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ChaffConfig struct {
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shutdown bool //set to inform chaffHelper to shut down
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enabled bool
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msecsMin uint //msecs min interval
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msecsMax uint //msecs max interval
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szMax uint // max size in bytes
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}
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// Conn is a HKex connection - a superset of net.Conn
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Conn struct {
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kex KEX // KEX alg (typedef uint8)
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m *sync.Mutex
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c net.Conn // which also implements io.Reader, io.Writer, ...
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h *hkex.HerraduraKEx // TODO: make an interface?
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cipheropts uint32 // post-KEx cipher/hmac options
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opts uint32 // post-KEx protocol options (caller-defined)
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WinCh chan WinSize
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Rows uint16
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Cols uint16
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chaff ChaffConfig
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closeStat *uint32 // close status (CSOExitStatus)
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r cipher.Stream //read cipherStream
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rm hash.Hash
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w cipher.Stream //write cipherStream
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wm hash.Hash
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dBuf *bytes.Buffer //decrypt buffer for Read()
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}
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)
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func (hc Conn) GetStatus() uint32 {
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return *hc.closeStat
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}
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func (hc *Conn) SetStatus(stat uint32) {
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*hc.closeStat = stat
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//fmt.Println("closeStat:", *hc.closeStat)
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log.Println("closeStat:", *hc.closeStat)
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}
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// ConnOpts returns the cipher/hmac options value, which is sent to the
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// peer but is not itself part of the KEx.
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//
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// (Used for protocol-level negotiations after KEx such as
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// cipher/HMAC algorithm options etc.)
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func (hc Conn) ConnOpts() uint32 {
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return hc.cipheropts
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}
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// SetConnOpts sets the cipher/hmac options value, which is sent to the
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// peer as part of KEx but not part of the KEx itself.
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//
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// opts - bitfields for cipher and hmac alg. to use after KEx
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func (hc *Conn) SetConnOpts(copts uint32) {
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hc.cipheropts = copts
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}
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// Opts returns the protocol options value, which is sent to the peer
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// but is not itself part of the KEx or connection (cipher/hmac) setup.
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//
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// Consumers of this lib may use this for protocol-level options not part
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// of the KEx or encryption info used by the connection.
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func (hc Conn) Opts() uint32 {
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return hc.opts
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}
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// SetOpts sets the protocol options value, which is sent to the peer
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// but is not itself part of the KEx or connection (cipher/hmac) setup.
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//
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// Consumers of this lib may use this for protocol-level options not part
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// of the KEx of encryption info used by the connection.
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//
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// opts - a uint32, caller-defined
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func (hc *Conn) SetOpts(opts uint32) {
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hc.opts = opts
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}
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func (hc *Conn) applyConnExtensions(extensions ...string) {
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for _, s := range extensions {
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switch s {
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case "KEX_HERRADURA":
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log.Println("[extension arg = KEX_HERRADURA]")
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hc.kex = KEX_HERRADURA
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break
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case "KEX_FOO":
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log.Println("[extension arg = KEX_FOO]")
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hc.kex = KEX_FOO
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break
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case "C_AES_256":
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log.Println("[extension arg = C_AES_256]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgAES256
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break
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case "C_TWOFISH_128":
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log.Println("[extension arg = C_TWOFISH_128]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgTwofish128
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break
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case "C_BLOWFISH_64":
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log.Println("[extension arg = C_BLOWFISH_64]")
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hc.cipheropts &= (0xFFFFFF00)
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hc.cipheropts |= CAlgBlowfish64
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break
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case "H_SHA256":
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log.Println("[extension arg = H_SHA256]")
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hc.cipheropts &= (0xFFFF00FF)
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hc.cipheropts |= (HmacSHA256 << 8)
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break
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default:
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log.Printf("[Dial ext \"%s\" ignored]\n", s)
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break
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}
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}
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}
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func HKExDialSetup(c net.Conn, hc *Conn) (err error) {
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// Send hkexnet.Conn parameters to remote side
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// d is value for Herradura key exchange
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fmt.Fprintf(c, "0x%s\n%08x:%08x\n", hc.h.D().Text(16),
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hc.cipheropts, hc.opts)
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d := big.NewInt(0)
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_, err = fmt.Fscanln(c, d)
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if err != nil {
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return err
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}
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// Read peer D over net.Conn (c)
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_, err = fmt.Fscanf(c, "%08x:%08x\n",
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&hc.cipheropts, &hc.opts)
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if err != nil {
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return err
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}
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hc.h.SetPeerD(d)
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log.Printf("** local D:%s\n", hc.h.D().Text(16))
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log.Printf("**(c)** peer D:%s\n", hc.h.PeerD().Text(16))
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hc.h.ComputeFA()
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log.Printf("**(c)** FA:%s\n", hc.h.FA())
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hc.r, hc.rm, err = hc.getStream(hc.h.FA())
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hc.w, hc.wm, err = hc.getStream(hc.h.FA())
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return
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}
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func HKExAcceptSetup(c net.Conn, hc *Conn) (err error) {
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// Read in hkexnet.Conn parameters over raw Conn c
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// d is value for Herradura key exchange
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d := big.NewInt(0)
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_, err = fmt.Fscanln(c, d)
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log.Printf("[Got d:%v]", d)
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if err != nil {
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return err
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}
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_, err = fmt.Fscanf(c, "%08x:%08x\n",
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&hc.cipheropts, &hc.opts)
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log.Printf("[Got cipheropts, opts:%v, %v]", hc.cipheropts, hc.opts)
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if err != nil {
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return err
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}
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hc.h.SetPeerD(d)
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log.Printf("** D:%s\n", hc.h.D().Text(16))
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log.Printf("**(s)** peerD:%s\n", hc.h.PeerD().Text(16))
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hc.h.ComputeFA()
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log.Printf("**(s)** FA:%s\n", hc.h.FA())
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// Send D and cipheropts/conn_opts to peer
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fmt.Fprintf(c, "0x%s\n%08x:%08x\n", hc.h.D().Text(16),
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hc.cipheropts, hc.opts)
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hc.r, hc.rm, err = hc.getStream(hc.h.FA())
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hc.w, hc.wm, err = hc.getStream(hc.h.FA())
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return
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}
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// Dial as net.Dial(), but with implicit key exchange to set up secure
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// channel on connect
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//
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// Can be called like net.Dial(), defaulting to C_AES_256/H_SHA256,
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// or additional option arguments can be passed amongst the following:
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//
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// "C_AES_256" | "C_TWOFISH_128"
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//
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// "H_SHA256"
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func Dial(protocol string, ipport string, extensions ...string) (hc *Conn, err error) {
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// Open raw Conn c
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c, err := net.Dial(protocol, ipport)
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if err != nil {
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return nil, err
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}
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// Init hkexnet.Conn hc over net.Conn c
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// NOTE: kex default of KEX_HERRADURA may be overridden by
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// future extension args to applyConnExtensions(), which is
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// called prior to Dial()
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hc = &Conn{m: &sync.Mutex{}, c: c, closeStat: new(uint32), h: hkex.New(0, 0), dBuf: new(bytes.Buffer)}
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hc.applyConnExtensions(extensions...)
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// TODO: Factor out ALL params following this to helpers for
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// specific KEx algs
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fmt.Fprintf(c, "%02x\n", hc.kex)
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// --
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*hc.closeStat = CSEStillOpen // open or prematurely-closed status
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// Perform Key Exchange according to client-request algorithm
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switch hc.kex {
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case KEX_HERRADURA:
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if HKExDialSetup(c, hc) != nil {
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return hc, nil
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}
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case KEX_FOO:
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// For testing: set up as HKEx anyway, but server via Accept() should
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// reject as invalid.
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//if FooKExDialSetup(c, hc) != nil {
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if HKExDialSetup(c, hc) != nil {
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return hc, nil
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}
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default:
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log.Printf("Invalid kex alg (%d), rejecting\n", hc.kex)
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return nil, errors.New("Invalid kex alg")
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}
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return
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}
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// Close a hkex.Conn
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func (hc *Conn) Close() (err error) {
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hc.DisableChaff()
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s := make([]byte, 4)
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binary.BigEndian.PutUint32(s, *hc.closeStat)
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hc.WritePacket(s, CSOExitStatus)
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err = hc.c.Close()
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log.Println("[Conn Closing]")
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return
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}
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// LocalAddr returns the local network address.
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func (hc *Conn) LocalAddr() net.Addr {
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return hc.c.LocalAddr()
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}
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// RemoteAddr returns the remote network address.
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func (hc *Conn) RemoteAddr() net.Addr {
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return hc.c.RemoteAddr()
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}
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// SetDeadline sets the read and write deadlines associated
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// with the connection. It is equivalent to calling both
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// SetReadDeadline and SetWriteDeadline.
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//
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// A deadline is an absolute time after which I/O operations
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// fail with a timeout (see type Error) instead of
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// blocking. The deadline applies to all future and pending
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// I/O, not just the immediately following call to Read or
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// Write. After a deadline has been exceeded, the connection
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// can be refreshed by setting a deadline in the future.
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//
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// An idle timeout can be implemented by repeatedly extending
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// the deadline after successful Read or Write calls.
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//
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// A zero value for t means I/O operations will not time out.
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func (hc *Conn) SetDeadline(t time.Time) error {
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return hc.c.SetDeadline(t)
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}
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// SetWriteDeadline sets the deadline for future Write calls
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// and any currently-blocked Write call.
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// Even if write times out, it may return n > 0, indicating that
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// some of the data was successfully written.
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// A zero value for t means Write will not time out.
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func (hc *Conn) SetWriteDeadline(t time.Time) error {
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return hc.c.SetWriteDeadline(t)
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}
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// SetReadDeadline sets the deadline for future Read calls
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// and any currently-blocked Read call.
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// A zero value for t means Read will not time out.
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func (hc *Conn) SetReadDeadline(t time.Time) error {
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return hc.c.SetReadDeadline(t)
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}
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/*---------------------------------------------------------------------*/
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// HKExListener is a Listener conforming to net.Listener
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//
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// See go doc net.Listener
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type HKExListener struct {
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l net.Listener
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}
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// Listen for a connection
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//
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// See go doc net.Listen
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func Listen(protocol string, ipport string) (hl HKExListener, e error) {
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l, err := net.Listen(protocol, ipport)
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if err != nil {
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return HKExListener{nil}, err
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}
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log.Println("[Listening]")
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hl.l = l
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return
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}
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// Close a hkex Listener - closes the Listener.
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// Any blocked Accept operations will be unblocked and return errors.
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//
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// See go doc net.Listener.Close
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func (hl HKExListener) Close() error {
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log.Println("[Listener Closed]")
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return hl.l.Close()
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}
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// Addr returns a the listener's network address.
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//
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// See go doc net.Listener.Addr
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func (hl HKExListener) Addr() net.Addr {
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return hl.l.Addr()
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}
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// Accept a client connection, conforming to net.Listener.Accept()
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//
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// See go doc net.Listener.Accept
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func (hl *HKExListener) Accept() (hc Conn, err error) {
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// Open raw Conn c
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c, err := hl.l.Accept()
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if err != nil {
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hc := Conn{m: &sync.Mutex{}, c: nil, h: nil, closeStat: new(uint32), cipheropts: 0, opts: 0,
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r: nil, w: nil}
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return hc, err
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}
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log.Println("[Accepted]")
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hc = Conn{ /*kex: from client,*/ m: &sync.Mutex{}, c: c, h: hkex.New(0, 0), closeStat: new(uint32), WinCh: make(chan WinSize, 1),
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dBuf: new(bytes.Buffer)}
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// TODO: Factor out ALL params following this to helpers for
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// specific KEx algs
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var kexAlg uint8
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_, err = fmt.Fscanln(c, &kexAlg)
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if err != nil {
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return hc, err
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}
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log.Printf("[Client proposed KEx alg: %v]\n", kexAlg)
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// --
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switch kexAlg {
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case KEX_HERRADURA:
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log.Printf("[KEx alg %d accepted]\n", kexAlg)
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if HKExAcceptSetup(c, &hc) != nil {
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return hc, nil
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}
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default:
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log.Printf("[KEx alg %d rejected]\n", kexAlg)
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return hc, errors.New("KEx rejected")
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}
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return
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}
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/*---------------------------------------------------------------------*/
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// Read into a byte slice
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//
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// See go doc io.Reader
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func (hc Conn) Read(b []byte) (n int, err error) {
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//log.Printf("[Decrypting...]\r\n")
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for {
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//log.Printf("hc.dBuf.Len(): %d\n", hc.dBuf.Len())
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if hc.dBuf.Len() > 0 /* len(b) */ {
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break
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}
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var ctrlStatOp uint8
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var hmacIn [4]uint8
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var payloadLen uint32
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// Read ctrl/status opcode (CSOHmacInvalid on hmac mismatch)
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err = binary.Read(hc.c, binary.BigEndian, &ctrlStatOp)
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log.Printf("[ctrlStatOp: %v]\n", ctrlStatOp)
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if ctrlStatOp == CSOHmacInvalid {
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// Other side indicated channel tampering, close channel
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hc.Close()
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return 1, errors.New("** ALERT - remote end detected HMAC mismatch - possible channel tampering **")
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}
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// Read the hmac and payload len first
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err = binary.Read(hc.c, binary.BigEndian, &hmacIn)
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// Normal client 'exit' from interactive session will cause
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// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
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if err != nil {
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if !strings.HasSuffix(err.Error(), "use of closed network connection") {
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//fmt.Println("[1]unexpected Read() err:", err)
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log.Println("[1]unexpected Read() err:", err)
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} else {
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//fmt.Println("[Client hung up]")
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log.Println("[Client hung up]")
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}
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return 0, err
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}
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err = binary.Read(hc.c, binary.BigEndian, &payloadLen)
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if err != nil {
|
|
if err.Error() != "EOF" {
|
|
log.Println("[2]unexpected Read() err:", err)
|
|
}
|
|
}
|
|
|
|
if payloadLen > MAX_PAYLOAD_LEN {
|
|
log.Printf("[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)
|
|
|
|
// Normal client 'exit' from interactive session will cause
|
|
// (on server side) err.Error() == "<iface/addr info ...>: use of closed network connection"
|
|
if err != nil && err.Error() != "EOF" {
|
|
if !strings.HasSuffix(err.Error(), "use of closed network connection") {
|
|
log.Println("[3]unexpected Read() err:", err)
|
|
} else {
|
|
log.Println("[Client hung up]")
|
|
}
|
|
}
|
|
|
|
log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
|
|
|
|
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 ot an intermediate buffer, draining it on demand of caller
|
|
decryptN, err := rs.Read(payloadBytes)
|
|
log.Printf(" <-ptext:\r\n%s\r\n", hex.Dump(payloadBytes[:n]))
|
|
if err != nil {
|
|
//fmt.Print(err)
|
|
//panic(err)
|
|
} else {
|
|
|
|
// 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(binary.BigEndian.Uint32(payloadBytes))
|
|
//!// If remote end is closing with an error, reply we're closing ours
|
|
//!if hc.GetStatus() != 0 {
|
|
//! log.Print("CSOExitStatus:", hc.GetStatus())
|
|
hc.Close()
|
|
//!}
|
|
} else {
|
|
log.Println("[truncated payload, cannot determine CSOExitStatus]")
|
|
*hc.closeStat = CSETruncCSO
|
|
}
|
|
} else {
|
|
hc.dBuf.Write(payloadBytes)
|
|
//log.Printf("hc.dBuf: %s\n", hex.Dump(hc.dBuf.Bytes()))
|
|
}
|
|
|
|
// Re-calculate hmac, compare with received value
|
|
hc.rm.Write(payloadBytes)
|
|
hTmp := hc.rm.Sum(nil)[0:4]
|
|
log.Printf("<%04x) HMAC:(i)%s (c)%02x\r\n", decryptN, hex.EncodeToString([]byte(hmacIn[0:])), hTmp)
|
|
|
|
if *hc.closeStat == CSETruncCSO {
|
|
log.Println("[cannot verify HMAC]")
|
|
} else {
|
|
// Log alert if hmac didn't match, corrupted channel
|
|
if !bytes.Equal(hTmp, []byte(hmacIn[0:])) /*|| hmacIn[0] > 0xf8*/ {
|
|
fmt.Println("** ALERT - detected HMAC mismatch, possible channel tampering **")
|
|
_, _ = hc.c.Write([]byte{CSOHmacInvalid})
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
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 ctrlStatusOp byte
|
|
func (hc *Conn) WritePacket(b []byte, op 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")
|
|
}
|
|
|
|
// 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.m.Lock()
|
|
//fmt.Printf("--== TOTAL payloadLen (b):%d\n", len(b))
|
|
payloadLen = uint32(len(b))
|
|
//!fmt.Printf(" --== payloadLen:%d\n", payloadLen)
|
|
log.Printf(" :>ptext:\r\n%s\r\n", hex.Dump(b[0:payloadLen]))
|
|
|
|
// Calculate hmac on payload
|
|
hc.wm.Write(b[0:payloadLen])
|
|
hmacOut = hc.wm.Sum(nil)[0:4]
|
|
|
|
log.Printf(" (%04x> HMAC(o):%s\r\n", payloadLen, hex.EncodeToString(hmacOut))
|
|
|
|
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}
|
|
_, err = ws.Write(b[0:payloadLen])
|
|
if err != nil {
|
|
panic(err)
|
|
}
|
|
log.Printf(" ->ctext:\r\n%s\r\n", hex.Dump(wb.Bytes()))
|
|
|
|
ctrlStatOp := op
|
|
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.m.Unlock()
|
|
|
|
if err != nil {
|
|
log.Println(err)
|
|
}
|
|
return
|
|
}
|
|
|
|
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 {
|
|
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
|
|
}
|
|
|
|
}
|
|
}()
|
|
}
|