xs/hkexnet.go

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/* Herradura - a Key exchange scheme in the style of Diffie-Hellman Key Exchange.
Copyright (C) 2017 Omar Alejandro Herrera Reyna
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
golang implementation by Russ Magee (rmagee_at_gmail.com) */
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package herradurakex
// Implementation of HKEx-wrapped versions of the golang standard
// 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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import (
"bytes"
"crypto/cipher"
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"fmt"
"log"
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"math/big"
"net"
"time"
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)
/*---------------------------------------------------------------------*/
// Conn is a HKex connection - a drop-in replacement for net.Conn
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type Conn struct {
c net.Conn // which also implements io.Reader, io.Writer, ...
h *HerraduraKEx
cipheropts uint32 // post-KEx cipher/hmac options
opts uint32 // post-KEx protocol options (caller-defined)
op uint8 // post-KEx 'op' (caller-defined)
r cipher.Stream
w cipher.Stream
}
// 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 (c Conn) ConnOpts() uint32 {
return c.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 (c Conn) SetConnOpts(copts uint32) {
c.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 (c Conn) Opts() uint32 {
return c.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 (c Conn) SetOpts(opts uint32) {
c.opts = opts
}
// Op returns the 'op' 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 to indicate connection-specific
// operations not part of the KEx or encryption info used by the connection.
func (c Conn) Op() uint8 {
return c.op
}
// SetOp sets the 'op' 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 to indicate connection-specific
// operations not part of the KEx or encryption info used by the connection.
//
// op - a uint8, caller-defined
func (c Conn) SetOp(op uint8) {
c.op = op
}
func (c Conn) applyConnExtensions(extensions ...string) {
for _, s := range extensions {
switch s {
case "C_AES_256":
log.Println("[extension arg = C_AES_256]")
c.cipheropts &= (0xFFFFFF00)
c.cipheropts |= CAlgAES256
break
case "C_TWOFISH_128":
log.Println("[extension arg = C_TWOFISH_128]")
c.cipheropts &= (0xFFFFFF00)
c.cipheropts |= CAlgTwofish128
break
case "C_BLOWFISH_64":
log.Println("[extension arg = C_BLOWFISH_64]")
c.cipheropts &= (0xFFFFFF00)
c.cipheropts |= CAlgBlowfish64
break
case "H_SHA256":
log.Println("[extension arg = H_SHA256]")
c.cipheropts &= (0xFFFF00FF)
c.cipheropts |= (HmacSHA256 << 8)
break
default:
log.Printf("[Dial ext \"%s\" ignored]\n", s)
break
}
}
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}
// Dial as net.Dial(), but with implicit HKEx PeerD read on connect
// Can be called like net.Dial(), defaulting to C_AES_256/H_SHA256,
// or additional option arguments can be passed amongst the following:
//
// "C_AES_256" | "C_TWOFISH_128"
//
// "H_SHA256"
func Dial(protocol string, ipport string, extensions ...string) (hc *Conn, err error) {
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c, err := net.Dial(protocol, ipport)
if err != nil {
return nil, err
}
hc = &Conn{c: c, h: New(0, 0), cipheropts: 0, opts: 0, op: 0, r: nil, w: nil}
hc.applyConnExtensions(extensions...)
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fmt.Fprintf(c, "0x%s\n%08x:%08x:%02x\n", hc.h.d.Text(16),
hc.cipheropts, hc.opts, hc.op)
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d := big.NewInt(0)
_, err = fmt.Fscanln(c, d)
if err != nil {
return nil, err
}
_, err = fmt.Fscanf(c, "%08x:%08x:%02x\n",
&hc.cipheropts, &hc.opts, &hc.op)
if err != nil {
return nil, err
}
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hc.h.PeerD = d
log.Printf("** D:%s\n", hc.h.d.Text(16))
log.Printf("**(c)** peerD:%s\n", hc.h.PeerD.Text(16))
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hc.h.FA()
log.Printf("**(c)** FA:%s\n", hc.h.fa)
hc.r = hc.getStream(hc.h.fa)
hc.w = hc.getStream(hc.h.fa)
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return
}
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// Close a hkex.Conn
func (c Conn) Close() (err error) {
err = c.c.Close()
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fmt.Println("[Conn Closing]")
return
}
// LocalAddr returns the local network address.
func (c Conn) LocalAddr() net.Addr {
return c.c.LocalAddr()
}
// RemoteAddr returns the remote network address.
func (c Conn) RemoteAddr() net.Addr {
return c.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 (c Conn) SetDeadline(t time.Time) error {
return 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 (c Conn) SetWriteDeadline(t time.Time) error {
return 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 (c Conn) SetReadDeadline(t time.Time) error {
return c.SetReadDeadline(t)
}
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/*---------------------------------------------------------------------*/
// HKExListener is a Listener conforming to net.Listener
//
// See go doc net.Listener
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type HKExListener struct {
l net.Listener
}
// Listen for a connection
//
// See go doc net.Listen
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func Listen(protocol string, ipport string) (hl HKExListener, e error) {
l, err := net.Listen(protocol, ipport)
if err != nil {
return HKExListener{nil}, err
}
fmt.Println("[Listening]")
hl.l = l
return
}
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// Close a hkex Listener
//
// See go doc io.Close
func (hl HKExListener) Close() error {
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fmt.Println("[Listener Closed]")
return hl.l.Close()
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}
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// Accept a client connection, conforming to net.Listener.Accept()
//
// See go doc net.Listener.Accept
func (hl HKExListener) Accept() (hc Conn, err error) {
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c, err := hl.l.Accept()
if err != nil {
return Conn{c: nil, h: nil, cipheropts: 0, opts: 0,
r: nil, w: nil}, err
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}
fmt.Println("[Accepted]")
hc = Conn{c: c, h: New(0, 0), cipheropts: 0, opts: 0, op: 0, r: nil, w: nil}
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d := big.NewInt(0)
_, err = fmt.Fscanln(c, d)
if err != nil {
return hc, err
}
_, err = fmt.Fscanf(c, "%08x:%08x:%02x\n",
&hc.cipheropts, &hc.opts, &hc.op)
if err != nil {
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return hc, err
}
hc.h.PeerD = d
log.Printf("** D:%s\n", hc.h.d.Text(16))
log.Printf("**(s)** peerD:%s\n", hc.h.PeerD.Text(16))
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hc.h.FA()
log.Printf("**(s)** FA:%s\n", hc.h.fa)
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fmt.Fprintf(c, "0x%s\n%08x:%08x:%02x\n", hc.h.d.Text(16),
hc.cipheropts, hc.opts, hc.op)
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hc.r = hc.getStream(hc.h.fa)
hc.w = hc.getStream(hc.h.fa)
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return
}
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/*---------------------------------------------------------------------*/
// Read into a byte slice
//
// See go doc io.Reader
func (c Conn) Read(b []byte) (n int, err error) {
log.Printf("[Decrypting...]\n")
//c.c.SetReadDeadline(time.Now().Add(1 * time.Second))
n, err = c.c.Read(b)
if err != nil && err.Error() != "EOF" {
//if neterr, ok := err.(net.Error); ok {
// fmt.Printf("[Read() timeout - %s]\n", neterr)
//} else {
// panic(err)
//}
}
log.Printf(" ctext:%+v\n", b[:n]) // print only used portion
db := bytes.NewBuffer(b[:n])
// 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: c.r, R: db}
n, err = rs.Read(b)
log.Printf(" ptext:%+v\n", b[:n])
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return
}
// Write a byte slice
//
// See go doc io.Writer
func (c Conn) Write(b []byte) (n int, err error) {
log.Printf("[Encrypting...]\n")
log.Printf(" ptext:%+v\n", b)
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: c.w, W: &wb}
_, err = ws.Write(b)
if err != nil {
panic(err)
}
log.Printf(" ctext:%+v\n", wb.Bytes())
n, err = c.c.Write(wb.Bytes())
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return
}