mirror of https://gogs.blitter.com/RLabs/xs
334 lines
9.7 KiB
Go
334 lines
9.7 KiB
Go
/* Herradura - a Key exchange scheme in the style of Diffie-Hellman Key Exchange.
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Copyright (C) 2017 Omar Alejandro Herrera Reyna
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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golang implementation by Russ Magee (rmagee_at_gmail.com) */
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package herradurakex
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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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import (
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"bytes"
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"crypto/cipher"
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"encoding/hex"
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"fmt"
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"hash"
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"log"
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"math/big"
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"net"
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"strings"
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"time"
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)
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/*---------------------------------------------------------------------*/
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// Conn is a HKex connection - a drop-in replacement for net.Conn
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type Conn struct {
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c net.Conn // which also implements io.Reader, io.Writer, ...
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h *HerraduraKEx
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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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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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}
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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 (c Conn) ConnOpts() uint32 {
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return c.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 (c *Conn) SetConnOpts(copts uint32) {
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c.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 (c Conn) Opts() uint32 {
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return c.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 (c *Conn) SetOpts(opts uint32) {
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c.opts = opts
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}
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func (c *Conn) applyConnExtensions(extensions ...string) {
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for _, s := range extensions {
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switch s {
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case "C_AES_256":
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log.Println("[extension arg = C_AES_256]")
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c.cipheropts &= (0xFFFFFF00)
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c.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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c.cipheropts &= (0xFFFFFF00)
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c.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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c.cipheropts &= (0xFFFFFF00)
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c.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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c.cipheropts &= (0xFFFF00FF)
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c.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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// Dial as net.Dial(), but with implicit HKEx PeerD read on connect
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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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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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hc = &Conn{c: c, h: New(0, 0), cipheropts: 0, opts: 0, r: nil, w: nil}
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hc.applyConnExtensions(extensions...)
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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 nil, 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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if err != nil {
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return nil, err
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}
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hc.h.PeerD = d
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log.Printf("** D:%s\n", hc.h.d.Text(16))
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log.Printf("**(c)** peerD:%s\n", hc.h.PeerD.Text(16))
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hc.h.FA()
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log.Printf("**(c)** FA:%s\n", hc.h.fa)
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hc.r, hc.rm = hc.getStream(hc.h.fa)
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hc.w, hc.wm = hc.getStream(hc.h.fa)
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return
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}
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// Close a hkex.Conn
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func (c Conn) Close() (err error) {
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err = c.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 (c Conn) LocalAddr() net.Addr {
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return c.c.LocalAddr()
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}
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// RemoteAddr returns the remote network address.
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func (c Conn) RemoteAddr() net.Addr {
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return c.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 (c Conn) SetDeadline(t time.Time) error {
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return 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 (c Conn) SetWriteDeadline(t time.Time) error {
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return 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 (c Conn) SetReadDeadline(t time.Time) error {
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return 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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c, err := hl.l.Accept()
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if err != nil {
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return Conn{c: nil, h: nil, cipheropts: 0, opts: 0,
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r: nil, w: nil}, err
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}
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log.Println("[Accepted]")
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hc = Conn{c: c, h: New(0, 0), cipheropts: 0, opts: 0, r: nil, w: nil}
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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 hc, 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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if err != nil {
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return hc, err
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}
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hc.h.PeerD = 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.FA()
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log.Printf("**(s)** FA:%s\n", hc.h.fa)
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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 = hc.getStream(hc.h.fa)
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hc.w, hc.wm = hc.getStream(hc.h.fa)
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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 (c Conn) Read(b []byte) (n int, err error) {
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//log.Printf("[Decrypting...]\r\n")
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n, err = c.c.Read(b)
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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 && err.Error() != "EOF" {
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if !strings.HasSuffix(err.Error(), "use of closed network connection") {
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log.Println("unexpected Read() err:", err)
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} else {
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log.Println("[Client hung up]")
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}
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}
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log.Printf(" <:ctext:\r\n%s\r\n", hex.Dump(b[:n])) //EncodeToString(b[:n])) // print only used portion
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db := bytes.NewBuffer(b[:n])
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// The StreamReader acts like a pipe, decrypting
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// whatever is available and forwarding the result
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// to the parameter of Read() as a normal io.Reader
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rs := &cipher.StreamReader{S: c.r, R: db}
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n, err = rs.Read(b)
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log.Printf(" <-ptext:\r\n%s\r\n", hex.Dump(b[:n])) //EncodeToString(b[:n]))
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return
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}
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// Write a byte slice
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//
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// See go doc io.Writer
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func (c Conn) Write(b []byte) (n int, err error) {
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//log.Printf("[Encrypting...]\r\n")
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log.Printf(" :>ptext:\r\n%s\r\n", hex.Dump(b)) //EncodeToString(b))
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var wb bytes.Buffer
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// The StreamWriter acts like a pipe, forwarding whatever is
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// written to it through the cipher, encrypting as it goes
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ws := &cipher.StreamWriter{S: c.w, W: &wb}
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_, err = ws.Write(b)
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if err != nil {
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panic(err)
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}
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log.Printf(" ->ctext:\r\n%s\r\n", hex.Dump(wb.Bytes())) //EncodeToString(b)) // print only used portion
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n, err = c.c.Write(wb.Bytes())
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return
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}
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