xs/hkexnet/hkextun.go

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// hkextun.go - Tunnel setup using an established hkexnet.Conn
// Copyright (c) 2017-2018 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 hkexnet
import (
"bytes"
"encoding/binary"
//"fmt"
//"io"
//"log"
"net"
//"blitter.com/go/hkexsh/logger"
)
type (
// Tunnels
// --
// 1. client is given (lport, remhost, rport) by local user
// 2. client sends [CSOTunReq:rport] to server
// client=> [CSOTunReq:rport] =>remhost
//
// remhost starts worker to receive/send data using rport
// remhost replies to client with rport to acknowledge tun is ready
// client<= [CSOTunAck:rport] <=remhost
// ... or if rhost rport refuses connection, sends
// [CSOTunRefused:rport]
//
// client starts worker to receive/send data using lport
// ... client disconnects: sends remhost [CSOTunClose:rport]
// ... or server disconnects: sends client [CSOTunClose:lport]
// server at any time sends [CSOTunRefused:rport] if daemon died
// --
// TunEndpoint [securePort:peer:dataPort]
TunEndpoint struct {
Rport uint16 // Names are from client's perspective
Lport uint16 // ... ie., RPort is on server, LPort is on client
Peer string //net.Addr
Ctl chan<- rune //See TunCtl_* consts
Data chan []byte
}
TunPacket struct {
n uint32
data []byte
}
)
func StartClientTunnel(hc *Conn, lport, rport uint16) {
if hc.tuns == nil {
hc.tuns = make(map[uint16]*TunEndpoint)
}
if hc.tuns[rport] == nil {
addrs, _ := net.InterfaceAddrs()
hc.tuns[rport] = &TunEndpoint{Peer: addrs[0].String(),
Lport: lport, Rport: rport, Ctl: make(chan<- rune)}
}
/*
go func() {
l, e := net.Listen("tcp", fmt.Sprintf(":%d", lport))
if e != nil {
fmt.Printf("[Could not get lport %d! (%s)\n", lport, e)
} else {
defer l.Close()
for {
c, e := l.Accept()
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
if e != nil {
log.Printf("Accept() got error(%v), hanging up.\n", e)
break
//log.Fatal(err)
} else {
log.Println("Accepted client")
// outside client -> tunnel lport
go func() {
var tunDst bytes.Buffer
binary.Write(&tunDst, binary.BigEndian, lport)
binary.Write(&tunDst, binary.BigEndian, rport)
for {
rBuf := make([]byte, 1024)
//Read data from c, encrypt/write via hc to client(lport)
n, e := c.Read(rBuf)
if e != nil {
if e == io.EOF {
logger.LogNotice(fmt.Sprintf("lport Disconnected: shutting down tunnel [%d:%d]\n", lport, rport))
} else {
logger.LogErr(fmt.Sprintf("Read error from lport of tun [%d:%d]\n%s", lport, rport, e))
}
hc.WritePacket(tunDst.Bytes(), CSOTunClose)
break
}
if n > 0 {
rBuf = append(tunDst.Bytes(), rBuf[:n]...)
logger.LogNotice(fmt.Sprintf("Got lport data:%v\n", tunDst.Bytes()))
hc.WritePacket(rBuf[:n+4], CSOTunData)
}
}
}()
// tunnel lport -> outside client (c)
go func() {
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
for {
//fmt.Printf("Reading from client hc.tuns[%d]\n", lport)
bytes, ok := <-hc.tuns[rport]
if ok {
//fmt.Printf("[Got this through tunnel:%v]\n", bytes)
c.Write(bytes)
} else {
fmt.Printf("[Channel closed?]\n")
//break
}
}
}()
}
}
}
}()
*/
}
func StartServerTunnel(hc *Conn, lport, rport uint16) {
if hc.tuns == nil {
hc.tuns = make(map[uint16]*TunEndpoint)
}
if hc.tuns[rport] == nil {
addrs, _ := net.InterfaceAddrs()
hc.tuns[rport] = &TunEndpoint{Peer: addrs[0].String(),
Lport: lport, Rport: rport, Ctl: make(chan<- rune)}
}
// Inform client of the tunPort
var resp bytes.Buffer
binary.Write(&resp, binary.BigEndian, hc.tuns[rport].Lport)
binary.Write(&resp, binary.BigEndian, hc.tuns[rport].Rport)
hc.WritePacket(resp.Bytes(), CSOTunSetupAck)
/*
t := TunEndpoint{Peer: addrs[0].String(), Lport: lport, Rport: rport}
var resp bytes.Buffer
binary.Write(&resp, binary.BigEndian, t.Lport)
//var dialHangup chan<- bool
c, err := net.Dial("tcp", fmt.Sprintf(":%d", rport))
if err != nil {
logger.LogErr(fmt.Sprintf("Nothing is serving at rport :%d!", rport))
binary.Write(&resp, binary.BigEndian, uint16(0))
// Inform client of the tunPort
hc.WritePacket(resp.Bytes(), CSOTunRefused)
} else {
binary.Write(&resp, binary.BigEndian, t.Rport)
logger.LogNotice(fmt.Sprintf("[Tunnel Opened - %d:%s:%d]", t.Lport, t.Peer, t.Rport))
//
// worker to read data from the rport (to encrypt & send to client)
//
go func() {
defer func() {
//if hc.tuns[rport] != nil {
// close(hc.tuns[rport])
// hc.tuns[rport] = nil
//}
c.Close()
}()
var tunDst bytes.Buffer
binary.Write(&tunDst, binary.BigEndian, t.Lport)
binary.Write(&tunDst, binary.BigEndian, t.Rport)
for {
rBuf := make([]byte, 1024)
// Read data from c, encrypt/write via hc to client(lport)
n, e := c.Read(rBuf)
if e != nil {
if e == io.EOF {
logger.LogNotice(fmt.Sprintf("rport Disconnected: shutting down tunnel %v\n", t))
} else {
logger.LogErr(fmt.Sprintf("Read error from rport of tun %v\n%s", t, e))
}
hc.WritePacket(resp.Bytes(), CSOTunClose)
fmt.Printf("Closing server rport net.Dial()\n")
break
}
if n > 0 {
rBuf = append(tunDst.Bytes(), rBuf[:n]...)
logger.LogNotice(fmt.Sprintf("Got rport data:%v", tunDst.Bytes()))
hc.WritePacket(rBuf[:n+4], CSOTunData)
}
}
}()
// worker to read data from client (already decrypted) & fwd to rport
go func() {
defer func() {
//if hc.tuns[rport] != nil {
//close(hc.tuns[rport])
//hc.tuns[rport] = nil
//}
c.Close()
}()
for {
rData, ok := <-hc.tuns[rport]
if ok {
logger.LogNotice(fmt.Sprintf("Got client data:%v", rData))
c.Write(rData)
} else {
logger.LogErr("!!! ERROR reading from hc.tuns[] channel !!!")
break
}
}
}()
}
*/
}