mirror of
https://gogs.blitter.com/RLabs/xs
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418 lines
13 KiB
Go
418 lines
13 KiB
Go
// hkextun.go - Tunnel setup using an established xsnet.Conn
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// Copyright (c) 2017-2019 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 xsnet
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import (
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"bytes"
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"encoding/binary"
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"fmt"
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"io"
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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/xs/logger"
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)
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type (
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// Tunnels
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// --
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// 1. client is given (lport, remhost, rport) by local user
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// 2. client sends [CSOTunReq:rport] to server
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// client=> [CSOTunReq:rport] =>remhost
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//
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// remhost starts worker to receive/send data using rport
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// remhost replies to client with rport to acknowledge tun is ready
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// client<= [CSOTunAck:rport] <=remhost
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// ... or if rhost rport refuses connection, sends
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// [CSOTunRefused:rport]
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//
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// client starts worker to receive/send data using lport
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// ... client disconnects: sends remhost [CSOTunClose:rport]
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// ... or server disconnects: sends client [CSOTunClose:lport]
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// server at any time sends [CSOTunRefused:rport] if daemon died
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// --
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// TunEndpoint [securePort:peer:dataPort]
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TunEndpoint struct {
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Rport uint16 // Names are from client's perspective
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Lport uint16 // ... ie., RPort is on server, LPort is on client
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Peer string //net.Addr
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Died bool // set by client upon receipt of a CSOTunDisconn
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KeepAlive uint32 // must be reset by client to keep server dial() alive
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Ctl chan rune //See TunCtl_* consts
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Data chan []byte
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}
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)
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func (hc *Conn) CollapseAllTunnels(client bool) {
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for k, t := range *hc.tuns {
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var tunDst bytes.Buffer
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binary.Write(&tunDst, binary.BigEndian, t.Lport)
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binary.Write(&tunDst, binary.BigEndian, t.Rport)
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if client {
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hc.WritePacket(tunDst.Bytes(), CSOTunHangup)
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} else {
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hc.WritePacket(tunDst.Bytes(), CSOTunDisconn)
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}
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delete(*hc.tuns, k)
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}
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}
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func (hc *Conn) InitTunEndpoint(lp uint16, p string /* net.Addr */, rp uint16) {
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hc.Lock()
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defer hc.Unlock()
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if (*hc.tuns) == nil {
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(*hc.tuns) = make(map[uint16]*TunEndpoint)
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}
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if (*hc.tuns)[rp] == nil {
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var addrs []net.Addr
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if p == "" {
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addrs, _ = net.InterfaceAddrs()
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p = addrs[0].String()
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}
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(*hc.tuns)[rp] = &TunEndpoint{ /*Status: CSOTunSetup,*/ Peer: p,
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Lport: lp, Rport: rp, Data: make(chan []byte, 1),
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Ctl: make(chan rune, 1)}
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logger.LogDebug(fmt.Sprintf("InitTunEndpoint [%d:%s:%d]", lp, p, rp))
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} else {
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logger.LogDebug(fmt.Sprintf("InitTunEndpoint [reusing] %v", (*hc.tuns)[rp]))
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if (*hc.tuns)[rp].Data == nil {
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// When re-using a tunnel it will have its
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// data channel removed on closure. Re-create it
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(*hc.tuns)[rp].Data = make(chan []byte, 1)
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}
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(*hc.tuns)[rp].KeepAlive = 0
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(*hc.tuns)[rp].Died = false
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}
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return
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}
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func (hc *Conn) StartClientTunnel(lport, rport uint16) {
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hc.InitTunEndpoint(lport, "", rport)
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go func() {
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var wg sync.WaitGroup
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for cmd := range (*hc.tuns)[rport].Ctl {
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if cmd == 'a' {
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l, e := net.Listen("tcp4", fmt.Sprintf(":%d", lport))
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if e != nil {
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logger.LogDebug(fmt.Sprintf("[ClientTun] Could not get lport %d! (%s)", lport, e))
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} else {
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logger.LogDebug(fmt.Sprintf("[ClientTun] Listening for client tunnel port %d", lport))
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for {
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c, e := l.Accept() // blocks until new conn
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// If tunnel is being re-used, re-init it
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if (*hc.tuns)[rport] == nil {
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hc.InitTunEndpoint(lport, "", rport)
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}
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// ask server to dial() its side, rport
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var tunDst bytes.Buffer
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binary.Write(&tunDst, binary.BigEndian, lport)
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binary.Write(&tunDst, binary.BigEndian, rport)
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hc.WritePacket(tunDst.Bytes(), CSOTunSetup)
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if e != nil {
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logger.LogDebug(fmt.Sprintf("[ClientTun] Accept() got error(%v), hanging up.", e))
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} else {
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logger.LogDebug(fmt.Sprintf("[ClientTun] Accepted tunnel client %v", (*hc.tuns)[rport]))
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// outside client -> tunnel lport
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wg.Add(1)
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go func() {
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defer func() {
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if c.Close() != nil {
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logger.LogDebug("[ClientTun] worker A: conn c already closed")
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} else {
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logger.LogDebug("[ClientTun] worker A: closed conn c")
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}
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wg.Done()
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}()
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logger.LogDebug("[ClientTun] worker A: starting")
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var tunDst bytes.Buffer
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binary.Write(&tunDst, binary.BigEndian, lport)
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binary.Write(&tunDst, binary.BigEndian, rport)
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for {
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rBuf := make([]byte, 1024)
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//Read data from c, encrypt/write via hc to client(lport)
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c.SetReadDeadline(time.Now().Add(200 * time.Millisecond))
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n, e := c.Read(rBuf)
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if e != nil {
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if e == io.EOF {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: lport Disconnected: shutting down tunnel %v", (*hc.tuns)[rport]))
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// if Died was already set, server-side already is gone.
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if hc.TunIsAlive(rport) {
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hc.WritePacket(tunDst.Bytes(), CSOTunHangup)
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}
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hc.ShutdownTun(rport) // FIXME: race-C
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break
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} else if strings.Contains(e.Error(), "i/o timeout") {
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if !hc.TunIsAlive(rport) {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: timeout: Server side died, hanging up %v", (*hc.tuns)[rport]))
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hc.ShutdownTun(rport)
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break
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}
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} else {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: Read error from lport of tun %v\n%s", (*hc.tuns)[rport], e))
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if hc.TunIsAlive(rport) {
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hc.WritePacket(tunDst.Bytes(), CSOTunHangup)
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}
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hc.ShutdownTun(rport)
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break
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}
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}
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if n > 0 {
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rBuf = append(tunDst.Bytes(), rBuf[:n]...)
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_, de := hc.WritePacket(rBuf[:n+4], CSOTunData)
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if de != nil {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker A: Error writing to tunnel %v, %s]\n", (*hc.tuns)[rport], de))
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break
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}
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}
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}
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logger.LogDebug("[ClientTun] worker A: exiting")
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}()
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// tunnel lport -> outside client (c)
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wg.Add(1)
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go func() {
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defer func() {
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if c.Close() != nil {
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logger.LogDebug("[ClientTun] worker B: conn c already closed")
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} else {
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logger.LogDebug("[ClientTun] worker B: closed conn c")
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}
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wg.Done()
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}()
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logger.LogDebug("[ClientTun] worker B: starting")
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for {
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bytes, ok := <-(*hc.tuns)[rport].Data // FIXME: race-C w/ShutdownTun calls
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if ok {
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c.SetWriteDeadline(time.Now().Add(200 * time.Millisecond))
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_, e := c.Write(bytes)
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if e != nil {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker B: lport conn closed"))
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break
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}
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} else {
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logger.LogDebug(fmt.Sprintf("[ClientTun] worker B: Channel was closed?"))
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break
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}
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}
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logger.LogDebug("[ClientTun] worker B: exiting")
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}()
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} // end Accept() worker block
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wg.Wait()
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// When both workers have exited due to a disconnect or other
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// condition, it's safe to remove the tunnel descriptor.
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logger.LogDebug("[ClientTun] workers exited")
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hc.ShutdownTun(rport)
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} // end for-accept
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} // end Listen() block
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}
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} // end t.Ctl for
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}()
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}
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func (hc *Conn) AgeTunnel(endp uint16) uint32 {
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hc.Lock()
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defer hc.Unlock()
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(*hc.tuns)[endp].KeepAlive += 1
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return (*hc.tuns)[endp].KeepAlive
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}
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func (hc *Conn) ResetTunnelAge(endp uint16) {
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hc.Lock()
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defer hc.Unlock()
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(*hc.tuns)[endp].KeepAlive = 0
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}
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func (hc *Conn) TunIsNil(endp uint16) bool {
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hc.Lock()
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defer hc.Unlock()
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return (*hc.tuns)[endp] == nil
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}
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func (hc *Conn) TunIsAlive(endp uint16) bool {
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hc.Lock()
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defer hc.Unlock()
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return !(*hc.tuns)[endp].Died
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}
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func (hc *Conn) MarkTunDead(endp uint16) {
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hc.Lock()
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defer hc.Unlock()
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(*hc.tuns)[endp].Died = true
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}
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func (hc *Conn) ShutdownTun(endp uint16) {
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hc.Lock()
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defer hc.Unlock()
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if (*hc.tuns)[endp] != nil {
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(*hc.tuns)[endp].Died = true
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if (*hc.tuns)[endp].Data != nil {
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close((*hc.tuns)[endp].Data)
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(*hc.tuns)[endp].Data = nil
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}
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}
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delete((*hc.tuns), endp)
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}
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func (hc *Conn) StartServerTunnel(lport, rport uint16) {
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hc.InitTunEndpoint(lport, "", rport)
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var err error
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go func() {
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var wg sync.WaitGroup
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//
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// worker to age server tunnel and kill it if keepalives
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// stop from client
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//
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wg.Add(1)
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go func() {
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defer wg.Done()
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for {
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time.Sleep(100 * time.Millisecond)
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if hc.TunIsNil(rport) {
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logger.LogDebug("[ServerTun] worker A: Client endpoint removed.")
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break
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}
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age := hc.AgeTunnel(rport)
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if age > 25 {
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hc.MarkTunDead(rport)
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logger.LogDebug("[ServerTun] worker A: Client died, hanging up.")
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break
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}
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}
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}()
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for cmd := range (*hc.tuns)[rport].Ctl {
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var c net.Conn
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logger.LogDebug(fmt.Sprintf("[ServerTun] got Ctl '%c'.", cmd))
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if cmd == 'd' {
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// if re-using tunnel, re-init it
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if hc.TunIsNil(rport) {
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hc.InitTunEndpoint(lport, "", rport)
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}
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logger.LogDebug("[ServerTun] dialling...")
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c, err = net.Dial("tcp4", fmt.Sprintf(":%d", rport))
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if err != nil {
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logger.LogDebug(fmt.Sprintf("[ServerTun] Dial() error for tun %v: %s", (*hc.tuns)[rport], err))
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var resp bytes.Buffer
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binary.Write(&resp, binary.BigEndian /*lport*/, uint16(0))
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binary.Write(&resp, binary.BigEndian, rport)
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hc.WritePacket(resp.Bytes(), CSOTunRefused)
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} else {
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logger.LogDebug(fmt.Sprintf("[ServerTun] Tunnel Opened - %v", (*hc.tuns)[rport]))
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var resp bytes.Buffer
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binary.Write(&resp, binary.BigEndian, lport)
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binary.Write(&resp, binary.BigEndian, rport)
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logger.LogDebug(fmt.Sprintf("[ServerTun] Writing CSOTunSetupAck %v", (*hc.tuns)[rport]))
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hc.WritePacket(resp.Bytes(), CSOTunSetupAck)
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//
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// worker to read data from the rport (to encrypt & send to client)
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//
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wg.Add(1)
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go func() {
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defer func() {
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logger.LogDebug("[ServerTun] worker A: deferred hangup")
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if c.Close() != nil {
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logger.LogDebug("[ServerTun] workerA: conn c already closed")
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}
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wg.Done()
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}()
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logger.LogDebug("[ServerTun] worker A: starting")
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var tunDst bytes.Buffer
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binary.Write(&tunDst, binary.BigEndian, (*hc.tuns)[rport].Lport)
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binary.Write(&tunDst, binary.BigEndian, (*hc.tuns)[rport].Rport)
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for {
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rBuf := make([]byte, 1024)
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// Read data from c, encrypt/write via hc to client(lport)
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c.SetReadDeadline(time.Now().Add(200 * time.Millisecond))
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n, e := c.Read(rBuf)
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if e != nil {
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if e == io.EOF {
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logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: rport Disconnected: shutting down tunnel %v", (*hc.tuns)[rport]))
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if hc.TunIsAlive(rport) {
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hc.WritePacket(tunDst.Bytes(), CSOTunDisconn)
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}
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hc.ShutdownTun(rport) // FIXME: race-A
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break
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} else if strings.Contains(e.Error(), "i/o timeout") {
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if !hc.TunIsAlive(rport) {
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logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: timeout: Server side died, hanging up %v", (*hc.tuns)[rport]))
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hc.ShutdownTun(rport) // FIXME: race-B
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break
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}
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} else {
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logger.LogDebug(fmt.Sprintf("[ServerTun] worker A: Read error from rport of tun %v: %s", (*hc.tuns)[rport], e))
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if hc.TunIsAlive(rport) {
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hc.WritePacket(tunDst.Bytes(), CSOTunDisconn)
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}
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hc.ShutdownTun(rport) // FIXME: race-C
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break
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}
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}
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if n > 0 {
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rBuf = append(tunDst.Bytes(), rBuf[:n]...)
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hc.WritePacket(rBuf[:n+4], CSOTunData)
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}
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}
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logger.LogDebug("[ServerTun] worker A: exiting")
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}()
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// worker to read data from client (already decrypted) & fwd to rport
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wg.Add(1)
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go func() {
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defer func() {
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logger.LogDebug("[ServerTun] worker B: deferred hangup")
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if c.Close() != nil {
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logger.LogDebug("[ServerTun] worker B: conn c already closed")
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}
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wg.Done()
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}()
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logger.LogDebug("[ServerTun] worker B: starting")
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for {
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rData, ok := <-(*hc.tuns)[rport].Data // FIXME: race-A, race-B, race-C (w/ShutdownTun() calls)
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if ok {
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c.SetWriteDeadline(time.Now().Add(200 * time.Millisecond))
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_, e := c.Write(rData)
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if e != nil {
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logger.LogDebug(fmt.Sprintf("[ServerTun] worker B: ERROR writing to rport conn"))
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break
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}
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} else {
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logger.LogDebug(fmt.Sprintf("[ServerTun] worker B: Channel was closed?"))
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break
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}
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}
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logger.LogDebug("[ServerTun] worker B: exiting")
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}()
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wg.Wait()
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} // end if Dialled successfully
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delete((*hc.tuns), rport)
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}
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} // t.Ctl read loop
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logger.LogDebug("[ServerTun] Tunnel exiting t.Ctl read loop - channel closed??")
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}()
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}
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