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Add standalone, pure Go port forwarding

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This commit is contained in:
Gary Talent 2017-01-27 14:49:58 -06:00
parent 12ec5e4f93
commit 913f70a2af
6 changed files with 81 additions and 137 deletions
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54
net.go Normal file
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@ -0,0 +1,54 @@
/*
Copyright 2016-2017 gtalent2@gmail.com
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package main
import (
"io"
"log"
"net"
)
const (
CONN_ACTIVE = iota
CONN_DISCONNECTED
)
type ConnStatus struct {
Status int
Err error
}
func portForward(wanConn *net.TCPConn, lanIp, port string, connStatus chan ConnStatus) {
done := make(chan error)
log.Print("Proxy: Connecting to ", lanIp+":"+port)
lanConn, err := net.Dial("tcp", lanIp+":"+port)
if err != nil {
log.Print("Proxy: LAN dial error:", err)
return
}
go forwardConn(wanConn, lanConn, done)
go forwardConn(lanConn, wanConn, done)
for i := 0; i < 2; i++ {
err = <-done
if err != nil {
log.Print("Proxy:", err)
}
}
wanConn.Close()
lanConn.Close()
connStatus <- ConnStatus{Status: CONN_DISCONNECTED, Err: err}
}
func forwardConn(writer, reader net.Conn, done chan error) {
_, err := io.Copy(writer, reader)
done <- err
}

51
net_freebsd.go
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@ -1,51 +0,0 @@
/*
Copyright 2016-2017 gtalent2@gmail.com
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package main
import (
"bytes"
"log"
"os/exec"
"strconv"
)
func addPortForward(ruleName, ip, port string) {
pfrule := "\"rdr pass on $dospin_ext_if proto { tcp, udp } from any to any port {" + port + "} -> " + ip + "\""
in, err := exec.Command("pfctl", "-a", "\"dospin_"+ruleName+"\"", "-f", "-").StdinPipe()
defer in.Close()
if err != nil {
log.Println("Port Forwarding:", err)
}
_, err = in.Write([]byte(pfrule))
if err != nil {
log.Println("Port Forwarding:", err)
}
}
func rmPortForward(ruleName string) {
_, err := exec.Command("pfctl", "-a", "\"dospin_"+ruleName+"\"", "-F", "rules").Output()
if err != nil {
log.Println("Port Forwarding:", err)
}
}
func portUsageCount(ports ...int) int {
cmd := "sockstat"
args := []string{"-4c"}
for _, v := range ports {
args = append(args, "-p")
args = append(args, strconv.Itoa(v))
}
out, err := exec.Command(cmd, args...).Output()
if err != nil {
log.Println("Port Usage Check: Could not run \""+cmd+"\":", err)
}
return bytes.Count(out, []byte{'\n'}) - 1
}

32
net_linux.go
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@ -1,32 +0,0 @@
/*
Copyright 2016-2017 gtalent2@gmail.com
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package main
import (
"log"
"os/exec"
)
func addPortForward(ruleName, localIp, remoteIp, port string) {
log.Println("Setting up port", port, "to", remoteIp)
cmdOut, err := exec.Command("iptables", "-t", "nat", "-A", "PREROUTING", "-p", "tcp", "--dport", port, "-j", "DNAT", "--to-destination", remoteIp+":"+port).Output()
if err != nil {
log.Println("iptables error:", err)
}
log.Println(cmdOut)
cmdOut, err = exec.Command("iptables", "-t", "nat", "-A", "POSTROUTING", "-p", "tcp", "-d", localIp, "--dport", port, "-j", "SNAT", "--to-source", remoteIp).Output()
if err != nil {
log.Println("iptables error:", err)
}
log.Println("iptables", "-t", "nat", "-A", "POSTROUTING", "-p", "tcp", "-d", localIp, "--dport", port, "-j", "SNAT", "--to-source", remoteIp)
}
func rmPortForward(ruleName string) {
log.Print("Port forwarding not currently implemented for Linux/iptables")
}

23
net_test.go
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@ -1,23 +0,0 @@
/*
Copyright 2016-2017 gtalent2@gmail.com
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this
file, You can obtain one at http://mozilla.org/MPL/2.0/.
*/
package main
import (
"net"
"strconv"
"testing"
)
func TestPortCount(t *testing.T) {
port := 49214
// listen on some port that nothing should be using for the sake of the test
go func() {
addr, _ := net.ResolveTCPAddr("tcp", "0.0.0.0:"+strconv.Itoa(port))
net.ListenTCP("tcp", addr)
}()
}

56
servermanager.go
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@ -11,6 +11,7 @@ import (
"log"
"net"
"strconv"
"time"
)
const (
@ -31,12 +32,14 @@ type ServerHandler interface {
}
type ServerManager struct {
name string
ports []int
in chan serverManagerEvent
done chan interface{}
usageScore int // spin down server when this reaches 0
server ServerHandler
name string
ports []int
in chan serverManagerEvent
done chan interface{}
connStatus chan ConnStatus
lastKeepAliveTime time.Time
usageScore int // spin down server when this reaches 0
server ServerHandler
}
func NewServerManager(name string, server ServerHandler, settings Settings) *ServerManager {
@ -58,11 +61,22 @@ func NewServerManager(name string, server ServerHandler, settings Settings) *Ser
func (me *ServerManager) Serve() {
// TODO: see if server is currently up, and setup port forwarding if so
fiveMin := time.Duration(5) * time.Minute
ticker := time.NewTicker(fiveMin)
// event loop
for running := true; running; {
select {
case status := <-me.connStatus:
if status.Status == CONN_ACTIVE {
me.lastKeepAliveTime = time.Now()
}
case action := <-me.in:
running = me.serveAction(action)
case <-ticker.C:
if time.Since(me.lastKeepAliveTime) > fiveMin {
me.Spindown()
}
}
}
@ -80,7 +94,7 @@ func (me *ServerManager) Spinup(c *net.TCPConn) {
/*
Sends the serve loop a spindown message.
*/
func (me *ServerManager) Spindown(c *net.TCPConn) {
func (me *ServerManager) Spindown() {
me.in <- serverManagerEvent{eventType: SERVERMANAGER_SPINDOWN}
}
@ -95,18 +109,6 @@ func (me *ServerManager) Done() {
<-me.done
}
func (me *ServerManager) addPortForwards(localIp, remoteIp string) {
log.Println("Ports:", me.ports)
for _, p := range me.ports {
port := strconv.Itoa(p)
addPortForward(me.name, localIp, remoteIp, port)
}
}
func (me *ServerManager) rmPortForwards() {
rmPortForward(me.name)
}
func (me *ServerManager) setupListener(port int) {
portStr := strconv.Itoa(port)
addr, err := net.ResolveTCPAddr("tcp", "0.0.0.0:"+portStr)
@ -125,14 +127,9 @@ func (me *ServerManager) setupListener(port int) {
conn, err := l.AcceptTCP()
if err != nil {
log.Print("Could not accept TCP connection:", err)
} else {
// connection accepted
} else { // connection accepted
// spinup machine
me.Spinup(conn)
// close existing connection, not doing anything with it
conn.Close()
}
}
}
@ -146,16 +143,15 @@ func (me *ServerManager) serveAction(event serverManagerEvent) bool {
targetIp, err := me.server.Spinup(me.name)
if err == nil {
log.Println("ServerManager: Got IP for", me.name+":", targetIp)
localIp := event.tcpConn.LocalAddr().String()
me.addPortForwards(localIp, targetIp)
wanAddr := event.tcpConn.LocalAddr().String()
_, port, _ := net.SplitHostPort(wanAddr)
go portForward(event.tcpConn, targetIp, port, me.connStatus)
} else {
log.Println("ServerManager: Could not spin up "+me.name+":", err)
}
case SERVERMANAGER_SPINDOWN:
err := me.server.Spindown(me.name)
if err == nil {
me.rmPortForwards()
} else {
if err != nil {
log.Println("ServerManager: Could not spin down "+me.name+":", err)
}
case SERVERMANAGER_STOP:

2
varstate.go
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@ -1,5 +1,5 @@
/*
Copyright 2016 gtalent2@gmail.com
Copyright 2016-2017 gtalent2@gmail.com
This Source Code Form is subject to the terms of the Mozilla Public
License, v. 2.0. If a copy of the MPL was not distributed with this