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server.go
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server.go
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package server
import (
"fmt"
"github.com/tuxychandru/pubsub"
"log"
"net"
"os/exec"
"strings"
"time"
)
type Server struct {
name string
localPort int
jumpHost string
remoteHost string
remotePort int
proxyPort int
envCmd string
pubsub *pubsub.PubSub
cmd *exec.Cmd
}
func New(name string, localPort int, jumpHost string, remoteHost string, remotePort int, envCommand string) *Server {
s := &Server{
name: name,
localPort: localPort,
jumpHost: jumpHost,
remoteHost: remoteHost,
remotePort: remotePort,
envCmd: envCommand,
}
s.pubsub = pubsub.New(0)
return s
}
func (s *Server) copyConn(from *net.TCPConn, to *net.TCPConn, complete chan bool) {
var err error
var bytes []byte = make([]byte, 1024)
var read int = 0
for {
read, err = from.Read(bytes)
if err != nil {
complete <- true
break
}
_, err = to.Write(bytes[:read])
if err != nil {
complete <- true
break
}
}
}
func (s *Server) proxyConn(lconn *net.TCPConn, rconn *net.TCPConn) {
// now proxy the connection
complete := make(chan bool)
go s.copyConn(lconn, rconn, complete)
go s.copyConn(rconn, lconn, complete)
<-complete
rconn.Close()
lconn.Close()
}
func (s *Server) connectConn(lconn *net.TCPConn) {
var rconn *net.TCPConn
for {
addr, err := net.ResolveTCPAddr("tcp", fmt.Sprintf("localhost:%d", s.proxyPort))
if err != nil {
log.Fatal(err)
}
rconn, err = net.DialTCP("tcp", nil, addr)
if err == nil {
break
}
// couldn't connect... wait for notice that we're connected
connectChan := s.pubsub.SubOnce("process-running")
log.Printf("%s: waiting for process...", s.name)
<-connectChan
}
log.Printf("%s: connected to local port, proxying", s.name)
s.proxyConn(lconn, rconn)
}
func (s *Server) heartbeat() {
c := time.Tick(1 * time.Second)
for _ = range c {
if s.cmd != nil {
s.pubsub.Pub(true, "process-running")
}
}
}
func (s *Server) handlePending(in <-chan *net.TCPConn) {
sshDone := make(chan bool)
go s.heartbeat()
for {
select {
case <-sshDone:
log.Printf("%s: ssh closed", s.name)
s.cmd = nil
case lconn := <-in:
log.Printf("%s: new connection received", s.name)
if s.cmd == nil {
// find an unused local port for the proxying
l, _ := net.Listen("tcp", "")
s.proxyPort = l.Addr().(*net.TCPAddr).Port
log.Printf("%s: using local proxy port %d", s.name, s.proxyPort)
l.Close()
notifyCmd := exec.Command("/usr/local/bin/terminal-notifier",
"-title", s.name,
"-message", "Tunnel connecting",
)
go notifyCmd.Run()
cmd := exec.Command("/usr/bin/ssh",
"-N",
"-o", "ExitOnForwardFailure=true",
"-L",
fmt.Sprintf("localhost:%d:%s:%d", s.proxyPort, s.remoteHost, s.remotePort),
s.jumpHost,
)
if s.envCmd != "" {
out, err := exec.Command("/bin/bash", "-c", s.envCmd).Output()
if err != nil {
log.Fatal(err)
}
log.Printf("%s: using custom environment %s", s.name, out)
cmd.Env = strings.Split(string(out), "\n")
}
log.Printf("%s: starting ssh\n", s.name)
err := cmd.Start()
if err != nil {
log.Fatal(err)
}
s.cmd = cmd
go func(cmd *exec.Cmd, done chan bool) {
cmd.Wait()
done <- true
}(cmd, sshDone)
}
go s.connectConn(lconn)
}
}
}
func (s *Server) Close() {
if s.cmd != nil {
log.Printf("%s: killing subprocess", s.name)
s.cmd.Process.Kill()
}
}
func (s *Server) Listen() error {
var err error
addrString := fmt.Sprintf("localhost:%d", s.localPort)
log.Println(addrString)
addr, err := net.ResolveTCPAddr("tcp", addrString)
if err != nil {
log.Fatal(err)
}
listener, err := net.ListenTCP("tcp", addr)
if err != nil {
log.Fatal(err)
}
pending := make(chan *net.TCPConn)
go s.handlePending(pending)
log.Printf("%s: listening on %d", s.name, s.localPort)
for {
conn, err := listener.AcceptTCP()
if err != nil {
log.Fatal(err)
}
pending <- conn
}
}