/
main.go
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/
main.go
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// Copyright (c) 2019 Timo Savola. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main
import (
"crypto/ed25519"
"crypto/tls"
"errors"
"flag"
"fmt"
"io"
"io/ioutil"
"log"
"net"
"os"
"path"
"strings"
"gateservice.net/listener/proxy"
"golang.org/x/crypto/ssh"
)
type portDesc struct {
name string
localAddr string
remotePort string
}
func main() {
if err := Main(); err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}
func Main() error {
flag.Usage = func() {
fmt.Fprintf(flag.CommandLine.Output(), "Usage: %s [options] remotehost\n", os.Args[0])
flag.PrintDefaults()
}
var identityFile string
if home := os.Getenv("HOME"); home != "" {
identityFile = path.Join(home, ".ssh/id_ed25519")
}
flag.StringVar(&identityFile, "i", identityFile, "ssh-ed25519 private key for remote connections")
var (
localCert string
localKey string
)
flag.StringVar(&localCert, "tls-cert", localCert, "Local certificate; TLS enabled for all listeners")
flag.StringVar(&localKey, "tls-key", localKey, "Local private key; TLS enabled for all listeners")
ports := []portDesc{
{"HTTP", "", "443"},
{"SMTP", "", "465"},
{"NNTP", "", "563"},
{"LDAP", "", "636"},
{"DNS", "", "853"},
{"FTP data", "", "989"},
{"FTP control", "", "990"},
{"Telnet", "", "992"},
{"IMAP", "", "993"},
{"POP3", "", "995"},
{"", "", "1111"},
{"Gemini", "", "1965"},
{"UUCP", "", "4031"},
{"SIP", "", "5061"},
{"XMPP client", "", "5223"},
{"STUN/TURN", "", "5349"},
{"AMQP", "", "5671"},
{"NETCONF", "", "6513"},
{"Syslog", "", "6514"},
{"IRC", "", "6697"},
{"MQTT", "", "8883"},
}
for i, p := range ports {
name := p.name
key := strings.ToLower(strings.Replace(strings.Replace(name, "/", "-", -1), " ", "-", -1))
if name == "" {
name = "custom protocol"
key = p.remotePort
}
flag.StringVar(&ports[i].localAddr, key, p.localAddr, fmt.Sprintf("Local %s listening port or address, forwarded to remote TLS port %s", name, p.remotePort))
}
flag.Parse()
if identityFile == "" || flag.NArg() != 1 {
flag.Usage()
os.Exit(2)
}
remoteHost := flag.Arg(0)
data, err := ioutil.ReadFile(identityFile)
if err != nil {
return err
}
x, err := ssh.ParseRawPrivateKey(data)
if err != nil {
return err
}
authKey, ok := x.(*ed25519.PrivateKey)
if !ok {
return fmt.Errorf("%s: not an ed25519 private key", identityFile)
}
var localTLS *tls.Config
if localCert != "" || localKey != "" {
cert, err := tls.LoadX509KeyPair(localCert, localKey)
if err != nil {
return err
}
localTLS = &tls.Config{
Certificates: []tls.Certificate{cert},
}
}
prox := proxy.New(*authKey)
done := make(chan error)
for _, p := range ports {
if p.localAddr != "" {
localAddr := p.localAddr
if !strings.Contains(":", localAddr) {
localAddr = "localhost:" + localAddr
}
go forward(done, localAddr, localTLS, remoteHost+":"+p.remotePort, prox)
}
}
return <-done
}
func forward(done chan<- error, localAddr string, localTLS *tls.Config, remoteAddr string, prox *proxy.Proxy) {
var err error
defer func() {
if err == nil {
err = errors.New("panic")
}
done <- fmt.Errorf("%s: %v", localAddr, err)
}()
l, err := net.Listen("tcp", localAddr)
if err != nil {
return
}
defer l.Close()
for {
var conn net.Conn
conn, err = l.Accept()
if err != nil {
return
}
go handle(conn.(*net.TCPConn), localTLS, remoteAddr, prox)
}
}
func handle(localTCPConn *net.TCPConn, localTLSConfig *tls.Config, remoteAddr string, prox *proxy.Proxy) {
var (
localTLSConn *tls.Conn
localConn io.ReadWriter
)
if localTLSConfig != nil {
localTLSConn = tls.Server(localTCPConn, localTLSConfig)
defer localTLSConn.Close()
localConn = localTLSConn
} else {
defer localTCPConn.Close()
localConn = localTCPConn
}
tag := localTCPConn.RemoteAddr().String()
log.Printf("%s: connect", tag)
defer log.Printf("%s: disconnect", tag)
remoteConn, err := prox.Dial("tcp", remoteAddr, nil)
if err != nil {
log.Printf("%s: %v", tag, err)
return
}
defer remoteConn.Close()
sendDone := make(chan struct{})
recvDone := make(chan struct{})
go transfer(sendDone, tag+": send", remoteConn, localConn)
go transfer(recvDone, tag+": recv", localConn, remoteConn)
for sendDone != nil || recvDone != nil {
select {
case <-sendDone:
sendDone = nil
if localTLSConn == nil {
localTCPConn.CloseRead()
}
case <-recvDone:
recvDone = nil
if localTLSConn != nil {
localTLSConn.CloseWrite()
} else {
localTCPConn.CloseWrite()
}
}
}
}
func transfer(done chan<- struct{}, tag string, dest io.Writer, src io.Reader) {
defer close(done)
if _, err := io.Copy(dest, src); err == nil {
log.Printf("%s done", tag)
} else {
log.Printf("%s: %v", tag, err)
}
}