/
expose.go
152 lines (125 loc) · 2.31 KB
/
expose.go
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package main
import (
"errors"
"fmt"
"net"
"os"
"strconv"
"github.com/hashicorp/yamux"
"io/ioutil"
)
func main() {
}
type host struct {
port string
hostName string
}
func (h *host) String() string {
return h.hostName + h.port
}
var defaultUpstream = host{
port: ":3800",
hostName: "localhost",
}
func parseArgs(args []string) error {
if len(os.Args) < 2 {
return errNotEnoughArgs
}
if os.Args[1] == "serve" {
return serve(defaultUpstream.port)
}
_, err := strconv.ParseUint(os.Args[1], 10, 16)
if err != nil {
return err
}
h := host{port: ":" + os.Args[1]}
return expose(defaultUpstream, h)
}
func serve(port string) error {
l, err := net.Listen("tcp", port)
if err != nil {
return err
}
for {
conn, err := l.Accept()
if err != nil {
return err
}
go handle(upstreamServe(conn))
}
return nil
}
func expose(upstream host, downstream host) error {
conn, err := net.Dial("tcp", upstream.String())
if err != nil {
return err
}
return downstreamServe(conn, downstream)
}
func downstreamServe(conn net.Conn, downstream host) error {
session, err := yamux.Server(conn, nil)
if err != nil {
return err
}
control, err := session.Accept()
if err != nil {
return err
}
laddr, err := ioutil.ReadAll(control)
fmt.Println(string(laddr))
if err != nil {
return err
}
for {
incoming, err := session.Accept()
if err != nil {
return err
}
outgoing, err := net.Dial("tcp", downstream.String())
if err != nil {
return err
}
go handle(proxy(incoming, outgoing))
}
return nil
}
func handle(err error) {
fmt.Fprintln(os.Stderr, err)
}
func upstreamServe(conn net.Conn) error {
l, err := net.Listen("tcp", ":0")
if err != nil {
return err
}
session, err := yamux.Client(conn, nil)
if err != nil {
return err
}
control, err := session.Open()
if err != nil {
return err
}
laddr := l.Addr().String()
if _, err := control.Write([]byte(laddr)); err != nil {
return err
}
if err := control.Close(); err != nil {
return err
}
for {
incoming, err := l.Accept()
if err != nil {
return err
}
downstream, err := session.Open()
if err != nil {
return err
}
go handle(proxy(incoming, downstream))
}
return nil
}
func proxy(incoming, downstream net.Conn) error {
// copy from incoming to downstream and vice versa
return nil
}