connect2.go

package main

import (
	"bufio"
	"errors"
	"io"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"strings"
)

func dial(proxy string, host string) (conn net.Conn, err error) {
	conn, err = net.Dial("tcp", proxy)
	if err != nil {
		return
	}
	req := &http.Request{
		Method: "CONNECT",
		URL:    &url.URL{Path: host},
		Host:   host,
		Header: make(http.Header),
	}
	req.Write(conn)
	var resp *http.Response
	resp, err = http.ReadResponse(bufio.NewReader(conn), req)
	if err != nil {
		return
	}
	if resp.StatusCode != 200 {
		err = errors.New(resp.Status)
		return
	}
	return
}

func relay(in io.Reader, out io.Writer, quit chan bool) (err error) {
	var n int
	b := make([]byte, 4096)
	for {
		n, err = in.Read(b)
		if err != nil {
			break
		}
		_, err = out.Write(b[:n])
		if err != nil {
			break
		}
	}
	quit <- true
	return
}

func main() {
	proxy := os.Getenv("HTTP_PROXY")
	host := ""
	for _, arg := range os.Args[1:] {
		if strings.HasPrefix(arg, "-proxy=") {
			proxy = arg[7:]
		} else {
			host = arg
		}
	}
	if host == "" {
		log.Fatal("Usage: " + os.Args[0] + " [hostname:port]")
	}
	conn, err := dial(proxy, host)
	if err != nil {
		log.Fatal(err)
	}

	quit := make(chan bool)
	go relay(conn, os.Stdout, quit)
	go relay(os.Stdin, conn, quit)
	<-quit
	conn.Close()
}