gistfile1.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"net"
	"strings"
)

func main() {
	listener, err := net.ListenTCP("tcp", &net.TCPAddr{Port: 8080})
	if err != nil {
		fmt.Printf("failed to listen on :8080: %s\n", err)
		return
	}

	for {
		c, err := listener.AcceptTCP()
		if err != nil {
			fmt.Printf("failed to accept: %s\n", err)
			return
		}
		go service(c)
	}
}

func service(c *net.TCPConn) {
	defer c.Close()

	c.SetReadTimeout(60 * 1000 * 1000 * 1000)
	lines := bufio.NewReader(c)

	headerBytes, isPrefix, err := lines.ReadLine()
	if err != nil || isPrefix {
		return
	}
	header := string(headerBytes)

	for {
		l, _, err := lines.ReadLine()
		if err != nil {
			return
		}
		if len(l) == 0 {
			break
		}
	}

	fmt.Printf("%s\n", header)
	parts := strings.Split(header, " ", -1)
	if parts[0] != "CONNECT" {
		c.Write([]byte("HTTP/1.1 500 Server Error\r\n\r\nServer Error.\r\n"))
		return
	}

	fmt.Printf("connecting to %s\n", parts[1])
	out, err := net.Dial("tcp", parts[1])
	if err != nil {
		fmt.Printf("failed to connect to %s\n", parts[1])
		return
	}

	c.Write([]byte("HTTP/1.1 200 Connected ok\r\n\r\n"))

	go io.Copy(out, lines)
	io.Copy(c, out)
}