package main
 
import (
  "bufio"
  "encoding/base64"
  "errors"
  "fmt"
  "io"
  "net"
  "net/url"
  "os"
  "path/filepath"
  "strconv"
  "strings"
  "unsafe"
)
 
func main() {
  if len(os.Args) != 3 {
    fmt.Printf(`usage: %s ip:port user:pass
 
get file:
 wget --auth-no-challenge --user=user --password=pass --content-disposition "http://ip:port?/home/tmp.txt"
 curl -u user:pass -OJ "http://ip:port?/home/tmp.txt"
post file:
 wget -qO - --auth-no-challenge --user=user --password=pass --post-file=C:\tmp.txt "http://ip:port?/home/tmp.txt"
 curl -u user:pass --data-binary @C:\tmp.txt "http://ip:port?/home/tmp.txt"
`, os.Args[0])
    return
  }
  addr, err := net.ResolveTCPAddr("tcp", os.Args[1])
  if err != nil {
    panic(err)
  }
  ser, err := net.ListenTCP("tcp", addr)
  if err != nil {
    panic(err)
  }
 
  fmt.Printf("Listen: [%s]\n", addr)
  authStr = "Basic " + base64.StdEncoding.EncodeToString([]byte(os.Args[2]))
  for {
    ln, err := ser.AcceptTCP()
    if err != nil {
      panic(err)
    }
    go func(l *net.TCPConn) {
      err := handleFile(l)
      if err != nil {
        respData(l, err.Error())
      }
      l.Close()
    }(ln)
  }
}
 
const (
  maxMemory = 10  20 // 緩存10MB
  respMsg  = "HTTP/1.1 200 OK\r\nContent-Type:text/plain;charset=utf-8\r\nContent-Disposition:attachment;filename=resp.txt\r\nContent-Length:%d\r\n\r\n%s"
  getHeader = "HTTP/1.1 200 OK\r\nContent-Type:application/octet-stream\r\nContent-Disposition:attachment;filename=%s\r\nContent-Length:%d\r\nContent-Transfer-Encoding:binary\r\n\r\n"
)
 
var authStr string // 授權信息
 
func respData(w io.Writer, data string) {
  msg := data + "\r\n"
  fmt.Fprintf(w, respMsg, len(msg), msg)
}
 
func handleFile(l *net.TCPConn) error {
  br := bufio.NewReaderSize(l, maxMemory)
  method, path, length, err := getHeaderMsg(br)
  if err != nil {
    return err
  }
  fmt.Printf("[%s - %s - %d]\n", method, path, length)
 
  if method == "GET" {
    return httpGetFile(path, l, length)
  }
  err = httpPostFile(path, br, length)
  if err != nil {
    return err
  }
  respData(l, "post ok")
  return nil
}
 
// 內存復用,更快速,省內存
func bytesToString(b []byte) string {
  return *(*string)(unsafe.Pointer(b))
}
 
func getHeaderMsg(r *bufio.Reader) (string, string, int64, error) {
  // 讀取第一行,提取有用信息
  line, _, err := r.ReadLine()
  if err != nil {
    return "", "", 0, err
  }
  header := strings.Fields(bytesToString(line))
  if len(header)  3 { // 首行至少3列數據
    return "", "", 0, errors.New("header error")
  }
  method, path := header[0], ""
 
  s := strings.Index(header[1], "?")
  if s >= 0 {
    path, _ = url.QueryUnescape(header[1][s+1:])
  }
  if path == "" { // ?號后面就是文件路徑,需要解碼url一下
    return "", "", 0, errors.New("path error")
  }
 
  var length int64
  if method == "GET" {
    fi, err := os.Stat(path)
    if err != nil {
      return "", "", 0, err
    }
    length = fi.Size() // GET請求提前得到文件大小
  } else if method != "POST" {
    return "", "", 0, errors.New(method + " not support")
  }
 
  var authCheck string
  for {
    line, _, err = r.ReadLine()
    if err != nil {
      return "", "", 0, err
    }
    if len(line) == 0 {
      break // 遇到空行,之后為請求體
    }
    header = strings.Split(bytesToString(line), ":")
    if len(header) == 2 { // 頭部[key: val]解析
      header[0] = strings.ToLower(strings.TrimSpace(header[0]))
      header[1] = strings.TrimSpace(header[1])
      if method == "POST"  header[0] == "content-length" {
        length, _ = strconv.ParseInt(header[1], 10, 64)
      } else if header[0] == "authorization" {
        authCheck = header[1]
      }
    }
  }
  if authCheck != authStr {
    return "", "", 0, errors.New("authorization error")
  }
  return method, path, length, nil
}
 
func httpPostFile(path string, r io.Reader, length int64) error {
  fw, err := os.Create(path)
  if err != nil {
    return err
  }
  defer fw.Close()
  pr := newProgress(r, length)
  _, err = io.CopyN(fw, pr, length)
  pr.Close()
  return err
}
 
func httpGetFile(path string, w io.Writer, size int64) error {
  fr, err := os.Open(path)
  if err != nil {
    return err
  }
  defer fr.Close()
  fmt.Fprintf(w, getHeader, filepath.Base(path), size)
  pr := newProgress(fr, size)
  _, err = io.Copy(w, pr)
  pr.Close()
  return err
}
 
type progress struct {
  r  io.Reader
  cnt int64
  rate chan int64
}
 
func newProgress(r io.Reader, size int64) io.ReadCloser {
  p := progress{r: r, rate: make(chan int64)}
  // 之所以這樣做進度,是因為打印耗性能,因此在協程中打印進度
  // 在處理數據中用非阻塞方式往chan中傳處理字節數
  go func(rate -chan int64, all int64) {
    for cur := range rate {
      fmt.Printf("\rhandle:%4d%%", cur*100/all)
    }
    fmt.Printf("\rhandle: 100%%\r\n\r\n")
  }(p.rate, size)
  return p
}
 
func (p *progress) Read(b []byte) (int, error) {
  n, err := p.r.Read(b)
  p.cnt += int64(n)
  select { // 非阻塞方式往chan中寫數據
  case p.rate - p.cnt:
  default:
  }
  return n, err
}
 
func (p *progress) Close() error {
  close(p.rate) // 關閉chan,通知打印協程退出
  return nil
}

usage: UpDownFile ip:port
 
get file:
 wget --auth-no-challenge --user=user --password=pass --content-disposition "http://ip:port?/home/tmp.txt"
 curl -u user:pass -OJ "http://ip:port?/home/tmp.txt"
post file:
 wget -qO - --auth-no-challenge --user=user --password=pass --post-file=C:\tmp.txt "http://ip:port?/home/tmp.txt"
 curl -u user:pass --data-binary @C:\tmp.txt "http://ip:port?/home/tmp.txt"