socks5.go

package socks5

import (
  "net"
  "time"
  "bytes"
  "errors"
  "bufio"
  "strconv"
  "strings"
  "net/http"
  "encoding/binary"
)



type Socks5RoundTripper struct {
  Proxy string
  Resp *http.Response
  conn net.Conn
  reqch chan *http.Response
  writech chan bool
  writer *bufio.Writer
  reader *bufio.Reader
  sendreq time.Duration
  recvresp time.Duration
  ModifyHeader func(*http.Header)
}

func (Socks5 *Socks5RoundTripper) generateRequest(req *http.Request) (message []byte, err error) {
  host := ""
  var port uint32
  var msg = make([]byte, 128)
  if len(req.URL.Host) > 120 {
    return nil, errors.New("req.URL.Host too long")
  }
  copy(msg, []byte("\x05\x01\x00\x03"))
  if !strings.Contains(req.URL.Host, ":") {
    host = req.URL.Host
    port = uint32(80)
  } else {
    hostAndPort := strings.Split(host, ":")
    host = hostAndPort[0]
    p, err := strconv.Atoi(hostAndPort[1])
    if err != nil {
      return nil, errors.New("Wired req.URL.Host")
    }
    port = uint32(p)
  }
  msg[4]= byte(len(host))
  copy(msg[5:], []byte(host))
  portBuf := make([]byte, 2)
  binary.BigEndian.PutUint16(portBuf, uint16(port))
  copy(msg[len(host)+5:], portBuf)
  return msg[:len(host)+7], nil
}

func (Socks5 *Socks5RoundTripper) readLoop(req *http.Request) {
  res, err := http.ReadResponse(Socks5.reader, req)
  if err != nil {
    Socks5.reqch <- nil
    return
  }
  Socks5.reqch <- res
}

func (Socks5 *Socks5RoundTripper) writeLoop(req *http.Request) {
  err := req.Write(Socks5.writer)
  if err == nil {
    Socks5.writer.Flush()
    Socks5.writech <- true
  } else {
    Socks5.writech <- false
  }
}

func (Socks5 *Socks5RoundTripper) RoundTrip(req *http.Request) (resp *http.Response, err error){
  Socks5.writech = make(chan bool, 1)
  Socks5.reqch = make(chan *http.Response, 1)
  if Socks5.ModifyHeader != nil {
    Socks5.ModifyHeader(&req.Header)
  }
  dialc := make(chan net.Conn, 1)
  var dialTimeout <-chan time.Time
  go func() {
    dialTimeout = time.After(1 * time.Second)
    conn, err := net.Dial("tcp", Socks5.Proxy)
    if err != nil {
      dialc <- nil
    }
    dialc <- conn
  }()
  select {
  case Socks5.conn = <-dialc:
    if Socks5.conn == nil {
      return nil, errors.New("socks5: net.Dial failed")
    }
  case <-dialTimeout:
    return nil, errors.New("socks5: connect proxy timeout")
  }
  if tcpconn, ok := Socks5.conn.(*net.TCPConn); ok {
    tcpconn.SetNoDelay(true)
  }
  Socks5.reader = bufio.NewReader(Socks5.conn)
  Socks5.writer = bufio.NewWriter(Socks5.conn)

  var sendHandleShakeChan = make(chan bool,  )
  var sendHandleShakeTimeout <-chan time.Time
  go func() {
    sendHandleShakeTimeout = time.After(1 * time.Second)
    _, err := Socks5.writer.Write([]byte("\x05\x01\x00"))
    if err != nil {
      sendHandleShakeChan <- false
    } else {
      sendHandleShakeChan <- true
      Socks5.writer.Flush()
    }
  }()

  select {
  case send := <-sendHandleShakeChan:
    if ! send {
      return nil, errors.New("socks5: handshake error")
    }
  case <-sendHandleShakeTimeout:
    return nil, errors.New("socks5: handshake timeout")
  }

  var recvHandShakeTimeout <-chan time.Time
  var recvHandShakeChan = make(chan []byte, 1)
  go func () {
    recvHandShakeTimeout = time.After(1 * time.Second)
    msg := make([]byte, 12)
    for {
      n, err := Socks5.reader.Read(msg)
      if n != 0 {
        break
      }
      if err != nil {
        recvHandShakeChan <- nil
      }
    }
    recvHandShakeChan <- msg
  }()
  select {
  case res := <-recvHandShakeChan:
    if !bytes.HasPrefix(res, []byte("\x05\x00")) {
      return nil, errors.New("sock5: handshake failed")
    }
  case <-recvHandShakeTimeout:
    return nil,  errors.New("socks5: send handshake timout")
  }

  var requestTimeout <-chan time.Time
  var requestChan = make(chan bool, 1)
  go func () {
    requestTimeout = time.After(1 * time.Second)
    msg, err := Socks5.generateRequest(req)
    if err != nil {
      requestChan <- false
      return
    }
    _, err = Socks5.writer.Write(msg)
    if err != nil {
      requestChan <- false
    } else {
      Socks5.writer.Flush()
      requestChan <- true
    }
  }()
  select {
  case res := <-requestChan:
    if !res {
      return nil, errors.New("socks5: send request failed")
    }
  case <-requestTimeout:
    return nil, errors.New("send request timeout")
  }

  var reqResponseTimeout <-chan time.Time
  var reqResponseChan = make(chan string, 1)
  go func () {
    reqResponseTimeout = time.After(5 * time.Second)
    msg := make([]byte, 12)
    _, err := Socks5.reader.Read(msg)
    if err != nil {
      reqResponseChan <- ""
    }
    reqResponseChan <- string(msg)
  }()
  select {
  case res := <-reqResponseChan:
    if !strings.HasPrefix(res, "\x05\x00") {
      return nil, errors.New("socks5: request failed")
    }
  case <-reqResponseTimeout:
    return nil, errors.New("socks5: request timeout")
  }
  var writeTimeout <-chan time.Time
  writeTimeout = time.After(Socks5.sendreq)
  go Socks5.writeLoop(req)
  select {
  case wc := <-Socks5.writech:
    if !wc {
      return nil, errors.New("socks5: write request failed")
    }
  case <-writeTimeout:
    return nil, errors.New("socks5: write request timeout")
  }
  var readTimeout <-chan time.Time
  readTimeout = time.After(Socks5.recvresp)
  go Socks5.readLoop(req)
  select {
  case rc := <-Socks5.reqch:
    if rc == nil {
      return nil, errors.New("socks5: wried response")
    }
    resp = rc
  case <-readTimeout:
    return nil, errors.New("socks5: remote timeout")
  }
  return
}


func SetProxy(url string) (err error) {
  _, err = net.ResolveTCPAddr("tcp", url)
  if err != nil {
    return err
  }
  http.DefaultClient = &http.Client{}
  socks5 := &Socks5RoundTripper{}
  socks5.Proxy = url
  socks5.sendreq = 30 * time.Second
  socks5.recvresp = 30 * time.Second
  http.DefaultClient.Transport = socks5
  return
}

func ModifyHeader(mh func(*http.Header)) {
  if st, ok := http.DefaultClient.Transport.(*Socks5RoundTripper); ok {
    st.ModifyHeader = mh
  }
}

func SetTimeout(sendreq, recvresp int64) {
  if st, ok := http.DefaultClient.Transport.(*Socks5RoundTripper); ok {
    if sendreq <= 0 || recvresp <= 0 {
      return
    }
    st.sendreq = time.Duration(sendreq)
    st.recvresp = time.Duration(recvresp)
  }
}

func UnsetProxy() {
  http.DefaultClient = &http.Client{}
}

socks5_example.go

func testGet(url string) {
  socks5.SetProxy("127.0.0.1:9988")
  socks5.ModifyHeader(func(header *http.Header) {
    header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64; rv:25.0) Gecko/20100101 Firefox/25.0")
  })
  resp, err := http.Get(url)
  if err != nil {
    panic(err)
  }
  fmt.Println(resp.Status)
  io.Copy(os.Stdout, resp.Body)
  fmt.Println("")
}

func main() {
  testGet(os.Args[1])
}