获取"127.0.0.1无法分配请求的地址" - http.Client

Question

我正在做的事情是相当直接的.我需要创建一个非常小而快的"代理"服务器.目前我有一个代理到(nodejs)和代理服务(go)的基线服务器.请原谅缺乏实际的"代理" - 只是现在测试.

基线服务

var http = require('http');
http.createServer(function (req, res) {
    // console.log("received request");
    res.writeHead(200, {'Content-Type': 'text/plain'});
      res.end('Hello World\n');
}).listen(8080, '127.0.0.1');
console.log('Server running at http://127.0.0.1:8080/');

代理服务

package main

import (
  "flag"
  "log"
  "net/http"
  "net/url"
)

var (
  listen = flag.String("listen", "0.0.0.0:9000", "listen on address")
  logp = flag.Bool("log", false, "enable logging")
)

func main() {
  flag.Parse()
  proxyHandler := http.HandlerFunc(proxyHandlerFunc)
  log.Fatal(http.ListenAndServe(*listen, proxyHandler))
  log.Println("Started router-server on 0.0.0.0:9000")
}

func proxyHandlerFunc(w http.ResponseWriter, r *http.Request) {
  // Log if requested
  if *logp {
    log.Println(r.URL)
  }

  /* 
   * Tweak the request as appropriate:
   *   - RequestURI may not be sent to client
   *   - Set new URL
   */
  r.RequestURI = ""
  u, err := url.Parse("http://localhost:8080/")
  if err != nil {
    log.Fatal(err)
  }
  r.URL = u

  // And proxy
  // resp, err := client.Do(r)
  c := make(chan *http.Response)
  go doRequest(c)
  resp := <-c
  if resp != nil {
    err := resp.Write(w)
    if err != nil {
      log.Println("Error writing response")
    } else {
      resp.Body.Close()
    }
  }
}


func doRequest(c chan *http.Response) {
  // new client for every request.
  client := &http.Client{}

  resp, err := client.Get("http://127.0.0.1:8080/test")
  if err != nil {
    log.Println(err)
    c <- nil
  } else {
    c <- resp
  }
}

正如标题中提到的那样,我的问题是我2013/10/28 21:22:30 Get http://127.0.0.1:8080/test: dial tcp 127.0.0.1:8080: can't assign requested address从doRequest函数中得到错误,而且我不知道为什么.谷歌搜索这个特定的错误产生看似无关的结果.

Answer 1

这段代码有两个主要问题.

1. 您没有处理客户端停止或使用keep alives(由getTimeoutServer在下面处理)
2. 您没有处理服务器(您的http.Client正在与之交谈)超时(由TimeoutConn在下面处理).

这可能是您耗尽本地端口的原因.我从过去的经验中知道node.js会非常积极地保持活力.

有许多小问题,在不需要的时候每次创建对象.创建不需要的goroutine(每个传入的请求在你处理它之前都在它自己的goroutine中).

这是一个快速刺(我没时间测试好).希望它会让你走上正确的轨道:(你会想要升级它以不在本地缓冲响应)

package main

import (
    "bytes"
    "errors"
    "flag"
    "fmt"
    "log"
    "net"
    "net/http"
    "net/url"
    "runtime"
    "strconv"
    "time"
)

const DEFAULT_IDLE_TIMEOUT = 5 * time.Second

var (
    listen       string
    logOn        bool
    localhost, _ = url.Parse("http://localhost:8080/")
    client       = &http.Client{
        Transport: &http.Transport{
            Proxy: NoProxyAllowed,
            Dial: func(network, addr string) (net.Conn, error) {
                return NewTimeoutConnDial(network, addr, DEFAULT_IDLE_TIMEOUT)
            },
        },
    }
)

func main() {
    runtime.GOMAXPROCS(runtime.NumCPU())
    flag.StringVar(&listen, "listen", "0.0.0.0:9000", "listen on address")
    flag.BoolVar(&logOn, "log", true, "enable logging")
    flag.Parse()
    server := getTimeoutServer(listen, http.HandlerFunc(proxyHandlerFunc))
    log.Printf("Starting router-server on %s\n", listen)
    log.Fatal(server.ListenAndServe())
}

func proxyHandlerFunc(w http.ResponseWriter, req *http.Request) {
    if logOn {
        log.Printf("%+v\n", req)
    }
    // Setup request URL
    origURL := req.URL
    req.URL = new(url.URL)
    *req.URL = *localhost
    req.URL.Path, req.URL.RawQuery, req.URL.Fragment = origURL.Path, origURL.RawQuery, origURL.Fragment
    req.RequestURI, req.Host = "", req.URL.Host
    // Perform request
    resp, err := client.Do(req)
    if err != nil {
        w.WriteHeader(http.StatusBadGateway)
        w.Write([]byte(fmt.Sprintf("%d - StatusBadGateway: %s", http.StatusBadGateway, err)))
        return
    }
    defer resp.Body.Close()
    var respBuffer *bytes.Buffer
    if resp.ContentLength != -1 {
        respBuffer = bytes.NewBuffer(make([]byte, 0, resp.ContentLength))
    } else {
        respBuffer = new(bytes.Buffer)
    }
    if _, err = respBuffer.ReadFrom(resp.Body); err != nil {
        w.WriteHeader(http.StatusBadGateway)
        w.Write([]byte(fmt.Sprintf("%d - StatusBadGateway: %s", http.StatusBadGateway, err)))
        return
    }
    // Write result of request
    headers := w.Header()
    var key string
    var val []string
    for key, val = range resp.Header {
        headers[key] = val
    }
    headers.Set("Content-Length", strconv.Itoa(respBuffer.Len()))
    w.WriteHeader(resp.StatusCode)
    w.Write(respBuffer.Bytes())
}

func getTimeoutServer(addr string, handler http.Handler) *http.Server {
    //keeps people who are slow or are sending keep-alives from eating all our sockets
    const (
        HTTP_READ_TO  = DEFAULT_IDLE_TIMEOUT
        HTTP_WRITE_TO = DEFAULT_IDLE_TIMEOUT
    )
    return &http.Server{
        Addr:         addr,
        Handler:      handler,
        ReadTimeout:  HTTP_READ_TO,
        WriteTimeout: HTTP_WRITE_TO,
    }
}

func NoProxyAllowed(request *http.Request) (*url.URL, error) {
    return nil, nil
}

//TimeoutConn-------------------------
//Put me in my own TimeoutConn.go ?

type TimeoutConn struct {
    net.Conn
    readTimeout, writeTimeout time.Duration
}

var invalidOperationError = errors.New("TimeoutConn does not support or allow .SetDeadline operations")

func NewTimeoutConn(conn net.Conn, ioTimeout time.Duration) (*TimeoutConn, error) {
    return NewTimeoutConnReadWriteTO(conn, ioTimeout, ioTimeout)
}

func NewTimeoutConnReadWriteTO(conn net.Conn, readTimeout, writeTimeout time.Duration) (*TimeoutConn, error) {
    this := &TimeoutConn{
        Conn:         conn,
        readTimeout:  readTimeout,
        writeTimeout: writeTimeout,
    }
    now := time.Now()
    err := this.Conn.SetReadDeadline(now.Add(this.readTimeout))
    if err != nil {
        return nil, err
    }
    err = this.Conn.SetWriteDeadline(now.Add(this.writeTimeout))
    if err != nil {
        return nil, err
    }
    return this, nil
}

func NewTimeoutConnDial(network, addr string, ioTimeout time.Duration) (net.Conn, error) {
    conn, err := net.DialTimeout(network, addr, ioTimeout)
    if err != nil {
        return nil, err
    }
    if conn, err = NewTimeoutConn(conn, ioTimeout); err != nil {
        return nil, err
    }
    return conn, nil
}

func (this *TimeoutConn) Read(data []byte) (int, error) {
    this.Conn.SetReadDeadline(time.Now().Add(this.readTimeout))
    return this.Conn.Read(data)
}

func (this *TimeoutConn) Write(data []byte) (int, error) {
    this.Conn.SetWriteDeadline(time.Now().Add(this.writeTimeout))
    return this.Conn.Write(data)
}

func (this *TimeoutConn) SetDeadline(time time.Time) error {
    return invalidOperationError
}

func (this *TimeoutConn) SetReadDeadline(time time.Time) error {
    return invalidOperationError
}

func (this *TimeoutConn) SetWriteDeadline(time time.Time) error {
    return invalidOperationError
}

Answer 2

我们遇到了这个问题，经过大量时间尝试调试后，我遇到了这个：https : //code.google.com/p/go/source/detail?r=d4e1ec84876c

如果客户端想要重用 TCP 连接的优势，这会将负担转移到客户端读取整个响应主体。

所以一定要在结束之前阅读整个正文，有几种方法可以做到。这个函数可以派上用场，通过记录尚未读取的额外字节并为您清除流以便它可以重用连接来让您查看是否有此问题：

func closeResponse(response *http.Response) error {
    // ensure we read the entire body
    bs, err2 := ioutil.ReadAll(response.Body)
    if err2 != nil {
        log.Println("Error during ReadAll!!", err2)
    }
    if len(bs) > 0 {
        log.Println("Had to read some bytes, not good!", bs, string(bs))
    }
    return response.Body.Close()
}

或者如果你真的不关心身体，你可以用这个丢弃它：

io.Copy(ioutil.Discard, response.Body)