http.ListenAndServe处理函数在端口80上执行两次 [英] http.ListenAndServe handler function executed twice on port 80

问题描述

如果我在端口8080上运行以下简单的http服务器代码，一切都按预期运行。如果我在端口80上运行相同的代码，只需更改端口，处理函数会在每次请求时执行两次。为什么以及如何解决它？

  // httptest项目main.go 
包裹主
 
进口（
净/ http
记录
fmt
html
）
 
 var count int 
 
 func defaultHandler（w http.ResponseWriter，r * http.Request）{
 count ++ 
 fmt.Fprintf（w，Hello，％q count =％d， html.EscapeString（r.URL.Path），count）
 fmt.Println（count，r.RemoteAddr）
} 
 
 func main（）{
 http .HandleFunc（/，defaultHandler）
 log.Fatal（http.ListenAndServe（：8080，nil））
} 
  

如果我在浏览器中输入localhost：8080，我会得到一个响应，计数从1开始，每增加一个新请求就增加1。

如果我将代码更改为端口80，并在浏览器中输入localhost或localhost：80，则会得到第一个响应，计数从1开始，但增加了2与每个以下请求。与此同时，控制台输出的print语句被执行两次。

终端控制台在端口80上运行时有3个请求：

 > go run main.go 
 1 [:: 1]：51335 
 2 [:: 1]：51335 
 3 [:: 1]：51335 
 4 [:: 1]：51335 
 5 [:: 1]：51335 
 6 [:: 1]：51335 
  

浏览器中的响应是 Hello，/count = 1 ， Hello，/count = 3 和 Hello，/count = 5 。

我一直在使用Go版本go1.9.2 windows / amd64和最新的Google Chrome浏览器在Windows 10上本地运行此程序。但是，我在远程Linux服务器上的一个简单Web应用程序中检测到该问题，其代码已使用go版本go1.9.1 linux / amd64进行编译。

>

解决方案

我刚刚在我的电脑上用Fiddler打开了它

浏览器发出2个请求

  GET / HTTP / 1.1 
 GET / favicon。 ico HTTP / 1.1 
  

favicon的请求也会被defaultHandler处理，这会导致count增量

我也尝试过使用firefox，它不会发送另一个favicon的请求。

If I run the following simple http server code on port 8080 everything works as expected. If I run the same code on port 80, by just changing the port, the handler function is executed twice with each request. Why, and how to fix it?

// httptest project main.go
package main

import (
    "net/http"
    "log"
    "fmt"
    "html"
)

var count int

func defaultHandler(w http.ResponseWriter, r *http.Request) {
    count++
    fmt.Fprintf(w, "Hello, %q count=%d", html.EscapeString(r.URL.Path), count)
    fmt.Println(count,r.RemoteAddr)
}

func main() {
    http.HandleFunc("/", defaultHandler)
    log.Fatal(http.ListenAndServe(":8080", nil))
}

If I enter localhost:8080 in the browser, I get a response with a count starting at 1 and increased by 1 with each new request.

If I change the code to port 80 and enter just localhost or localhost:80 in the browser, I get a first response with a count starting at 1 but increased by two with each following request. At the same time the print statement for the console output is executed twice.

Terminal console when running on port 80 with 3 requests:

>go run main.go
1 [::1]:51335
2 [::1]:51335
3 [::1]:51335
4 [::1]:51335
5 [::1]:51335
6 [::1]:51335

The responses in the browser are Hello, "/" count=1, Hello, "/" count=3 and Hello, "/" count=5.

I've been running this locally on Windows 10 with Go version go1.9.2 windows/amd64 and the latest Google Chrome Browser.

However, I detected the issue in a simple web application on a remote Linux server where the code has been compiled with go version go1.9.1 linux/amd64.

解决方案

i just tried it on my pc with Fiddler open

I noticed when navigating to the url using Google Chrome, the browser makes 2 request

GET / HTTP/1.1
GET /favicon.ico HTTP/1.1

the request for the favicon also gets handled by the defaultHandler, which causes the count to increment

I also tried with firefox and it doesn't send another request for the favicon

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