HTTP Header 在线解析
----


## 1. 当前你的 Header 
UserAgent: CCBot/2.0 (https://commoncrawl.org/faq/)
Protocol: HTTP/1.1
Method: GET
Host: dhcp.cn
RemoteAddr: 172.16.0.1:16954
RequestURI: /header
Body: 
X-Forwarded-For: 34.231.244.12
X-Forwarded-Port: 
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Referer: 
 

## 2. 通过 curl 命令模拟发送

### 2.1 GET 请求示例 

```bash
$ curl  https://dhcp.cn/header/shop 
UserAgent: curl/7.64.1
Protocol: HTTP/1.1
Method: GET
Host: dhcp.cn
RemoteAddr: 127.0.0.6:47740
RequestURI: /header/shop
Body:
X-Forwarded-For: xxx.xx.xx.x
Accept: */*
Referer:
```

### 2.1 POST 请求示例

```bash
$ curl -XPOST -H 'X-Forwarded-For: 192.168.1.1' -H "content-Type: application/JSON"  https://dhcp.cn/header/shop  -d '{"age": 22}'
UserAgent: curl/7.64.1
Protocol: HTTP/1.1
Method: POST
Host: dhcp.cn
RemoteAddr: 127.0.0.6:47740
RequestURI: /header/shop
Body: {"age": 22}
X-Forwarded-For: 192.168.1.1,xx.xx.xx.xx
Accept: */*
Referer:
```



## 3. Golang 获取 HTTP Header

以下是一个完整的基于 Golang 实现的 HTTP Server，打印 HTTP Header。

```golang
package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
)

func main() {

	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {

		body, _ := ioutil.ReadAll(r.Body) // 获取 Body，因为 r.Body 的类型是 io.ReadCloser，而不是 string

		fmt.Fprintf(w, "UserAgent: %s\n", r.UserAgent())                         // 示例：curl/7.64.1，r.UserAgent() 是字符串，直接打印即可
		fmt.Fprintf(w, "Protocol: %s\n", r.Proto)                                // 示例：HTTP/1.1
		fmt.Fprintf(w, "Method: %s\n", r.Method)                                 // 示例：GET
		fmt.Fprintf(w, "Host: %s\n", r.Host)                                     // 示例：192.168.31.125，请求主机
		fmt.Fprintf(w, "RemoteAddr: %s\n", r.RemoteAddr)                         // 示例：192.168.31.125:54642，客户端地址（如果用了负载均衡器，请通过 X-Forwarded-For 来获取客户端真实IP）
		fmt.Fprintf(w, "RequestURI: %s\n", r.RequestURI)                         // 示例：/mall，请求URI
		fmt.Fprintf(w, "Header: %s\n", r.Header)                                 // 示例：map[Accept:[*/*] Content-Length:[11] Content-Type:[application/JSON] User-Agent:[curl/7.64.1] X-Forwarded-For:[192.168.1.1]]
		fmt.Fprintf(w, "Body: %s\n", body)                                       // 示例：{"age": 22}，例如POST 请求的 Body
		fmt.Fprintf(w, "X-Forwarded-For: %s\n", r.Header.Get("X-Forwarded-For")) // 示例：192.168.1.1，自定义Header，一般有负载均衡器的场景会把客户端的真实IP存储在这里
		fmt.Fprintf(w, "Accept: %s\n", r.Header.Get("Accept"))                   // 示例：*/*

	})

	log.Println("Starting server ...")
	log.Fatal(http.ListenAndServe(":80", nil))
}
```