Golang中的服务器头中间件

Question

I'm trying to set Server Header on every Response. I'm trying to achieve this, using a Middleware for Gin. However, this does not set the Header, for some reason. I've tried to debug this so far, and I could not understand why this should not work. Probably I'm missing something here.

Here is the code

package main

import "fmt"
import "github.com/gin-gonic/gin"

const SERVER_INFO = "Some-Play-Server"

type ServerHeader struct {
    gin.ResponseWriter
    ServerInfo string
}

func (w *ServerHeader) Write(data []byte) (int, error) {
    if w.Header().Get("Server") == "" {
        w.Header().Add("Server", w.ServerInfo)
    }

    return w.ResponseWriter.Write(data)
}

func InitServerHeader() gin.HandlerFunc {
    return func(c *gin.Context) {
        writer := &ServerHeader{c.Writer, SERVER_INFO}
        c.Writer = writer
        c.Next()
    }
}

func main() {
    mux := gin.Default()
    mux.Use(InitServerHeader())
    mux.GET("/", func(c *gin.Context) {
        c.String(200, "OK")
    })

    fmt.Println("Server Listening on 0.0.0.0:8080")
    mux.Run(":8080")
}

And, here is the Test Output

❯ curl -v http://localhost:8080/
* About to connect() to localhost port 8080 (#0)
* Connected to localhost (::1) port 8080 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.30.0
> Host: localhost:8080
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: text/plain
< Date: Wed, 13 Aug 2014 16:54:21 GMT
< Content-Length: 2
< 
OK

Answer 1

You did not use the right method for that ..

package main

import "fmt"
import "github.com/gin-gonic/gin"

const SERVER_INFO = "Some-Play-Server"

type ServerHeader struct {
    gin.ResponseWriter
    ServerInfo string
}

func (w *ServerHeader) WriteHeader(code int) {
    if w.Header().Get("Server") == "" {
        w.Header().Add("Server", w.ServerInfo)
    }

    w.ResponseWriter.WriteHeader(code)
}

func InitServerHeader() gin.HandlerFunc {
    return func(c *gin.Context) {
        writer := &ServerHeader{c.Writer, SERVER_INFO}
        c.Writer = writer
        c.Next()
    }
}

func main() {
    mux := gin.Default()
    mux.Use(InitServerHeader())
    mux.GET("/", func(c *gin.Context) {
        c.String(200, "OK")
    })

    fmt.Println("Server Listening on 0.0.0.0:8080")
    mux.Run(":8080")
}

Here is the Output

$ curl -v 'http://localhost:8080/'
* About to connect() to localhost port 8080 (#0)
* Connected to localhost (::1) port 8080 (#0)
> GET / HTTP/1.1
> User-Agent: curl/7.30.0
> Host: localhost:8080
> Accept: */*
> 
< HTTP/1.1 200 OK
< Content-Type: text/plain
< Server: Some-Play-Server
< Date: Thu, 14 Aug 2014 00:41:27 GMT
< Content-Length: 2
< 
OK