Transform http.Response into array of bytes

I am trying to develop a tcp proxy, in this tcp proxy I will have to manipulate both http and tcp requests.

At the moment for the incoming request I detect if it is an http or tcp request, if it is an http then I parse it into an http.Request:

func (s *TcpProxy) OnMessage(c *connection.Connection, ctx interface{}, data []byte) interface{} {
	reader := bytes.NewReader(data)
	newReader := bufio.NewReader(reader)
	req, err := http.ReadRequest(newReader)
    // This is an http request
}

Now I manipulate the request conveniently since I can use the methods exposed from that interface, then eventually I will send the response back from my proxy to the service that received the inbound request.

func (s *TcpProxy) OnMessage(c *connection.Connection, ctx interface{}, data []byte) interface{} {
    reader := bytes.NewReader(data)
	newReader := bufio.NewReader(reader)
	req, err := http.ReadRequest(newReader)
	// Manipulate http request
    // ...
    // Proxy the request
    proxyReq, err := http.NewRequest(req.Method, proxyUrl, req.Body)

	// Capture the duration while making a request to the destination service.
	res, err := httpClient.Do(proxyReq)
    
    buf := res.ToBuffer() // <= How can I achieve this
   
	c.Send(buf)

	c.Close()
	return nil
}

However I cannot find a way to convert back the response into an array of bytes or string, am I missing something?

An http.Request object has a Write method:

>
> func (r *Request) Write(w io.Writer) error
>
>
> Write writes an HTTP/1.1 request, which is the header and body, in wire format.

You can use this to write the bytes into a buffer object. For example:

package main

import (
	"bytes"
	"fmt"
	"net/http"
)

func main() {
	var buf bytes.Buffer

	req, err := http.NewRequest("GET", "http://google.com", nil)
	if err != nil {
		panic(err)
	}

	client := &http.Client{}
	res, err := client.Do(req)
	if err != nil {
		panic(err)
	}
    defer res.Body.Close()

	if err := res.Write(&buf); err != nil {
		panic(err)
	}

	// ...do whatever you want with the buffer here...
	fmt.Println(buf.String())
}

A Buffer object has a Bytes method that will return a byte array, if that's what you want.