Transform http.Response into array of bytes - go

Question

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?

Answer 1

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.