golang httputil.NewSingleHostReverseProxy how to read response and modify the response? - go

Question

I've a reverse proxy like this:
Iam using RoundTrip but this proxy server don't work correctly.
How to correctly read and modify response?
and somebody create proxy server via NewSingleHostReverseProxy.
Please Help.
package main
import (
"bytes"
"fmt"
"io/ioutil"
"net/http"
"net/http/httputil"
"net/url"
)
type transport struct {
http.RoundTripper
}
func (t *transport) RoundTrip(req *http.Request) (resp *http.Response, err error) {
resp, err = t.RoundTripper.RoundTrip(req)
if err != nil {
return nil, err
}
b, err := ioutil.ReadAll(resp.Body)
if err != nil {
return nil, err
}
err = resp.Body.Close()
if err != nil {
return nil, err
}
b = bytes.Replace(b, []byte("Google"), []byte("GOOGLE"), -1)
body := ioutil.NopCloser(bytes.NewReader(b))
resp.Body = body
return resp, nil
}
func sameHost(handler http.Handler) http.Handler {
return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
r.Host = r.URL.Host
handler.ServeHTTP(w, r)
})
}
func main() {
u, _ := url.Parse("http://habrahabr.ru")
reverseProxy := httputil.NewSingleHostReverseProxy(u)
reverseProxy.Transport = &transport{http.DefaultTransport}
// wrap that proxy with our sameHost function
singleHosted := sameHost(reverseProxy)
http.ListenAndServe(":3000", singleHosted)
}

Answer 1

When you are going to http:// for most good sites (for example your habrahabr.ru) there is a redirect to https://, so request to http will return something like 301 Moved Permanently and you will not find content that you seek for. Also, after correct to https, make sure that site does not use javascript to load content, you can easily check this by curl:
curl localhost:3000
Also use some logging to determine what's wrong.