Access HTTPS via HTTP proxy with basic authentication - authentication

Question

I am trying to make a GET request against an HTTPS URL using proxy with username/password authorization (auth is required by the proxy not the website).
Here's what I do:
package main
import (
"crypto/tls"
"encoding/base64"
"fmt"
"net/http"
"net/http/httputil"
"net/url"
)
func main() {
ua := "Mozilla/5.0 (Windows NT 6.1"
basic := "Basic " + base64.StdEncoding.EncodeToString([]byte("username:mypass"))
req, err := http.NewRequest("GET", "https://api.ipify.org/", nil)
proxyUrl, _ := url.Parse("http://myproxy.com:9999")
fmt.Println(basic) // Basic dXNlcm5hbWU6bXlwYXNz
req.Header.Add("Proxy-Authorization", basic)
req.Header.Add("User-Agent", ua)
bb, _ := httputil.DumpRequest(req, false)
fmt.Println(string(bb))
/*
Get / HTTP/1.1
Host: api.ipify.org
Proxy-Authorization: Basic dXNlcm5hbWU6bXlwYXNz
User-Agent: Mozilla/5.0 (Windows NT 6.1
*/
client := &http.Client{
Transport: &http.Transport{
TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
Proxy: http.ProxyURL(proxyUrl),
},
}
resp, err := client.Do(req)
fmt.Println(err) // Proxy Authentication Required
fmt.Println(resp) // <nil>
}
The catch is that when I try to do a request to an HTTP (not HTTPS) site it goes fine, but if I make HTTPS request it fails (see above the message).
I tested the proxy with my browser (FireFox) and everything goes well, I looked for the headers through firebug and added everything relevant to the request (above). I've double-triple-checked the basic value and everything else but without any luck.
So does some one have any idea why this happens or at least how do I research the problem?
The last thing to add is that I can use a public HTTP proxy (that doesn't require any auth) in this case and problems seem to start when auth enters in this process (the error also suggests that).
P.S. Unfortunately I cannot share the proxy IP, port and username cause it is against their policy.

Answer 1

package main
import (
"crypto/tls"
"fmt"
"net/url"
"net/http"
)
func main() {
req, err := http.NewRequest("GET", "https://api.ipify.org/", nil)
proxyUrl, _ := url.Parse("http://username:password#127.0.0.1:9999")
client := &http.Client{
Transport: &http.Transport{
TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
Proxy: http.ProxyURL(proxyUrl),
},
}
_, err = client.Do(req)
fmt.Println(err)
}