http: ReverseProxy adds "Transfer-Encoding: chunked" to GET requests #1999
Description
I wrote a simple reverse proxy using the built in http.ReverseProxy (thank you).
Snooping with tcpdump on the backend, I noticed that a "Transfer-Encoding:
chunked" header had been added to the GET request, even though there was no body
and GET requests don't need a body in the first place.
This may or may not be legal HTTP, but it certainly confuses some servers out there
(notably www.google.com!)
What steps will reproduce the problem?
package main
import (
"http"
"flag"
"log"
)
var (
httpAddr = flag.String("http", ":12345", "HTTP service address")
backendAddr = flag.String("backend", "www.google.com", "backend address")
)
func director(req *http.Request) {
req.URL.Scheme = "http"
req.URL.Host = *backendAddr
req.Host = *backendAddr
}
func main() {
flag.Parse()
proxy := &http.ReverseProxy{Director: director}
err := http.ListenAndServe(*httpAddr, proxy)
if err != nil {
log.Fatal("ListenAndServe: ", err.String())
}
}
(some fields elided for anonymity)
browser -> proxy
--------
GET / HTTP/1.1
Host: XXX:12345
User-Agent: XXX
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Cookie: XXX Cache-Control: max-age=0
Connection: keep-alive
--------
proxy -> www.google.com
--------
GET / HTTP/1.1
Host: www.google.com
User-Agent: XXX
Transfer-Encoding: chunked
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Charset: ISO-8859-1,utf-8;q=0.7,*;q=0.3
Accept-Encoding: gzip,deflate,sdch
Accept-Language: en-US,en;q=0.8
Cache-Control: max-age=0
Connection: keep-alive
Cookie: XXX
X-Forwarded-For: XXX
0
--------