net/http: ServeMux redirect loses query info

[sdwarwick]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.7.1 windows/amd64

What operating system and processor architecture are you using (go env)?

go version go1.7.1 windows/amd64

What did you do?

this error cannot be seen on play as it requires http.

package main

import (
	"fmt"
	"net/http"
)

func main() {

	http.HandleFunc("/testOne", testOneHandler)  // no slash at end or you lose the query string
	http.HandleFunc("/testTwo/", testTwoHandler) // no slash at end or you lose the query string

	http.ListenAndServe(":8008", nil)

}

func testOneHandler(w http.ResponseWriter, r *http.Request) {

	textOut := r.URL.Query()
	fmt.Fprintln(w, textOut)

	return
}

func testTwoHandler(w http.ResponseWriter, r *http.Request) {

	textOut := r.URL.Query()
	fmt.Fprintln(w, textOut)
	return
}

What did you expect to see?

This version works:
input URL: http://localhost:8008/testOne?this=that
result: URL stays the same, and the output is: map[this:[that]]

This doesn't:

input URL: http://localhost:8008/testTwo?this=that

result: URL is redirected to http://localhost:8008/testTwo/
there is no output.

conclusion:
query strings are lost when the input URL and the http router have a "/" at the end of the selector.

this error was initially reported in #5382,

I hope that this is sufficient information.

[bradfitz]

In summary:

bradfitz@gdev:~$ curl 'http://localhost:8080/testOne?foo=bar' 
/testOne?foo=bar
bradfitz@gdev:~$ curl 'http://localhost:8080/testOne/?foo=bar'
404 page not found
bradfitz@gdev:~$ curl 'http://localhost:8080/testTwo?foo=bar'
<a href="/testTwo/">Moved Permanently</a>.

bradfitz@gdev:~$ curl 'http://localhost:8080/testTwo/?foo=bar'
/testTwo/?foo=bar

I assume your question is about my third case? (http://localhost:8080/testTwo?foo=bar)

But you said http://localhost:8080/testTwo/?foo=bar in your bug report, which I assume is a mistake.

What is your actual bug report?

[sdwarwick]

correct, I edited the issue to reflect the typo. The error is in case #3 where a re-direct occurs and doesn't forward the query string. Thanks for looking at this.

[bradfitz]

Not a regression from Go 1.7, so targetting Go 1.9.

[odeke-em]

And here is a playground runnable repro https://play.golang.org/p/t0sLqU5tIS for anyone who wants to test or fix the bug.

[gopherbot]

CL https://golang.org/cl/43779 mentions this issue.

[odeke-em]

I've mailed https://go-review.googlesource.com/43779.

[odeke-em]

I was just whetting my appetite for Kubernetes code and testing it out, then noticed that this bug fix breaks their two of their tests(which seemed to rely on the old buggy behavior)

with the test failing when they encounter:

server_test.go:1327: 7: response location: expected http://localhost:12345/exec, got http://localhost:12345/exec?ignore=1&command=ls&command=-a&output=1

Just a note as am also going to file a bug on their project for them too, to keep vigilant when they update to Go1.9.

[bradfitz]

@odeke-em, nice find! Yeah, if you could send them a PR to make their test work with either Go 1.8 or Go 1.9, that'd save everybody a lot of hassle later. Thanks!

[odeke-em]

Aye aye, done sent in kubernetes/kubernetes#46306.

[odeke-em]

From offline discussions with @bradfitz, the closing CL broke the builds at tip and didn't account for the case where Redirect was invoked directly with a full URL that itself had its own query string. Reopening this issue.

[gopherbot]

CL https://golang.org/cl/44100 mentions this issue.

[bradfitz]

We should only change ServeMux, not func Redirect.

[gopherbot]

Change https://golang.org/cl/61210 mentions this issue: net/http: make ServeMux redirect mux at the runtime

[namusyaka]

@odeke-em Could you take a look at the CL?

[odeke-em]

Thank you for the ping @namusyaka, and thank you for the CL, I am going to take a look at it in a few.

[namusyaka]

@sdwarwick The issue has been fixed by this commit. Please let me know if you still have the issue.