New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

net/http: DefaultServeMux incorrectly redirect (301) to path if path includes `%2F%2F` #21955

Open
kalbasit opened this Issue Sep 21, 2017 · 10 comments

Comments

Projects
None yet
7 participants
@kalbasit

kalbasit commented Sep 21, 2017

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

go version go1.9 linux/amd64

Does this issue reproduce with the latest release?

yes

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

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/kalbasit/code/personal/base"
GORACE=""
GOROOT="/usr/lib/go"
GOTOOLDIR="/usr/lib/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build643957992=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"

What did you do?

package main

import "net/http"

func main() {
	http.ListenAndServe(":8878", nil)
}
curl 'http://localhost:8878/path:a%2F%2Fgoogle.com%2F'

What did you expect to see?

404 page not found

What did you see instead?

<a href="/path:a/google.com/">Moved Permanently</a>.

NOTE: this does not happen if alice was used instead of the http.DefaultServeMux

@kalbasit kalbasit changed the title from net/http incorrectly redirect (301) to path if path includes `%2F%2F` to net/http.DefaultServeMux incorrectly redirect (301) to path if path includes `%2F%2F` Sep 21, 2017

@ericlagergren

This comment has been minimized.

Contributor

ericlagergren commented Sep 21, 2017

FWIW it happens even with

  • http://localhost:8878//
  • http://localhost:8878/fdsfklasdjfldsajfldksajf/sdfssdf//sdfdsaf

The key aspect being two consecutive /s. It's redirected to a path without two /s.

@crvv

This comment has been minimized.

Contributor

crvv commented Sep 22, 2017

Redirecting http://localhost:8878// to http://localhost:8878/ is correct.
But redirecting http://localhost:8878/%2F to http://localhost:8878/ is not correct.
I think this is a bug to be fixed.

@ianlancetaylor ianlancetaylor changed the title from net/http.DefaultServeMux incorrectly redirect (301) to path if path includes `%2F%2F` to net/http: DefaultServeMux incorrectly redirect (301) to path if path includes `%2F%2F` Mar 30, 2018

@ianlancetaylor ianlancetaylor added this to the Unplanned milestone Mar 30, 2018

@ianlancetaylor

This comment has been minimized.

Contributor

ianlancetaylor commented Mar 30, 2018

@namusyaka

This comment has been minimized.

Member

namusyaka commented Mar 30, 2018

I fixed similar bug in the past, so I will confirm this.

@namusyaka namusyaka self-assigned this Mar 30, 2018

@gopherbot

This comment has been minimized.

gopherbot commented Mar 30, 2018

Change https://golang.org/cl/103696 mentions this issue: net/http: avoid incorrect redirection on paths containing encoded slashes

@tombergan

This comment has been minimized.

Contributor

tombergan commented Apr 5, 2018

I'm not sure if this actually a bug in the first place. The URL reported in the original comment is:

http://localhost:8878/path:a%2F%2Fgoogle.com%2F

The decoded path is:

/path:a//google.com/

ServerMux.Handler uses path.Clean. That path clearly has a double slash and path.Clean translates double slashes to single slashes. Also see here. The godoc for ServerMux.Handler says:

// If the path is not in its canonical form, the
// handler will be an internally-generated handler that redirects
// to the canonical path.

If there's an open question here, the question is around the definition of "canonical path". Does the canonical path convert double slashes to single slashes? If so, does it also convert %2F%2F to "/"? If yes to both questions, there's no bug. Otherwise, there's a bug. AFAICT, these questions are not answered in any documentation. In net/http/server_tests.go, serverMuxTests does not have a case for double slashes, so I suspect this question hasn't come up until now.

@namusyaka

This comment has been minimized.

Member

namusyaka commented Apr 23, 2018

@tombergan Thank you for the clear explanation. I'll investigate this problem again.

@namusyaka

This comment has been minimized.

Member

namusyaka commented Apr 28, 2018

@tombergan @bradfitz

As a countermeasure against this similar problem, there is nginx merge_slashes syntax.
Even with nginx, the above options are used for cases where you do not want to integrate encoded duplicate slashes into one.

And then, I have take a look at RFC-3986 for confirming the encoded double slashes validity.
According to it, the encoded string pchar is considered valid.

   path          = path-abempty    ; begins with "/" or is empty
                 / path-absolute   ; begins with "/" but not "//"
                 / path-noscheme   ; begins with a non-colon segment
                 / path-rootless   ; begins with a segment
                 / path-empty      ; zero characters

   path-abempty  = *( "/" segment )
   path-absolute = "/" [ segment-nz *( "/" segment ) ]
   path-noscheme = segment-nz-nc *( "/" segment )
   path-rootless = segment-nz *( "/" segment )
   path-empty    = 0<pchar>

   segment       = *pchar
   segment-nz    = 1*pchar
   segment-nz-nc = 1*( unreserved / pct-encoded / sub-delims / "@" )
                 ; non-zero-length segment without any colon ":"

   pchar         = unreserved / pct-encoded / sub-delims / ":" / "@"

   query         = *( pchar / "/" / "?" )

   fragment      = *( pchar / "/" / "?" )

   pct-encoded   = "%" HEXDIG HEXDIG

Therefore, I think, if we follow RFC-3986, the current behavior is buggy.

@namusyaka

This comment has been minimized.

Member

namusyaka commented May 4, 2018

@bradfitz ping? If my survey is reasonable, I'm going to try to improve the patch based on this survey result.
Do you have any opinion?

alexmt added a commit to alexmt/argo-cd that referenced this issue Jun 4, 2018

alexmt added a commit to argoproj/argo-cd that referenced this issue Jun 4, 2018

@namusyaka

This comment has been minimized.

Member

namusyaka commented Jun 24, 2018

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment