x/net/html: 'noscript' inner HTML parsing issue #16318

bearburger · 2016-07-11T10:52:07Z

What version of Go are you using (go version)?
```
go1.6 windows/amd64
```

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

set GOARCH=amd64                                  
set GOBIN=                                        
set GOEXE=.exe                                    
set GOHOSTARCH=amd64                              
set GOHOSTOS=windows                              
set GOOS=windows                                  
set GOPATH=F:\go\path64                           
set GORACE=                                       
set GOROOT=F:\go\root16                           
set GOTOOLDIR=F:\go\root16\pkg\tool\windows_amd64 
set GO15VENDOREXPERIMENT=1                        
set CC=gcc                                        
set GOGCCFLAGS=-m64 -mthreads -fmessage-length=0  
set CXX=g++                                       
set CGO_ENABLED=1

What did you do?

package main

import (
    "golang.org/x/net/html"
    "log"
    "bytes"
)


func main() {
    data := "<noscript><img src='https://golang.org/doc/gopher/frontpage.png' /></noscript><p><img src='https://golang.org/doc/gopher/doc.png' /></p>"
    if document, err := html.Parse(bytes.NewReader([]byte(data))); err == nil {
        var parser func(*html.Node)

        parser = func(n *html.Node) {
            if n.Data == "img" {
                log.Println(n.Attr[0].Val)
            }
            if n.Data == "noscript" {
                // here is the issue - noscript tag inner html is represented as TextNode and can't be used as ElementNode
                log.Println("noscript", n.FirstChild.Type == html.TextNode, n.FirstChild.Data)
            }
            for c := n.FirstChild; c != nil; c = c.NextSibling {
                parser(c)
            }
        }

        parser(document)
    } else {
        log.Panicln("Parse html error", err)
    }
}

What did you expect to see?

2016/07/11 13:47:33 noscript false img
2016/07/11 13:47:33 https://golang.org/doc/gopher/frontpage.png
2016/07/11 13:47:33 https://golang.org/doc/gopher/doc.png

What did you see instead?

2016/07/11 13:39:57 noscript true <img src='https://golang.org/doc/gopher/frontpage.png' />
2016/07/11 13:39:57 https://golang.org/doc/gopher/doc.png

The text was updated successfully, but these errors were encountered:

roma86 · 2016-07-11T12:25:14Z

Same here

Mac OS 10.11.5

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

go version go1.6.2 darwin/amd64

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

OARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GOOS="darwin"
GOPATH="/Users/Georg/Develop/Go"
GORACE=""
GOROOT="/usr/local/Cellar/go/1.6.2/libexec"
GOTOOLDIR="/usr/local/Cellar/go/1.6.2/libexec/pkg/tool/darwin_amd64"
GO15VENDOREXPERIMENT="1"
CC="clang"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fno-common"
CXX="clang++"
CGO_ENABLED="1"

Detailed explanation with code and source html

bearburger · 2016-07-11T16:31:52Z

Here is the fix but I need someone who completely understand how parser and tokenizer works as I'm not sure if there is no side effects of my changes. Also I'm not sure if it works as it should in edge case tests like <noscript><iframe></noscript>. All tests are updated to new version so I think for one of the core package maintainers shouldn't be hard to understand what has been changed and check if it works OK.

nathan-osman · 2016-12-05T03:48:35Z

According to W3C, <noscript> may contain other elements, so this is clearly incorrect behavior. Can we please apply @bearburger's commit and get this fixed?

riking · 2017-05-03T20:33:23Z

@bearburger the test changes for that seem wrong: I'm pretty sure that

<!doctype html><noscript><iframe></noscript>X

should be parsed as

| <!DOCTYPE html>
| <html>
|   <body>
|     <noscript>
|       <iframe>
|     "X"

bearburger · 2017-05-03T20:45:19Z

@riking you are right - iframe can't include other tags.

riking · 2017-05-03T20:52:23Z

I meant that the </noscript> should force closing of all unclosed tags until the noscript open tag. There's a mechanism for that, right? Like how closing a </table> would close still-open <td>s.

<!doctype html><noscript><div></noscript>X
should give the same parse structure.

andlabs · 2017-09-01T22:27:01Z

Is there a workaround I can use until this is resolved? Should I recursively tokenize z.Text() for a <noscript>? And if so, would NewTokenizerFragment("noscript") just do the same thing as this bug?

hryamzik · 2017-09-01T22:53:02Z

reg, err := regexp.Compile("</?noscript>")
safeHTMLBytes := reg.ReplaceAll(data, []byte{})

andlabs · 2017-09-02T02:47:57Z

That is such a bad solution that I am tempted to file an issue on the project linked about it. It will not capture every case (uppercase, attributes, whitespace, etc.) and it will capture false positives. A solution must exist that does not attempt to transform input outside the scope of x/net/html.

nathan-osman · 2017-09-02T05:33:35Z

I have a package affected by this issue as well. The simplest solution is to just feed the content back into the parser:

https://github.com/nathan-osman/go-sechat/blob/563300db9224ed01797dfe1f89f489e8eb9dd5ba/auth.go#L65

Assuming this bug is eventually fixed, I'll need to come up with a way to determine whether the recursive parsing is necessary at runtime.

winteraz · 2017-11-03T02:57:24Z

Is this accepted as a valid bug? I just found that noscript children are not parsed and I've found this issue.

ghost · 2017-12-01T02:14:30Z

Discovered this yesterday working with goquery. While I could parse the noscript tag contents (get document.Find("noscript").Text(), pass it to strings.NewReader(), then goquery.NewDocumentFromReader()), this is clumsy.

mmasouras · 2018-09-07T23:00:12Z

I stumbled upon this as well, everything under in my document is returned as one text node.

alin04 · 2018-10-03T17:01:13Z

It's odd that 12.2.6.4.5 isn't implemented in parse.go
https://html.spec.whatwg.org/multipage/parsing.html#parsing-main-inheadnoscript

Ah, upon further inspection, parser assumes scripting is always enabled. There is no support for scripting = false (that I can see). Therefore, this behavior (to treat noscript contents as raw text) is correct.

https://html.spec.whatwg.org/multipage/scripting.html#the-noscript-element

The ask, then, is that parse.go supports scripting disabled mode.

driusan · 2018-12-07T16:17:20Z

Even if the parser does assume scripting is enabled the behaviour is still wrong. The spec says "it represents nothing if scripting is enabled", and it's being represented as a TextNode by the parser.

The documentation for the package also doesn't state anywhere that it acts as if scripting is enabled (which is the opposite of what most people would for assume for a Go HTML parser given the lack of javascript engines written in Go.)

gopherbot · 2019-04-17T08:32:51Z

Change https://golang.org/cl/172557 mentions this issue: html: add "in head noscript" im support

In the spec 12.2.6.4.5, the "in head noscript" insertion mode is defined. However, this package and its parser doesn't have the insertion mode, because the scripting=false case is not considered currently. This commit adds a test and a support for the "in head noscript" insertion mode. This change has no effect on the actual behavior. Updates golang/go#16318 Change-Id: I9314c3342bea27fa2acf2fa7d980a127ee0fbf91 Reviewed-on: https://go-review.googlesource.com/c/net/+/172557 Reviewed-by: Nigel Tao <nigeltao@golang.org>

namusyaka · 2019-04-24T10:42:00Z

This behavior can be considered correct given that scripting is always true.
On the other hand, we have now incorporated the implementation of in head noscript im into the x/net/html package.
There is no way to use this im at this time, but I think it would be nice to provide some way to configure the scripting property as a public API.
I ask @nigeltao for making decision on this.

jimmyfrasche · 2019-04-24T13:41:48Z

Isn't scripting being true itself a deviation from the spec?

alin04 · 2019-04-24T16:17:23Z

Scripting enabled/disabled should be configurable in order to support emulating different browser contexts.

https://html.spec.whatwg.org/multipage/webappapis.html#enabling-and-disabling-scripting

namusyaka · 2019-04-24T16:22:52Z

Yes, I'm sorry if my previous comment made you confusing, but I was thinking about how to make the scripting property configurable.

nigeltao · 2019-04-26T06:33:53Z

Yeah, we should have some way to configure scripting. I'd also like to keep API compatibility, and room for future configuration options. Perhaps some new functions like

func ParseWithOptions(r io.Reader, opts ...ParseOptions) (*Node, error) { etc }
func ParseFragmentWithOptions(r io.Reader, context *Node, opts ...ParseOptions) (*Node, error) { etc }

type ParseOption func(*parser)

func ParseOptionEnableScripting(enable bool) ParseOption {
  return func(p *parser) {
    p.scripting = enable
  }
}

Call sites would look like:

doc, err := html.ParseWithOptions(r, html.ParseOptionEnableScripting(false))

The "options are functions" pattern here is the same as e.g. https://github.com/golang/text/blob/master/internal/ucd/ucd.go#L134

gopherbot · 2019-04-26T17:48:51Z

Change https://golang.org/cl/174157 mentions this issue: html: implement ParseWithOptions and ParseFragmentWithOptions

marcobeierer · 2019-09-26T22:10:47Z

@nigeltao
Thank you for the fix for this issue and the work done.

I just ran into this issue and investigated it and if I see it right, the fix is not complete yet. It just fixes parsing noscript elements in the head, but not outside of head. Outside of head the content of the noscript element is still treated as text.

According to the specs the content of noscript elements should be parsed normally outside of head.

Outside of head elements, if scripting is disabled for the noscript element
The noscript element's content model is transparent, with the additional restriction that a noscript element must not have a noscript element as an ancestor (that is, noscript can't be nested).

I may create a pull request to fix this, but have to work through the Contribution Guide first next week.

bearburger changed the title ~~x/net/html 'noscript' inner HTML parsing issue~~ x/net/html: 'noscript' inner HTML parsing issue Jul 11, 2016

quentinmit added this to the Unreleased milestone Jul 29, 2016

nathan-osman mentioned this issue Dec 5, 2016

<noscript> causes selector to fail PuerkitoBio/goquery#139

Open

dzaikos mentioned this issue Jun 22, 2018

Updated Sanitizer to better handle noscript tags. miniflux/v2#157

Merged

namusyaka added the NeedsDecision label Apr 24, 2019

gopherbot closed this as completed in golang/net@9ce7a69 May 1, 2019

hryamzik mentioned this issue May 1, 2019

Replace noscript hack with a proper parsing win-ansible/goansible#4

Open

golang locked and limited conversation to collaborators Sep 25, 2020

gopherbot added the FrozenDueToAge label Sep 25, 2020

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x/net/html: 'noscript' inner HTML parsing issue #16318

x/net/html: 'noscript' inner HTML parsing issue #16318

bearburger commented Jul 11, 2016 •

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roma86 commented Jul 11, 2016

bearburger commented Jul 11, 2016 •

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nathan-osman commented Dec 5, 2016 •

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riking commented May 3, 2017 •

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bearburger commented May 3, 2017

riking commented May 3, 2017 •

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andlabs commented Sep 1, 2017 •

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hryamzik commented Sep 1, 2017 •

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andlabs commented Sep 2, 2017 •

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nathan-osman commented Sep 2, 2017 •

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winteraz commented Nov 3, 2017

ghost commented Dec 1, 2017

mmasouras commented Sep 7, 2018

alin04 commented Oct 3, 2018 •

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driusan commented Dec 7, 2018

gopherbot commented Apr 17, 2019

namusyaka commented Apr 24, 2019 •

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jimmyfrasche commented Apr 24, 2019

alin04 commented Apr 24, 2019

namusyaka commented Apr 24, 2019 •

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nigeltao commented Apr 26, 2019

gopherbot commented Apr 26, 2019

marcobeierer commented Sep 26, 2019

x/net/html: 'noscript' inner HTML parsing issue #16318

x/net/html: 'noscript' inner HTML parsing issue #16318

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bearburger commented Jul 11, 2016 • edited Loading

roma86 commented Jul 11, 2016

bearburger commented Jul 11, 2016 • edited Loading

nathan-osman commented Dec 5, 2016 • edited Loading

riking commented May 3, 2017 • edited Loading

bearburger commented May 3, 2017

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winteraz commented Nov 3, 2017

ghost commented Dec 1, 2017

mmasouras commented Sep 7, 2018

alin04 commented Oct 3, 2018 • edited Loading

driusan commented Dec 7, 2018

gopherbot commented Apr 17, 2019

namusyaka commented Apr 24, 2019 • edited Loading

jimmyfrasche commented Apr 24, 2019

alin04 commented Apr 24, 2019

namusyaka commented Apr 24, 2019 • edited Loading

nigeltao commented Apr 26, 2019

gopherbot commented Apr 26, 2019

marcobeierer commented Sep 26, 2019

bearburger commented Jul 11, 2016 •

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bearburger commented Jul 11, 2016 •

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riking commented May 3, 2017 •

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