fix: sanitize HTML from Mastodon servers (#788)

zio/stable
jviide 2023-01-05 09:21:09 +02:00 committed by GitHub
parent 777066508e
commit 5c0e1790fa
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3 changed files with 260 additions and 50 deletions

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@ -1,7 +1,7 @@
// @unimport-disable
import type { Emoji } from 'masto'
import type { Node } from 'ultrahtml'
import { TEXT_NODE, parse, render, walkSync } from 'ultrahtml'
import { ELEMENT_NODE, TEXT_NODE, h, parse, render } from 'ultrahtml'
import { findAndReplaceEmojisInText } from '@iconify/utils'
import { emojiRegEx, getEmojiAttributes } from '../config/emojis'
@ -19,53 +19,43 @@ export function decodeHtml(text: string) {
* with interop of custom emojis and inline Markdown syntax
*/
export function parseMastodonHTML(html: string, customEmojis: Record<string, Emoji> = {}, markdown = true, forTiptap = false) {
// unicode emojis to images, but only if not converting HTML for Tiptap
let processed = forTiptap ? html : replaceUnicodeEmoji(html)
// custom emojis
processed = processed.replace(/:([\w-]+?):/g, (_, name) => {
const emoji = customEmojis[name]
if (emoji)
return `<img src="${emoji.url}" alt=":${name}:" class="custom-emoji" data-emoji-id="${name}" />`
return `:${name}:`
})
if (markdown) {
// handle code blocks
processed = processed
// Handle code blocks
html = html
.replace(/>(```|~~~)(\w*)([\s\S]+?)\1/g, (_1, _2, lang, raw) => {
const code = htmlToText(raw)
const classes = lang ? ` class="language-${lang}"` : ''
return `><pre><code${classes}>${code}</code></pre>`
})
walkSync(parse(processed), (node) => {
if (node.type !== TEXT_NODE)
return
const replacements = [
[/\*\*\*(.*?)\*\*\*/g, '<b><em>$1</em></b>'],
[/\*\*(.*?)\*\*/g, '<b>$1</b>'],
[/\*(.*?)\*/g, '<em>$1</em>'],
[/~~(.*?)~~/g, '<del>$1</del>'],
[/`([^`]+?)`/g, '<code>$1</code>'],
] as any
for (const [re, replacement] of replacements) {
for (const match of node.value.matchAll(re)) {
if (node.loc) {
const start = match.index! + node.loc[0].start
const end = start + match[0].length + node.loc[0].start
processed = processed.slice(0, start) + match[0].replace(re, replacement) + processed.slice(end)
}
else {
processed = processed.replace(match[0], match[0].replace(re, replacement))
}
}
}
})
}
return parse(processed)
// Always sanitize the raw HTML data *after* it has been modified
const basicClasses = filterClasses(/^(h-\S*|p-\S*|u-\S*|dt-\S*|e-\S*|mention|hashtag|ellipsis|invisible)$/u)
return transformSync(parse(html), [
sanitize({
// Allow basic elements as seen in https://github.com/mastodon/mastodon/blob/17f79082b098e05b68d6f0d38fabb3ac121879a9/lib/sanitize_ext/sanitize_config.rb
br: {},
p: {},
a: {
href: filterHref(),
class: basicClasses,
rel: set('nofollow noopener noreferrer'),
target: set('_blank'),
},
span: {
class: basicClasses,
},
// Allow elements potentially created for Markdown code blocks above
pre: {},
code: {
class: filterClasses(/^language-\w+$/),
},
}),
// Unicode emojis to images, but only if not converting HTML for Tiptap
!forTiptap ? replaceUnicodeEmoji() : noopTransform(),
markdown ? formatMarkdown() : noopTransform(),
replaceCustomEmoji(customEmojis),
])
}
/**
@ -133,12 +123,210 @@ export function treeToText(input: Node): string {
return pre + body + post
}
/**
* Replace unicode emojis with locally hosted images
*/
export function replaceUnicodeEmoji(html: string) {
return findAndReplaceEmojisInText(emojiRegEx, html, (match) => {
const attrs = getEmojiAttributes(match)
return `<img src="${attrs.src}" alt="${attrs.alt}" class="${attrs.class}" />`
}) || html
// A tree transform function takes an ultrahtml Node object and returns
// new content that will replace the given node in the tree.
// Returning a null removes the node from the tree.
// Strings get converted to text nodes.
// The input node's children have been transformed before the node itself
// gets transformed.
type Transform = (node: Node) => (Node | string)[] | Node | string | null
// Helpers for transforming (filtering, modifying, ...) a parsed HTML tree
// by running the given chain of transform functions one-by-one.
function transformSync(doc: Node, transforms: Transform[]) {
function visit(node: Node, transform: Transform, isRoot = false) {
if (Array.isArray(node.children)) {
const children = [] as (Node | string)[]
for (let i = 0; i < node.children.length; i++) {
const result = visit(node.children[i], transform)
if (Array.isArray(result))
children.push(...result)
else if (result)
children.push(result)
}
node.children = children.map((value) => {
if (typeof value === 'string')
return { type: TEXT_NODE, value, parent: node }
value.parent = node
return value
})
}
return isRoot ? node : transform(node)
}
for (const transform of transforms)
doc = visit(doc, transform, true) as Node
return doc
}
// A transformation that does nothing. Useful for conditional transform chains.
function noopTransform(): Transform {
return node => node
}
// A tree transform for sanitizing elements & their attributes.
type AttrSanitizers = Record<string, (value: string | undefined) => string | undefined>
function sanitize(allowedElements: Record<string, AttrSanitizers>): Transform {
return (node) => {
if (node.type !== ELEMENT_NODE)
return node
if (!Object.prototype.hasOwnProperty.call(allowedElements, node.name))
return null
const attrSanitizers = allowedElements[node.name]
const attrs = {} as Record<string, string>
for (const [name, func] of Object.entries(attrSanitizers)) {
const value = func(node.attributes[name])
if (value !== undefined)
attrs[name] = value
}
node.attributes = attrs
return node
}
}
function filterClasses(allowed: RegExp) {
return (c: string | undefined) => {
if (!c)
return undefined
return c.split(/\s/g).filter(cls => allowed.test(cls)).join(' ')
}
}
function set(value: string) {
return () => value
}
function filterHref() {
const LINK_PROTOCOLS = new Set([
'http:',
'https:',
'dat:',
'dweb:',
'ipfs:',
'ipns:',
'ssb:',
'gopher:',
'xmpp:',
'magnet:',
'gemini:',
])
return (href: string | undefined) => {
if (href === undefined)
return undefined
// Allow relative links
if (href.startsWith('/') || href.startsWith('.'))
return href
let url
try {
url = new URL(href)
}
catch (err) {
if (err instanceof TypeError)
return undefined
throw err
}
if (LINK_PROTOCOLS.has(url.protocol))
return url.toString()
return '#'
}
}
function replaceUnicodeEmoji(): Transform {
return (node) => {
if (node.type !== TEXT_NODE)
return node
let start = 0
const matches = [] as (string | Node)[]
findAndReplaceEmojisInText(emojiRegEx, node.value, (match, result) => {
const attrs = getEmojiAttributes(match)
matches.push(result.slice(start))
matches.push(h('img', { src: attrs.src, alt: attrs.alt, class: attrs.class }))
start = result.length + match.match.length
return undefined
})
if (matches.length === 0)
return node
matches.push(node.value.slice(start))
return matches.filter(Boolean)
}
}
function replaceCustomEmoji(customEmojis: Record<string, Emoji>): Transform {
return (node) => {
if (node.type !== TEXT_NODE)
return node
const split = node.value.split(/:([\w-]+?):/g)
if (split.length === 1)
return node
return split.map((name, i) => {
if (i % 2 === 0)
return name
const emoji = customEmojis[name]
if (!emoji)
return `:${name}:`
return h('img', { 'src': emoji.url, 'alt': `:${name}:`, 'class': 'custom-emoji', 'data-emoji-id': name })
}).filter(Boolean)
}
}
function formatMarkdown(): Transform {
const replacements: [RegExp, (c: (string | Node)[]) => Node][] = [
[/\*\*\*(.*?)\*\*\*/g, c => h('b', null, [h('em', null, c)])],
[/\*\*(.*?)\*\*/g, c => h('b', null, c)],
[/\*(.*?)\*/g, c => h('em', null, c)],
[/~~(.*?)~~/g, c => h('del', null, c)],
[/`([^`]+?)`/g, c => h('code', null, c)],
]
function process(value: string) {
const results = [] as (string | Node)[]
let start = 0
while (true) {
let found: { match: RegExpMatchArray; replacer: (c: (string | Node)[]) => Node } | undefined
for (const [re, replacer] of replacements) {
re.lastIndex = start
const match = re.exec(value)
if (match) {
if (!found || match.index < found.match.index!)
found = { match, replacer }
}
}
if (!found)
break
results.push(value.slice(start, found.match.index))
results.push(found.replacer(process(found.match[1])))
start = found.match.index! + found.match[0].length
}
results.push(value.slice(start))
return results.filter(Boolean)
}
return (node) => {
if (node.type !== TEXT_NODE)
return node
return process(node.value)
}
}

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@ -1,5 +1,12 @@
// Vitest Snapshot v1
exports[`content-rich > JavaScript hrefs get removed 1`] = `
"<p>
<a href=\\"#\\" rel=\\"nofollow noopener noreferrer\\" target=\\"_blank\\">click me</a>
</p>
"
`;
exports[`content-rich > code frame 1`] = `
"<p>Testing code block</p><p><pre lang=\\"ts\\">import { useMouse, usePreferredDark } from &#39;@vueuse/core&#39;
// tracks mouse position
@ -10,7 +17,13 @@ const isDark = usePreferredDark()</pre></p>"
exports[`content-rich > code frame 2 1`] = `
"<p>
<span class=\\"h-card\\"><a class=\\"u-url mention\\" to=\\"/mas.to/@antfu\\"></a></span>
<span class=\\"h-card\\"
><a
class=\\"u-url mention\\"
rel=\\"nofollow noopener noreferrer\\"
to=\\"/mas.to/@antfu\\"
></a
></span>
Testing<br />
<pre lang=\\"ts\\">const a = hello</pre>
</p>
@ -62,3 +75,8 @@ exports[`content-rich > link + mention 1`] = `
</p>
"
`;
exports[`content-rich > script tags get removed 1`] = `
"<p></p>
"
`;

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@ -23,7 +23,11 @@ const isDark = usePreferredDark()
exports[`html-parse > code frame 2 > html 1`] = `
"<p>
<span class=\\"h-card\\"
><a href=\\"https://mas.to/@antfu\\" class=\\"u-url mention\\"
><a
href=\\"https://mas.to/@antfu\\"
class=\\"u-url mention\\"
rel=\\"nofollow noopener noreferrer\\"
target=\\"_blank\\"
>@<span>antfu</span></a
></span
>