mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-25 10:46:01 +03:00
191 lines
6.6 KiB
Go
191 lines
6.6 KiB
Go
// GoToSocial
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// Copyright (C) GoToSocial Authors admin@gotosocial.org
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// SPDX-License-Identifier: AGPL-3.0-or-later
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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package text
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import (
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"html"
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"regexp"
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"strings"
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"github.com/microcosm-cc/bluemonday"
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)
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// Regular HTML policy is an adapted version of the default
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// bluemonday UGC policy, with some tweaks of our own.
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// See: https://github.com/microcosm-cc/bluemonday#usage
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var regular *bluemonday.Policy = func() *bluemonday.Policy {
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p := bluemonday.NewPolicy()
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// AllowStandardAttributes will enable "id", "title" and
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// the language specific attributes "dir" and "lang" on
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// all elements that are allowed
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p.AllowStandardAttributes()
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/*
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LAYOUT AND FORMATTING
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*/
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// "aside" is permitted and takes no attributes.
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/aside
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p.AllowElements("article", "aside")
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// "details" is permitted, including the "open" attribute
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// which can either be blank or the value "open".
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/details
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p.AllowAttrs("open").Matching(regexp.MustCompile(`(?i)^(|open)$`)).OnElements("details")
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// "section" is permitted and takes no attributes.
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/section
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p.AllowElements("section")
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// "summary" is permitted and takes no attributes.
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/summary
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p.AllowElements("summary")
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// "h1" through "h6" are permitted and take no attributes.
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p.AllowElements("h1", "h2", "h3", "h4", "h5", "h6")
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// "hgroup" is permitted and takes no attributes.
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/hgroup
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p.AllowElements("hgroup")
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// "blockquote" is permitted, including the "cite"
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// attribute which must be a standard URL.
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p.AllowAttrs("cite").OnElements("blockquote")
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// "br" "div" "hr" "p" "span" "wbr" are permitted and take no attributes
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p.AllowElements("br", "div", "hr", "p", "span", "wbr")
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// The following are all inline phrasing elements:
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p.AllowElements("abbr", "acronym", "cite", "code", "dfn", "em",
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"figcaption", "mark", "s", "samp", "strong", "sub", "sup", "var")
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// "q" is permitted and "cite" is a URL and handled by URL policies
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p.AllowAttrs("cite").OnElements("q")
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// "time" is permitted
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p.AllowAttrs("datetime").Matching(bluemonday.ISO8601).OnElements("time")
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// Block and inline elements that impart no
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// semantic meaning but style the document.
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// Underlines, italics, bold, strikethrough etc.
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p.AllowElements("b", "i", "pre", "small", "strike", "tt", "u")
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// "del" "ins" are permitted
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p.AllowAttrs("cite").Matching(bluemonday.Paragraph).OnElements("del", "ins")
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p.AllowAttrs("datetime").Matching(bluemonday.ISO8601).OnElements("del", "ins")
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// Enable ordered, unordered, and definition lists.
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p.AllowLists()
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// Class needed on span for mentions, which look like this when assembled:
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// `<span class="h-card"><a href="https://example.org/users/targetAccount" class="u-url mention">@<span>someusername</span></a></span>`
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p.AllowAttrs("class").OnElements("span")
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/*
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LANGUAGE FORMATTING
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*/
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// "bdi" "bdo" are permitted on "dir".
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/dir
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p.AllowAttrs("dir").Matching(bluemonday.Direction).OnElements("bdi", "bdo")
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// "rp" "rt" "ruby" are permitted. See:
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// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/rp
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// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/rt
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// https://developer.mozilla.org/en-US/docs/Web/HTML/Element/ruby
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p.AllowElements("rp", "rt", "ruby")
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/*
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CODE BLOCKS
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*/
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// Permit language tags for code elements.
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p.AllowAttrs("class").Matching(regexp.MustCompile("^language-[a-zA-Z0-9]+$")).OnElements("code")
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// Don't sanitize HTML inside code blocks.
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p.SkipElementsContent("code", "pre")
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/*
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LINKS AND LINK SAFETY.
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*/
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// Permit hyperlinks.
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p.AllowAttrs("class", "href", "rel").OnElements("a")
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// URLs must be parseable by net/url.Parse().
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p.RequireParseableURLs(true)
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// Most common URL schemes only.
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p.AllowURLSchemes("mailto", "http", "https")
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// Force rel="noreferrer".
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel/noreferrer
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p.RequireNoReferrerOnLinks(true)
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// Add rel="nofollow" on all fully qualified (not relative) links.
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel#nofollow
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p.RequireNoFollowOnFullyQualifiedLinks(true)
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// Force crossorigin="anonymous"
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/crossorigin#anonymous
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p.RequireCrossOriginAnonymous(true)
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// Force target="_blank".
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// See: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a#target
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p.AddTargetBlankToFullyQualifiedLinks(true)
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return p
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}()
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// '[C]an be thought of as equivalent to stripping all HTML
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// elements and their attributes as it has nothing on its allowlist.
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// An example usage scenario would be blog post titles where HTML
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// tags are not expected at all and if they are then the elements
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// and the content of the elements should be stripped. This is a
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// very strict policy.'
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//
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// Source: https://github.com/microcosm-cc/bluemonday#usage
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var strict *bluemonday.Policy = bluemonday.StrictPolicy()
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// removeHTML strictly removes *all* recognized
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// HTML elements from the given string.
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func removeHTML(in string) string {
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return strict.Sanitize(in)
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}
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// SanitizeToHTML sanitizes only risky html elements
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// from the given string, allowing safe ones through.
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func SanitizeToHTML(in string) string {
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return regular.Sanitize(in)
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}
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// SanitizeToPlaintext runs text through basic sanitization.
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// This removes any html elements that were in the string,
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// and returns clean plaintext.
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func SanitizeToPlaintext(in string) string {
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// Unescape first to catch any tricky critters.
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content := html.UnescapeString(in)
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// Remove all detected HTML.
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content = removeHTML(content)
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// Unescape again to return plaintext.
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content = html.UnescapeString(content)
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return strings.TrimSpace(content)
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}
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