gotosocial/internal/text/sanitize.go

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// GoToSocial
// Copyright (C) GoToSocial Authors admin@gotosocial.org
// SPDX-License-Identifier: AGPL-3.0-or-later
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package text
import (
"html"
"regexp"
"strings"
"github.com/microcosm-cc/bluemonday"
)
// '[A]llows a broad selection of HTML elements and attributes that are safe for user generated content.
// Note that this policy does not allow iframes, object, embed, styles, script, etc.
// An example usage scenario would be blog post bodies where a variety of formatting is expected along with the potential for TABLEs and IMGs.'
//
// Source: https://github.com/microcosm-cc/bluemonday#usage
var regular *bluemonday.Policy = bluemonday.UGCPolicy().
RequireNoReferrerOnLinks(true).
RequireNoFollowOnLinks(false). // remove the global default which adds rel="nofollow" to all links including local relative
RequireNoFollowOnFullyQualifiedLinks(true). // add rel="nofollow" on all external links
RequireCrossOriginAnonymous(true).
AddTargetBlankToFullyQualifiedLinks(true).
AllowAttrs("class", "href", "rel").OnElements("a").
AllowAttrs("class").OnElements("span").
AllowAttrs("class").Matching(regexp.MustCompile("^language-[a-zA-Z0-9]+$")).OnElements("code").
SkipElementsContent("code", "pre")
// '[C]an be thought of as equivalent to stripping all HTML elements and their attributes as it has nothing on its allowlist.
// An example usage scenario would be blog post titles where HTML tags are not expected at all
// and if they are then the elements and the content of the elements should be stripped. This is a very strict policy.'
//
// Source: https://github.com/microcosm-cc/bluemonday#usage
var strict *bluemonday.Policy = bluemonday.StrictPolicy()
// removeHTML strictly removes *all* recognized HTML elements from the given string.
func removeHTML(in string) string {
return strict.Sanitize(in)
}
// SanitizeHTML sanitizes risky html elements from the given string, allowing only safe ones through.
func SanitizeHTML(in string) string {
return regular.Sanitize(in)
}
// SanitizePlaintext runs text through basic sanitization. This removes
// any html elements that were in the string, and returns clean plaintext.
func SanitizePlaintext(in string) string {
content := html.UnescapeString(in)
content = removeHTML(content)
content = html.UnescapeString(content)
return strings.TrimSpace(content)
}