forgejo/modules/markup/sanitizer.go
zeripath 88c2e24360
Add KaTeX rendering to Markdown. (#20571)
This PR adds mathematical rendering with KaTeX.

The first step is to add a Goldmark extension that detects the latex
(and tex) mathematics delimiters.

The second step to make this extension only run if math support is
enabled.

The second step is to then add KaTeX CSS and JS to the head which will
load after the dom is rendered.

Fix #3445

Signed-off-by: Andrew Thornton <art27@cantab.net>

Signed-off-by: Andrew Thornton <art27@cantab.net>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
2022-09-14 00:33:37 +08:00

165 lines
5.7 KiB
Go

// Copyright 2017 The Gitea Authors. All rights reserved.
// Copyright 2017 The Gogs Authors. All rights reserved.
// Use of this source code is governed by a MIT-style
// license that can be found in the LICENSE file.
package markup
import (
"io"
"regexp"
"sync"
"code.gitea.io/gitea/modules/setting"
"github.com/microcosm-cc/bluemonday"
)
// Sanitizer is a protection wrapper of *bluemonday.Policy which does not allow
// any modification to the underlying policies once it's been created.
type Sanitizer struct {
defaultPolicy *bluemonday.Policy
rendererPolicies map[string]*bluemonday.Policy
init sync.Once
}
var sanitizer = &Sanitizer{}
// NewSanitizer initializes sanitizer with allowed attributes based on settings.
// Multiple calls to this function will only create one instance of Sanitizer during
// entire application lifecycle.
func NewSanitizer() {
sanitizer.init.Do(func() {
InitializeSanitizer()
})
}
// InitializeSanitizer (re)initializes the current sanitizer to account for changes in settings
func InitializeSanitizer() {
sanitizer.rendererPolicies = map[string]*bluemonday.Policy{}
sanitizer.defaultPolicy = createDefaultPolicy()
for name, renderer := range renderers {
sanitizerRules := renderer.SanitizerRules()
if len(sanitizerRules) > 0 {
policy := createDefaultPolicy()
addSanitizerRules(policy, sanitizerRules)
sanitizer.rendererPolicies[name] = policy
}
}
}
func createDefaultPolicy() *bluemonday.Policy {
policy := bluemonday.UGCPolicy()
// For JS code copy and Mermaid loading state
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^code-block( is-loading)?$`)).OnElements("pre")
// For Chroma markdown plugin
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^(chroma )?language-[\w-]+( display)?( is-loading)?$`)).OnElements("code")
// Checkboxes
policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
policy.AllowAttrs("checked", "disabled", "data-source-position").OnElements("input")
// Custom URL-Schemes
if len(setting.Markdown.CustomURLSchemes) > 0 {
policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
}
// Allow classes for anchors
policy.AllowAttrs("class").Matching(regexp.MustCompile(`ref-issue( ref-external-issue)?`)).OnElements("a")
// Allow classes for task lists
policy.AllowAttrs("class").Matching(regexp.MustCompile(`task-list-item`)).OnElements("li")
// Allow icons
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^icon(\s+[\p{L}\p{N}_-]+)+$`)).OnElements("i")
// Allow unlabelled labels
policy.AllowNoAttrs().OnElements("label")
// Allow classes for emojis
policy.AllowAttrs("class").Matching(regexp.MustCompile(`emoji`)).OnElements("img")
// Allow icons, emojis, chroma syntax and keyword markup on span
policy.AllowAttrs("class").Matching(regexp.MustCompile(`^((icon(\s+[\p{L}\p{N}_-]+)+)|(emoji)|(language-math display)|(language-math inline))$|^([a-z][a-z0-9]{0,2})$|^` + keywordClass + `$`)).OnElements("span")
// Allow 'style' attribute on text elements.
policy.AllowAttrs("style").OnElements("span", "p")
// Allow 'color' property for the style attribute on text elements.
policy.AllowStyles("color").OnElements("span", "p")
// Allow generally safe attributes
generalSafeAttrs := []string{
"abbr", "accept", "accept-charset",
"accesskey", "action", "align", "alt",
"aria-describedby", "aria-hidden", "aria-label", "aria-labelledby",
"axis", "border", "cellpadding", "cellspacing", "char",
"charoff", "charset", "checked",
"clear", "cols", "colspan", "color",
"compact", "coords", "datetime", "dir",
"disabled", "enctype", "for", "frame",
"headers", "height", "hreflang",
"hspace", "ismap", "label", "lang",
"maxlength", "media", "method",
"multiple", "name", "nohref", "noshade",
"nowrap", "open", "prompt", "readonly", "rel", "rev",
"rows", "rowspan", "rules", "scope",
"selected", "shape", "size", "span",
"start", "summary", "tabindex", "target",
"title", "type", "usemap", "valign", "value",
"vspace", "width", "itemprop",
}
generalSafeElements := []string{
"h1", "h2", "h3", "h4", "h5", "h6", "h7", "h8", "br", "b", "i", "strong", "em", "a", "pre", "code", "img", "tt",
"div", "ins", "del", "sup", "sub", "p", "ol", "ul", "table", "thead", "tbody", "tfoot", "blockquote",
"dl", "dt", "dd", "kbd", "q", "samp", "var", "hr", "ruby", "rt", "rp", "li", "tr", "td", "th", "s", "strike", "summary",
"details", "caption", "figure", "figcaption",
"abbr", "bdo", "cite", "dfn", "mark", "small", "span", "time", "wbr",
}
policy.AllowAttrs(generalSafeAttrs...).OnElements(generalSafeElements...)
policy.AllowAttrs("itemscope", "itemtype").OnElements("div")
// FIXME: Need to handle longdesc in img but there is no easy way to do it
// Custom keyword markup
addSanitizerRules(policy, setting.ExternalSanitizerRules)
return policy
}
func addSanitizerRules(policy *bluemonday.Policy, rules []setting.MarkupSanitizerRule) {
for _, rule := range rules {
if rule.AllowDataURIImages {
policy.AllowDataURIImages()
}
if rule.Element != "" {
if rule.Regexp != nil {
policy.AllowAttrs(rule.AllowAttr).Matching(rule.Regexp).OnElements(rule.Element)
} else {
policy.AllowAttrs(rule.AllowAttr).OnElements(rule.Element)
}
}
}
}
// Sanitize takes a string that contains a HTML fragment or document and applies policy whitelist.
func Sanitize(s string) string {
NewSanitizer()
return sanitizer.defaultPolicy.Sanitize(s)
}
// SanitizeReader sanitizes a Reader
func SanitizeReader(r io.Reader, renderer string, w io.Writer) error {
NewSanitizer()
policy, exist := sanitizer.rendererPolicies[renderer]
if !exist {
policy = sanitizer.defaultPolicy
}
return policy.SanitizeReaderToWriter(r, w)
}