forgejo/modules/markdown/sanitizer.go

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// 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 markdown
import (
"regexp"
"sync"
"code.gitea.io/gitea/modules/log"
"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 {
policy *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() {
log.Trace("Markdown: sanitizer initialization requested")
sanitizer.init.Do(func() {
sanitizer.policy = bluemonday.UGCPolicy()
// We only want to allow HighlightJS specific classes for code blocks
sanitizer.policy.AllowAttrs("class").Matching(regexp.MustCompile(`^language-\w+$`)).OnElements("code")
// Checkboxes
sanitizer.policy.AllowAttrs("type").Matching(regexp.MustCompile(`^checkbox$`)).OnElements("input")
sanitizer.policy.AllowAttrs("checked", "disabled").OnElements("input")
// Custom URL-Schemes
sanitizer.policy.AllowURLSchemes(setting.Markdown.CustomURLSchemes...)
log.Trace("Markdown: sanitizer initialized")
})
}
// Sanitize takes a string that contains a HTML fragment or document and applies policy whitelist.
func Sanitize(s string) string {
if sanitizer.policy == nil {
NewSanitizer()
}
return sanitizer.policy.Sanitize(s)
}
// SanitizeBytes takes a []byte slice that contains a HTML fragment or document and applies policy whitelist.
func SanitizeBytes(b []byte) []byte {
if len(b) == 0 {
// nothing to sanitize
return b
}
if sanitizer.policy == nil {
NewSanitizer()
}
return sanitizer.policy.SanitizeBytes(b)
}