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gitea/modules/markup/html.go

445 lines
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// Copyright 2017 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package markup
import (
"bytes"
"io"
"regexp"
"slices"
"strings"
"sync"
"code.gitea.io/gitea/modules/markup/common"
"golang.org/x/net/html"
"golang.org/x/net/html/atom"
"mvdan.cc/xurls/v2"
)
// Issue name styles
const (
IssueNameStyleNumeric = "numeric"
IssueNameStyleAlphanumeric = "alphanumeric"
IssueNameStyleRegexp = "regexp"
)
type globalVarsType struct {
hashCurrentPattern *regexp.Regexp
shortLinkPattern *regexp.Regexp
anyHashPattern *regexp.Regexp
comparePattern *regexp.Regexp
fullURLPattern *regexp.Regexp
emailRegex *regexp.Regexp
blackfridayExtRegex *regexp.Regexp
emojiShortCodeRegex *regexp.Regexp
issueFullPattern *regexp.Regexp
filesChangedFullPattern *regexp.Regexp
codePreviewPattern *regexp.Regexp
tagCleaner *regexp.Regexp
nulCleaner *strings.Replacer
}
var globalVars = sync.OnceValue[*globalVarsType](func() *globalVarsType {
v := &globalVarsType{}
// NOTE: All below regex matching do not perform any extra validation.
// Thus a link is produced even if the linked entity does not exist.
// While fast, this is also incorrect and lead to false positives.
// TODO: fix invalid linking issue
// valid chars in encoded path and parameter: [-+~_%.a-zA-Z0-9/]
// hashCurrentPattern matches string that represents a commit SHA, e.g. d8a994ef243349f321568f9e36d5c3f444b99cae
// Although SHA1 hashes are 40 chars long, SHA256 are 64, the regex matches the hash from 7 to 64 chars in length
// so that abbreviated hash links can be used as well. This matches git and GitHub usability.
v.hashCurrentPattern = regexp.MustCompile(`(?:\s|^|\(|\[)([0-9a-f]{7,64})(?:\s|$|\)|\]|[.,:](\s|$))`)
// shortLinkPattern matches short but difficult to parse [[name|link|arg=test]] syntax
v.shortLinkPattern = regexp.MustCompile(`\[\[(.*?)\]\](\w*)`)
// anyHashPattern splits url containing SHA into parts
v.anyHashPattern = regexp.MustCompile(`https?://(?:\S+/){4,5}([0-9a-f]{40,64})(/[-+~%./\w]+)?(\?[-+~%.\w&=]+)?(#[-+~%.\w]+)?`)
// comparePattern matches "http://domain/org/repo/compare/COMMIT1...COMMIT2#hash"
v.comparePattern = regexp.MustCompile(`https?://(?:\S+/){4,5}([0-9a-f]{7,64})(\.\.\.?)([0-9a-f]{7,64})?(#[-+~_%.a-zA-Z0-9]+)?`)
// fullURLPattern matches full URL like "mailto:...", "https://..." and "ssh+git://..."
v.fullURLPattern = regexp.MustCompile(`^[a-z][-+\w]+:`)
// emailRegex is definitely not perfect with edge cases,
// it is still accepted by the CommonMark specification, as well as the HTML5 spec:
// http://spec.commonmark.org/0.28/#email-address
// https://html.spec.whatwg.org/multipage/input.html#e-mail-state-(type%3Demail)
v.emailRegex = regexp.MustCompile("(?:\\s|^|\\(|\\[)([a-zA-Z0-9.!#$%&'*+\\/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?(?:\\.[a-zA-Z0-9]{2,}(?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?)+)(?:\\s|$|\\)|\\]|;|,|\\?|!|\\.(\\s|$))")
// blackfridayExtRegex is for blackfriday extensions create IDs like fn:user-content-footnote
v.blackfridayExtRegex = regexp.MustCompile(`[^:]*:user-content-`)
// emojiShortCodeRegex find emoji by alias like :smile:
v.emojiShortCodeRegex = regexp.MustCompile(`:[-+\w]+:`)
// example: https://domain/org/repo/pulls/27#hash
v.issueFullPattern = regexp.MustCompile(`https?://(?:\S+/)[\w_.-]+/[\w_.-]+/(?:issues|pulls)/((?:\w{1,10}-)?[1-9][0-9]*)([\?|#](\S+)?)?\b`)
// example: https://domain/org/repo/pulls/27/files#hash
v.filesChangedFullPattern = regexp.MustCompile(`https?://(?:\S+/)[\w_.-]+/[\w_.-]+/pulls/((?:\w{1,10}-)?[1-9][0-9]*)/files([\?|#](\S+)?)?\b`)
// codePreviewPattern matches "http://domain/.../{owner}/{repo}/src/commit/{commit}/{filepath}#L10-L20"
v.codePreviewPattern = regexp.MustCompile(`https?://\S+/([^\s/]+)/([^\s/]+)/src/commit/([0-9a-f]{7,64})(/\S+)#(L\d+(-L\d+)?)`)
v.tagCleaner = regexp.MustCompile(`<((?:/?\w+/\w+)|(?:/[\w ]+/)|(/?[hH][tT][mM][lL]\b)|(/?[hH][eE][aA][dD]\b))`)
v.nulCleaner = strings.NewReplacer("\000", "")
return v
})
// IsFullURLBytes reports whether link fits valid format.
func IsFullURLBytes(link []byte) bool {
return globalVars().fullURLPattern.Match(link)
}
func IsFullURLString(link string) bool {
return globalVars().fullURLPattern.MatchString(link)
}
func IsNonEmptyRelativePath(link string) bool {
return link != "" && !IsFullURLString(link) && link[0] != '/' && link[0] != '?' && link[0] != '#'
}
// CustomLinkURLSchemes allows for additional schemes to be detected when parsing links within text
func CustomLinkURLSchemes(schemes []string) {
schemes = append(schemes, "http", "https")
withAuth := make([]string, 0, len(schemes))
validScheme := regexp.MustCompile(`^[a-z]+$`)
for _, s := range schemes {
if !validScheme.MatchString(s) {
continue
}
without := false
for _, sna := range xurls.SchemesNoAuthority {
if s == sna {
without = true
break
}
}
if without {
s += ":"
} else {
s += "://"
}
withAuth = append(withAuth, s)
}
common.GlobalVars().LinkRegex, _ = xurls.StrictMatchingScheme(strings.Join(withAuth, "|"))
}
type postProcessError struct {
context string
err error
}
func (p *postProcessError) Error() string {
return "PostProcess: " + p.context + ", " + p.err.Error()
}
type processor func(ctx *RenderContext, node *html.Node)
var defaultProcessors = []processor{
fullIssuePatternProcessor,
comparePatternProcessor,
codePreviewPatternProcessor,
fullHashPatternProcessor,
shortLinkProcessor,
linkProcessor,
mentionProcessor,
issueIndexPatternProcessor,
commitCrossReferencePatternProcessor,
hashCurrentPatternProcessor,
emailAddressProcessor,
emojiProcessor,
emojiShortCodeProcessor,
}
// PostProcess does the final required transformations to the passed raw HTML
// data, and ensures its validity. Transformations include: replacing links and
// emails with HTML links, parsing shortlinks in the format of [[Link]], like
// MediaWiki, linking issues in the format #ID, and mentions in the format
// @user, and others.
func PostProcess(ctx *RenderContext, input io.Reader, output io.Writer) error {
return postProcess(ctx, defaultProcessors, input, output)
}
var commitMessageProcessors = []processor{
fullIssuePatternProcessor,
comparePatternProcessor,
fullHashPatternProcessor,
linkProcessor,
mentionProcessor,
issueIndexPatternProcessor,
commitCrossReferencePatternProcessor,
hashCurrentPatternProcessor,
emailAddressProcessor,
emojiProcessor,
emojiShortCodeProcessor,
}
// RenderCommitMessage will use the same logic as PostProcess, but will disable
// the shortLinkProcessor and will add a defaultLinkProcessor if defaultLink is
// set, which changes every text node into a link to the passed default link.
func RenderCommitMessage(ctx *RenderContext, content string) (string, error) {
procs := commitMessageProcessors
return renderProcessString(ctx, procs, content)
}
var commitMessageSubjectProcessors = []processor{
fullIssuePatternProcessor,
comparePatternProcessor,
fullHashPatternProcessor,
linkProcessor,
mentionProcessor,
issueIndexPatternProcessor,
commitCrossReferencePatternProcessor,
hashCurrentPatternProcessor,
emojiShortCodeProcessor,
emojiProcessor,
}
var emojiProcessors = []processor{
emojiShortCodeProcessor,
emojiProcessor,
}
// RenderCommitMessageSubject will use the same logic as PostProcess and
// RenderCommitMessage, but will disable the shortLinkProcessor and
// emailAddressProcessor, will add a defaultLinkProcessor if defaultLink is set,
// which changes every text node into a link to the passed default link.
func RenderCommitMessageSubject(ctx *RenderContext, defaultLink, content string) (string, error) {
procs := slices.Clone(commitMessageSubjectProcessors)
procs = append(procs, func(ctx *RenderContext, node *html.Node) {
ch := &html.Node{Parent: node, Type: html.TextNode, Data: node.Data}
node.Type = html.ElementNode
node.Data = "a"
node.DataAtom = atom.A
node.Attr = []html.Attribute{{Key: "href", Val: defaultLink}, {Key: "class", Val: "muted"}}
node.FirstChild, node.LastChild = ch, ch
})
return renderProcessString(ctx, procs, content)
}
// RenderIssueTitle to process title on individual issue/pull page
func RenderIssueTitle(ctx *RenderContext, title string) (string, error) {
// do not render other issue/commit links in an issue's title - which in most cases is already a link.
return renderProcessString(ctx, []processor{
emojiShortCodeProcessor,
emojiProcessor,
}, title)
}
func renderProcessString(ctx *RenderContext, procs []processor, content string) (string, error) {
var buf strings.Builder
if err := postProcess(ctx, procs, strings.NewReader(content), &buf); err != nil {
return "", err
}
return buf.String(), nil
}
// RenderDescriptionHTML will use similar logic as PostProcess, but will
// use a single special linkProcessor.
func RenderDescriptionHTML(ctx *RenderContext, content string) (string, error) {
return renderProcessString(ctx, []processor{
descriptionLinkProcessor,
emojiShortCodeProcessor,
emojiProcessor,
}, content)
}
// RenderEmoji for when we want to just process emoji and shortcodes
// in various places it isn't already run through the normal markdown processor
func RenderEmoji(ctx *RenderContext, content string) (string, error) {
return renderProcessString(ctx, emojiProcessors, content)
}
func postProcess(ctx *RenderContext, procs []processor, input io.Reader, output io.Writer) error {
defer ctx.Cancel()
// FIXME: don't read all content to memory
rawHTML, err := io.ReadAll(input)
if err != nil {
return err
}
// parse the HTML
node, err := html.Parse(io.MultiReader(
// prepend "<html><body>"
strings.NewReader("<html><body>"),
// Strip out nuls - they're always invalid
bytes.NewReader(globalVars().tagCleaner.ReplaceAll([]byte(globalVars().nulCleaner.Replace(string(rawHTML))), []byte("&lt;$1"))),
// close the tags
strings.NewReader("</body></html>"),
))
if err != nil {
return &postProcessError{"invalid HTML", err}
}
if node.Type == html.DocumentNode {
node = node.FirstChild
}
visitNode(ctx, procs, node)
newNodes := make([]*html.Node, 0, 5)
if node.Data == "html" {
node = node.FirstChild
for node != nil && node.Data != "body" {
node = node.NextSibling
}
}
if node != nil {
if node.Data == "body" {
child := node.FirstChild
for child != nil {
newNodes = append(newNodes, child)
child = child.NextSibling
}
} else {
newNodes = append(newNodes, node)
}
}
// Render everything to buf.
for _, node := range newNodes {
if err := html.Render(output, node); err != nil {
return &postProcessError{"error rendering processed HTML", err}
}
}
return nil
}
func isEmojiNode(node *html.Node) bool {
if node.Type == html.ElementNode && node.Data == atom.Span.String() {
for _, attr := range node.Attr {
if (attr.Key == "class" || attr.Key == "data-attr-class") && strings.Contains(attr.Val, "emoji") {
return true
}
}
}
return false
}
func visitNode(ctx *RenderContext, procs []processor, node *html.Node) *html.Node {
// Add user-content- to IDs and "#" links if they don't already have them
for idx, attr := range node.Attr {
val := strings.TrimPrefix(attr.Val, "#")
notHasPrefix := !(strings.HasPrefix(val, "user-content-") || globalVars().blackfridayExtRegex.MatchString(val))
if attr.Key == "id" && notHasPrefix {
node.Attr[idx].Val = "user-content-" + attr.Val
}
if attr.Key == "href" && strings.HasPrefix(attr.Val, "#") && notHasPrefix {
node.Attr[idx].Val = "#user-content-" + val
}
}
switch node.Type {
case html.TextNode:
for _, proc := range procs {
proc(ctx, node) // it might add siblings
}
case html.ElementNode:
if isEmojiNode(node) {
// TextNode emoji will be converted to `<span class="emoji">`, then the next iteration will visit the "span"
// if we don't stop it, it will go into the TextNode again and create an infinite recursion
return node.NextSibling
} else if node.Data == "code" || node.Data == "pre" {
return node.NextSibling // ignore code and pre nodes
} else if node.Data == "img" {
return visitNodeImg(ctx, node)
} else if node.Data == "video" {
return visitNodeVideo(ctx, node)
} else if node.Data == "a" {
procs = emojiProcessors // Restrict text in links to emojis
}
for n := node.FirstChild; n != nil; {
n = visitNode(ctx, procs, n)
}
default:
}
return node.NextSibling
}
// createKeyword() renders a highlighted version of an action keyword
func createKeyword(ctx *RenderContext, content string) *html.Node {
// CSS class for action keywords (e.g. "closes: #1")
const keywordClass = "issue-keyword"
span := &html.Node{
Type: html.ElementNode,
Data: atom.Span.String(),
Attr: []html.Attribute{},
}
span.Attr = append(span.Attr, ctx.RenderInternal.NodeSafeAttr("class", keywordClass))
text := &html.Node{
Type: html.TextNode,
Data: content,
}
span.AppendChild(text)
return span
}
func createLink(ctx *RenderContext, href, content, class string) *html.Node {
a := &html.Node{
Type: html.ElementNode,
Data: atom.A.String(),
Attr: []html.Attribute{{Key: "href", Val: href}},
}
if !RenderBehaviorForTesting.DisableInternalAttributes {
a.Attr = append(a.Attr, html.Attribute{Key: "data-markdown-generated-content"})
}
if class != "" {
a.Attr = append(a.Attr, ctx.RenderInternal.NodeSafeAttr("class", class))
}
text := &html.Node{
Type: html.TextNode,
Data: content,
}
a.AppendChild(text)
return a
}
// replaceContent takes text node, and in its content it replaces a section of
// it with the specified newNode.
func replaceContent(node *html.Node, i, j int, newNode *html.Node) {
replaceContentList(node, i, j, []*html.Node{newNode})
}
// replaceContentList takes text node, and in its content it replaces a section of
// it with the specified newNodes. An example to visualize how this can work can
// be found here: https://play.golang.org/p/5zP8NnHZ03s
func replaceContentList(node *html.Node, i, j int, newNodes []*html.Node) {
// get the data before and after the match
before := node.Data[:i]
after := node.Data[j:]
// Replace in the current node the text, so that it is only what it is
// supposed to have.
node.Data = before
// Get the current next sibling, before which we place the replaced data,
// and after that we place the new text node.
nextSibling := node.NextSibling
for _, n := range newNodes {
node.Parent.InsertBefore(n, nextSibling)
}
if after != "" {
node.Parent.InsertBefore(&html.Node{
Type: html.TextNode,
Data: after,
}, nextSibling)
}
}