gitea/modules/markup/html_link.go

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// Copyright 2024 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package markup
import (
"net/url"
"path"
"path/filepath"
"strings"
"code.gitea.io/gitea/modules/markup/common"
"code.gitea.io/gitea/modules/util"
"golang.org/x/net/html"
"golang.org/x/net/html/atom"
)
func ResolveLink(ctx *RenderContext, link, userContentAnchorPrefix string) (result string, resolved bool) {
isAnchorFragment := link != "" && link[0] == '#'
if !isAnchorFragment && !IsFullURLString(link) {
linkBase := ctx.Links.Base
if ctx.IsMarkupContentWiki() {
// no need to check if the link should be resolved as a wiki link or a wiki raw link
// just use wiki link here, and it will be redirected to a wiki raw link if necessary
linkBase = ctx.Links.WikiLink()
} else if ctx.Links.BranchPath != "" || ctx.Links.TreePath != "" {
// if there is no BranchPath, then the link will be something like "/owner/repo/src/{the-file-path}"
// and then this link will be handled by the "legacy-ref" code and be redirected to the default branch like "/owner/repo/src/branch/main/{the-file-path}"
linkBase = ctx.Links.SrcLink()
}
link, resolved = util.URLJoin(linkBase, link), true
}
if isAnchorFragment && userContentAnchorPrefix != "" {
link, resolved = userContentAnchorPrefix+link[1:], true
}
return link, resolved
}
func shortLinkProcessor(ctx *RenderContext, node *html.Node) {
next := node.NextSibling
for node != nil && node != next {
m := globalVars().shortLinkPattern.FindStringSubmatchIndex(node.Data)
if m == nil {
return
}
content := node.Data[m[2]:m[3]]
tail := node.Data[m[4]:m[5]]
props := make(map[string]string)
// MediaWiki uses [[link|text]], while GitHub uses [[text|link]]
// It makes page handling terrible, but we prefer GitHub syntax
// And fall back to MediaWiki only when it is obvious from the look
// Of text and link contents
sl := strings.Split(content, "|")
for _, v := range sl {
if equalPos := strings.IndexByte(v, '='); equalPos == -1 {
// There is no equal in this argument; this is a mandatory arg
if props["name"] == "" {
if IsFullURLString(v) {
// If we clearly see it is a link, we save it so
// But first we need to ensure, that if both mandatory args provided
// look like links, we stick to GitHub syntax
if props["link"] != "" {
props["name"] = props["link"]
}
props["link"] = strings.TrimSpace(v)
} else {
props["name"] = v
}
} else {
props["link"] = strings.TrimSpace(v)
}
} else {
// There is an equal; optional argument.
sep := strings.IndexByte(v, '=')
key, val := v[:sep], html.UnescapeString(v[sep+1:])
// When parsing HTML, x/net/html will change all quotes which are
// not used for syntax into UTF-8 quotes. So checking val[0] won't
// be enough, since that only checks a single byte.
if len(val) > 1 {
if (strings.HasPrefix(val, "“") && strings.HasSuffix(val, "”")) ||
(strings.HasPrefix(val, "") && strings.HasSuffix(val, "")) {
const lenQuote = len("")
val = val[lenQuote : len(val)-lenQuote]
} else if (strings.HasPrefix(val, "\"") && strings.HasSuffix(val, "\"")) ||
(strings.HasPrefix(val, "'") && strings.HasSuffix(val, "'")) {
val = val[1 : len(val)-1]
} else if strings.HasPrefix(val, "'") && strings.HasSuffix(val, "") {
const lenQuote = len("")
val = val[1 : len(val)-lenQuote]
}
}
props[key] = val
}
}
var name, link string
if props["link"] != "" {
link = props["link"]
} else if props["name"] != "" {
link = props["name"]
}
if props["title"] != "" {
name = props["title"]
} else if props["name"] != "" {
name = props["name"]
} else {
name = link
}
name += tail
image := false
ext := filepath.Ext(link)
switch ext {
// fast path: empty string, ignore
case "":
// leave image as false
case ".jpg", ".jpeg", ".png", ".tif", ".tiff", ".webp", ".gif", ".bmp", ".ico", ".svg":
image = true
}
childNode := &html.Node{}
linkNode := &html.Node{
FirstChild: childNode,
LastChild: childNode,
Type: html.ElementNode,
Data: "a",
DataAtom: atom.A,
}
childNode.Parent = linkNode
absoluteLink := IsFullURLString(link)
if !absoluteLink {
if image {
link = strings.ReplaceAll(link, " ", "+")
} else {
link = strings.ReplaceAll(link, " ", "-") // FIXME: it should support dashes in the link, eg: "the-dash-support.-"
}
if !strings.Contains(link, "/") {
link = url.PathEscape(link) // FIXME: it doesn't seem right and it might cause double-escaping
}
}
if image {
if !absoluteLink {
link = util.URLJoin(ctx.Links.ResolveMediaLink(ctx.IsMarkupContentWiki()), link)
}
title := props["title"]
if title == "" {
title = props["alt"]
}
if title == "" {
title = path.Base(name)
}
alt := props["alt"]
if alt == "" {
alt = name
}
// make the childNode an image - if we can, we also place the alt
childNode.Type = html.ElementNode
childNode.Data = "img"
childNode.DataAtom = atom.Img
childNode.Attr = []html.Attribute{
{Key: "src", Val: link},
{Key: "title", Val: title},
{Key: "alt", Val: alt},
}
if alt == "" {
childNode.Attr = childNode.Attr[:2]
}
} else {
link, _ = ResolveLink(ctx, link, "")
childNode.Type = html.TextNode
childNode.Data = name
}
linkNode.Attr = []html.Attribute{{Key: "href", Val: link}}
replaceContent(node, m[0], m[1], linkNode)
node = node.NextSibling.NextSibling
}
}
// linkProcessor creates links for any HTTP or HTTPS URL not captured by
// markdown.
func linkProcessor(ctx *RenderContext, node *html.Node) {
next := node.NextSibling
for node != nil && node != next {
m := common.GlobalVars().LinkRegex.FindStringIndex(node.Data)
if m == nil {
return
}
uri := node.Data[m[0]:m[1]]
replaceContent(node, m[0], m[1], createLink(ctx, uri, uri, "" /*link*/))
node = node.NextSibling.NextSibling
}
}
// descriptionLinkProcessor creates links for DescriptionHTML
func descriptionLinkProcessor(ctx *RenderContext, node *html.Node) {
next := node.NextSibling
for node != nil && node != next {
m := common.GlobalVars().LinkRegex.FindStringIndex(node.Data)
if m == nil {
return
}
uri := node.Data[m[0]:m[1]]
replaceContent(node, m[0], m[1], createDescriptionLink(uri, uri))
node = node.NextSibling.NextSibling
}
}
func createDescriptionLink(href, content string) *html.Node {
textNode := &html.Node{
Type: html.TextNode,
Data: content,
}
linkNode := &html.Node{
FirstChild: textNode,
LastChild: textNode,
Type: html.ElementNode,
Data: "a",
DataAtom: atom.A,
Attr: []html.Attribute{
{Key: "href", Val: href},
{Key: "target", Val: "_blank"},
{Key: "rel", Val: "noopener noreferrer"},
},
}
textNode.Parent = linkNode
return linkNode
}