Add middleware to intercept social media bot requests and return OG meta tags for share links, enabling rich previews on platforms like Facebook, Twitter, Discord, etc.pull/3234/head
WittF
1 week ago
parent
47218607ff
commit
572859fd1f
@ -0,0 +1,255 @@
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package middleware
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import (
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"bytes"
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"crypto/subtle"
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"fmt"
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"html/template"
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"net/url"
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"strings"
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"github.com/cloudreve/Cloudreve/v4/application/dependency"
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"github.com/cloudreve/Cloudreve/v4/ent"
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"github.com/cloudreve/Cloudreve/v4/inventory"
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"github.com/cloudreve/Cloudreve/v4/inventory/types"
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"github.com/cloudreve/Cloudreve/v4/pkg/cluster/routes"
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"github.com/cloudreve/Cloudreve/v4/pkg/hashid"
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"github.com/gin-gonic/gin"
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)
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const (
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ogStatusInvalidLink = "Invalid Link"
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ogStatusShareUnavailable = "Share Unavailable"
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ogStatusPasswordRequired = "Password Required"
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ogStatusNeedLogin = "Login Required"
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)
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type ogData struct {
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SiteName string
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Title string
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Description string
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ImageURL string
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ShareURL string
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RedirectURL string
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}
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const ogHTMLTemplate = `<!DOCTYPE html>
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<html>
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<head>
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<meta charset="utf-8">
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<meta property="og:title" content="{{.Title}}">
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<meta property="og:description" content="{{.Description}}">
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<meta property="og:image" content="{{.ImageURL}}">
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<meta property="og:url" content="{{.ShareURL}}">
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<meta property="og:type" content="website">
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<meta property="og:site_name" content="{{.SiteName}}">
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<meta name="twitter:card" content="summary">
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<meta name="twitter:title" content="{{.Title}}">
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<meta name="twitter:description" content="{{.Description}}">
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<meta name="twitter:image" content="{{.ImageURL}}">
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<title>{{.Title}} - {{.SiteName}}</title>
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</head>
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<body>
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<script>window.location.href = "{{.RedirectURL}}";</script>
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<noscript><a href="{{.RedirectURL}}">{{.Title}}</a></noscript>
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</body>
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</html>`
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var ogTemplate = template.Must(template.New("og").Parse(ogHTMLTemplate))
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var socialMediaBots = []string{
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"facebookexternalhit",
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"facebookcatalog",
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"facebot",
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"twitterbot",
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"linkedinbot",
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"discordbot",
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"telegrambot",
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"slackbot",
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"whatsapp",
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}
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func isSocialMediaBot(ua string) bool {
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ua = strings.ToLower(ua)
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for _, bot := range socialMediaBots {
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if strings.Contains(ua, bot) {
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return true
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}
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}
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return false
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}
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// SharePreview 为社交媒体爬虫渲染OG预览页面
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func SharePreview(dep dependency.Dep) gin.HandlerFunc {
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return func(c *gin.Context) {
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if !isSocialMediaBot(c.GetHeader("User-Agent")) {
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c.Next()
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return
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}
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id, password := extractShareParams(c)
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if id == "" {
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c.Next()
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return
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}
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html := renderShareOGPage(c, dep, id, password)
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c.Header("Content-Type", "text/html; charset=utf-8")
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c.Header("Cache-Control", "public, no-cache")
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c.String(200, html)
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c.Abort()
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}
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}
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func extractShareParams(c *gin.Context) (id, password string) {
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urlPath := c.Request.URL.Path
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if strings.HasPrefix(urlPath, "/s/") {
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parts := strings.Split(strings.TrimPrefix(urlPath, "/s/"), "/")
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if len(parts) >= 1 && parts[0] != "" {
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id = parts[0]
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if len(parts) >= 2 {
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password = parts[1]
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}
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}
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} else if urlPath == "/home" || urlPath == "/home/" {
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rawPath := c.Query("path")
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if strings.HasPrefix(rawPath, "cloudreve://") {
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u, err := url.Parse(rawPath)
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if err != nil {
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return "", ""
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}
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if strings.ToLower(u.Host) != "share" || u.User == nil {
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return "", ""
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}
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id = u.User.Username()
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password, _ = u.User.Password()
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}
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}
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if len(id) > 32 || len(password) > 32 {
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return "", ""
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}
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return id, password
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}
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func renderShareOGPage(c *gin.Context, dep dependency.Dep, id, password string) string {
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settings := dep.SettingProvider()
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siteBasic := settings.SiteBasic(c)
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pwa := settings.PWA(c)
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base := settings.SiteURL(c)
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data := &ogData{
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SiteName: siteBasic.Name,
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Title: siteBasic.Name,
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Description: siteBasic.Description,
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ShareURL: routes.MasterShareUrl(base, id, "").String(),
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RedirectURL: routes.MasterShareLongUrl(id, password).String(),
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}
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if pwa.LargeIcon != "" {
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data.ImageURL = resolveURL(base, pwa.LargeIcon)
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} else if pwa.MediumIcon != "" {
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data.ImageURL = resolveURL(base, pwa.MediumIcon)
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}
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shareID, err := dep.HashIDEncoder().Decode(id, hashid.ShareID)
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if err != nil {
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data.Description = ogStatusInvalidLink
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return renderOGHTML(data)
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}
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share, err := loadShareForOG(c, dep, shareID)
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if err != nil {
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if ent.IsNotFound(err) {
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data.Description = ogStatusInvalidLink
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} else {
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data.Description = ogStatusShareUnavailable
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}
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return renderOGHTML(data)
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}
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if err := inventory.IsValidShare(share); err != nil {
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data.Description = ogStatusShareUnavailable
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return renderOGHTML(data)
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}
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if !canAnonymousAccessShare(c, dep) {
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data.Description = ogStatusNeedLogin
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return renderOGHTML(data)
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}
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if share.Password != "" && subtle.ConstantTimeCompare([]byte(share.Password), []byte(password)) != 1 {
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data.Description = ogStatusPasswordRequired
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return renderOGHTML(data)
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}
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targetFile := share.Edges.File
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if targetFile != nil {
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fileName := targetFile.Name
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fileType := types.FileType(targetFile.Type)
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data.Title = fileName
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if fileType == types.FileTypeFolder {
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data.Description = "Folder"
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} else {
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data.Description = formatFileSize(targetFile.Size)
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}
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if share.Edges.User != nil && share.Edges.User.Nick != "" {
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data.Description += " · " + share.Edges.User.Nick
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}
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}
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return renderOGHTML(data)
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}
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func loadShareForOG(c *gin.Context, dep dependency.Dep, shareID int) (*ent.Share, error) {
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ctx := inventory.WithShareEagerLoad(c)
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return dep.ShareClient().GetByID(ctx, shareID)
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}
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func canAnonymousAccessShare(c *gin.Context, dep dependency.Dep) bool {
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anonymousGroup, err := dep.GroupClient().AnonymousGroup(c)
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if err != nil {
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return false
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}
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return anonymousGroup.Permissions.Enabled(int(types.GroupPermissionShareDownload))
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}
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func renderOGHTML(data *ogData) string {
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var buf bytes.Buffer
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if err := ogTemplate.Execute(&buf, data); err != nil {
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return ""
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}
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return buf.String()
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}
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func resolveURL(base *url.URL, path string) string {
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if strings.HasPrefix(path, "http://") || strings.HasPrefix(path, "https://") {
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return path
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}
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return base.ResolveReference(&url.URL{Path: path}).String()
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}
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func formatFileSize(size int64) string {
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const (
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KB = 1024
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MB = 1024 * KB
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GB = 1024 * MB
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TB = 1024 * GB
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)
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switch {
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case size >= TB:
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return fmt.Sprintf("%.2f TB", float64(size)/TB)
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case size >= GB:
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return fmt.Sprintf("%.2f GB", float64(size)/GB)
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case size >= MB:
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return fmt.Sprintf("%.2f MB", float64(size)/MB)
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case size >= KB:
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return fmt.Sprintf("%.2f KB", float64(size)/KB)
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default:
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return fmt.Sprintf("%d B", size)
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}
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}
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