Display fediverse:creator header tag on posts

This uses the fediverse actor a blog author has added in
the Verification field on their blog, looking up the handle
locally to display it in the `fediverse:creator` tag. If
it doesn't exist locally, the tag is simply left out.

activitypub.go

@@ -971,6 +971,24 @@ func getRemoteUserFromHandle(app *App, handle string) (*RemoteUser, error) {
 	return &u, nil
 }
 
+// getRemoteUserFromURL retrieves the profile page of a remote user
+// from the @user@server.tld handle
+func getRemoteUserFromURL(app *App, urlStr string) (*RemoteUser, error) {
+	u := RemoteUser{URL: urlStr}
+	var urlVal, handle sql.NullString
+	err := app.db.QueryRow("SELECT id, actor_id, inbox, shared_inbox, url, handle FROM remoteusers WHERE url = ?", urlStr).Scan(&u.ID, &u.ActorID, &u.Inbox, &u.SharedInbox, &urlVal, &handle)
+	switch {
+	case err == sql.ErrNoRows:
+		return nil, ErrRemoteUserNotFound
+	case err != nil:
+		log.Error("Couldn't get remote user from URL %s: %v", urlStr, err)
+		return nil, err
+	}
+	u.URL = urlVal.String
+	u.Handle = handle.String
+	return &u, nil
+}
+
 func getActor(app *App, actorIRI string) (*activitystreams.Person, *RemoteUser, error) {
 	log.Info("Fetching actor %s locally", actorIRI)
 	actor := &activitystreams.Person{}

collections.go

@@ -639,6 +639,7 @@ type CollectionPage struct {
 	CanPin          bool
 	Username        string
 	Monetization    string
+	FediverseAuthor string
 	Flash           template.HTML
 	Collections     *[]Collection
 	PinnedPosts     *[]PublicPost

posts.go

@@ -149,6 +149,7 @@ type (
 		IsCustomDomain  bool
 		Monetization    string
 		Verification    string
+		FediverseAuthor string
 		PinnedPosts     *[]PublicPost
 		IsFound         bool
 		IsAdmin         bool
@@ -1614,6 +1615,18 @@ Are you sure it was ever here?`,
 		tp.IsPinned = len(*tp.PinnedPosts) > 0 && PostsContains(tp.PinnedPosts, p)
 		tp.Monetization = coll.Monetization
 		tp.Verification = coll.Verification
+		if tp.Verification != "" {
+			// Fetch info for fediverse:creator tag
+			ru, err := getRemoteUserFromURL(app, coll.Verification)
+			if err != nil {
+				if debugging {
+					log.Info("showing rel=me tag, but no local handle for %s", coll.Verification)
+				}
+			} else {
+				// Though we don't store handles with leading @, strip it here just in case
+				tp.FediverseAuthor = "@" + strings.TrimLeft(ru.Handle, "@")
+			}
+		}
 
 		if !postFound {
 			w.WriteHeader(http.StatusNotFound)

templates/include/post-render.tmpl

@@ -4,6 +4,7 @@
 		<meta name="monetization" content="{{.DisplayMonetization}}" />
 	{{- end}}
 	{{if .Verification -}}
+		{{if .FediverseAuthor}}<meta name="fediverse:creator" content="{{.FediverseAuthor}}">{{end}}
 		<link rel="me" href="{{.Verification}}" />
 	{{- end}}
 {{end}}