[feature] Add `meta robots` tag; allow robots to index profile card if user is Discoverable (#842)

* rework robots.txt response

* don't let robots snippet from statuses/threads

* allow robots to index if user is Discoverable

* add license text

internal/api/security/robots.go

@@ -1,3 +1,21 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
 package security
 
 import (
@@ -7,11 +25,33 @@ import (
 )
 
 const robotsString = `User-agent: *
-Disallow: /
+Crawl-delay: 500
+# api stuff
+Disallow: /api/
+# auth/login stuff
+Disallow: /auth/
+Disallow: /oauth/
+Disallow: /check_your_email
+Disallow: /wait_for_approval
+Disallow: /account_disabled
+# well known stuff
+Disallow: /.well-known/
+# files
+Disallow: /fileserver/
+# s2s AP stuff
+Disallow: /users/
+Disallow: /emoji/
+# panels
+Disallow: /admin
+Disallow: /user
+Disallow: /settings/
 `
 
-// RobotsGETHandler returns the most restrictive possible robots.txt file in response to a call to /robots.txt.
-// The response instructs bots with *any* user agent not to index the instance at all.
+// RobotsGETHandler returns a decent robots.txt that prevents crawling
+// the api, auth pages, settings pages, etc.
+//
+// More granular robots meta tags are then applied for web pages
+// depending on user preferences (see internal/web).
 func (m *Module) RobotsGETHandler(c *gin.Context) {
 	c.String(http.StatusOK, robotsString)
 }

internal/web/profile.go

@@ -82,6 +82,12 @@ func (m *Module) profileGETHandler(c *gin.Context) {
 		return
 	}
 
+	// only allow search engines / robots to view this page if account is discoverable
+	var robotsMeta string
+	if account.Discoverable {
+		robotsMeta = robotsAllowSome
+	}
+
 	// we should only show the 'back to top' button if the
 	// profile visitor is paging through statuses
 	showBackToTop := false
@@ -112,6 +118,7 @@ func (m *Module) profileGETHandler(c *gin.Context) {
 		"instance":         instance,
 		"account":          account,
 		"ogMeta":           ogBase(instance).withAccount(account),
+		"robotsMeta":       robotsMeta,
 		"statuses":         statusResp.Items,
 		"statuses_next":    statusResp.NextLink,
 		"show_back_to_top": showBackToTop,

internal/web/robots.go

@@ -0,0 +1,24 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package web
+
+// https://developers.google.com/search/docs/crawling-indexing/robots-meta-tag#robotsmeta
+const (
+	robotsAllowSome = "nofollow, noarchive, nositelinkssearchbox, max-image-preview:standard"
+)

web/template/header.tmpl

@@ -6,6 +6,7 @@
 	<meta charset="UTF-8">
 	<meta http-equiv="X-UA-Compatible" content="IE=edge">
 	<meta name="viewport" content="width=device-width, initial-scale=1.0">
+	<meta name="robots" content="{{ if .robotsMeta }}{{ .robotsMeta }}{{ else }}noindex, nofollow{{ end }}">
 	{{ if .ogMeta }}{{ if .ogMeta.Locale }}<meta name="og:locale" content="{{ .ogMeta.Locale }}">
 	{{ end }}<meta name="og:type" content="{{ .ogMeta.ResourceType }}">
 	<meta name="og:title" content="{{ .ogMeta.Title }}">

web/template/profile.tmpl

@@ -29,7 +29,7 @@
     </div>
     <h2 id="recent">Latest public toots</h2>
 	    {{ if not .statuses }}
-        <div class="nothinghere">Nothing here!</div>
+        <div data-nosnippet class="nothinghere">Nothing here!</div>
         {{ else }}
         <div class="thread">
             {{ range .statuses }}

web/template/status.tmpl

@@ -1,4 +1,4 @@
-<div class="contentgrid">
+<div data-nosnippet class="contentgrid">
 	<a href="{{.Account.URL}}" class="avatar"><img src="{{.Account.Avatar}}" alt=""></a>
 	<a href="{{.Account.URL}}" class="displayname">{{if .Account.DisplayName}}{{emojify .Account.Emojis (escape .Account.DisplayName)}}{{else}}{{.Account.Username}}{{end}}</a>
 	<a href="{{.Account.URL}}" class="username">@{{.Account.Acct}}</a>
@@ -52,4 +52,4 @@
 		<div id="favorites"><i aria-label="Favorites" class="fa fa-star"></i> {{.FavouritesCount}}</div>
 	</div>
 </div>
-<a href="{{.URL}}" class="toot-link">View toot</a>
+<a data-nosnippet href="{{.URL}}" class="toot-link">View toot</a>

web/template/thread.tmpl

@@ -1,6 +1,6 @@
 {{ template "header.tmpl" .}}
 <main>
-	<div class="thread">
+	<div data-nosnippet class="thread">
 		{{range .context.Ancestors}}
 		<div class="toot">
 			{{ template "status.tmpl" .}}