[feature] Public list of suspended domains (#1362)

* basic rendered domain blocklist (unauthenticated!)

* style basic domain block list

* better formatting for domain blocklist

* add opt-in config option for showing suspended domains

* format/linter

* re-use InstancePeersGet for web-accessible domain blocklist

* reword explanation, border styling

* always attach blocklist handler, update error message

* domain blocklist error message grammar

internal/web/domain-blocklist.go

@@ -0,0 +1,71 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2023 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
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	apiutil "github.com/superseriousbusiness/gotosocial/internal/api/util"
+	"github.com/superseriousbusiness/gotosocial/internal/config"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+)
+
+const (
+	domainBlockListPath = "/about/suspended"
+)
+
+func (m *Module) domainBlockListGETHandler(c *gin.Context) {
+	authed, err := oauth.Authed(c, false, false, false, false)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	if !config.GetInstanceExposeSuspendedWeb() && (authed.Account == nil || authed.User == nil) {
+		err := fmt.Errorf("this instance does not expose the list of suspended domains publicly")
+		apiutil.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	host := config.GetHost()
+	instance, err := m.processor.InstanceGet(c.Request.Context(), host)
+	if err != nil {
+		apiutil.ErrorHandler(c, gtserror.NewErrorInternalError(err), m.processor.InstanceGet)
+		return
+	}
+
+	domainBlocks, errWithCode := m.processor.InstancePeersGet(c.Request.Context(), true, false, false)
+	if errWithCode != nil {
+		apiutil.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	c.HTML(http.StatusOK, "domain-blocklist.tmpl", gin.H{
+		"instance":  instance,
+		"ogMeta":    ogBase(instance),
+		"blocklist": domainBlocks,
+		"stylesheets": []string{
+			assetsPathPrefix + "/Fork-Awesome/css/fork-awesome.min.css",
+		},
+		"javascript": []string{distPathPrefix + "/frontend.js"},
+	})
+}

internal/web/robots.go

@@ -49,7 +49,9 @@ Disallow: /emoji/
 # panels
 Disallow: /admin
 Disallow: /user
-Disallow: /settings/`
+Disallow: /settings/
+# domain blocklist
+Disallow: /about/suspended`
 )
 
 // robotsGETHandler returns a decent robots.txt that prevents crawling

internal/web/web.go

@@ -100,6 +100,8 @@ func (m *Module) Route(r router.Router, mi ...gin.HandlerFunc) {
 	r.AttachHandler(http.MethodGet, confirmEmailPath, m.confirmEmailGETHandler)
 	r.AttachHandler(http.MethodGet, robotsPath, m.robotsGETHandler)
 
+	r.AttachHandler(http.MethodGet, domainBlockListPath, m.domainBlockListGETHandler)
+
 	/*
 		Attach redirects from old endpoints to current ones for backwards compatibility
 	*/