refactor: send and accept only spec-compliant AP headers

5 files changed, 194 insertions, 176 deletions

diff --git a/src/activitypub.js b/src/activitypub.js
index 857dce8..a6f4ada 100644
--- a/src/activitypub.js
+++ b/src/activitypub.js
@@ -10,6 +10,7 @@ const domain = config.general.domain;
 const siteName = config.general.site_name;
 const isFederated = config.general.is_federated;
 import Event from "./models/Event.js";
+import { activityPubContentType, alternateActivityPubContentType } from "./lib/activitypub.js";
 
 // This alphabet (used to generate all event, group, etc. IDs) is missing '-'
 // because ActivityPub doesn't like it in IDs
@@ -35,9 +36,9 @@ export function createActivityPubActor(
             "https://www.w3.org/ns/activitystreams",
             "https://w3id.org/security/v1",
             {
-              "toot": "http://joinmastodon.org/ns#",
-              "discoverable": "toot:discoverable",
-              "indexable": "toot:indexable"
+                "toot": "http://joinmastodon.org/ns#",
+                "discoverable": "toot:discoverable",
+                "indexable": "toot:indexable"
             },
         ],
         indexable: false,
@@ -93,9 +94,9 @@ export function createActivityPubEvent(
             "https://www.w3.org/ns/activitystreams",
             "https://w3id.org/security/v1",
             {
-              "toot": "http://joinmastodon.org/ns#",
-              "discoverable": "toot:discoverable",
-              "indexable": "toot:indexable"
+                "toot": "http://joinmastodon.org/ns#",
+                "discoverable": "toot:discoverable",
+                "indexable": "toot:indexable"
             },
         ],
         indexable: false,
@@ -219,8 +220,8 @@ export function signAndSend(message, eventID, targetDomain, inbox, callback) {
                         Date: d.toUTCString(),
                         Signature: header,
                         Digest: `SHA-256=${digest}`,
-                        "Content-Type": "application/activity+json",
-                        Accept: "application/activity+json",
+                        "Content-Type": activityPubContentType,
+                        Accept: activityPubContentType,
                     },
                     method: "POST",
                     json: true,
@@ -257,7 +258,7 @@ export function signAndSend(message, eventID, targetDomain, inbox, callback) {
                                             "addActivityPubMessage",
                                             "success",
                                             "ActivityPubMessage added to event " +
-                                                eventID,
+                                            eventID,
                                         );
                                         callback(null, message.id, 200);
                                     })
@@ -266,9 +267,9 @@ export function signAndSend(message, eventID, targetDomain, inbox, callback) {
                                             "addActivityPubMessage",
                                             "error",
                                             "Attempt to add ActivityPubMessage to event " +
-                                                eventID +
-                                                " failed with error: " +
-                                                err,
+                                            eventID +
+                                            " failed with error: " +
+                                            err,
                                         );
                                         callback(err, null, 500);
                                     });
@@ -463,7 +464,7 @@ export function broadcastUpdateMessage(apObject, followers, eventID) {
 }
 
 export function broadcastDeleteMessage(apObject, followers, eventID, callback) {
-    callback = callback || function () {};
+    callback = callback || function () { };
     if (!isFederated) {
         callback([]);
         return;
@@ -560,7 +561,7 @@ export function broadcastDeleteMessage(apObject, followers, eventID, callback) {
 // this sends a message "to:" an individual fediverse user
 export function sendDirectMessage(apObject, actorId, eventID, callback) {
     if (!isFederated) return;
-    callback = callback || function () {};
+    callback = callback || function () { };
     const guidCreate = crypto.randomBytes(16).toString("hex");
     const guidObject = crypto.randomBytes(16).toString("hex");
     let d = new Date();
@@ -618,7 +619,7 @@ export function sendDirectMessage(apObject, actorId, eventID, callback) {
 
 export function sendAcceptMessage(thebody, eventID, targetDomain, callback) {
     if (!isFederated) return;
-    callback = callback || function () {};
+    callback = callback || function () { };
     const guid = crypto.randomBytes(16).toString("hex");
     const actorId = thebody.actor;
     let message = {
@@ -666,8 +667,8 @@ function _handleFollow(req, res) {
         {
             url: req.body.actor,
             headers: {
-                Accept: "application/activity+json",
-                "Content-Type": "application/activity+json",
+                Accept: activityPubContentType,
+                "Content-Type": activityPubContentType,
             },
         },
         function (error, response, body) {
@@ -794,9 +795,9 @@ function _handleFollow(req, res) {
                                     "addEventFollower",
                                     "error",
                                     "Attempt to add follower to event " +
-                                        eventID +
-                                        " failed with error: " +
-                                        err,
+                                    eventID +
+                                    " failed with error: " +
+                                    err,
                                 );
                                 return res
                                     .status(500)
@@ -851,9 +852,9 @@ function _handleUndoFollow(req, res) {
                                 "removeEventFollower",
                                 "error",
                                 "Attempt to remove follower from event " +
-                                    eventID +
-                                    " failed with error: " +
-                                    err,
+                                eventID +
+                                " failed with error: " +
+                                err,
                             );
                             return res.send(
                                 "Database error, please try again :(",
@@ -887,8 +888,8 @@ function _handleAcceptEvent(req, res) {
                     {
                         url: actor,
                         headers: {
-                            Accept: "application/activity+json",
-                            "Content-Type": "application/activity+json",
+                            Accept: activityPubContentType,
+                            "Content-Type": activityPubContentType,
                         },
                     },
                     function (error, response, body) {
@@ -913,7 +914,7 @@ function _handleAcceptEvent(req, res) {
                                         "addEventAttendee",
                                         "success",
                                         "Attendee added to event " +
-                                            req.params.eventID,
+                                        req.params.eventID,
                                     );
                                     // get the new attendee with its hidden id from the full event
                                     let fullAttendee = fullEvent.attendees.find(
@@ -947,9 +948,9 @@ function _handleAcceptEvent(req, res) {
                                         "addEventAttendee",
                                         "error",
                                         "Attempt to add attendee to event " +
-                                            req.params.eventID +
-                                            " failed with error: " +
-                                            err,
+                                        req.params.eventID +
+                                        " failed with error: " +
+                                        err,
                                     );
                                     return res
                                         .status(500)
@@ -996,7 +997,7 @@ function _handleUndoAcceptEvent(req, res) {
                         "oneClickUnattend",
                         "success",
                         "Attendee removed via one click unattend " +
-                            req.params.eventID,
+                        req.params.eventID,
                     );
                 });
             }
@@ -1039,8 +1040,8 @@ function _handleCreateNote(req, res) {
                             {
                                 url: attributedTo,
                                 headers: {
-                                    Accept: "application/activity+json",
-                                    "Content-Type": "application/activity+json",
+                                    Accept: activityPubContentType,
+                                    "Content-Type": activityPubContentType,
                                 },
                             },
                             function (error, response, body) {
@@ -1069,7 +1070,7 @@ function _handleCreateNote(req, res) {
                                                 "addEventAttendee",
                                                 "success",
                                                 "Attendee added to event " +
-                                                    req.params.eventID,
+                                                req.params.eventID,
                                             );
                                             // get the new attendee with its hidden id from the full event
                                             let fullAttendee =
@@ -1105,9 +1106,9 @@ function _handleCreateNote(req, res) {
                                                 "addEventAttendee",
                                                 "error",
                                                 "Attempt to add attendee to event " +
-                                                    req.params.eventID +
-                                                    " failed with error: " +
-                                                    err,
+                                                req.params.eventID +
+                                                " failed with error: " +
+                                                err,
                                             );
                                             return res
                                                 .status(500)
@@ -1169,7 +1170,7 @@ function _handleDelete(req, res) {
                     return (
                         comment.activityJson &&
                         JSON.parse(comment.activityJson).object.id ===
-                            req.body.object.id
+                        req.body.object.id
                     );
                 },
             );
@@ -1189,11 +1190,11 @@ function _handleDelete(req, res) {
                         "deleteComment",
                         "error",
                         "Attempt to delete comment " +
-                            req.body.object.id +
-                            "from event " +
-                            eventWithComment.id +
-                            " failed with error: " +
-                            err,
+                        req.body.object.id +
+                        "from event " +
+                        eventWithComment.id +
+                        " failed with error: " +
+                        err,
                     );
                     return res.sendStatus(500);
                 });
@@ -1233,8 +1234,8 @@ function _handleCreateNoteComment(req, res) {
                 {
                     url: req.body.actor,
                     headers: {
-                        Accept: "application/activity+json",
-                        "Content-Type": "application/activity+json",
+                        Accept: activityPubContentType,
+                        "Content-Type": activityPubContentType,
                     },
                 },
                 function (error, response, actor) {
@@ -1296,13 +1297,13 @@ function _handleCreateNoteComment(req, res) {
                                             "addEventComment",
                                             "error",
                                             "Attempt to add comment to event " +
-                                                eventID +
-                                                " failed with error: " +
-                                                err,
+                                            eventID +
+                                            " failed with error: " +
+                                            err,
                                         );
                                         res.status(500).send(
                                             "Database error, please try again :(" +
-                                                err,
+                                            err,
                                         );
                                     });
                             },
@@ -1387,7 +1388,7 @@ export function createWebfinger(eventID, domain) {
         links: [
             {
                 rel: "self",
-                type: "application/activity+json",
+                type: alternateActivityPubContentType,
                 href: `https://${domain}/${eventID}`,
             },
         ],
diff --git a/src/app.ts b/src/app.ts
index 3370d27..f3c99c7 100755
--- a/src/app.ts
+++ b/src/app.ts
@@ -9,6 +9,10 @@ import group from "./routes/group.js";
 import staticPages from "./routes/static.js";
 
 import { initEmailService } from "./lib/email.js";
+import {
+    activityPubContentType,
+    alternateActivityPubContentType,
+} from "./lib/activitypub.js";
 
 const app = express();
 
@@ -48,8 +52,8 @@ app.set("hbsInstance", hbsInstance);
 app.use(express.static("public"));
 
 // Body parser //
-app.use(express.json({ type: "application/activity+json" }));
-app.use(express.json({ type: "application/ld+json" }));
+app.use(express.json({ type: alternateActivityPubContentType }));
+app.use(express.json({ type: activityPubContentType }));
 app.use(express.json({ type: "application/json" }));
 app.use(express.urlencoded({ extended: true }));
 
diff --git a/src/lib/activitypub.ts b/src/lib/activitypub.ts
index 0a3db7b..11f0770 100644
--- a/src/lib/activitypub.ts
+++ b/src/lib/activitypub.ts
@@ -1,9 +1,22 @@
-import { Request } from "express";
+import { Request, Response } from "express";
 
+// From https://www.w3.org/TR/activitypub/#client-to-server-interactions:
+// "Servers MAY interpret a Content-Type or Accept header of application/activity+json
+// as equivalent to application/ld+json; profile="https://www.w3.org/ns/activitystreams"
+// for client-to-server interactions.
+// For best compatibility, we always send application/ld+json; profile="https://www.w3.org/ns/activitystreams"
+// and accept both application/ld+json; profile="https://www.w3.org/ns/activitystreams" and application/activity+json.
+export const activityPubContentType =
+    'application/ld+json; profile="https://www.w3.org/ns/activitystreams"';
+export const alternateActivityPubContentType = "application/activity+json";
+
+// Cf. https://www.w3.org/TR/activitypub/#retrieving-objects
 export const acceptsActivityPub = (req: Request) => {
-    return (
-        req.headers.accept &&
-        (req.headers.accept.includes("application/activity+json") ||
-            req.headers.accept.includes("application/ld+json"))
+    const validAcceptHeaders = [
+        activityPubContentType,
+        alternateActivityPubContentType,
+    ];
+    return validAcceptHeaders.some(
+        (header) => req.headers.accept?.includes(header),
     );
 };
diff --git a/src/routes.js b/src/routes.js
index d59a738..360f387 100755
--- a/src/routes.js
+++ b/src/routes.js
@@ -22,6 +22,7 @@ import {
 import Event from "./models/Event.js";
 import EventGroup from "./models/EventGroup.js";
 import path from "path";
+import { activityPubContentType } from "./lib/activitypub.js";
 
 const config = getConfig();
 const domain = config.general.domain;
@@ -104,9 +105,9 @@ schedule.scheduleJob("59 23 * * *", function (fireDate) {
                                 "deleteOldEvents",
                                 "error",
                                 "Attempt to delete old event " +
-                                    id +
-                                    " failed with error: " +
-                                    err,
+                                id +
+                                " failed with error: " +
+                                err,
                             );
                         });
                 };
@@ -123,9 +124,9 @@ schedule.scheduleJob("59 23 * * *", function (fireDate) {
                                     "deleteOldEvents",
                                     "error",
                                     "Attempt to delete event image for old event " +
-                                        event.id +
-                                        " failed with error: " +
-                                        err,
+                                    event.id +
+                                    " failed with error: " +
+                                    err,
                                 );
                             }
                             // Image removed
@@ -172,9 +173,9 @@ schedule.scheduleJob("59 23 * * *", function (fireDate) {
                 "deleteOldEvents",
                 "error",
                 "Attempt to delete old event " +
-                    event.id +
-                    " failed with error: " +
-                    err,
+                event.id +
+                " failed with error: " +
+                err,
             );
         });
 
@@ -227,9 +228,9 @@ router.post("/deleteimage/:eventID/:editToken", (req, res) => {
                             "deleteEventImage",
                             "error",
                             "Attempt to delete event image for event " +
-                                req.params.eventID +
-                                " failed with error: " +
-                                err,
+                            req.params.eventID +
+                            " failed with error: " +
+                            err,
                         );
                     }
                     // Image removed
@@ -250,9 +251,9 @@ router.post("/deleteimage/:eventID/:editToken", (req, res) => {
                                 "deleteEventImage",
                                 "error",
                                 "Attempt to delete event image for event " +
-                                    req.params.eventID +
-                                    " failed with error: " +
-                                    err,
+                                req.params.eventID +
+                                " failed with error: " +
+                                err,
                             );
                         });
                 },
@@ -294,9 +295,9 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                                         "deleteEvent",
                                         "error",
                                         "Attempt to delete event " +
-                                            req.params.eventID +
-                                            " failed with error: " +
-                                            err,
+                                        req.params.eventID +
+                                        " failed with error: " +
+                                        err,
                                     );
                                 }
                             },
@@ -316,9 +317,9 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                                                     "deleteEvent",
                                                     "error",
                                                     "Attempt to delete event image for event " +
-                                                        req.params.eventID +
-                                                        " failed with error: " +
-                                                        err,
+                                                    req.params.eventID +
+                                                    " failed with error: " +
+                                                    err,
                                                 );
                                             }
                                             // Image removed
@@ -326,8 +327,8 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                                                 "deleteEvent",
                                                 "success",
                                                 "Event " +
-                                                    req.params.eventID +
-                                                    " deleted",
+                                                req.params.eventID +
+                                                " deleted",
                                             );
                                         },
                                     );
@@ -349,7 +350,7 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                                     if (attendeeEmails.length) {
                                         console.log(
                                             "Sending emails to: " +
-                                                attendeeEmails,
+                                            attendeeEmails,
                                         );
                                         req.app.get("hbsInstance").renderView(
                                             "./views/emails/deleteEvent/deleteEventHtml.handlebars",
@@ -408,15 +409,15 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                             .catch((err) => {
                                 res.send(
                                     "Sorry! Something went wrong (error deleting): " +
-                                        err,
+                                    err,
                                 );
                                 addToLog(
                                     "deleteEvent",
                                     "error",
                                     "Attempt to delete event " +
-                                        req.params.eventID +
-                                        " failed with error: " +
-                                        err,
+                                    req.params.eventID +
+                                    " failed with error: " +
+                                    err,
                                 );
                             });
                     },
@@ -428,8 +429,8 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                     "deleteEvent",
                     "error",
                     "Attempt to delete event " +
-                        req.params.eventID +
-                        " failed with error: token does not match",
+                    req.params.eventID +
+                    " failed with error: token does not match",
                 );
             }
         })
@@ -439,9 +440,9 @@ router.post("/deleteevent/:eventID/:editToken", (req, res) => {
                 "deleteEvent",
                 "error",
                 "Attempt to delete event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    err,
+                req.params.eventID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -474,9 +475,9 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                                 "deleteEventGroup",
                                 "error",
                                 "Attempt to delete event group " +
-                                    req.params.eventGroupID +
-                                    " failed with error: " +
-                                    err,
+                                req.params.eventGroupID +
+                                " failed with error: " +
+                                err,
                             );
                         }
                     },
@@ -496,9 +497,9 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                                             "deleteEventGroup",
                                             "error",
                                             "Attempt to delete event image for event group " +
-                                                req.params.eventGroupID +
-                                                " failed with error: " +
-                                                err,
+                                            req.params.eventGroupID +
+                                            " failed with error: " +
+                                            err,
                                         );
                                     }
                                 },
@@ -515,8 +516,8 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                                     "deleteEventGroup",
                                     "success",
                                     "Event group " +
-                                        req.params.eventGroupID +
-                                        " deleted",
+                                    req.params.eventGroupID +
+                                    " deleted",
                                 );
                                 res.writeHead(302, {
                                     Location: "/",
@@ -526,30 +527,30 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                             .catch((err) => {
                                 res.send(
                                     "Sorry! Something went wrong (error deleting): " +
-                                        err,
+                                    err,
                                 );
                                 addToLog(
                                     "deleteEventGroup",
                                     "error",
                                     "Attempt to delete event group " +
-                                        req.params.eventGroupID +
-                                        " failed with error: " +
-                                        err,
+                                    req.params.eventGroupID +
+                                    " failed with error: " +
+                                    err,
                                 );
                             });
                     })
                     .catch((err) => {
                         res.send(
                             "Sorry! Something went wrong (error deleting): " +
-                                err,
+                            err,
                         );
                         addToLog(
                             "deleteEventGroup",
                             "error",
                             "Attempt to delete event group " +
-                                req.params.eventGroupID +
-                                " failed with error: " +
-                                err,
+                            req.params.eventGroupID +
+                            " failed with error: " +
+                            err,
                         );
                     });
             } else {
@@ -559,8 +560,8 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                     "deleteEventGroup",
                     "error",
                     "Attempt to delete event group " +
-                        req.params.eventGroupID +
-                        " failed with error: token does not match",
+                    req.params.eventGroupID +
+                    " failed with error: token does not match",
                 );
             }
         })
@@ -570,9 +571,9 @@ router.post("/deleteeventgroup/:eventGroupID/:editToken", (req, res) => {
                 "deleteEventGroup",
                 "error",
                 "Attempt to delete event group " +
-                    req.params.eventGroupID +
-                    " failed with error: " +
-                    err,
+                req.params.eventGroupID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -590,9 +591,9 @@ router.post("/attendee/provision", async (req, res) => {
             "provisionEventAttendee",
             "error",
             "Attempt to provision attendee in event " +
-                req.query.eventID +
-                " failed with error: " +
-                e,
+            req.query.eventID +
+            " failed with error: " +
+            e,
         );
         return res.sendStatus(500);
     });
@@ -608,9 +609,9 @@ router.post("/attendee/provision", async (req, res) => {
             "provisionEventAttendee",
             "error",
             "Attempt to provision attendee in event " +
-                req.query.eventID +
-                " failed with error: " +
-                e,
+            req.query.eventID +
+            " failed with error: " +
+            e,
         );
         return res.sendStatus(500);
     });
@@ -646,9 +647,9 @@ router.post("/attendevent/:eventID", async (req, res) => {
             "attendEvent",
             "error",
             "Attempt to attend event " +
-                req.params.eventID +
-                " failed with error: " +
-                e,
+            req.params.eventID +
+            " failed with error: " +
+            e,
         );
         return res.sendStatus(500);
     });
@@ -747,9 +748,9 @@ router.post("/attendevent/:eventID", async (req, res) => {
                 "addEventAttendee",
                 "error",
                 "Attempt to add attendee to event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    error,
+                req.params.eventID +
+                " failed with error: " +
+                error,
             );
         });
 });
@@ -825,9 +826,9 @@ router.post("/unattendevent/:eventID", (req, res) => {
                 "removeEventAttendee",
                 "error",
                 "Attempt to remove attendee from event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    err,
+                req.params.eventID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -906,9 +907,9 @@ router.get("/oneclickunattendevent/:eventID/:attendeeID", (req, res) => {
                 "removeEventAttendee",
                 "error",
                 "Attempt to remove attendee by admin from event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    err,
+                req.params.eventID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -979,9 +980,9 @@ router.post("/removeattendee/:eventID/:attendeeID", (req, res) => {
                 "removeEventAttendee",
                 "error",
                 "Attempt to remove attendee by admin from event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    err,
+                req.params.eventID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -1055,11 +1056,11 @@ router.post("/subscribe/:eventGroupID", (req, res) => {
                 "addSubscription",
                 "error",
                 "Attempt to subscribe " +
-                    req.body.emailAddress +
-                    " to event group " +
-                    req.params.eventGroupID +
-                    " failed with error: " +
-                    error,
+                req.body.emailAddress +
+                " to event group " +
+                req.params.eventGroupID +
+                " failed with error: " +
+                error,
             );
             return res.sendStatus(500);
         });
@@ -1087,11 +1088,11 @@ router.get("/unsubscribe/:eventGroupID", (req, res) => {
                 "removeSubscription",
                 "error",
                 "Attempt to unsubscribe " +
-                    req.query.email +
-                    " from event group " +
-                    req.params.eventGroupID +
-                    " failed with error: " +
-                    error,
+                req.query.email +
+                " from event group " +
+                req.params.eventGroupID +
+                " failed with error: " +
+                error,
             );
             return res.sendStatus(500);
         });
@@ -1217,9 +1218,9 @@ router.post("/post/comment/:eventID", (req, res) => {
                         "addEventComment",
                         "error",
                         "Attempt to add comment to event " +
-                            req.params.eventID +
-                            " failed with error: " +
-                            err,
+                        req.params.eventID +
+                        " failed with error: " +
+                        err,
                     );
                 });
         },
@@ -1250,9 +1251,9 @@ router.post("/post/reply/:eventID/:commentID", (req, res) => {
                         "addEventReply",
                         "success",
                         "Reply added to comment " +
-                            commentID +
-                            " in event " +
-                            req.params.eventID,
+                        commentID +
+                        " in event " +
+                        req.params.eventID,
                     );
                     // broadcast an identical message to all followers, will show in their home timeline
                     const guidObject = crypto.randomBytes(16).toString("hex");
@@ -1348,11 +1349,11 @@ router.post("/post/reply/:eventID/:commentID", (req, res) => {
                         "addEventReply",
                         "error",
                         "Attempt to add reply to comment " +
-                            commentID +
-                            " in event " +
-                            req.params.eventID +
-                            " failed with error: " +
-                            err,
+                        commentID +
+                        " in event " +
+                        req.params.eventID +
+                        " failed with error: " +
+                        err,
                     );
                 });
         },
@@ -1388,17 +1389,17 @@ router.post("/deletecomment/:eventID/:commentID/:editToken", (req, res) => {
                     .catch((err) => {
                         res.send(
                             "Sorry! Something went wrong (error deleting): " +
-                                err,
+                            err,
                         );
                         addToLog(
                             "deleteComment",
                             "error",
                             "Attempt to delete comment " +
-                                req.params.commentID +
-                                "from event " +
-                                req.params.eventID +
-                                " failed with error: " +
-                                err,
+                            req.params.commentID +
+                            "from event " +
+                            req.params.eventID +
+                            " failed with error: " +
+                            err,
                         );
                     });
             } else {
@@ -1408,10 +1409,10 @@ router.post("/deletecomment/:eventID/:commentID/:editToken", (req, res) => {
                     "deleteComment",
                     "error",
                     "Attempt to delete comment " +
-                        req.params.commentID +
-                        "from event " +
-                        req.params.eventID +
-                        " failed with error: token does not match",
+                    req.params.commentID +
+                    "from event " +
+                    req.params.eventID +
+                    " failed with error: token does not match",
                 );
             }
         })
@@ -1421,11 +1422,11 @@ router.post("/deletecomment/:eventID/:commentID/:editToken", (req, res) => {
                 "deleteComment",
                 "error",
                 "Attempt to delete comment " +
-                    req.params.commentID +
-                    "from event " +
-                    req.params.eventID +
-                    " failed with error: " +
-                    err,
+                req.params.commentID +
+                "from event " +
+                req.params.eventID +
+                " failed with error: " +
+                err,
             );
         });
 });
@@ -1452,8 +1453,8 @@ router.post("/activitypub/inbox", (req, res) => {
         {
             url: signature_header.keyId,
             headers: {
-                Accept: "application/activity+json",
-                "Content-Type": "application/activity+json",
+                Accept: activityPubContentType,
+                "Content-Type": activityPubContentType,
             },
         },
         function (error, response, actor) {
diff --git a/src/routes/frontend.ts b/src/routes/frontend.ts
index c405572..cc97ab8 100644
--- a/src/routes/frontend.ts
+++ b/src/routes/frontend.ts
@@ -6,6 +6,10 @@ import getConfig, { frontendConfig } from "../lib/config.js";
 import { addToLog, exportICal } from "../helpers.js";
 import Event from "../models/Event.js";
 import EventGroup, { IEventGroup } from "../models/EventGroup.js";
+import {
+    acceptsActivityPub,
+    activityPubContentType,
+} from "../lib/activitypub.js";
 
 const config = getConfig();
 
@@ -174,13 +178,8 @@ router.get("/:eventID", async (req: Request, res: Response) => {
                 : null,
             url: `https://${config.general.domain}/` + req.params.eventID,
         };
-        if (
-            req.headers.accept &&
-            (req.headers.accept.includes("application/activity+json") ||
-                req.headers.accept.includes("application/json") ||
-                req.headers.accept.includes("application/json+ld"))
-        ) {
-            res.header("Content-Type", "application/activity+json").send(
+        if (acceptsActivityPub(req)) {
+            res.header("Content-Type", activityPubContentType).send(
                 JSON.parse(event.activityPubActor || "{}"),
             );
         } else {