fix: generate asset permalinks on the canonical Commons host

server/api/projectfiles.ts

@@ -1,4 +1,4 @@
-import logger from "../logger.js";
+import logger, { childLogger } from "../logger.js";
 import { NextFunction, Request, Response } from "express";
 import conductorErrors from "../conductor-errors.js";
 import ProjectFile, {
@@ -22,8 +22,10 @@ import { isObjectIdOrHexString } from "mongoose";
 import async from "async";
 import {
   assembleUrl,
+  getCommonsCanonicalURL,
   getPaginationOffset,
   getRandomOffset,
+  isCanonicalCommonsInstance,
 } from "../util/helpers.js";
 import {
   CopyObjectCommand,
@@ -75,6 +77,7 @@ import { generateVideoStreamURL } from "../util/videoutils.js";
 import axios from "axios";
 import mime from "mime";
 
+const permalinkLog = childLogger("permalink");
 const filesStorage = multer.memoryStorage();
 const MAX_UPLOAD_FILES = 20;
 const MAX_UPLOAD_FILE_SIZE = 100000000; // 100mb
@@ -634,14 +637,6 @@ async function getPermanentLink(
       });
     }
 
-    const { orgID } = project;
-    const organization = await Organization.findOne({ orgID }).lean();
-    if (!organization) {
-      return res.status(404).send({
-        err: true,
-        errMsg: conductorErrors.err11,
-      });
-    }
     const projectFile = await ProjectFile.findOne({
       projectID,
       fileID,
@@ -659,8 +654,7 @@ async function getPermanentLink(
         errMsg: conductorErrors.err29
       });
     }
-    const domain = organization.domain;
-    const permanentLink = `${domain}/permalink/${projectID}/${fileID}`;
+    const permanentLink = `${getCommonsCanonicalURL()}/permalink/${projectID}/${fileID}`;
     return res.status(200).send({
       error: false,
       url: permanentLink,
@@ -675,13 +669,39 @@ async function getPermanentLink(
   }
 }
 
+function receivingHost(req: Request) {
+  return (req.get("host") || "").toLowerCase();
+}
+
 async function redirectPermanentLink(
-  req: ZodReqWithOptionalUser<z.infer<typeof getProjectFileDownloadURLSchema>>,
+  req: Request &
+    ZodReqWithOptionalUser<z.infer<typeof getProjectFileDownloadURLSchema>>,
   res: Response
 ) {
   try {
     const { projectID, fileID } = req.params;
     const { direct } = req.query;
+
+    if (!isCanonicalCommonsInstance()) {
+      const queryIndex = req.originalUrl.indexOf("?");
+      const query = queryIndex === -1 ? "" : req.originalUrl.slice(queryIndex);
+      const target = `${getCommonsCanonicalURL()}/permalink/${projectID}/${fileID}${query}`;
+      if (target.endsWith(req.originalUrl)) {
+        permalinkLog.warn(
+          { host: receivingHost(req) },
+          "canonical host check rejected its own origin; skipping redirect"
+        );
+      } else {
+        permalinkLog.debug(
+          { host: receivingHost(req) },
+          "redirecting permalink to canonical host"
+        );
+        return res
+          .setHeader("Cache-Control", "no-store")
+          .redirect(302, target);
+      }
+    }
+
     const project = await Project.findOne({ projectID }).lean();
 
     if (!project) {
@@ -692,7 +712,7 @@ async function redirectPermanentLink(
     }
 
     if (!direct) {
-      return res.redirect('https://commons.libretexts.org/download/' + projectID + '/' + fileID);
+      return res.redirect(`${getCommonsCanonicalURL()}/download/${projectID}/${fileID}`);
     }
 
     const downloadURLs = await downloadProjectFiles(

server/util/helpers.js

@@ -218,6 +218,48 @@ export const getProductionURL = () => {
     return process.env.CONDUCTOR_DOMAIN || '';
 };
 
+const DEFAULT_COMMONS_CANONICAL_URL = "https://commons.libretexts.org";
+
+/**
+ * Origin of the permanent Commons host. Asset permalinks are generated and
+ * resolved against this origin, not the instance's own CONDUCTOR_DOMAIN.
+ * Set COMMONS_CANONICAL_DOMAIN (host or absolute URL) so staging points at
+ * the staging commons host.
+ *
+ * @returns {string} Origin with no trailing slash.
+ */
+export const getCommonsCanonicalURL = () => {
+    const configured = (process.env.COMMONS_CANONICAL_DOMAIN || "").trim();
+    const raw = configured || DEFAULT_COMMONS_CANONICAL_URL;
+    const withProtocol = /^https?:\/\//i.test(raw) ? raw : `https://${raw}`;
+    try {
+        return new URL(withProtocol).origin;
+    } catch {
+        logger.warn(
+            { configured },
+            "Invalid COMMONS_CANONICAL_DOMAIN, falling back to default"
+        );
+        return DEFAULT_COMMONS_CANONICAL_URL;
+    }
+};
+
+/**
+ * Whether this Conductor instance is the permanent Commons host.
+ * Compares CONDUCTOR_DOMAIN (this instance) to getCommonsCanonicalURL().
+ *
+ * @returns {boolean}
+ */
+export const isCanonicalCommonsInstance = () => {
+    const self = (process.env.CONDUCTOR_DOMAIN || "").trim();
+    if (!self) return false;
+    const withProtocol = /^https?:\/\//i.test(self) ? self : `https://${self}`;
+    try {
+        return new URL(withProtocol).origin === getCommonsCanonicalURL();
+    } catch {
+        return false;
+    }
+};
+
 /**
  * Removes a leading slash, if any, from a string.
  *