Import source: backend/src/routes/links

Import the existing local project snapshot. This commit organizes existing files; it does not represent newly developed functionality.

backend/src/routes/links.ts

@@ -0,0 +1,89 @@
+import express from 'express';
+import { HttpError } from '../middleware/errorHandler.js';
+import { store } from '../services/store.js';
+import { fileToApi } from '../utils/files.js';
+import { getPreviewKind, getPreviewMeta } from '../utils/preview.js';
+import * as gdrive from '../utils/gdrive.js';
+import { recordEventInDb } from '../services/analytics.js';
+import { rateLimit } from '../middleware/rateLimit.js';
+
+const router = express.Router();
+
+function isExpired(expiresAt: string) {
+  return new Date(expiresAt).getTime() <= Date.now();
+}
+
+router.get('/:linkId', async (req, res) => {
+  const ip = req.ip;
+  const userAgent = req.headers['user-agent'] as string;
+  const referrer = (req.headers.referer || req.headers.referrer) as string;
+
+  const file = await store.update((db) => {
+    const row = db.files.find((f) => f.linkId === req.params.linkId && f.status === 'uploaded');
+    if (!row) return null;
+    if (isExpired(row.expiresAt)) {
+      row.status = 'expired';
+      row.deletedAt = new Date().toISOString();
+      return null;
+    }
+    recordEventInDb(db, row.linkId, 'view', ip, userAgent, referrer);
+    return row;
+  });
+
+  if (!file) throw new HttpError(404, 'LINK_NOT_FOUND', 'Shared file not found or expired');
+  res.json({ data: fileToApi(file) });
+});
+
+// Limit downloads and previews to 60 per minute per IP to prevent egress flooding
+const downloadLimiter = rateLimit(60, 60000);
+
+/** Increment download counter then redirect to Google Drive's direct download URL. */
+router.get('/:linkId/download', downloadLimiter, async (req, res) => {
+  const ip = req.ip;
+  const userAgent = req.headers['user-agent'] as string;
+  const referrer = (req.headers.referer || req.headers.referrer) as string;
+
+  const file = await store.update((db) => {
+    const row = db.files.find((f) => f.linkId === req.params.linkId && f.status === 'uploaded');
+    if (!row || isExpired(row.expiresAt)) return null;
+    recordEventInDb(db, row.linkId, 'download', ip, userAgent, referrer);
+    return row;
+  });
+
+  if (!file) throw new HttpError(404, 'LINK_NOT_FOUND', 'Shared file not found or expired');
+  res.redirect(302, gdrive.downloadUrl(file.gdriveId));
+});
+
+/**
+ * Stream preview content directly from Drive via rclone cat — no disk writes.
+ * Only available for supported types under the preview size limit.
+ * The browser follows this as a normal src= URL (img, video, audio, iframe, fetch).
+ */
+router.get('/:linkId/preview', downloadLimiter, async (req, res) => {
+  const db = await store.read();
+  const file = db.files.find((f) => f.linkId === req.params.linkId && f.status === 'uploaded');
+  if (!file || isExpired(file.expiresAt)) {
+    throw new HttpError(404, 'LINK_NOT_FOUND', 'Shared file not found or expired');
+  }
+
+  const preview = getPreviewMeta(file);
+  const kind = getPreviewKind(file.mimeType);
+  if (!preview.available || !kind) {
+    throw new HttpError(413, 'PREVIEW_NOT_AVAILABLE', 'Preview is not available for this file');
+  }
+
+  const contentType = kind === 'text' ? 'text/plain; charset=utf-8' : file.mimeType;
+
+  res.setHeader('X-Content-Type-Options', 'nosniff');
+  res.setHeader('Content-Type', contentType);
+  res.setHeader('Content-Disposition', `inline; filename="${encodeURIComponent(file.originalName)}"`);
+  res.setHeader('Content-Security-Policy', "default-src 'none'; style-src 'unsafe-inline'");
+
+  const fileStream = await gdrive.getStream(file.gdriveId);
+  fileStream.pipe(res);
+  fileStream.on('error', () => {
+    if (!res.headersSent) res.status(502).json({ error: 'STREAM_ERROR', message: 'Could not stream file from storage' });
+  });
+});
+
+export { router as linksRouter };