feat: implement calendar management features including create, update, and delete functionalities

app/api/fetch-ical/route.ts

@@ -0,0 +1,108 @@
+import { NextRequest, NextResponse } from 'next/server';
+
+const MAX_RESPONSE_SIZE = 10 * 1024 * 1024; // 10MB
+const FETCH_TIMEOUT_MS = 15000;
+
+function isValidExternalUrl(urlString: string): boolean {
+  let url: URL;
+  try {
+    url = new URL(urlString);
+  } catch {
+    return false;
+  }
+
+  if (url.protocol !== 'https:' && url.protocol !== 'http:') {
+    return false;
+  }
+
+  const hostname = url.hostname.toLowerCase();
+
+  // Block private/internal hostnames
+  if (
+    hostname === 'localhost' ||
+    hostname === '127.0.0.1' ||
+    hostname === '::1' ||
+    hostname === '0.0.0.0' ||
+    hostname.endsWith('.local') ||
+    hostname.endsWith('.internal') ||
+    hostname.endsWith('.arpa') ||
+    hostname.startsWith('10.') ||
+    hostname.startsWith('192.168.') ||
+    hostname.startsWith('169.254.') ||
+    /^172\.(1[6-9]|2\d|3[01])\./.test(hostname)
+  ) {
+    return false;
+  }
+
+  // Block URLs with credentials
+  if (url.username || url.password) {
+    return false;
+  }
+
+  return true;
+}
+
+export async function POST(request: NextRequest) {
+  let body: { url?: string };
+  try {
+    body = await request.json();
+  } catch {
+    return NextResponse.json({ error: 'Invalid request body' }, { status: 400 });
+  }
+
+  const { url } = body;
+
+  if (!url || typeof url !== 'string') {
+    return NextResponse.json({ error: 'URL is required' }, { status: 400 });
+  }
+
+  if (!isValidExternalUrl(url)) {
+    return NextResponse.json({ error: 'Invalid or disallowed URL' }, { status: 400 });
+  }
+
+  try {
+    const controller = new AbortController();
+    const timeout = setTimeout(() => controller.abort(), FETCH_TIMEOUT_MS);
+
+    const response = await fetch(url, {
+      signal: controller.signal,
+      headers: {
+        'Accept': 'text/calendar, application/ics, text/plain, */*',
+        'User-Agent': 'JMAP-Webmail/1.0 Calendar-Fetcher',
+      },
+      redirect: 'follow',
+    });
+
+    clearTimeout(timeout);
+
+    if (!response.ok) {
+      return NextResponse.json(
+        { error: `Remote server returned ${response.status}` },
+        { status: 502 }
+      );
+    }
+
+    const contentLength = response.headers.get('content-length');
+    if (contentLength && parseInt(contentLength) > MAX_RESPONSE_SIZE) {
+      return NextResponse.json({ error: 'File too large' }, { status: 413 });
+    }
+
+    const buffer = await response.arrayBuffer();
+    if (buffer.byteLength > MAX_RESPONSE_SIZE) {
+      return NextResponse.json({ error: 'File too large' }, { status: 413 });
+    }
+
+    return new NextResponse(buffer, {
+      status: 200,
+      headers: {
+        'Content-Type': 'text/calendar',
+        'Content-Length': buffer.byteLength.toString(),
+      },
+    });
+  } catch (error: unknown) {
+    if (error instanceof Error && error.name === 'AbortError') {
+      return NextResponse.json({ error: 'Request timed out' }, { status: 504 });
+    }
+    return NextResponse.json({ error: 'Failed to fetch calendar' }, { status: 502 });
+  }
+}