refactor: extract metadata fetcher into reusable utility

packages/server/src/routes/utils.ts

@@ -1,22 +1,6 @@
 import type { FastifyInstance } from 'fastify';
-import dns from 'dns';
 import { authenticate } from '../utils/auth.js';
-import * as cheerio from 'cheerio';
+import { fetchUrlMetadata } from '../utils/metadataFetcher.js';
-
-function isPrivateIp(ip: string): boolean {
-  // IPv4
-  if (ip.startsWith('127.') || ip.startsWith('0.') || ip === '0.0.0.0') return true;
-  if (ip.startsWith('10.')) return true;
-  if (ip.startsWith('192.168.')) return true;
-  if (ip.startsWith('169.254.')) return true;
-  if (ip.startsWith('172.')) {
-    const second = parseInt(ip.split('.')[1] ?? '', 10);
-    if (second >= 16 && second <= 31) return true;
-  }
-  // IPv6
-  if (ip === '::1' || ip.startsWith('fc') || ip.startsWith('fd') || ip.startsWith('fe80')) return true;
-  return false;
-}
 
 export async function utilRoutes(app: FastifyInstance): Promise<void> {
   app.get<{ Querystring: { url: string } }>('/api/utils/metadata', {
@@ -28,71 +12,11 @@ export async function utilRoutes(app: FastifyInstance): Promise<void> {
       return reply.code(400).send({ error: 'URL is required' });
     }
 
-    // Validate URL scheme
+    const metadata = await fetchUrlMetadata(url);
-    let parsed: URL;
+    if (!metadata) {
-    try {
-      parsed = new URL(url);
-    } catch {
-      return reply.code(400).send({ error: 'Invalid URL' });
-    }
-
-    if (!['http:', 'https:'].includes(parsed.protocol)) {
-      return reply.code(400).send({ error: 'Only HTTP(S) URLs are supported' });
-    }
-
-    // Resolve hostname and block private/internal IPs
-    let address: string;
-    try {
-      const result = await dns.promises.lookup(parsed.hostname);
-      address = result.address;
-    } catch {
       return reply.code(200).send({});
     }
 
-    if (isPrivateIp(address)) {
-      return reply.code(400).send({ error: 'URLs pointing to private/internal addresses are not allowed' });
-    }
-
-    const controller = new AbortController();
-    const timeout = setTimeout(() => controller.abort(), 5000);
-    try {
-      const response = await fetch(url, {
-        headers: {
-          'User-Agent': 'BackspaceBot/1.0',
-        },
-        signal: controller.signal,
-        redirect: 'follow',
-      });
-      clearTimeout(timeout);
-
-      if (!response.ok) {
-        return reply.code(200).send({});
-      }
-
-      // Reject oversized responses
-      const contentLength = parseInt(response.headers.get('content-length') ?? '0', 10);
-      if (contentLength > 512_000) {
-        return reply.code(200).send({});
-      }
-
-      const html = await response.text();
-      const safeHtml = html.length > 512_000 ? html.slice(0, 512_000) : html;
-
-      const $ = cheerio.load(safeHtml);
-
-      const metadata = {
-        title: $('meta[property="og:title"]').attr('content') || $('title').text(),
-        description: $('meta[property="og:description"]').attr('content') || $('meta[name="description"]').attr('content'),
-        image: $('meta[property="og:image"]').attr('content'),
-        siteName: $('meta[property="og:site_name"]').attr('content'),
-        url: url,
-      };
-
     return reply.code(200).send(metadata);
-    } catch (err) {
-      return reply.code(200).send({}); // Fail silently with empty object
-    } finally {
-      clearTimeout(timeout);
-    }
   });
 }

packages/server/src/utils/metadataFetcher.ts

@@ -0,0 +1,112 @@
+import dns from 'dns';
+import * as cheerio from 'cheerio';
+
+export function isPrivateIp(ip: string): boolean {
+  // IPv4
+  if (ip.startsWith('127.') || ip.startsWith('0.') || ip === '0.0.0.0') return true;
+  if (ip.startsWith('10.')) return true;
+  if (ip.startsWith('192.168.')) return true;
+  if (ip.startsWith('169.254.')) return true;
+  if (ip.startsWith('172.')) {
+    const second = parseInt(ip.split('.')[1] ?? '', 10);
+    if (second >= 16 && second <= 31) return true;
+  }
+  // IPv6
+  if (ip === '::1' || ip.startsWith('fc') || ip.startsWith('fd') || ip.startsWith('fe80')) return true;
+  return false;
+}
+
+export interface UrlMetadata {
+  title: string | null;
+  description: string | null;
+  image: string | null;
+  siteName: string | null;
+  url: string;
+}
+
+export async function fetchUrlMetadata(url: string): Promise<UrlMetadata | null> {
+  // Validate URL scheme
+  let parsed: URL;
+  try {
+    parsed = new URL(url);
+  } catch {
+    return null;
+  }
+
+  if (!['http:', 'https:'].includes(parsed.protocol)) {
+    return null;
+  }
+
+  // Resolve hostname and block private/internal IPs
+  let address: string;
+  try {
+    const result = await dns.promises.lookup(parsed.hostname);
+    address = result.address;
+  } catch {
+    return null;
+  }
+
+  if (isPrivateIp(address)) {
+    return null;
+  }
+
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), 5000);
+  try {
+    const response = await fetch(url, {
+      headers: {
+        'User-Agent': 'BackspaceBot/1.0',
+      },
+      signal: controller.signal,
+      redirect: 'follow',
+    });
+    clearTimeout(timeout);
+
+    if (!response.ok) {
+      return null;
+    }
+
+    // Early exit if Content-Length > 512KB
+    const contentLength = parseInt(response.headers.get('content-length') ?? '0', 10);
+    if (contentLength > 512_000) {
+      return null;
+    }
+
+    // Stream-read the body with a hard 512KB byte limit to prevent OOM from chunked responses
+    if (!response.body) return null;
+    const reader = response.body.getReader();
+    const decoder = new TextDecoder();
+    let html = '';
+    let bytesRead = 0;
+    while (true) {
+      const { done, value } = await reader.read();
+      if (done) break;
+      bytesRead += value.length;
+      if (bytesRead > 512_000) {
+        reader.cancel();
+        break;
+      }
+      html += decoder.decode(value, { stream: true });
+    }
+    html += decoder.decode(); // flush remaining
+
+    const $ = cheerio.load(html);
+
+    const metadata: UrlMetadata = {
+      title: $('meta[property="og:title"]').attr('content') ?? $('title').text() ?? null,
+      description:
+        $('meta[property="og:description"]').attr('content') ??
+        $('meta[name="description"]').attr('content') ??
+        null,
+      image: $('meta[property="og:image"]').attr('content') ?? null,
+      siteName: $('meta[property="og:site_name"]').attr('content') ?? null,
+      url,
+    };
+
+    return metadata;
+  } catch {
+    return null;
+  } finally {
+    clearTimeout(timeout);
+  }
+}