feat: Add chat embeds v1

Youtube and Website metadata embeds

server/src/routes/ssrf-guard.ts

@@ -0,0 +1,119 @@
+import { lookup } from 'dns/promises';
+
+const MAX_REDIRECTS = 5;
+
+function isPrivateIp(ip: string): boolean {
+  if (
+    ip === '127.0.0.1' ||
+    ip === '::1' ||
+    ip === '0.0.0.0' ||
+    ip === '::'
+  )
+    return true;
+
+  // 10.x.x.x
+  if (ip.startsWith('10.'))
+    return true;
+
+  // 172.16.0.0 - 172.31.255.255
+  if (ip.startsWith('172.')) {
+    const second = parseInt(ip.split('.')[1], 10);
+
+    if (second >= 16 && second <= 31)
+      return true;
+  }
+
+  // 192.168.x.x
+  if (ip.startsWith('192.168.'))
+    return true;
+
+  // 169.254.x.x (link-local, AWS metadata)
+  if (ip.startsWith('169.254.'))
+    return true;
+
+  // IPv6 private ranges (fc00::/7, fe80::/10)
+  const lower = ip.toLowerCase();
+
+  if (lower.startsWith('fc') || lower.startsWith('fd') || lower.startsWith('fe80'))
+    return true;
+
+  return false;
+}
+
+export async function resolveAndValidateHost(url: string): Promise<boolean> {
+  let hostname: string;
+
+  try {
+    hostname = new URL(url).hostname;
+  } catch {
+    return false;
+  }
+
+  // Block obvious private hostnames
+  if (hostname === 'localhost' || hostname === 'metadata.google.internal')
+    return false;
+
+  // If hostname is already an IP literal, check it directly
+  if (/^[\d.]+$/.test(hostname) || hostname.startsWith('['))
+    return !isPrivateIp(hostname.replace(/[[\]]/g, ''));
+
+  try {
+    const { address } = await lookup(hostname);
+
+    return !isPrivateIp(address);
+  } catch {
+    return false;
+  }
+}
+
+export interface SafeFetchOptions {
+  signal?: AbortSignal;
+  headers?: Record<string, string>;
+}
+
+/**
+ * Fetches a URL while following redirects safely, validating each
+ * hop against SSRF (private/reserved IPs, blocked hostnames).
+ *
+ * The caller must validate the initial URL with `resolveAndValidateHost`
+ * before calling this function.
+ */
+export async function safeFetch(url: string, options: SafeFetchOptions = {}): Promise<Response | undefined> {
+  let currentUrl = url;
+  let response: Response | undefined;
+
+  for (let redirects = 0; redirects <= MAX_REDIRECTS; redirects++) {
+    response = await fetch(currentUrl, {
+      redirect: 'manual',
+      signal: options.signal,
+      headers: options.headers
+    });
+
+    const location = response.headers.get('location');
+
+    if (response.status >= 300 && response.status < 400 && location) {
+      let nextUrl: string;
+
+      try {
+        nextUrl = new URL(location, currentUrl).href;
+      } catch {
+        break;
+      }
+
+      if (!/^https?:\/\//i.test(nextUrl))
+        break;
+
+      const redirectAllowed = await resolveAndValidateHost(nextUrl);
+
+      if (!redirectAllowed)
+        break;
+
+      currentUrl = nextUrl;
+      continue;
+    }
+
+    break;
+  }
+
+  return response;
+}