chore: initial deploy bundle

apps/api/src/services/csrf.service.ts

@@ -0,0 +1,130 @@
+import crypto from 'crypto';
+import { logger } from '../lib/logger';
+
+/**
+ * CSRF token validation compatible with Python's `itsdangerous`
+ * `URLSafeTimedSerializer` (which Flask-WTF uses).
+ *
+ * Token format:  <b64url_payload>.<b64url_timestamp>.<b64url_signature>
+ *
+ * Default algorithm (itsdangerous ≥ 2.0):
+ *   - digest:  SHA-512 (HMAC)
+ *   - salt:    "itsdangerous.Signer" (or app-specific, e.g. "csrf-token")
+ *   - derived_key = HMAC(secret, salt + "signer").digest()
+ *   - signature = HMAC(derived_key, payload + "." + timestamp).digest()
+ *
+ * Timestamp: seconds since 2011-01-01 (itsdangerous epoch), base64url-encoded big-endian.
+ */
+
+const ITSDANGEROUS_EPOCH = 1293840000; // 2011-01-01 UTC in unix time
+
+let csrfSecret: string | null = null;
+let csrfSalt = 'itsdangerous.Signer';
+let csrfDigest: 'sha1' | 'sha256' | 'sha512' = 'sha512';
+let csrfMaxAgeSec = 60 * 60 * 24 * 7; // 7 days
+
+export async function loadCsrfSecret(
+  addr: string,
+  token: string,
+  mount: string,
+  path: string,
+): Promise<void> {
+  const { fetchVaultKV2 } = await import('../config/vault');
+
+  const secrets = await fetchVaultKV2(addr, token, mount, path);
+  if (!secrets) {
+    logger.warn('Failed to load CSRF secret from Vault');
+    return;
+  }
+
+  const secret = secrets.secret_key || secrets.SECRET_KEY || secrets.key || secrets.csrf_secret;
+  if (!secret) {
+    logger.warn('CSRF secret not found in Vault payload (expected key: secret_key)');
+    return;
+  }
+
+  csrfSecret = secret;
+  if (secrets.salt) csrfSalt = secrets.salt;
+  if (secrets.digest === 'sha1' || secrets.digest === 'sha256' || secrets.digest === 'sha512') {
+    csrfDigest = secrets.digest as 'sha1' | 'sha256' | 'sha512';
+  }
+  if (secrets.max_age_sec) {
+    const n = parseInt(secrets.max_age_sec);
+    if (!Number.isNaN(n) && n > 0) csrfMaxAgeSec = n;
+  }
+
+  logger.info(`CSRF secret loaded (digest=${csrfDigest}, salt="${csrfSalt}", max_age=${csrfMaxAgeSec}s)`);
+}
+
+export function isCsrfConfigured(): boolean {
+  return csrfSecret !== null;
+}
+
+function b64urlDecode(s: string): Buffer {
+  // itsdangerous strips padding
+  const pad = s.length % 4 === 0 ? 0 : 4 - (s.length % 4);
+  const padded = s + '='.repeat(pad);
+  return Buffer.from(padded.replace(/-/g, '+').replace(/_/g, '/'), 'base64');
+}
+
+function deriveKey(secret: string, salt: string, digest: string): Buffer {
+  // itsdangerous `Signer.derive_key`: HMAC(secret, salt + "signer")
+  return crypto.createHmac(digest, secret).update(salt + 'signer').digest();
+}
+
+function decodeTimestamp(encoded: string): number {
+  const raw = b64urlDecode(encoded);
+  let ts = 0;
+  for (const b of raw) ts = (ts << 8) | b;
+  return ts + ITSDANGEROUS_EPOCH;
+}
+
+export interface CsrfVerifyResult {
+  valid: boolean;
+  reason?: string;
+}
+
+export function verifyCsrfToken(token: string): CsrfVerifyResult {
+  if (!csrfSecret) return { valid: false, reason: 'CSRF secret not loaded' };
+  if (!token || typeof token !== 'string') return { valid: false, reason: 'Empty token' };
+
+  const lastDot = token.lastIndexOf('.');
+  if (lastDot < 0) return { valid: false, reason: 'Malformed token (no signature)' };
+
+  const payloadTs = token.slice(0, lastDot); // "<payload>.<timestamp>"
+  const sigStr = token.slice(lastDot + 1);
+
+  const prevDot = payloadTs.lastIndexOf('.');
+  if (prevDot < 0) return { valid: false, reason: 'Malformed token (no timestamp)' };
+
+  const tsStr = payloadTs.slice(prevDot + 1);
+
+  const derived = deriveKey(csrfSecret, csrfSalt, csrfDigest);
+  const expectedSig = crypto.createHmac(csrfDigest, derived).update(payloadTs).digest();
+
+  let actualSig: Buffer;
+  try {
+    actualSig = b64urlDecode(sigStr);
+  } catch {
+    return { valid: false, reason: 'Invalid signature encoding' };
+  }
+
+  if (expectedSig.length !== actualSig.length) {
+    return { valid: false, reason: 'Signature length mismatch' };
+  }
+  if (!crypto.timingSafeEqual(expectedSig, actualSig)) {
+    return { valid: false, reason: 'Signature mismatch' };
+  }
+
+  // Timestamp check
+  try {
+    const issuedAt = decodeTimestamp(tsStr);
+    const now = Math.floor(Date.now() / 1000);
+    if (issuedAt > now + 60) return { valid: false, reason: 'Token from the future' };
+    if (now - issuedAt > csrfMaxAgeSec) return { valid: false, reason: 'Token expired' };
+  } catch {
+    return { valid: false, reason: 'Invalid timestamp' };
+  }
+
+  return { valid: true };
+}