fix(backend): implemented jwt token invalidation so users cannot use it after expiry

7project/backend/app/core/security.py

@@ -0,0 +1,45 @@
+from typing import Optional
+import re
+import jwt
+from fastapi import Request
+
+# Simple in-memory revocation store. In production, consider Redis or database.
+_REVOKED_TOKENS: set[str] = set()
+
+# Bearer token regex
+_BEARER_RE = re.compile(r"^[Bb]earer\s+(.+)$")
+
+
+def extract_bearer_token(request: Request) -> Optional[str]:
+    auth = request.headers.get("authorization")
+    if not auth:
+        return None
+    m = _BEARER_RE.match(auth)
+    if not m:
+        return None
+    return m.group(1).strip()
+
+
+def revoke_token(token: str) -> None:
+    if token:
+        _REVOKED_TOKENS.add(token)
+
+
+def is_token_revoked(token: str) -> bool:
+    return token in _REVOKED_TOKENS
+
+
+def decode_and_verify_jwt(token: str, secret: str) -> dict:
+    """
+    Decode the JWT using the shared secret, verifying expiration and signature.
+    Audience is not verified here to be compatible with fastapi-users default tokens.
+    Raises jwt.ExpiredSignatureError if expired.
+    Raises jwt.InvalidTokenError for other issues.
+    Returns the decoded payload dict on success.
+    """
+    return jwt.decode(
+        token,
+        secret,
+        algorithms=["HS256"],
+        options={"verify_aud": False},
+    )  # verify_exp is True by default