JWT handling

api/kiwi_vpn_api/config.py

@@ -2,8 +2,10 @@ from __future__ import annotations
 
 import functools
 import json
+from datetime import datetime, timedelta
 from enum import Enum
 
+from jose import JWTError, jwt
 from jose.constants import ALGORITHMS
 from passlib.context import CryptContext
 from pydantic import BaseModel, BaseSettings, Field
@@ -45,6 +47,53 @@ class JWTConfig(BaseModel):
     hash_algorithm: str = ALGORITHMS.HS256
     expiry_minutes: int = 30
 
+    async def encode(
+        self,
+        username: str,
+        expiry_minutes: int | None = None,
+    ) -> str:
+        if expiry_minutes is None:
+            expiry_minutes = self.expiry_minutes
+
+        return jwt.encode(
+            {
+                "sub": username,
+                "exp": datetime.utcnow() + timedelta(minutes=expiry_minutes),
+            },
+            self.secret,
+            algorithm=self.hash_algorithm,
+        )
+
+    async def decode(
+        self,
+        token: str,
+    ) -> str | None:
+        # decode JWT token
+        try:
+            payload = jwt.decode(
+                token,
+                self.secret,
+                algorithms=[self.hash_algorithm],
+            )
+
+        except JWTError:
+            return None
+
+        # check expiry
+        expiry = payload.get("exp")
+        if expiry is None:
+            return None
+
+        if datetime.fromtimestamp(expiry) < datetime.utcnow():
+            return None
+
+        # get username
+        username = payload.get("sub")
+        if username is None:
+            return None
+
+        return username
+
 
 class CryptoConfig(BaseModel):
     schemes: list[str] = ["bcrypt"]

api/kiwi_vpn_api/routers/user.py

@@ -1,12 +1,10 @@
-from datetime import datetime, timedelta
 
 from fastapi import APIRouter, Depends, HTTPException, status
 from fastapi.security import OAuth2PasswordBearer, OAuth2PasswordRequestForm
-from jose import JWTError, jwt
 from pydantic import BaseModel
 from sqlalchemy.orm import Session
 
-from ..config import Config, JWTConfig
+from ..config import Config
 from ..db import Connection, schemas
 
 router = APIRouter(prefix="/user")
@@ -20,28 +18,6 @@ class Token(BaseModel):
     token_type: str
 
 
-class TokenData(BaseModel):
-    username: str | None = None
-
-
-def create_access_token(
-    data: dict,
-    jwt_config: JWTConfig,
-    expires_delta: timedelta | None = None,
-):
-    to_encode = data.copy()
-
-    if expires_delta is None:
-        expires_delta = timedelta(minutes=jwt_config.expiry_minutes)
-
-    to_encode.update({"exp": datetime.utcnow() + expires_delta})
-    return jwt.encode(
-        to_encode,
-        jwt_config.secret,
-        algorithm=jwt_config.hash_algorithm,
-    )
-
-
 @router.post("/auth", response_model=Token)
 async def login(
     form_data: OAuth2PasswordRequestForm = Depends(),
@@ -62,11 +38,7 @@ async def login(
             headers={"WWW-Authenticate": "Bearer"},
         )
 
-    access_token = create_access_token(
-        data={"sub": user.name},
-        jwt_config=config.jwt,
-    )
-
+    access_token = await config.jwt.encode(user.name)
     return {"access_token": access_token, "token_type": "bearer"}
 
 
@@ -75,25 +47,16 @@ async def dep_get_current_user(
     db: Session = Depends(Connection.get),
     config: Config = Depends(Config.get),
 ):
-    credentials_exception = HTTPException(
+    username = await config.jwt.decode(token)
+    user = schemas.User.get(db, username)
+
+    if user is None:
+        raise HTTPException(
             status_code=status.HTTP_401_UNAUTHORIZED,
             detail="Could not validate credentials",
             headers={"WWW-Authenticate": "Bearer"},
         )
-    try:
-        payload = jwt.decode(token, config.jwt.secret, algorithms=[
-                             config.jwt.hash_algorithm])
-        username: str = payload.get("sub")
-        if username is None:
-            raise credentials_exception
-        token_data = TokenData(username=username)
-    except JWTError:
-        raise credentials_exception
 
-    user = schemas.User.get(db, token_data.username)
-
-    if user is None:
-        raise credentials_exception
     return user