Remove OAuthToken from db (use authlib dict); basic OAuth2 service provider with Forgejo

TODO

@@ -0,0 +1,3 @@
+https://docs.authlib.org/en/latest/oauth/2/intro.html#intro-oauth2
+
+https://www.keycloak.org/docs/latest/authorization_services/index.html

pyproject.toml

@@ -11,6 +11,7 @@ dependencies = [
   "fastapi[standard]>=0.115.6",
   "itsdangerous>=2.2.0",
   "passlib[bcrypt]>=1.7.4",
+  "pkce>=1.0.3",
   "pydantic-settings>=2.7.1",
   "python-jose[cryptography]>=3.3.0",
   "requests>=2.32.3",

src/oidc_test/auth_utils.py

@@ -4,12 +4,13 @@ from datetime import datetime
 import logging
 
 from fastapi import HTTPException, Request, status
+from authlib.oauth2.rfc6749 import OAuth2Token
 from authlib.integrations.starlette_client import OAuth, OAuthError, StarletteOAuth2App
 
 # from authlib.oauth1.auth import OAuthToken
 # from authlib.oauth2.auth import OAuth2Token
 
-from .models import OAuth2Token, User
+from .models import User
 from .database import db
 from .settings import settings
 
@@ -23,7 +24,7 @@ def get_provider(request: Request) -> StarletteOAuth2App:
     It can be used in Depends()"""
     if (oidc_provider_id := request.session.get("oidc_provider_id")) is None:
         raise HTTPException(
-            status.HTTP_500_INTERNAL_SERVER_ERROR,
+            status.HTTP_503_SERVICE_UNAVAILABLE,
             "Not logged in (no provider in session)",
         )
     try:
@@ -43,7 +44,7 @@ async def get_current_user(request: Request) -> User:
         raise HTTPException(status.HTTP_401_UNAUTHORIZED, "Token unknown")
     user = await db.get_user(user_sub)
     ## Check if the token is expired
-    if token.expires_at < datetime.timestamp(datetime.now()):
+    if token.is_expired():
         oidc_provider = get_provider(request=request)
         ## Ask a new refresh token from the provider
         logger.info(f"Token expired for user {user.name}")
@@ -117,4 +118,10 @@ def update_token(*args, **kwargs):
     ...
 
 
+async def get_token(request: Request) -> OAuth2Token:
+    if (token := await db.get_token(request.session.get("token"))) is None:
+        raise HTTPException(status.HTTP_401_UNAUTHORIZED, "No token")
+    return token
+
+
 authlib_oauth = OAuth(cache=None, fetch_token=fetch_token, update_token=update_token)

src/oidc_test/database.py

@@ -1,9 +1,11 @@
-# Implement a fake in-memory database interface for demo purpose
+"""Fake in-memory database interface for demo purpose"""
+
 import logging
 
 from authlib.integrations.starlette_client.apps import StarletteOAuth2App
 
-from .models import User, OAuth2Token, Role
+from .models import User, Role
+from authlib.oauth2.rfc6749 import OAuth2Token
 
 logger = logging.getLogger(__name__)
 
@@ -37,11 +39,11 @@ class Database:
     async def get_user(self, sub: str) -> User:
         return self.users[sub]
 
-    async def add_token(self, token_dict: dict, user: User) -> None:
-        self.tokens[token_dict['id_token']] = OAuth2Token.from_dict(token_dict=token_dict, user=user)
+    async def add_token(self, token: OAuth2Token, user: User) -> None:
+        self.tokens[token["id_token"]] = token
 
-    async def get_token(self, name) -> OAuth2Token | None:
-        return self.tokens.get(name)
+    async def get_token(self, id_token: str) -> OAuth2Token | None:
+        return self.tokens.get(id_token)
 
 
 db = Database()

src/oidc_test/main.py

@@ -10,12 +10,15 @@ from urllib.parse import urlencode
 
 from httpx import HTTPError
 from fastapi import Depends, FastAPI, HTTPException, Request, status
-from fastapi.responses import HTMLResponse, RedirectResponse
+from fastapi.responses import HTMLResponse, RedirectResponse, JSONResponse
 from fastapi.templating import Jinja2Templates
 from fastapi.security import OpenIdConnect
 from starlette.middleware.sessions import SessionMiddleware
 from authlib.integrations.starlette_client.apps import StarletteOAuth2App
-from authlib.integrations.starlette_client import OAuthError
+from authlib.integrations.base_client import OAuthError
+from authlib.integrations.httpx_client import AsyncOAuth2Client
+from authlib.oauth2.rfc6749 import OAuth2Token
+from pkce import generate_code_verifier, generate_pkce_pair
 
 from .settings import settings
 from .models import User
@@ -25,6 +28,7 @@ from .auth_utils import (
     get_current_user_or_none,
     get_current_user,
     authlib_oauth,
+    get_token,
 )
 from .auth_misc import pretty_details
 from .database import db
@@ -77,8 +81,7 @@ for provider in settings.oidc.providers:
 
 @app.get("/login/{oidc_provider_id}")
 async def login(request: Request, oidc_provider_id: str) -> RedirectResponse:
-    """Login with the provider id,
-    by giving the browser a redirect to its authorize page.
+    """Login with the provider id, giving the browser a redirect to its authorize page.
     The provider is expected to send the browser back to our own /auth/{oidc_provider_id} url
     with the token.
     """
@@ -87,9 +90,20 @@ async def login(request: Request, oidc_provider_id: str) -> RedirectResponse:
         provider_: StarletteOAuth2App = getattr(authlib_oauth, oidc_provider_id)
     except AttributeError:
         raise HTTPException(status.HTTP_401_UNAUTHORIZED, "No such provider")
+    if (
+        code_challenge_method := _providers[oidc_provider_id].code_challenge_method
+    ) is not None:
+        client = AsyncOAuth2Client(..., code_challenge_method=code_challenge_method)
+        code_verifier = generate_code_verifier()
+        logger.debug("TODO: PKCE")
+    else:
+        code_verifier = None
     try:
         response = await provider_.authorize_redirect(
-            request, redirect_uri, access_type="offline"
+            request,
+            redirect_uri,
+            access_type="offline",
+            code_verifier=code_verifier,
         )
         return response
     except HTTPError:
@@ -106,7 +120,7 @@ async def auth(request: Request, oidc_provider_id: str) -> RedirectResponse:
     except AttributeError:
         raise HTTPException(status.HTTP_401_UNAUTHORIZED, "No such provider")
     try:
-        token = await oidc_provider.authorize_access_token(request)
+        token: OAuth2Token = await oidc_provider.authorize_access_token(request)
     except OAuthError as error:
         raise HTTPException(status.HTTP_401_UNAUTHORIZED, detail=error.error)
     # Remember the oidc_provider in the session
@@ -166,7 +180,7 @@ async def logout(
         logger.warn(f"Cannot find end_session_endpoint for provider {provider.name}")
         return RedirectResponse(request.url_for("non_compliant_logout"))
     post_logout_uri = request.url_for("home")
-    if (id_token := await db.get_token(request.session.pop("token", None))) is None:
+    if (token := await db.get_token(request.session.pop("token", None))) is None:
         logger.warn("No session in db for the token")
         return RedirectResponse(request.url_for("home"))
     logout_url = (
@@ -175,7 +189,7 @@ async def logout(
         + urlencode(
             {
                 "post_logout_redirect_uri": post_logout_uri,
-                "id_token_hint": id_token.raw_id_token,
+                "id_token_hint": token["id_token"],
                 "cliend_id": "oidc_local_test",
             }
         )
@@ -260,6 +274,44 @@ async def get_protected_by_foorole_or_barrole(request: Request) -> HTMLResponse:
     return HTMLResponse("<h1>Only users with foorole or barrole can see this</h1>")
 
 
+@app.get("/introspect")
+async def get_introspect(
+    request: Request,
+    provider: Annotated[StarletteOAuth2App, Depends(get_provider)],
+    token: Annotated[OAuth2Token, Depends(get_token)],
+) -> JSONResponse:
+    if (
+        response := await provider.get(
+            provider.server_metadata["introspection_endpoint"],
+            token=token,
+        )
+    ).is_success:
+        return response.json()
+    else:
+        raise HTTPException(status_code=response.status_code, detail=response.text)
+
+
+@app.get("/oauth2-forgejo-test")
+async def get_forgejo_user_info(
+    request: Request,
+    user: Annotated[User, Depends(get_current_user)],
+    provider: Annotated[StarletteOAuth2App, Depends(get_provider)],
+    token: Annotated[OAuth2Token, Depends(get_token)],
+) -> HTMLResponse:
+    if (
+        response := await provider.get(
+            "/api/v1/user/repos",
+            # headers={"Authorization": f"token {token['access_token']}"},
+            token=token,
+        )
+    ).is_success:
+        repos = response.json()
+        names = [repo["name"] for repo in repos]
+        return HTMLResponse(f"{user.name} has {len(repos)} repos: {', '.join(names)}")
+    else:
+        raise HTTPException(status_code=response.status_code, detail=response.text)
+
+
 # @app.get("/fast_api_depends")
 # def fast_api_depends(
 #    token: Annotated[str, Depends(fastapi_providers["Keycloak"])]

src/oidc_test/models.py

@@ -1,8 +1,16 @@
 from functools import cached_property
 from typing import Self
 
-from pydantic import computed_field, AnyHttpUrl, EmailStr, ConfigDict
+from pydantic import (
+    computed_field,
+    AnyHttpUrl,
+    EmailStr,
+    ConfigDict,
+    GetCoreSchemaHandler,
+)
+from pydantic_core import CoreSchema, core_schema
 from authlib.integrations.starlette_client.apps import StarletteOAuth2App
+from authlib.oauth2.rfc6749 import OAuth2Token as OAuth2Token_authlib
 from sqlmodel import SQLModel, Field
 
 
@@ -45,33 +53,3 @@ class User(UserBase):
     @cached_property
     def roles_as_set(self) -> set[str]:
         return set([role.name for role in self.roles])
-
-
-class OAuth2Token(SQLModel):
-    name: str = Field(primary_key=True)
-    token_type: str  # = Field(max_length=40)
-    access_token: str  # = Field(max_length=2000)
-    raw_id_token: str
-    refresh_token: str  # = Field(max_length=200)
-    expires_at: int  # = PositiveIntegerField()
-    user: User  # = ForeignKey(User)
-
-    def to_token(self):
-        return dict(
-            access_token=self.access_token,
-            token_type=self.token_type,
-            refresh_token=self.refresh_token,
-            expires_at=self.expires_at,
-        )
-
-    @classmethod
-    def from_dict(cls, token_dict: dict, user: User) -> Self:
-        return cls(
-            name=token_dict["access_token"],
-            access_token=token_dict["access_token"],
-            raw_id_token=token_dict["id_token"],
-            token_type=token_dict["token_type"],
-            refresh_token=token_dict["refresh_token"],
-            expires_at=token_dict["expires_at"],
-            user=user,
-        )

src/oidc_test/settings.py

@@ -20,7 +20,7 @@ class OIDCProvider(BaseModel):
     client_id: str
     client_secret: str = ""
     # For PKCE (not implemented yet)
-    # code_challenge_method: str | None = None
+    code_challenge_method: str | None = None
     hint: str = "No hint"
 
     @computed_field

src/oidc_test/templates/base.html

@@ -120,7 +120,7 @@
         if (xmlHttp.readyState == 4) {
           elem.classList.add("hasResponseStatus")
           elem.classList.add("status-" + xmlHttp.status)
-          elem.title = "Response code: " + xmlHttp.status
+          elem.title = "Response code: " + xmlHttp.status + " - " + xmlHttp.statusText
         }
       }
       xmlHttp.open("GET", elem.href, true) // true for asynchronous 

src/oidc_test/templates/home.html

@@ -109,6 +109,8 @@
       <a href="protected-by-foorole-and-barrole">Auth + foorole and barrole protected content</a>
       <a href="fast_api_depends" class="hidden">Using FastAPI Depends</a>
       <a href="other">Other</a>
+      <a href="oauth2-forgejo-test">OAuth2 test (forgejo user info)</a>
+      <a href="introspect">Introspect token</a>
     </div>
   {% if user_info_details %}
     <div class="debug-auth">

uv.lock

@@ -490,6 +490,7 @@ dependencies = [
     { name = "fastapi", extra = ["standard"] },
     { name = "itsdangerous" },
     { name = "passlib", extra = ["bcrypt"] },
+    { name = "pkce" },
     { name = "pydantic-settings" },
     { name = "python-jose", extra = ["cryptography"] },
     { name = "requests" },
@@ -509,6 +510,7 @@ requires-dist = [
     { name = "fastapi", extras = ["standard"], specifier = ">=0.115.6" },
     { name = "itsdangerous", specifier = ">=2.2.0" },
     { name = "passlib", extras = ["bcrypt"], specifier = ">=1.7.4" },
+    { name = "pkce", specifier = ">=1.0.3" },
     { name = "pydantic-settings", specifier = ">=2.7.1" },
     { name = "python-jose", extras = ["cryptography"], specifier = ">=3.3.0" },
     { name = "requests", specifier = ">=2.32.3" },
@@ -565,6 +567,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/9e/c3/059298687310d527a58bb01f3b1965787ee3b40dce76752eda8b44e9a2c5/pexpect-4.9.0-py2.py3-none-any.whl", hash = "sha256:7236d1e080e4936be2dc3e326cec0af72acf9212a7e1d060210e70a47e253523", size = 63772 },
 ]
 
+[[package]]
+name = "pkce"
+version = "1.0.3"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/29/ea/ddd845c2ec21bf1e8555c782b32dc39b82f0b12764feb9f73ccbb2470f13/pkce-1.0.3.tar.gz", hash = "sha256:9775fd76d8a743d39b87df38af1cd04a58c9b5a5242d5a6350ef343d06814ab6", size = 2757 }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/15/51/52c22ec0812d25f5bf297a01153604bfa7bfa59ed66f6cd8345beb3c2b2a/pkce-1.0.3-py3-none-any.whl", hash = "sha256:55927e24c7d403b2491ebe182b95d9dcb1807643243d47e3879fbda5aad4471d", size = 3200 },
+]
+
 [[package]]
 name = "pluggy"
 version = "1.5.0"