Merge branch 'main' into ks123/role-assigning

10 files changed, 378 insertions, 57 deletions

diff --git a/backend/__init__.py b/backend/__init__.py
index a3704a0..220b457 100644
--- a/backend/__init__.py
+++ b/backend/__init__.py
@@ -7,10 +7,21 @@ from starlette.middleware.cors import CORSMiddleware
 
 from backend import constants
 from backend.authentication import JWTAuthenticationBackend
-from backend.route_manager import create_route_map
 from backend.middleware import DatabaseMiddleware, ProtectedDocsMiddleware
+from backend.route_manager import create_route_map
 from backend.validation import api
 
+ORIGINS = [
+    r"(https://[^.?#]*--pydis-forms\.netlify\.app)",  # Netlify Previews
+    r"(https?://[^.?#]*.forms-frontend.pages.dev)",  # Cloudflare Previews
+]
+
+if not constants.PRODUCTION:
+    # Allow all hosts on non-production deployments
+    ORIGINS.append(r"(.*)")
+
+ALLOW_ORIGIN_REGEX = "|".join(ORIGINS)
+
 sentry_sdk.init(
     dsn=constants.FORMS_BACKEND_DSN,
     send_default_pii=True,
@@ -20,13 +31,13 @@ sentry_sdk.init(
 middleware = [
     Middleware(
         CORSMiddleware,
-        # TODO: Convert this into a RegEx that works for prod, netlify & previews
-        allow_origins=["*"],
+        allow_origins=["https://forms.pythondiscord.com"],
+        allow_origin_regex=ALLOW_ORIGIN_REGEX,
         allow_headers=[
-            "Authorization",
             "Content-Type"
         ],
-        allow_methods=["*"]
+        allow_methods=["*"],
+        allow_credentials=True
     ),
     Middleware(DatabaseMiddleware),
     Middleware(AuthenticationMiddleware, backend=JWTAuthenticationBackend()),
diff --git a/backend/authentication/backend.py b/backend/authentication/backend.py
index f1d2ece..c7590e9 100644
--- a/backend/authentication/backend.py
+++ b/backend/authentication/backend.py
@@ -1,6 +1,6 @@
-import jwt
 import typing as t
 
+import jwt
 from starlette import authentication
 from starlette.requests import Request
 
@@ -13,18 +13,18 @@ class JWTAuthenticationBackend(authentication.AuthenticationBackend):
     """Custom Starlette authentication backend for JWT."""
 
     @staticmethod
-    def get_token_from_header(header: str) -> str:
-        """Parse JWT token from header value."""
+    def get_token_from_cookie(cookie: str) -> str:
+        """Parse JWT token from cookie."""
         try:
-            prefix, token = header.split()
+            prefix, token = cookie.split()
         except ValueError:
             raise authentication.AuthenticationError(
-                "Unable to split prefix and token from Authorization header."
+                "Unable to split prefix and token from authorization cookie."
             )
 
         if prefix.upper() != "JWT":
             raise authentication.AuthenticationError(
-                f"Invalid Authorization header prefix '{prefix}'."
+                f"Invalid authorization cookie prefix '{prefix}'."
             )
 
         return token
@@ -33,11 +33,11 @@ class JWTAuthenticationBackend(authentication.AuthenticationBackend):
         self, request: Request
     ) -> t.Optional[tuple[authentication.AuthCredentials, authentication.BaseUser]]:
         """Handles JWT authentication process."""
-        if "Authorization" not in request.headers:
+        cookie = request.cookies.get("token")
+        if not cookie:
             return None
 
-        auth = request.headers["Authorization"]
-        token = self.get_token_from_header(auth)
+        token = self.get_token_from_cookie(cookie)
 
         try:
             payload = jwt.decode(token, constants.SECRET_KEY, algorithms=["HS256"])
@@ -46,7 +46,22 @@ class JWTAuthenticationBackend(authentication.AuthenticationBackend):
 
         scopes = ["authenticated"]
 
-        if payload.get("admin") is True:
+        if not payload.get("token"):
+            raise authentication.AuthenticationError("Token is missing from JWT.")
+        if not payload.get("refresh"):
+            raise authentication.AuthenticationError(
+                "Refresh token is missing from JWT."
+            )
+
+        try:
+            user_details = payload.get("user_details")
+            if not user_details or not user_details.get("id"):
+                raise authentication.AuthenticationError("Improper user details.")
+        except Exception:
+            raise authentication.AuthenticationError("Could not parse user details.")
+
+        user = User(token, user_details)
+        if await user.fetch_admin_status(request):
             scopes.append("admin")
 
-        return authentication.AuthCredentials(scopes), User(token, payload)
+        return authentication.AuthCredentials(scopes), user
diff --git a/backend/authentication/user.py b/backend/authentication/user.py
index f40c68c..857c2ed 100644
--- a/backend/authentication/user.py
+++ b/backend/authentication/user.py
@@ -1,6 +1,11 @@
 import typing as t
 
+import jwt
 from starlette.authentication import BaseUser
+from starlette.requests import Request
+
+from backend.constants import SECRET_KEY
+from backend.discord import fetch_user_details
 
 
 class User(BaseUser):
@@ -9,6 +14,7 @@ class User(BaseUser):
     def __init__(self, token: str, payload: dict[str, t.Any]) -> None:
         self.token = token
         self.payload = payload
+        self.admin = False
 
     @property
     def is_authenticated(self) -> bool:
@@ -23,3 +29,23 @@ class User(BaseUser):
     @property
     def discord_mention(self) -> str:
         return f"<@{self.payload['id']}>"
+
+    @property
+    def decoded_token(self) -> dict[str, any]:
+        return jwt.decode(self.token, SECRET_KEY, algorithms=["HS256"])
+
+    async def fetch_admin_status(self, request: Request) -> bool:
+        self.admin = await request.state.db.admins.find_one(
+            {"_id": self.payload["id"]}
+        ) is not None
+
+        return self.admin
+
+    async def refresh_data(self) -> None:
+        """Fetches user data from discord, and updates the instance."""
+        self.payload = await fetch_user_details(self.decoded_token.get("token"))
+
+        updated_info = self.decoded_token
+        updated_info["user_details"] = self.payload
+
+        self.token = jwt.encode(updated_info, SECRET_KEY, algorithm="HS256")
diff --git a/backend/constants.py b/backend/constants.py
index 812bef4..7ea4519 100644
--- a/backend/constants.py
+++ b/backend/constants.py
@@ -1,14 +1,19 @@
+import binascii
+import os
+from enum import Enum
+
 from dotenv import load_dotenv
-load_dotenv()
 
-import os  # noqa
-import binascii  # noqa
-from enum import Enum  # noqa
+load_dotenv()
 
 
 FRONTEND_URL = os.getenv("FRONTEND_URL", "https://forms.pythondiscord.com")
 DATABASE_URL = os.getenv("DATABASE_URL")
 MONGO_DATABASE = os.getenv("MONGO_DATABASE", "pydis_forms")
+SNEKBOX_URL = os.getenv("SNEKBOX_URL", "http://snekbox.default.svc.cluster.local/eval")
+
+PRODUCTION = os.getenv("PRODUCTION", "True").lower() != "false"
+PRODUCTION_URL = "https://forms.pythondiscord.com"
 
 OAUTH2_CLIENT_ID = os.getenv("OAUTH2_CLIENT_ID")
 OAUTH2_CLIENT_SECRET = os.getenv("OAUTH2_CLIENT_SECRET")
diff --git a/backend/discord.py b/backend/discord.py
index 1dc8ed7..e5c7f8f 100644
--- a/backend/discord.py
+++ b/backend/discord.py
@@ -2,20 +2,25 @@
 import httpx
 
 from backend.constants import (
-    DISCORD_API_BASE_URL, OAUTH2_CLIENT_ID, OAUTH2_CLIENT_SECRET, OAUTH2_REDIRECT_URI
+    DISCORD_API_BASE_URL, OAUTH2_CLIENT_ID, OAUTH2_CLIENT_SECRET
 )
 
 
-async def fetch_bearer_token(access_code: str) -> dict:
+async def fetch_bearer_token(code: str, redirect: str, *, refresh: bool) -> dict:
     async with httpx.AsyncClient() as client:
         data = {
             "client_id": OAUTH2_CLIENT_ID,
             "client_secret": OAUTH2_CLIENT_SECRET,
-            "grant_type": "authorization_code",
-            "code": access_code,
-            "redirect_uri": OAUTH2_REDIRECT_URI
+            "redirect_uri": f"{redirect}/callback"
         }
 
+        if refresh:
+            data["grant_type"] = "refresh_token"
+            data["refresh_token"] = code
+        else:
+            data["grant_type"] = "authorization_code"
+            data["code"] = code
+
         r = await client.post(f"{DISCORD_API_BASE_URL}/oauth2/token", headers={
             "Content-Type": "application/x-www-form-urlencoded"
         }, data=data)
diff --git a/backend/routes/auth/authorize.py b/backend/routes/auth/authorize.py
index 975936a..d4587f0 100644
--- a/backend/routes/auth/authorize.py
+++ b/backend/routes/auth/authorize.py
@@ -2,26 +2,101 @@
 Use a token received from the Discord OAuth2 system to fetch user information.
 """
 
+import datetime
+from typing import Union
+
 import httpx
 import jwt
 from pydantic.fields import Field
 from pydantic.main import BaseModel
 from spectree.response import Response
+from starlette import responses
+from starlette.authentication import requires
 from starlette.requests import Request
-from starlette.responses import JSONResponse
 
+from backend import constants
+from backend.authentication.user import User
 from backend.constants import SECRET_KEY
-from backend.route import Route
 from backend.discord import fetch_bearer_token, fetch_user_details
+from backend.route import Route
 from backend.validation import ErrorMessage, api
 
+AUTH_FAILURE = responses.JSONResponse({"error": "auth_failure"}, status_code=400)
+
 
 class AuthorizeRequest(BaseModel):
     token: str = Field(description="The access token received from Discord.")
 
 
 class AuthorizeResponse(BaseModel):
-    token: str = Field(description="A JWT token containing the user information")
+    username: str = Field("Discord display name.")
+    expiry: str = Field("ISO formatted timestamp of expiry.")
+
+
+async def process_token(
+        bearer_token: dict,
+        request: Request
+) -> Union[AuthorizeResponse, AUTH_FAILURE]:
+    """Post a bearer token to Discord, and return a JWT and username."""
+    interaction_start = datetime.datetime.now()
+
+    try:
+        user_details = await fetch_user_details(bearer_token["access_token"])
+    except httpx.HTTPStatusError:
+        AUTH_FAILURE.delete_cookie("token")
+        return AUTH_FAILURE
+
+    max_age = datetime.timedelta(seconds=int(bearer_token["expires_in"]))
+    token_expiry = interaction_start + max_age
+
+    data = {
+        "token": bearer_token["access_token"],
+        "refresh": bearer_token["refresh_token"],
+        "user_details": user_details,
+        "expiry": token_expiry.isoformat()
+    }
+
+    token = jwt.encode(data, SECRET_KEY, algorithm="HS256")
+    user = User(token, user_details)
+
+    response = responses.JSONResponse({
+        "username": user.display_name,
+        "expiry": token_expiry.isoformat()
+    })
+
+    await set_response_token(response, request, token, bearer_token["expires_in"])
+    return response
+
+
+async def set_response_token(
+        response: responses.Response,
+        request: Request,
+        new_token: str,
+        expiry: int
+) -> None:
+    """Helper that handles logic for updating a token in a set-cookie response."""
+    origin_url = request.headers.get("origin")
+
+    if origin_url == constants.PRODUCTION_URL:
+        domain = request.url.netloc
+        samesite = "strict"
+
+    elif not constants.PRODUCTION:
+        domain = None
+        samesite = "strict"
+
+    else:
+        domain = request.url.netloc
+        samesite = "None"
+
+    response.set_cookie(
+        "token", f"JWT {new_token}",
+        secure=constants.PRODUCTION,
+        httponly=True,
+        samesite=samesite,
+        domain=domain,
+        max_age=expiry
+    )
 
 
 class AuthorizeRoute(Route):
@@ -37,22 +112,38 @@ class AuthorizeRoute(Route):
         resp=Response(HTTP_200=AuthorizeResponse, HTTP_400=ErrorMessage),
         tags=["auth"]
     )
-    async def post(self, request: Request) -> JSONResponse:
+    async def post(self, request: Request) -> responses.JSONResponse:
         """Generate an authorization token."""
         data = await request.json()
-
         try:
-            bearer_token = await fetch_bearer_token(data["token"])
-            user_details = await fetch_user_details(bearer_token["access_token"])
+            url = request.headers.get("origin")
+            bearer_token = await fetch_bearer_token(data["token"], url, refresh=False)
         except httpx.HTTPStatusError:
-            return JSONResponse({
-                "error": "auth_failure"
-            }, status_code=400)
+            return AUTH_FAILURE
 
-        user_details["admin"] = await request.state.db.admins.find_one(
-            {"_id": user_details["id"]}
-        ) is not None
+        return await process_token(bearer_token, request)
+
+
+class TokenRefreshRoute(Route):
+    """
+    Use the refresh code from a JWT to get a new token and generate a new JWT token.
+    """
 
-        token = jwt.encode(user_details, SECRET_KEY, algorithm="HS256")
+    name = "refresh"
+    path = "/refresh"
+
+    @requires(["authenticated"])
+    @api.validate(
+        resp=Response(HTTP_200=AuthorizeResponse, HTTP_400=ErrorMessage),
+        tags=["auth"]
+    )
+    async def post(self, request: Request) -> responses.JSONResponse:
+        """Refresh an authorization token."""
+        try:
+            token = request.user.decoded_token.get("refresh")
+            url = request.headers.get("origin")
+            bearer_token = await fetch_bearer_token(token, url, refresh=True)
+        except httpx.HTTPStatusError:
+            return AUTH_FAILURE
 
-        return JSONResponse({"token": token})
+        return await process_token(bearer_token, request)
diff --git a/backend/routes/forms/form.py b/backend/routes/forms/form.py
index b6b722e..1c6e44a 100644
--- a/backend/routes/forms/form.py
+++ b/backend/routes/forms/form.py
@@ -10,6 +10,7 @@ from starlette.responses import JSONResponse
 
 from backend.models import Form
 from backend.route import Route
+from backend.routes.forms.unittesting import filter_unittests
 from backend.validation import ErrorMessage, OkayResponse, api
 
 
@@ -26,7 +27,7 @@ class SingleForm(Route):
     @api.validate(resp=Response(HTTP_200=Form, HTTP_404=ErrorMessage), tags=["forms"])
     async def get(self, request: Request) -> JSONResponse:
         """Returns single form information by ID."""
-        admin = request.user.payload["admin"] if request.user.is_authenticated else False  # noqa
+        admin = request.user.admin if request.user.is_authenticated else False
 
         filters = {
             "_id": request.path_params["form_id"]
@@ -37,6 +38,9 @@ class SingleForm(Route):
 
         if raw_form := await request.state.db.forms.find_one(filters):
             form = Form(**raw_form)
+            if not admin:
+                form = filter_unittests(form)
+
             return JSONResponse(form.dict(admin=admin))
 
         return JSONResponse({"error": "not_found"}, status_code=404)
diff --git a/backend/routes/forms/submit.py b/backend/routes/forms/submit.py
index 37f76e0..23444a0 100644
--- a/backend/routes/forms/submit.py
+++ b/backend/routes/forms/submit.py
@@ -4,6 +4,7 @@ Submit a form.
 
 import asyncio
 import binascii
+import datetime
 import hashlib
 import uuid
 from typing import Any, Optional
@@ -17,10 +18,12 @@ from starlette.requests import Request
 from starlette.responses import JSONResponse
 
 from backend import constants
-from backend.authentication import User
+from backend.authentication.user import User
 from backend.models import Form, FormResponse
 from backend.route import Route
-from backend.validation import AuthorizationHeaders, ErrorMessage, api
+from backend.routes.auth.authorize import set_response_token
+from backend.routes.forms.unittesting import execute_unittest
+from backend.validation import ErrorMessage, api
 
 HCAPTCHA_VERIFY_URL = "https://hcaptcha.com/siteverify"
 HCAPTCHA_HEADERS = {
@@ -57,13 +60,37 @@ class SubmitForm(Route):
             HTTP_404=ErrorMessage,
             HTTP_400=ErrorMessage
         ),
-        headers=AuthorizationHeaders,
         tags=["forms", "responses"]
     )
     async def post(self, request: Request) -> JSONResponse:
         """Submit a response to the form."""
-        data = await request.json()
+        response = await self.submit(request)
+
+        # Silently try to update user data
+        try:
+            if hasattr(request.user, User.refresh_data.__name__):
+                old = request.user.token
+                await request.user.refresh_data()
+
+                if old != request.user.token:
+                    try:
+                        expiry = datetime.datetime.fromisoformat(
+                            request.user.decoded_token.get("expiry")
+                        )
+                    except ValueError:
+                        expiry = None
+
+                    expiry_seconds = (expiry - datetime.datetime.now()).seconds
+                    await set_response_token(response, request, request.user.token, expiry_seconds)
+
+        except httpx.HTTPStatusError:
+            pass
 
+        return response
+
+    async def submit(self, request: Request) -> JSONResponse:
+        """Helper method for handling submission logic."""
+        data = await request.json()
         data["timestamp"] = None
 
         if form := await request.state.db.forms.find_one(
@@ -104,8 +131,12 @@ class SubmitForm(Route):
             if constants.FormFeatures.REQUIRES_LOGIN.value in form.features:
                 if request.user.is_authenticated:
                     response["user"] = request.user.payload
+                    response["user"]["admin"] = request.user.admin
 
-                    if constants.FormFeatures.COLLECT_EMAIL.value in form.features and "email" not in response["user"]:  # noqa
+                    if (
+                            constants.FormFeatures.COLLECT_EMAIL.value in form.features
+                            and "email" not in response["user"]
+                    ):
                         return JSONResponse({
                             "error": "email_required"
                         }, status_code=400)
@@ -133,6 +164,23 @@ class SubmitForm(Route):
             except ValidationError as e:
                 return JSONResponse(e.errors(), status_code=422)
 
+            # Run unittests if needed
+            if any("unittests" in question.data for question in form.questions):
+                unittest_results = await execute_unittest(response_obj, form)
+
+                if not all(test.passed for test in unittest_results):
+                    # Return 500 if we encountered an internal error (code 99).
+                    status_code = 500 if any(
+                        test.return_code == 99 for test in unittest_results
+                    ) else 403
+
+                    return JSONResponse({
+                        "error": "failed_tests",
+                        "test_results": [
+                            test._asdict() for test in unittest_results if not test.passed
+                        ]
+                    }, status_code=status_code)
+
             await request.state.db.responses.insert_one(
                 response_obj.dict(by_alias=True)
             )
diff --git a/backend/routes/forms/unittesting.py b/backend/routes/forms/unittesting.py
new file mode 100644
index 0000000..3854314
--- /dev/null
+++ b/backend/routes/forms/unittesting.py
@@ -0,0 +1,127 @@
+import base64
+from collections import namedtuple
+from itertools import count
+from textwrap import indent
+
+import httpx
+from httpx import HTTPStatusError
+
+from backend.constants import SNEKBOX_URL
+from backend.models import FormResponse, Form
+
+with open("resources/unittest_template.py") as file:
+    TEST_TEMPLATE = file.read()
+
+
+UnittestResult = namedtuple("UnittestResult", "question_id return_code passed result")
+
+
+def filter_unittests(form: Form) -> Form:
+    """
+    Replace the unittest data section of code questions with the number of test cases.
+
+    This is used to redact the exact tests when sending the form back to the frontend.
+    """
+    for question in form.questions:
+        if question.type == "code" and "unittests" in question.data:
+            question.data["unittests"] = len(question.data["unittests"])
+
+    return form
+
+
+def _make_unit_code(units: dict[str, str]) -> str:
+    """Compose a dict mapping unit names to their code into an actual class body."""
+    result = ""
+
+    for unit_name, unit_code in units.items():
+        result += (
+            f"\ndef test_{unit_name.lstrip('#')}(unit):"  # Function definition
+            f"\n{indent(unit_code, '    ')}"  # Unit code
+        )
+
+    return indent(result, "    ")
+
+
+def _make_user_code(code: str) -> str:
+    """Compose the user code into an actual base64-encoded string variable."""
+    code = base64.b64encode(code.encode("utf8")).decode("utf8")
+    return f'USER_CODE = b"{code}"'
+
+
+async def _post_eval(code: str) -> dict[str, str]:
+    """Post the eval to snekbox and return the response."""
+    async with httpx.AsyncClient() as client:
+        data = {"input": code}
+        response = await client.post(SNEKBOX_URL, json=data, timeout=10)
+
+        response.raise_for_status()
+        return response.json()
+
+
+async def execute_unittest(form_response: FormResponse, form: Form) -> list[UnittestResult]:
+    """Execute all the unittests in this form and return the results."""
+    unittest_results = []
+
+    for question in form.questions:
+        if question.type == "code" and "unittests" in question.data:
+            passed = False
+
+            # Tests starting with an hashtag should have censored names.
+            hidden_test_counter = count(1)
+            hidden_tests = {
+                test.lstrip("#").lstrip("test_"): next(hidden_test_counter)
+                for test in question.data["unittests"].keys()
+                if test.startswith("#")
+            }
+
+            # Compose runner code
+            unit_code = _make_unit_code(question.data["unittests"])
+            user_code = _make_user_code(form_response.response[question.id])
+
+            code = TEST_TEMPLATE.replace("### USER CODE", user_code)
+            code = code.replace("### UNIT CODE", unit_code)
+
+            try:
+                response = await _post_eval(code)
+            except HTTPStatusError:
+                return_code = 99
+                result = "Unable to contact code runner."
+            else:
+                return_code = int(response["returncode"])
+
+                # Parse the stdout if the tests ran successfully
+                if return_code == 0:
+                    stdout = response["stdout"]
+                    passed = bool(int(stdout[0]))
+
+                    # If the test failed, we have to populate the result string.
+                    if not passed:
+                        failed_tests = stdout[1:].strip().split(";")
+
+                        # Redact failed hidden tests
+                        for i, failed_test in enumerate(failed_tests.copy()):
+                            if failed_test in hidden_tests:
+                                failed_tests[i] = f"hidden_test_{hidden_tests[failed_test]}"
+
+                        result = ";".join(failed_tests)
+                    else:
+                        result = ""
+                elif return_code in (5, 6, 99):
+                    result = response["stdout"]
+                # Killed by NsJail
+                elif return_code == 137:
+                    return_code = 7
+                    result = "Timed out or ran out of memory."
+                # Another code has been returned by CPython because of another failure.
+                else:
+                    return_code = 99
+                    result = "Internal error."
+
+            unittest_results.append(UnittestResult(
+                question_id=question.id,
+                return_code=return_code,
+                passed=passed,
+                result=result
+            ))
+
+    return unittest_results
diff --git a/backend/validation.py b/backend/validation.py
index e696683..8771924 100644
--- a/backend/validation.py
+++ b/backend/validation.py
@@ -1,6 +1,5 @@
 """Utilities for providing API payload validation."""
 
-from typing import Optional
 from pydantic.fields import Field
 from pydantic.main import BaseModel
 from spectree import SpecTree
@@ -18,13 +17,3 @@ class ErrorMessage(BaseModel):
 
 class OkayResponse(BaseModel):
     status: str = "ok"
-
-
-class AuthorizationHeaders(BaseModel):
-    authorization: Optional[str] = Field(
-        title="Authorization",
-        description=(
-            "The Authorization JWT token received from the "
-            "authorize route in the format `JWT {token}`"
-        )
-    )