Make post oauth next url redirect more robust, handle q params better

src/khoj/routers/auth.py

@@ -3,6 +3,7 @@ import datetime
 import logging
 import os
 from typing import Optional
+from urllib.parse import parse_qs, urlencode, urlparse, urlunparse
 
 import requests
 from fastapi import APIRouter, Depends
@@ -204,23 +205,33 @@ async def auth_post(request: Request):
 
 @auth_router.get("/redirect")
 async def auth(request: Request):
-    next_url = get_next_url(request)
-    for q in request.query_params:
-        if q in ["code", "state", "scope", "authuser", "prompt", "session_state", "access_type"]:
-            continue
-        if q != "next":
-            next_url += f"&{q}={request.query_params[q]}"
+    next_url_path = get_next_url(request)
 
-    code = request.query_params.get("code")
+    # Add query params from request, excluding OAuth params to next URL
+    oauth_params = {"code", "state", "scope", "authuser", "prompt", "session_state", "access_type", "next"}
+    query_params = {param: value for param, value in request.query_params.items() if param not in oauth_params}
 
-    # 1. Construct the full redirect URI including domain
+    # Rebuild next URL with updated query params
+    parsed_next_url_path = urlparse(next_url_path)
+    next_url = urlunparse(
+        (
+            parsed_next_url_path.scheme,
+            parsed_next_url_path.netloc,
+            parsed_next_url_path.path,
+            parsed_next_url_path.params,
+            urlencode(query_params, doseq=True),
+            parsed_next_url_path.fragment,
+        )
+    )
+
+    # Construct the full redirect URI including domain
     base_url = str(request.base_url).rstrip("/")
-
     if not DISABLE_HTTPS:
         base_url = base_url.replace("http://", "https://")
-
     redirect_uri = f"{base_url}{request.app.url_path_for('auth')}"
 
+    # Build the payload for the token request
+    code = request.query_params.get("code")
     payload = {
         "code": code,
         "client_id": os.environ["GOOGLE_CLIENT_ID"],
@@ -229,12 +240,14 @@ async def auth(request: Request):
         "grant_type": "authorization_code",
     }
 
+    # Request the token from Google
     verified_data = requests.post(
         "https://oauth2.googleapis.com/token",
         headers={"Content-Type": "application/x-www-form-urlencoded"},
         data=payload,
     )
 
+    # Validate the OAuth response
     if verified_data.status_code != 200:
         logger.error(f"Token request failed: {verified_data.text}")
         try:
@@ -245,20 +258,24 @@ async def auth(request: Request):
         verified_data.raise_for_status()
 
     credential = verified_data.json().get("id_token")
-
     if not credential:
         logger.error("Missing id_token in OAuth response")
         return RedirectResponse(url="/login?error=invalid_token", status_code=HTTP_302_FOUND)
 
+    # Validate the OAuth token
     try:
         idinfo = id_token.verify_oauth2_token(credential, google_requests.Request(), os.environ["GOOGLE_CLIENT_ID"])
     except OAuthError as error:
         return HTMLResponse(f"<h1>{error.error}</h1>")
+
+    # Get or create the authenticated user in the database
     khoj_user = await get_or_create_user(idinfo)
 
+    # Set the user session if the user is authenticated
     if khoj_user:
         request.session["user"] = dict(idinfo)
 
+        # Send a welcome email to new users
         if datetime.timedelta(minutes=3) > (datetime.datetime.now(datetime.timezone.utc) - khoj_user.date_joined):
             asyncio.create_task(send_welcome_email(idinfo["name"], idinfo["email"]))
             update_telemetry_state(
@@ -269,6 +286,7 @@ async def auth(request: Request):
             )
             logger.log(logging.INFO, f"🥳 New User Created: {khoj_user.uuid}")
 
+    # Redirect the user to the next URL
     return RedirectResponse(url=next_url, status_code=HTTP_302_FOUND)