extract sent_from_logged_counter(request)

counter/utils.py

@@ -0,0 +1,36 @@
+from urllib.parse import urlparse
+
+from django.http import HttpRequest
+from django.urls import resolve
+
+from counter.models import Counter
+
+
+def sent_from_logged_counter(request: HttpRequest) -> bool:
+    """Check if the request is sent from a device logged to a counter.
+
+    The request must also be sent within the frame of a counter's activity.
+    Trying to use this function to manage access to non-sas
+    related resources probably won't work.
+
+    A request is considered as coming from a logged counter if :
+
+    - Its referer comes from the counter app
+      (eg. fetching user pictures from the click UI)
+      or the request path belongs to the counter app
+      (eg. the barman went back to the main by missclick and go back
+      to the counter)
+    - The current session has a counter token associated with it.
+    - A counter with this token exists.
+    """
+    referer = urlparse(request.META["HTTP_REFERER"]).path
+    path_ok = (
+        request.resolver_match.app_name == "counter"
+        or resolve(referer).app_name == "counter"
+    )
+    return (
+        path_ok
+        and "counter_token" in request.session
+        and request.session["counter_token"]
+        and Counter.objects.filter(token=request.session["counter_token"]).exists()
+    )