[middleware] add lib/acl_middleware

halfapi/lib/acl_middleware.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+from starlette.requests import Request
+from starlette.exceptions import HTTPException
+
+@app.middleware('http')
+async def acl_middleware(request: Request, call_next):
+    """ Checks the "acls" key in the scope and applies the
+        corresponding functions in the current module's acl lib.
+
+        Raises an exception if no acl function returns True
+    """
+    print(f'Hit acl {__name__} middleware')
+
+    for acl_fnct_name in request.scope['acls']:
+        print(f'Will apply {acl_fnct_name}')
+        try:
+            fct = getattr(acl, acl_fct_name)
+            if fct(request) is True:
+                print(f'{fct} : {fct(request)}\n')
+
+                return await call_next(request)
+
+        except AttributeError as e:
+            print(f'No ACL function "{acl_fct_name}" in {__name__} module')
+            print(e)
+            break
+
+        except Exception as e:
+            print(e)
+            raise HTTPException(500)
+
+    raise HTTPException(401)