Take weak ETags in consideration on StaticFiles (#2334)

neolooong · karpetrosyan · Kludex · web-flow · commit 3c8ab8e74a8c · 2023-12-16T07:13:21.000-07:00
Co-authored-by: Kar Petrosyan &lt;92274156+karpetrosyan@users.noreply.github.com&gt;
Co-authored-by: Marcelo Trylesinski &lt;marcelotryle@gmail.com&gt;
diff --git a/starlette/responses.py b/starlette/responses.py
@@ -311,7 +311,7 @@ def set_stat_headers(self, stat_result: os.stat_result) -> None:
         content_length = str(stat_result.st_size)
         last_modified = formatdate(stat_result.st_mtime, usegmt=True)
         etag_base = str(stat_result.st_mtime) + "-" + str(stat_result.st_size)
-        etag = md5_hexdigest(etag_base.encode(), usedforsecurity=False)
+        etag = f'"{md5_hexdigest(etag_base.encode(), usedforsecurity=False)}"'
 
         self.headers.setdefault("content-length", content_length)
         self.headers.setdefault("last-modified", last_modified)
diff --git a/starlette/staticfiles.py b/starlette/staticfiles.py
@@ -225,7 +225,7 @@ def is_not_modified(
         try:
             if_none_match = request_headers["if-none-match"]
             etag = response_headers["etag"]
-            if if_none_match == etag:
+            if etag in [tag.strip(" W/") for tag in if_none_match.split(",")]:
                 return True
         except KeyError:
             pass
diff --git a/tests/test_staticfiles.py b/tests/test_staticfiles.py
@@ -208,6 +208,11 @@ def test_staticfiles_304_with_etag_match(tmpdir, test_client_factory):
     second_resp = client.get("/example.txt", headers={"if-none-match": last_etag})
     assert second_resp.status_code == 304
     assert second_resp.content == b""
+    second_resp = client.get(
+        "/example.txt", headers={"if-none-match": f'W/{last_etag}, "123"'}
+    )
+    assert second_resp.status_code == 304
+    assert second_resp.content == b""
 
 
 def test_staticfiles_304_with_last_modified_compare_last_req(
