Accept case-insensitive range unit names in http_range

CHANGES/13580.bugfix.rst

@@ -0,0 +1,4 @@
+Fixed ``BaseRequest.http_range`` rejecting valid case-insensitive range
+unit names (e.g. ``Range: Bytes=0-499``), which made ``FileResponse``
+return ``416 Requested Range Not Satisfiable`` for satisfiable ranges
+-- by :user:`Manny7717`.

CHANGES/13581.bugfix.rst

@@ -0,0 +1 @@
+13580.bugfix.rst

CONTRIBUTORS.txt

@@ -258,6 +258,7 @@ Lukasz Marcin Dobrzanski
 Lukshya Supyal
 Lénárd Szolnoki
 Makc Belousow
+Manny7717
 Manuel Miranda
 Marat Sharafutdinov
 Marc Mueller

aiohttp/web_request.py

@@ -641,7 +641,8 @@ def http_range(self) -> "slice[int, int, int]":
         if rng is not None:
             try:
                 pattern = r"^bytes=(\d*)-(\d*)$"
-                start, end = re.findall(pattern, rng, re.ASCII)[0]
+                # Range unit names are case-insensitive (RFC 9110 §14.1.1).
+                start, end = re.findall(pattern, rng, re.ASCII | re.IGNORECASE)[0]
             except IndexError:  # pattern was not found in header
                 raise ValueError("range not in acceptable format")
 

tests/test_web_request.py

@@ -316,6 +316,15 @@ def test_range_non_ascii() -> None:
         req.http_range
 
 
+def test_range_to_slice_uppercase_unit() -> None:
+    # Range unit names are case-insensitive (RFC 9110 §14.1.1).
+    req = make_mocked_request(
+        "GET", "/", headers=CIMultiDict([("RANGE", "Bytes=0-499")])
+    )
+    assert isinstance(req.http_range, slice)
+    assert req.http_range.start == 0 and req.http_range.stop == 500
+
+
 def test_non_keepalive_on_http10() -> None:
     req = make_mocked_request("GET", "/", version=HttpVersion(1, 0))
     assert not req.keep_alive