Support setting response header size limits (aio-libs#6559)

<!-- Thank you for your contribution! -->

Allow the user to set the response header limits. The properties
max_line_size, max_headers and max_field_size can be set on
ClientSession creation. Default values are: `max_line_size=8190`
`max_headers=32768` and `max_field_size=8190`.
Thus the user can set and - when needed - receive bigger response
headers.

No

- [x] I think the code is well written
- [x] Unit tests for the changes exist
- [ ] Documentation reflects the changes
- [ ] If you provide code modification, please add yourself to
`CONTRIBUTORS.txt`
  * The format is &lt;Name&gt; &lt;Surname&gt;.
  * Please keep alphabetical order, the file is sorted by names.
- [x] Add a new news fragment into the `CHANGES` folder
  * name it `<issue_id>.<type>` for example (588.bugfix)
* if you don't have an `issue_id` change it to the pr id after creating
the pr
  * ensure type is one of the following:
    * `.feature`: Signifying a new feature.
    * `.bugfix`: Signifying a bug fix.
    * `.doc`: Signifying a documentation improvement.
    * `.removal`: Signifying a deprecation or removal of public API.
* `.misc`: A ticket has been closed, but it is not of interest to users.
* Make sure to use full sentences with correct case and punctuation, for
example: "Fix issue with non-ascii contents in doctest text files."

---------

Co-authored-by: Josef Prenner <josef@cloudomation.com>
Co-authored-by: Sam Bull <aa6bs0@sambull.org>
(cherry picked from commit ecd9c72)

CHANGES/2304.feature

@@ -0,0 +1 @@
+Support setting response header parameters max_line_size and max_field_size.

aiohttp/client.py

@@ -165,31 +165,30 @@ class ClientTimeout:
 class ClientSession:
     """First-class interface for making HTTP requests."""
 
-    ATTRS = frozenset(
-        [
-            "_base_url",
-            "_source_traceback",
-            "_connector",
-            "requote_redirect_url",
-            "_loop",
-            "_cookie_jar",
-            "_connector_owner",
-            "_default_auth",
-            "_version",
-            "_json_serialize",
-            "_requote_redirect_url",
-            "_timeout",
-            "_raise_for_status",
-            "_auto_decompress",
-            "_trust_env",
-            "_default_headers",
-            "_skip_auto_headers",
-            "_request_class",
-            "_response_class",
-            "_ws_response_class",
-            "_trace_configs",
-            "_read_bufsize",
-        ]
+    __slots__ = (
+        "_base_url",
+        "_source_traceback",
+        "_connector",
+        "_loop",
+        "_cookie_jar",
+        "_connector_owner",
+        "_default_auth",
+        "_version",
+        "_json_serialize",
+        "_requote_redirect_url",
+        "_timeout",
+        "_raise_for_status",
+        "_auto_decompress",
+        "_trust_env",
+        "_default_headers",
+        "_skip_auto_headers",
+        "_request_class",
+        "_response_class",
+        "_ws_response_class",
+        "_trace_configs",
+        "_read_bufsize",
+        "_max_line_size",
+        "_max_field_size",
     )
 
     _source_traceback: Optional[traceback.StackSummary] = None
@@ -223,6 +222,8 @@ def __init__(
         requote_redirect_url: bool = True,
         trace_configs: Optional[List[TraceConfig]] = None,
         read_bufsize: int = 2**16,
+        max_line_size: int = 8190,
+        max_field_size: int = 8190,
     ) -> None:
         if loop is None:
             if connector is not None:
@@ -296,6 +297,8 @@ def __init__(
         self._trust_env = trust_env
         self._requote_redirect_url = requote_redirect_url
         self._read_bufsize = read_bufsize
+        self._max_line_size = max_line_size
+        self._max_field_size = max_field_size
 
         # Convert to list of tuples
         if headers:
@@ -393,6 +396,8 @@ async def _request(
         trace_request_ctx: Optional[SimpleNamespace] = None,
         read_bufsize: Optional[int] = None,
         auto_decompress: Optional[bool] = None,
+        max_line_size: Optional[int] = None,
+        max_field_size: Optional[int] = None,
     ) -> ClientResponse:
 
         # NOTE: timeout clamps existing connect and read timeouts.  We cannot
@@ -458,6 +463,12 @@ async def _request(
         if auto_decompress is None:
             auto_decompress = self._auto_decompress
 
+        if max_line_size is None:
+            max_line_size = self._max_line_size
+
+        if max_field_size is None:
+            max_field_size = self._max_field_size
+
         traces = [
             Trace(
                 self,
@@ -564,6 +575,8 @@ async def _request(
                         read_timeout=real_timeout.sock_read,
                         read_bufsize=read_bufsize,
                         timeout_ceil_threshold=self._connector._timeout_ceil_threshold,
+                        max_line_size=max_line_size,
+                        max_field_size=max_field_size,
                     )
 
                     try:
@@ -1247,6 +1260,8 @@ def request(
     connector: Optional[BaseConnector] = None,
     read_bufsize: Optional[int] = None,
     loop: Optional[asyncio.AbstractEventLoop] = None,
+    max_line_size: int = 8190,
+    max_field_size: int = 8190,
 ) -> _SessionRequestContextManager:
     """Constructs and sends a request.
 
@@ -1318,6 +1333,8 @@ def request(
             proxy=proxy,
             proxy_auth=proxy_auth,
             read_bufsize=read_bufsize,
+            max_line_size=max_line_size,
+            max_field_size=max_field_size,
         ),
         session,
     )

aiohttp/client_proto.py

@@ -146,6 +146,8 @@ def set_response_params(
         read_timeout: Optional[float] = None,
         read_bufsize: int = 2**16,
         timeout_ceil_threshold: float = 5,
+        max_line_size: int = 8190,
+        max_field_size: int = 8190,
     ) -> None:
         self._skip_payload = skip_payload
 
@@ -162,6 +164,8 @@ def set_response_params(
             response_with_body=not skip_payload,
             read_until_eof=read_until_eof,
             auto_decompress=auto_decompress,
+            max_line_size=max_line_size,
+            max_field_size=max_field_size,
         )
 
         if self._tail:

tests/test_client_functional.py

@@ -3077,3 +3077,105 @@ async def handler(request):
         assert resp.status == 200
         assert await resp.text() == "ok"
         assert resp.headers["Content-Type"] == "text/plain; charset=utf-8"
+
+
+async def test_max_field_size_session_default(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(headers={"Custom": "x" * 8190})
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+
+    async with await client.get("/") as resp:
+        assert resp.headers["Custom"] == "x" * 8190
+
+
+async def test_max_field_size_session_default_fail(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(headers={"Custom": "x" * 8191})
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+    with pytest.raises(aiohttp.ClientResponseError):
+        await client.get("/")
+
+
+async def test_max_field_size_session_explicit(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(headers={"Custom": "x" * 8191})
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app, max_field_size=8191)
+
+    async with await client.get("/") as resp:
+        assert resp.headers["Custom"] == "x" * 8191
+
+
+async def test_max_field_size_request_explicit(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(headers={"Custom": "x" * 8191})
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+
+    async with await client.get("/", max_field_size=8191) as resp:
+        assert resp.headers["Custom"] == "x" * 8191
+
+
+async def test_max_line_size_session_default(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(status=200, reason="x" * 8190)
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+
+    async with await client.get("/") as resp:
+        assert resp.reason == "x" * 8190
+
+
+async def test_max_line_size_session_default_fail(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(status=200, reason="x" * 8192)
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+    with pytest.raises(aiohttp.ClientResponseError):
+        await client.get("/")
+
+
+async def test_max_line_size_session_explicit(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(status=200, reason="x" * 8191)
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app, max_line_size=8191)
+
+    async with await client.get("/") as resp:
+        assert resp.reason == "x" * 8191
+
+
+async def test_max_line_size_request_explicit(aiohttp_client: Any) -> None:
+    async def handler(request):
+        return web.Response(status=200, reason="x" * 8191)
+
+    app = web.Application()
+    app.add_routes([web.get("/", handler)])
+
+    client = await aiohttp_client(app)
+
+    async with await client.get("/", max_line_size=8191) as resp:
+        assert resp.reason == "x" * 8191