Raise '400: Content-Length can't be present with Transfer-Encoding' i…

…f both Content-Length and Transfer-Encoding are sent by peer (#6182)

CHANGES/6182.bugfix

@@ -0,0 +1 @@
+Raise ``400: Content-Length can't be present with Transfer-Encoding`` if both ``Content-Length`` and ``Transfer-Encoding`` are sent by peer by both C and Python implementations

aiohttp/http_parser.py

@@ -28,6 +28,7 @@
 from .base_protocol import BaseProtocol
 from .helpers import NO_EXTENSIONS, BaseTimerContext
 from .http_exceptions import (
+    BadHttpMessage,
     BadStatusLine,
     ContentEncodingError,
     ContentLengthError,
@@ -489,8 +490,15 @@ def parse_headers(
 
         # chunking
         te = headers.get(hdrs.TRANSFER_ENCODING)
-        if te and "chunked" in te.lower():
-            chunked = True
+        if te is not None:
+            te_lower = te.lower()
+            if "chunked" in te_lower:
+                chunked = True
+
+            if hdrs.CONTENT_LENGTH in headers:
+                raise BadHttpMessage(
+                    "Content-Length can't be present with Transfer-Encoding",
+                )
 
         return (headers, raw_headers, close_conn, encoding, upgrade, chunked)
 

tests/test_http_parser.py

@@ -291,7 +291,20 @@ def test_request_chunked(parser) -> None:
     assert isinstance(payload, streams.StreamReader)
 
 
-def test_conn_upgrade(parser) -> None:
+def test_request_te_chunked_with_content_length(parser: Any) -> None:
+    text = (
+        b"GET /test HTTP/1.1\r\n"
+        b"content-length: 1234\r\n"
+        b"transfer-encoding: chunked\r\n\r\n"
+    )
+    with pytest.raises(
+        http_exceptions.BadHttpMessage,
+        match="Content-Length can't be present with Transfer-Encoding",
+    ):
+        parser.feed_data(text)
+
+
+def test_conn_upgrade(parser: Any) -> None:
     text = (
         b"GET /test HTTP/1.1\r\n"
         b"connection: upgrade\r\n"