Handle lower-case http headers in _Mulitpart_Parser_Protocol

changelog.d/17545.bugfix

@@ -0,0 +1 @@
+Handle lower-case http headers in _Mulitpart_Parser_Protocol.

synapse/http/client.py

@@ -1057,11 +1057,11 @@ def dataReceived(self, incoming_data: bytes) -> None:
         if not self.parser:
 
             def on_header_field(data: bytes, start: int, end: int) -> None:
-                if data[start:end] == b"Location":
+                if data[start:end].lower() == b"location":
                     self.has_redirect = True
-                if data[start:end] == b"Content-Disposition":
+                if data[start:end].lower() == b"content-disposition":
                     self.in_disposition = True
-                if data[start:end] == b"Content-Type":
+                if data[start:end].lower() == b"content-type":
                     self.in_content_type = True
 
             def on_header_value(data: bytes, start: int, end: int) -> None:

tests/http/test_client.py

@@ -51,6 +51,7 @@
 class ReadMultipartResponseTests(TestCase):
     data1 = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: text/plain\r\nContent-Disposition: inline; filename=test_upload\r\n\r\nfile_"
     data2 = b"to_stream\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n"
+    data3 = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\ncontent-type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\ncontent-type: text/plain\r\ncontent-disposition: inline; filename=test_upload\r\n\r\nfile_"
 
     redirect_data = b"\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nContent-Type: application/json\r\n\r\n{}\r\n--6067d4698f8d40a0a794ea7d7379d53a\r\nLocation: https://cdn.example.org/ab/c1/2345.txt\r\n\r\n--6067d4698f8d40a0a794ea7d7379d53a--\r\n\r\n"
 
@@ -118,6 +119,29 @@ def test_parse_file(self) -> None:
             multipart_response.disposition, b"inline; filename=test_upload"
         )
 
+    def test_parse_file_lowercase_headers(self) -> None:
+        """
+        Check that a multipart response containing a file is properly parsed
+        into the json/file parts, and the json and file are properly captured if the http headers are lowercased
+        """
+        result, deferred, protocol = self._build_multipart_response(249, 250)
+
+        # Start sending data.
+        protocol.dataReceived(self.data3)
+        protocol.dataReceived(self.data2)
+        # Close the connection.
+        protocol.connectionLost(Failure(ResponseDone()))
+
+        multipart_response: MultipartResponse = deferred.result  # type: ignore[assignment]
+
+        self.assertEqual(multipart_response.json, b"{}")
+        self.assertEqual(result.getvalue(), b"file_to_stream")
+        self.assertEqual(multipart_response.length, len(b"file_to_stream"))
+        self.assertEqual(multipart_response.content_type, b"text/plain")
+        self.assertEqual(
+            multipart_response.disposition, b"inline; filename=test_upload"
+        )
+
     def test_parse_redirect(self) -> None:
         """
         check that a multipart response containing a redirect is properly parsed and redirect url is