Preserve header casing

Author: tomchristie

h11/_connection.py

@@ -560,27 +560,27 @@ def _clean_up_response_headers_for_sending(self, response):
             # but the HTTP spec says that if our peer does this then we have
             # to fix it instead of erroring out, so we'll accord the user the
             # same respect).
-            headers = set_comma_header(headers, b"content-length", [])
+            headers = set_comma_header(headers, b"Content-Length", [])
             if self.their_http_version is None or self.their_http_version < b"1.1":
                 # Either we never got a valid request and are sending back an
                 # error (their_http_version is None), so we assume the worst;
                 # or else we did get a valid HTTP/1.0 request, so we know that
                 # they don't understand chunked encoding.
-                headers = set_comma_header(headers, b"transfer-encoding", [])
+                headers = set_comma_header(headers, b"Transfer-Encoding", [])
                 # This is actually redundant ATM, since currently we
                 # unconditionally disable keep-alive when talking to HTTP/1.0
                 # peers. But let's be defensive just in case we add
                 # Connection: keep-alive support later:
                 if self._request_method != b"HEAD":
                     need_close = True
             else:
-                headers = set_comma_header(headers, b"transfer-encoding", ["chunked"])
+                headers = set_comma_header(headers, b"Transfer-Encoding", ["chunked"])
 
         if not self._cstate.keep_alive or need_close:
             # Make sure Connection: close is set
             connection = set(get_comma_header(headers, b"connection"))
             connection.discard(b"keep-alive")
             connection.add(b"close")
-            headers = set_comma_header(headers, b"connection", sorted(connection))
+            headers = set_comma_header(headers, b"Connection", sorted(connection))
 
         response.headers = headers

h11/_headers.py

@@ -170,12 +170,14 @@ def get_comma_header(headers, name):
 
 def set_comma_header(headers, name, new_values):
     # The header name `name` is expected to be lower-case bytes.
+    raw_name = name
+    name = name.lower()
     new_headers = []
     for found_raw_name, found_name, found_raw_value in headers.raw_items:
         if found_name != name:
             new_headers.append((found_raw_name, found_raw_value))
     for new_value in new_values:
-        new_headers.append((name, new_value))
+        new_headers.append((raw_name, new_value))
     return normalize_and_validate(new_headers)
 
 

h11/_writers.py

@@ -41,10 +41,10 @@ def write_headers(headers, write):
     raw_items = headers.raw_items
     for raw_name, name, value in raw_items:
         if name == b"host":
-            write(bytesmod(b"%s: %s\r\n", (name, value)))
+            write(bytesmod(b"%s: %s\r\n", (raw_name, value)))
     for raw_name, name, value in raw_items:
         if name != b"host":
-            write(bytesmod(b"%s: %s\r\n", (name, value)))
+            write(bytesmod(b"%s: %s\r\n", (raw_name, value)))
     write(b"\r\n")
 
 

h11/tests/test_connection.py

@@ -96,7 +96,7 @@ def test_Connection_basics_and_content_length():
         ),
     )
     assert data == (
-        b"GET / HTTP/1.1\r\n" b"host: example.com\r\n" b"content-length: 10\r\n\r\n"
+        b"GET / HTTP/1.1\r\n" b"Host: example.com\r\n" b"Content-Length: 10\r\n\r\n"
     )
 
     for conn in p.conns:
@@ -113,7 +113,7 @@ def test_Connection_basics_and_content_length():
     assert data == b"HTTP/1.1 100 \r\n\r\n"
 
     data = p.send(SERVER, Response(status_code=200, headers=[("Content-Length", "11")]))
-    assert data == b"HTTP/1.1 200 \r\ncontent-length: 11\r\n\r\n"
+    assert data == b"HTTP/1.1 200 \r\nContent-Length: 11\r\n\r\n"
 
     for conn in p.conns:
         assert conn.states == {CLIENT: SEND_BODY, SERVER: SEND_BODY}
@@ -243,7 +243,7 @@ def test_server_talking_to_http10_client():
     # We automatically Connection: close back at them
     assert (
         c.send(Response(status_code=200, headers=[]))
-        == b"HTTP/1.1 200 \r\nconnection: close\r\n\r\n"
+        == b"HTTP/1.1 200 \r\nConnection: close\r\n\r\n"
     )
 
     assert c.send(Data(data=b"12345")) == b"12345"
@@ -303,7 +303,7 @@ def test_automatic_transfer_encoding_in_response():
         receive_and_get(c, b"GET / HTTP/1.0\r\n\r\n")
         assert (
             c.send(Response(status_code=200, headers=user_headers))
-            == b"HTTP/1.1 200 \r\nconnection: close\r\n\r\n"
+            == b"HTTP/1.1 200 \r\nConnection: close\r\n\r\n"
         )
         assert c.send(Data(data=b"12345")) == b"12345"
 
@@ -876,7 +876,7 @@ def test_errors():
         if role is SERVER:
             assert (
                 c.send(Response(status_code=400, headers=[]))
-                == b"HTTP/1.1 400 \r\nconnection: close\r\n\r\n"
+                == b"HTTP/1.1 400 \r\nConnection: close\r\n\r\n"
             )
 
     # After an error sending, you can no longer send
@@ -988,14 +988,14 @@ def setup(method, http_version):
         c = setup(method, b"1.1")
         assert (
             c.send(Response(status_code=200, headers=[])) == b"HTTP/1.1 200 \r\n"
-            b"transfer-encoding: chunked\r\n\r\n"
+            b"Transfer-Encoding: chunked\r\n\r\n"
         )
 
         # No Content-Length, HTTP/1.0 peer, frame with connection: close
         c = setup(method, b"1.0")
         assert (
             c.send(Response(status_code=200, headers=[])) == b"HTTP/1.1 200 \r\n"
-            b"connection: close\r\n\r\n"
+            b"Connection: close\r\n\r\n"
         )
 
         # Content-Length + Transfer-Encoding, TE wins
@@ -1011,7 +1011,7 @@ def setup(method, http_version):
                 )
             )
             == b"HTTP/1.1 200 \r\n"
-            b"transfer-encoding: chunked\r\n\r\n"
+            b"Transfer-Encoding: chunked\r\n\r\n"
         )
 
 

h11/tests/test_io.py

@@ -31,12 +31,12 @@
             target="/a",
             headers=[("Host", "foo"), ("Connection", "close")],
         ),
-        b"GET /a HTTP/1.1\r\nhost: foo\r\nconnection: close\r\n\r\n",
+        b"GET /a HTTP/1.1\r\nHost: foo\r\nConnection: close\r\n\r\n",
     ),
     (
         (SERVER, SEND_RESPONSE),
         Response(status_code=200, headers=[("Connection", "close")], reason=b"OK"),
-        b"HTTP/1.1 200 OK\r\nconnection: close\r\n\r\n",
+        b"HTTP/1.1 200 OK\r\nConnection: close\r\n\r\n",
     ),
     (
         (SERVER, SEND_RESPONSE),
@@ -48,7 +48,7 @@
         InformationalResponse(
             status_code=101, headers=[("Upgrade", "websocket")], reason=b"Upgrade"
         ),
-        b"HTTP/1.1 101 Upgrade\r\nupgrade: websocket\r\n\r\n",
+        b"HTTP/1.1 101 Upgrade\r\nUpgrade: websocket\r\n\r\n",
     ),
     (
         (SERVER, SEND_RESPONSE),
@@ -435,7 +435,7 @@ def test_ChunkedWriter():
 
     assert (
         dowrite(w, EndOfMessage(headers=[("Etag", "asdf"), ("a", "b")]))
-        == b"0\r\netag: asdf\r\na: b\r\n\r\n"
+        == b"0\r\nEtag: asdf\r\na: b\r\n\r\n"
     )
 
 
@@ -503,5 +503,5 @@ def test_host_comes_first():
     tw(
         write_headers,
         normalize_and_validate([("foo", "bar"), ("Host", "example.com")]),
-        b"host: example.com\r\nfoo: bar\r\n\r\n",
+        b"Host: example.com\r\nfoo: bar\r\n\r\n",
     )