Handle Daphne-Root-Path for websockets, adding root_path to scope. (#453)

Signed-off-by: Alejandro R. Sedeño <asedeno@mit.edu>

daphne/ws_protocol.py

@@ -31,17 +31,21 @@ class WebSocketProtocol(WebSocketServerProtocol):
         self.server.protocol_connected(self)
         self.request = request
         self.protocol_to_accept = None
+        self.root_path = self.server.root_path
         self.socket_opened = time.time()
         self.last_ping = time.time()
         try:
-            # Sanitize and decode headers
+            # Sanitize and decode headers, potentially extracting root path
             self.clean_headers = []
             for name, value in request.headers.items():
                 name = name.encode("ascii")
                 # Prevent CVE-2015-0219
                 if b"_" in name:
                     continue
-                self.clean_headers.append((name.lower(), value.encode("latin1")))
+                if name.lower() == b"daphne-root-path":
+                    self.root_path = unquote(value)
+                else:
+                    self.clean_headers.append((name.lower(), value.encode("latin1")))
             # Get client address if possible
             peer = self.transport.getPeer()
             host = self.transport.getHost()
@@ -76,6 +80,7 @@ class WebSocketProtocol(WebSocketServerProtocol):
                     "type": "websocket",
                     "path": unquote(self.path.decode("ascii")),
                     "raw_path": self.path,
+                    "root_path": self.root_path,
                     "headers": self.clean_headers,
                     "query_string": self._raw_query_string,  # Passed by HTTP protocol
                     "client": self.client_addr,

tests/test_websocket.py

@@ -192,6 +192,30 @@ class TestWebsocket(DaphneTestCase):
         self.assertEqual(scope["path"], "/foo/bar")
         self.assertEqual(scope["raw_path"], b"/foo%2Fbar")
 
+    @given(daphne_path=http_strategies.http_path())
+    @settings(max_examples=5, deadline=2000)
+    def test_root_path(self, *, daphne_path):
+        """
+        Tests root_path handling.
+        """
+        headers = [("Daphne-Root-Path", parse.quote(daphne_path))]
+        with DaphneTestingInstance() as test_app:
+            test_app.add_send_messages([{"type": "websocket.accept"}])
+            self.websocket_handshake(
+                test_app,
+                path="/",
+                headers=headers,
+            )
+            # Validate the scope and messages we got
+            scope, _ = test_app.get_received()
+
+        # Daphne-Root-Path is not included in the returned 'headers' section.
+        self.assertNotIn(
+            "daphne-root-path", (header[0].lower() for header in scope["headers"])
+        )
+        # And what we're looking for, root_path being set.
+        self.assertEqual(scope["root_path"], daphne_path)
+
     def test_text_frames(self):
         """
         Tests we can send and receive text frames.