Fixed #24: Configurable root_name options

README.rst

@@ -14,6 +14,7 @@ to power Django Channels.
 It supports automatic negotiation of protocols; there's no need for URL
 prefixing to determine WebSocket endpoints versus HTTP endpoints.
 
+
 Running
 -------
 
@@ -21,3 +22,21 @@ Simply point Daphne to your ASGI channel layer instance, and optionally
 set a bind address and port (defaults to localhost, port 8000)::
 
     daphne -b 0.0.0.0 -p 8001 django_project.asgi:channel_layer
+
+
+Root Path (SCRIPT_NAME)
+-----------------------
+
+In order to set the root path for Daphne, which is the equivalent of the
+WSGI ``SCRIPT_NAME`` setting, you have two options:
+
+* Pass a header value ``DAPHNE_ROOT_PATH``, with the desired root path as a
+  URLencoded ASCII value
+
+* Set the ``--root-path`` commandline option with the desired root path as a
+  URLencoded ASCII value
+
+The header takes precedence if both are set. As with ``SCRIPT_ALIAS``, the value
+should start with a slash, but not end with one; for example::
+
+    daphne --root-path=/forum django_project.asgi:channel_layer

daphne/cli.py

@@ -77,6 +77,12 @@ class CommandLineInterface(object):
             help='The WebSocket protocols you wish to support',
             default=None,
         )
+        self.parser.add_argument(
+            '--root-path',
+            dest='root_path',
+            help='The setting for the ASGI root_path variable',
+            default="",
+        )
 
     @classmethod
     def entrypoint(cls):
@@ -131,4 +137,5 @@ class CommandLineInterface(object):
             ping_interval=args.ping_interval,
             action_logger=AccessLogGenerator(access_log_stream) if access_log_stream else None,
             ws_protocols=args.ws_protocols,
+            root_path=args.root_path,
         ).run()

daphne/http_protocol.py

@@ -109,14 +109,18 @@ class WebRequest(http.Request):
                 self.reply_channel = None
             # Boring old HTTP.
             else:
-                # Sanitize and decode headers
+                # Sanitize and decode headers, potentially extracting root path
                 self.clean_headers = []
+                self.root_path = self.factory.root_path
                 for name, values in self.requestHeaders.getAllRawHeaders():
                     # Prevent CVE-2015-0219
                     if b"_" in name:
                         continue
                     for value in values:
-                        self.clean_headers.append((name.lower(), value))
+                        if name.lower() == "asgi_root_path":
+                            self.root_path = self.unquote(value)
+                        else:
+                            self.clean_headers.append((name.lower(), value))
                 logger.debug("HTTP %s request for %s", self.method, self.reply_channel)
                 self.content.seek(0, 0)
                 # Send message
@@ -127,6 +131,7 @@ class WebRequest(http.Request):
                         "http_version": "1.1",
                         "method": self.method.decode("ascii"),
                         "path": self.unquote(self.path),
+                        "root_path": self.root_path,
                         "scheme": "http",
                         "query_string": self.unquote(self.query_string, plus_as_space=True),
                         "headers": self.clean_headers,
@@ -268,7 +273,7 @@ class HTTPFactory(http.HTTPFactory):
 
     protocol = HTTPProtocol
 
-    def __init__(self, channel_layer, action_logger=None, timeout=120, websocket_timeout=86400, ping_interval=20, ws_protocols=None):
+    def __init__(self, channel_layer, action_logger=None, timeout=120, websocket_timeout=86400, ping_interval=20, ws_protocols=None, root_path=""):
         http.HTTPFactory.__init__(self)
         self.channel_layer = channel_layer
         self.action_logger = action_logger
@@ -281,6 +286,7 @@ class HTTPFactory(http.HTTPFactory):
         self.ws_factory = WebSocketFactory(self, protocols=ws_protocols)
         self.ws_factory.protocol = WebSocketProtocol
         self.ws_factory.reply_protocols = self.reply_protocols
+        self.root_path = root_path
 
     def reply_channels(self):
         return self.reply_protocols.keys()

daphne/server.py

@@ -20,6 +20,7 @@ class Server(object):
         websocket_timeout=None,
         ping_interval=20,
         ws_protocols=None,
+        root_path="",
     ):
         self.channel_layer = channel_layer
         self.host = host
@@ -33,6 +34,7 @@ class Server(object):
         # channel layer's group_expiry value if present, or one day if not.
         self.websocket_timeout = websocket_timeout or getattr(channel_layer, "group_expiry", 86400)
         self.ws_protocols = ws_protocols
+        self.root_path = root_path
 
     def run(self):
         self.factory = HTTPFactory(
@@ -42,6 +44,7 @@ class Server(object):
             websocket_timeout=self.websocket_timeout,
             ping_interval=self.ping_interval,
             ws_protocols=self.ws_protocols,
+            root_path=self.root_path,
         )
         if self.unix_socket:
             reactor.listenUNIX(self.unix_socket, self.factory)