JezK
Edit File: wsgi.py
from io import BytesIO from tempfile import SpooledTemporaryFile from asgiref.sync import AsyncToSync, sync_to_async class WsgiToAsgi: """ Wraps a WSGI application to make it into an ASGI application. """ def __init__(self, wsgi_application): self.wsgi_application = wsgi_application async def __call__(self, scope, receive, send): """ ASGI application instantiation point. We return a new WsgiToAsgiInstance here with the WSGI app and the scope, ready to respond when it is __call__ed. """ await WsgiToAsgiInstance(self.wsgi_application)(scope, receive, send) class WsgiToAsgiInstance: """ Per-socket instance of a wrapped WSGI application """ def __init__(self, wsgi_application): self.wsgi_application = wsgi_application self.response_started = False self.response_content_length = None async def __call__(self, scope, receive, send): if scope["type"] != "http": raise ValueError("WSGI wrapper received a non-HTTP scope") self.scope = scope with SpooledTemporaryFile(max_size=65536) as body: # Alright, wait for the http.request messages while True: message = await receive() if message["type"] != "http.request": raise ValueError("WSGI wrapper received a non-HTTP-request message") body.write(message.get("body", b"")) if not message.get("more_body"): break body.seek(0) # Wrap send so it can be called from the subthread self.sync_send = AsyncToSync(send) # Call the WSGI app await self.run_wsgi_app(body) def build_environ(self, scope, body): """ Builds a scope and request body into a WSGI environ object. """ environ = { "REQUEST_METHOD": scope["method"], "SCRIPT_NAME": scope.get("root_path", "").encode("utf8").decode("latin1"), "PATH_INFO": scope["path"].encode("utf8").decode("latin1"), "QUERY_STRING": scope["query_string"].decode("ascii"), "SERVER_PROTOCOL": "HTTP/%s" % scope["http_version"], "wsgi.version": (1, 0), "wsgi.url_scheme": scope.get("scheme", "http"), "wsgi.input": body, "wsgi.errors": BytesIO(), "wsgi.multithread": True, "wsgi.multiprocess": True, "wsgi.run_once": False, } # Get server name and port - required in WSGI, not in ASGI if "server" in scope: environ["SERVER_NAME"] = scope["server"][0] environ["SERVER_PORT"] = str(scope["server"][1]) else: environ["SERVER_NAME"] = "localhost" environ["SERVER_PORT"] = "80" if "client" in scope: environ["REMOTE_ADDR"] = scope["client"][0] # Go through headers and make them into environ entries for name, value in self.scope.get("headers", []): name = name.decode("latin1") if name == "content-length": corrected_name = "CONTENT_LENGTH" elif name == "content-type": corrected_name = "CONTENT_TYPE" else: corrected_name = "HTTP_%s" % name.upper().replace("-", "_") # HTTPbis say only ASCII chars are allowed in headers, but we latin1 just in case value = value.decode("latin1") if corrected_name in environ: value = environ[corrected_name] + "," + value environ[corrected_name] = value return environ def start_response(self, status, response_headers, exc_info=None): """ WSGI start_response callable. """ # Don't allow re-calling once response has begun if self.response_started: raise exc_info[1].with_traceback(exc_info[2]) # Don't allow re-calling without exc_info if hasattr(self, "response_start") and exc_info is None: raise ValueError( "You cannot call start_response a second time without exc_info" ) # Extract status code status_code, _ = status.split(" ", 1) status_code = int(status_code) # Extract headers headers = [ (name.lower().encode("ascii"), value.encode("ascii")) for name, value in response_headers ] # Extract content-length self.response_content_length = None for name, value in response_headers: if name.lower() == "content-length": self.response_content_length = int(value) # Build and send response start message. self.response_start = { "type": "http.response.start", "status": status_code, "headers": headers, } @sync_to_async def run_wsgi_app(self, body): """ Called in a subthread to run the WSGI app. We encapsulate like this so that the start_response callable is called in the same thread. """ # Translate the scope and incoming request body into a WSGI environ environ = self.build_environ(self.scope, body) # Run the WSGI app bytes_sent = 0 for output in self.wsgi_application(environ, self.start_response): # If this is the first response, include the response headers if not self.response_started: self.response_started = True self.sync_send(self.response_start) # If the application supplies a Content-Length header if self.response_content_length is not None: # The server should not transmit more bytes to the client than the header allows bytes_allowed = self.response_content_length - bytes_sent if len(output) > bytes_allowed: output = output[:bytes_allowed] self.sync_send( {"type": "http.response.body", "body": output, "more_body": True} ) bytes_sent += len(output) # The server should stop iterating over the response when enough data has been sent if bytes_sent == self.response_content_length: break # Close connection if not self.response_started: self.response_started = True self.sync_send(self.response_start) self.sync_send({"type": "http.response.body"})