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105 lines
4.0 KiB
105 lines
4.0 KiB
3 years ago
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import gzip
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import io
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from starlette.datastructures import Headers, MutableHeaders
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from starlette.types import ASGIApp, Message, Receive, Scope, Send
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class GZipMiddleware:
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def __init__(
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self, app: ASGIApp, minimum_size: int = 500, compresslevel: int = 9
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) -> None:
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self.app = app
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self.minimum_size = minimum_size
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self.compresslevel = compresslevel
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async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
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if scope["type"] == "http":
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headers = Headers(scope=scope)
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if "gzip" in headers.get("Accept-Encoding", ""):
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responder = GZipResponder(
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self.app, self.minimum_size, compresslevel=self.compresslevel
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)
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await responder(scope, receive, send)
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return
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await self.app(scope, receive, send)
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class GZipResponder:
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def __init__(self, app: ASGIApp, minimum_size: int, compresslevel: int = 9) -> None:
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self.app = app
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self.minimum_size = minimum_size
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self.send: Send = unattached_send
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self.initial_message: Message = {}
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self.started = False
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self.gzip_buffer = io.BytesIO()
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self.gzip_file = gzip.GzipFile(
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mode="wb", fileobj=self.gzip_buffer, compresslevel=compresslevel
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)
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async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
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self.send = send
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await self.app(scope, receive, self.send_with_gzip)
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async def send_with_gzip(self, message: Message) -> None:
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message_type = message["type"]
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if message_type == "http.response.start":
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# Don't send the initial message until we've determined how to
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# modify the outgoing headers correctly.
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self.initial_message = message
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elif message_type == "http.response.body" and not self.started:
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self.started = True
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body = message.get("body", b"")
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more_body = message.get("more_body", False)
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if len(body) < self.minimum_size and not more_body:
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# Don't apply GZip to small outgoing responses.
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await self.send(self.initial_message)
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await self.send(message)
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elif not more_body:
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# Standard GZip response.
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self.gzip_file.write(body)
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self.gzip_file.close()
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body = self.gzip_buffer.getvalue()
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headers = MutableHeaders(raw=self.initial_message["headers"])
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headers["Content-Encoding"] = "gzip"
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headers["Content-Length"] = str(len(body))
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headers.add_vary_header("Accept-Encoding")
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message["body"] = body
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await self.send(self.initial_message)
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await self.send(message)
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else:
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# Initial body in streaming GZip response.
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headers = MutableHeaders(raw=self.initial_message["headers"])
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headers["Content-Encoding"] = "gzip"
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headers.add_vary_header("Accept-Encoding")
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del headers["Content-Length"]
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self.gzip_file.write(body)
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message["body"] = self.gzip_buffer.getvalue()
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self.gzip_buffer.seek(0)
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self.gzip_buffer.truncate()
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await self.send(self.initial_message)
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await self.send(message)
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elif message_type == "http.response.body":
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# Remaining body in streaming GZip response.
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body = message.get("body", b"")
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more_body = message.get("more_body", False)
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self.gzip_file.write(body)
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if not more_body:
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self.gzip_file.close()
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message["body"] = self.gzip_buffer.getvalue()
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self.gzip_buffer.seek(0)
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self.gzip_buffer.truncate()
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await self.send(message)
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async def unattached_send(message: Message) -> None:
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raise RuntimeError("send awaitable not set") # pragma: no cover
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