124 lines
4.1 KiB
Python
124 lines
4.1 KiB
Python
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# Code to read HTTP data
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#
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# Strategy: each writer takes an event + a write-some-bytes function, which is
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# calls.
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#
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# WRITERS is a dict describing how to pick a reader. It maps states to either:
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# - a writer
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# - or, for body writers, a dict of framin-dependent writer factories
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from ._events import Data, EndOfMessage
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from ._state import CLIENT, IDLE, SEND_BODY, SEND_RESPONSE, SERVER
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from ._util import LocalProtocolError
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__all__ = ["WRITERS"]
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def write_headers(headers, write):
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# "Since the Host field-value is critical information for handling a
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# request, a user agent SHOULD generate Host as the first header field
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# following the request-line." - RFC 7230
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raw_items = headers._full_items
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for raw_name, name, value in raw_items:
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if name == b"host":
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write(b"%s: %s\r\n" % (raw_name, value))
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for raw_name, name, value in raw_items:
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if name != b"host":
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write(b"%s: %s\r\n" % (raw_name, value))
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write(b"\r\n")
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def write_request(request, write):
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if request.http_version != b"1.1":
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raise LocalProtocolError("I only send HTTP/1.1")
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write(b"%s %s HTTP/1.1\r\n" % (request.method, request.target))
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write_headers(request.headers, write)
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# Shared between InformationalResponse and Response
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def write_any_response(response, write):
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if response.http_version != b"1.1":
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raise LocalProtocolError("I only send HTTP/1.1")
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status_bytes = str(response.status_code).encode("ascii")
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# We don't bother sending ascii status messages like "OK"; they're
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# optional and ignored by the protocol. (But the space after the numeric
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# status code is mandatory.)
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#
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# XX FIXME: could at least make an effort to pull out the status message
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# from stdlib's http.HTTPStatus table. Or maybe just steal their enums
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# (either by import or copy/paste). We already accept them as status codes
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# since they're of type IntEnum < int.
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write(b"HTTP/1.1 %s %s\r\n" % (status_bytes, response.reason))
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write_headers(response.headers, write)
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class BodyWriter:
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def __call__(self, event, write):
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if type(event) is Data:
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self.send_data(event.data, write)
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elif type(event) is EndOfMessage:
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self.send_eom(event.headers, write)
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else: # pragma: no cover
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assert False
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#
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# These are all careful not to do anything to 'data' except call len(data) and
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# write(data). This allows us to transparently pass-through funny objects,
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# like placeholder objects referring to files on disk that will be sent via
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# sendfile(2).
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#
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class ContentLengthWriter(BodyWriter):
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def __init__(self, length):
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self._length = length
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def send_data(self, data, write):
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self._length -= len(data)
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if self._length < 0:
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raise LocalProtocolError("Too much data for declared Content-Length")
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write(data)
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def send_eom(self, headers, write):
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if self._length != 0:
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raise LocalProtocolError("Too little data for declared Content-Length")
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if headers:
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raise LocalProtocolError("Content-Length and trailers don't mix")
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class ChunkedWriter(BodyWriter):
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def send_data(self, data, write):
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# if we encoded 0-length data in the naive way, it would look like an
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# end-of-message.
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if not data:
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return
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write(b"%x\r\n" % len(data))
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write(data)
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write(b"\r\n")
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def send_eom(self, headers, write):
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write(b"0\r\n")
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write_headers(headers, write)
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class Http10Writer(BodyWriter):
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def send_data(self, data, write):
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write(data)
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def send_eom(self, headers, write):
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if headers:
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raise LocalProtocolError("can't send trailers to HTTP/1.0 client")
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# no need to close the socket ourselves, that will be taken care of by
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# Connection: close machinery
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WRITERS = {
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(CLIENT, IDLE): write_request,
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(SERVER, IDLE): write_any_response,
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(SERVER, SEND_RESPONSE): write_any_response,
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SEND_BODY: {
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"chunked": ChunkedWriter,
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"content-length": ContentLengthWriter,
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"http/1.0": Http10Writer,
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},
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}
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