[Twisted-Python] Aborting a connection attempt when HTTPS client detected on HTTP only server?

Michael Schlenker msc at contact.de
Thu Feb 28 09:49:06 EST 2013

Am 11.02.2013 15:51, schrieb Itamar Turner-Trauring:
> On Mon, Feb 11, 2013 at 9:24 AM, Michael Schlenker <msc at contact.de
> <mailto:msc at contact.de>> wrote:
>     Is there some pre-made solution, or would i have to hook into the
>     connection setup of twisted.web and check the first few bytes for the
>     signs of an SSL Handshake signature?
> Subclassing the HTTP protocol class and just adding a check in
> dataReceived is probably the easiest thing to do, yes. Might be worth
> filing a ticket for this as well. My guess is the logic would be
> something like "in dataReceived, if you've not hit first line, and any
> byte is non-ASCII, close connection", which has the nice property of
> being more general than just SSL. Or perhaps check what Apache does exactly.
Okay, solved it like this:

from twisted.web import server, http

class HTTPChannel(http.HTTPChannel):
    HTTP Channel that recognizes connection attempts via non-HTTP
    and closes the connection in such cases.

    def __init__(self):
        self.__request_line_received = False

    def lineReceived(self, line):
        self.__request_line_received = True
        http.HTTPChannel.lineReceived(self, line)

    def dataReceived(self, data):
        if not self.__request_line_received:
            # check for any binary garbage, e.g. not ASCII
            # e.g. ssl connection attempt
            except UnicodeDecodeError:
                return self.transport.loseConnection()
        http.HTTPChannel.dataReceived(self, data)

class Site(server.Site):
    protocol = HTTPChannel

Works fine. Thx for the suggestion to check for ASCII.


Michael Schlenker
Software Architect

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