Tom,
I guess LineReceiver can help you with that, it's a matter of using a
different delimiter. Here is a rough sketch of something you can start
exploring:
from __future__ import print_function
from twisted.internet import reactor, protocol, endpoints, defer
from twisted.protocols import basic
class PostfixProtocol(basic.LineReceiver):
# Assuming Postfix sends '\r\n' line breaks (does it?)
delimiter = '\r\n\r\n'
def lineReceived(self, multi_line):
input_dict = {
k: v for k, v in (
line.split('=') for line in multi_line.split('\r\n')
)
}
self.gotPostfixRequest(input_dict)
def gotPostfixRequest(self, request_dict):
# Silly deferred-based implementation.
d = defer.Deferred()
d.addCallback(self.sendPostfixAction)
# Simulate a deferred being fired with success.
reactor.callLater(1, d.callback, 'OK')
def sendPostfixAction(self, response):
# NOTE: Sends self.delimiter after the payload.
# Use self.tranport.write if you don't want it.
self.sendLine('action={}'.format(response))
if __name__ == '__main__':
ep = endpoints.serverFromString(reactor, 'tcp:10000')
f = protocol.Factory()
f.protocol = PostfixProtocol
ep.listen(f)
reactor.run()
Key ideas:
- PostfixProtocol overrides LineReceiver's delimiter (setting it to
'\r\n\r\n')
- lineReceived parses the muti_line and calls gotPostfixRequest.
- gotPostfixRequest should decide (or delegate, you choice) what kind of
response to send back.
- sendPostfixAction sends a response back to Postfix.
Notes:
- The multi_line parsing code is short(ish) but not very robust. It may
fail in bad ways with invalid input.
- The gotPostfixRequest implementation is written for the sake of a
deferred-based example.
Does this help you in any way?
Cheers,
--
exvito
On Tue, Nov 17, 2015 at 4:56 PM, Tom Boland <t...@t0mb.net> wrote:
> Greetings all.
>
> This may be a very basic question. I'm hoping to implement a postfix
> policy check client in twisted. It's a simple protocol. You send
> newline separated key value pairs like:
>
> recipient=em...@ddr.ess
> sender=anot...@ddr.ess
> size=1024
> helo_name=mail.server
> etc..
>
> you terminate the request with an additional newline. The response
> comes back like
>
> action=OK
>
> You can send mutliple requests in the same connection. What I'm
> envisaging is a module that can be used to provide a deferred
> request/response pairing to my calling application. The module class
> will manage the single connection to the postfix policy daemon (I'm
> actually going to have persistent connections to a few daemons), and
> reconnect when necessary etc. Any requests will return a deferred that
> I can add callbacks to. How would you design this with twisted? I can
> easily envisage a way of using a clientfactory to instantiate separate
> connections for each request/response, but actually being able to simply
> send a request and receive the single response for that request is
> something I'm struggling to do within a LineReceiver instance (for
> instance). Would the twisted.protocols.amp module help given that I
> can't change the server-side protocol?
>
> Any advice much appreciated!
>
> Thanks. Tom.
>
> _______________________________________________
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--
--
exvito
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