On Wed, Nov 18, 2015 at 9:28 AM, Tom Boland <t...@t0mb.net> wrote:
> I think what you've provided me with is useful for me, but I think it's
> backwards for my purposes, as I need to be connecting to the policy daemon
> rather than being the policy daemon!
>
> I wanted to do this with deferred calls in case one of the policy daemons
> becomes unreachable and blocks my application. Do you think I should do
> something differently in that regard? My SQL lookups are done
> synchronously. If the database server goes away, I've got bigger problems
> anyway!
>
So maybe something like this is more likely to be useful:
#!/usr/bin/env python
from __future__ import print_function
from twisted.internet import reactor, protocol, endpoints, defer
from twisted.protocols import basic
class PostfixProtocol(basic.LineReceiver):
# Assuming Postfix uses '\r\n' line breaks (does it?)
delimiter = '\r\n'
def __init__(self):
self.action = None
self.action_deferred = None
def lineReceived(self, line):
if '=' in line:
self.action = line.split('=')[1]
elif line == '':
self.action_deferred.callback(self.action)
self.action_deferred = None
else:
# oops, bad input
pass
def sendPostfixRequest(self, request_dict):
if not self.action_deferred is None:
raise Exception('transaction pending')
for k, v in request_dict.items():
self.sendLine('{}={}'.format(k,v))
# Empty line signals we're done
self.sendLine('')
self.action_deferred = defer.Deferred()
return self.action_deferred
@defer.inlineCallbacks
def checkPostfixPolicy(request_dict):
ep = endpoints.clientFromString(reactor, 'tcp:host=127.0.0.1:
port=10000')
p = yield endpoints.connectProtocol(ep, PostfixProtocol())
action = yield p.sendPostfixRequest(request_dict)
print('got: {}'.format(action))
reactor.stop()
if __name__ == '__main__':
request_dict = {
'recipient': 'em...@ddr.ess',
'sender': 'em...@ddr.ess',
}
reactor.callWhenRunning(checkPostfixPolicy, request_dict)
reactor.run()
Highlights:
- This is not the same protocol as before, in particular it uses a
different delimiter.
- It assumes the response is also terminated with an empty line (does it?).
- It more than one outstanding response: a different exception should be
used.
- The input processing is very rudimentary and failure-prone.
- checkPostfixPolicy could, of course, return instead of printing. :)
Cheers,
--
exvito
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