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from zope.interface import implements
from twisted.mail import smtp
from twisted.internet.protocol import ServerFactory
from twisted.internet import reactor
from twisted.internet import defer
from email.Header import Header
from StringIO import StringIO
class SMTPFactory(ServerFactory):
"""
Factory for an SMTP server with encrypted relaying capabilities.
"""
def buildProtocol(self, addr):
"Return a protocol suitable for the job."
smtpProtocol = smtp.SMTP(SMTPDelivery())
smtpProtocol.factory = self
return smtpProtocol
class SMTPDelivery(object):
"""
Validate email addresses and handle message delivery.
"""
implements(smtp.IMessageDelivery)
def __init__(self):
self.gpgkey = ''
def receivedHeader(self, helo, origin, recipients):
myHostname, clientIP = helo
headerValue = "by %s from %s with ESMTP ; %s" % (
myHostname, clientIP, smtp.rfc822date( ))
# email.Header.Header used for automatic wrapping of long lines
return "Received: %s" % Header(headerValue)
def validateTo(self, user):
"""Assert existence of GPG public key for a recipient."""
# for now just accept any receipient
print "Accepting mail for %s..." % user.dest
return lambda: EncryptedMessage(user, self.gpgkey)
def validateFrom(self, helo, originAddress):
# accept mail from anywhere. To reject an address, raise
# smtp.SMTPBadSender here.
return originAddress
class EncryptedMessage():
"""
Receive plaintext from client, encrypt it and send message to
recipients.
"""
implements(smtp.IMessage)
SMTP_HOSTNAME = "mail.riseup.net"
SMTP_PORT = 25
def __init__(self, user, gpgkey):
self.user = user
self.gpgkey = gpgkey
self.getSMTPInfo()
self.lines = []
def lineReceived(self, line):
"""Store email DATA lines as they arrive."""
self.lines.append(line)
def eomReceived(self):
"""Encrypt and send message."""
print "Message data complete."
self.lines.append('') # add a trailing newline
return self.sendMail()
def connectionLost(self):
print "Connection lost unexpectedly!"
# unexpected loss of connection; don't save
del(self.lines)
def sendSuccess(self, r):
print r
reactor.stop()
def sendError(self, e):
print e
reactor.stop()
def sendMail(self):
self.lines = [self.lines[0]] + \
["From: %s" % self.user.orig.addrstr] + \
["To: %s" % self.user.dest.addrstr] + \
self.lines[1:]
msg = '\n'.join(self.lines)
d = defer.Deferred()
factory = smtp.ESMTPSenderFactory(self.smtp_username,
self.smtp_password,
self.smtp_username,
self.user.dest.addrstr,
StringIO(msg),
d)
# the next call is TSL-powered!
reactor.connectTCP(self.SMTP_HOSTNAME, self.SMTP_PORT, factory)
d.addCallback(self.sendSuccess)
d.addErrback(self.sendError)
#reactor.run()
return d
# this will be replaced by some other mechanism of obtaining credentials
# for SMTP server.
def getSMTPInfo(self):
f = open('/var/tmp/smtp-info.txt', 'r')
self.smtp_host = f.readline().rstrip()
self.smtp_port = f.readline().rstrip()
self.smtp_username = f.readline().rstrip()
self.smtp_password = f.readline().rstrip()
f.close()
# run server
if __name__ == "__main__":
import sys
reactor.listenTCP(25, SMTPFactory())
reactor.run()
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