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## To roll your own milter, create a class that extends Milter.
# This is a useless example to show basic features of Milter.
# See the pymilter project at https://pymilter.org based
# on Sendmail's milter API
# This code is open-source on the same terms as Python.
## Milter calls methods of your class at milter events.
## Return REJECT,TEMPFAIL,ACCEPT to short circuit processing for a message.
## You can also add/del recipients, replacebody, add/del headers, etc.
from __future__ import print_function
import Milter
try:
from StringIO import StringIO as BytesIO
except:
from io import BytesIO
import time
import email
from email import message_from_binary_file
from email import policy
import mimetypes
import os
import sys
from socket import AF_INET, AF_INET6
from Milter.utils import parse_addr
if True:
# for logging process - usually not needed
from multiprocessing import Process as Thread, Queue
else:
from threading import Thread
from Queue import Queue
logq = None
class myMilter(Milter.Base):
def __init__(self): # A new instance with each new connection.
self.id = Milter.uniqueID() # Integer incremented with each call.
# each connection runs in its own thread and has its own myMilter
# instance. Python code must be thread safe. This is trivial if only stuff
# in myMilter instances is referenced.
@Milter.noreply
def connect(self, IPname, family, hostaddr):
# (self, 'ip068.subnet71.example.com', AF_INET, ('215.183.71.68', 4720) )
# (self, 'ip6.mxout.example.com', AF_INET6,
# ('3ffe:80e8:d8::1', 4720, 1, 0) )
self.IP = hostaddr[0]
self.port = hostaddr[1]
if family == AF_INET6:
self.flow = hostaddr[2]
self.scope = hostaddr[3]
else:
self.flow = None
self.scope = None
self.IPname = IPname # Name from a reverse IP lookup
self.H = None
self.fp = None
self.receiver = self.getsymval('j')
self.log("connect from %s at %s" % (IPname, hostaddr) )
return Milter.CONTINUE
## def hello(self,hostname):
def hello(self, heloname):
# (self, 'mailout17.dallas.texas.example.com')
self.H = heloname
self.log("HELO %s" % heloname)
if heloname.find('.') < 0: # illegal helo name
# NOTE: example only - too many real braindead clients to reject on this
self.setreply('550','5.7.1','Sheesh people! Use a proper helo name!')
return Milter.REJECT
return Milter.CONTINUE
## def envfrom(self,f,*str):
def envfrom(self, mailfrom, *str):
self.F = mailfrom
self.R = [] # list of recipients
self.fromparms = Milter.dictfromlist(str) # ESMTP parms
self.user = self.getsymval('{auth_authen}') # authenticated user
self.log("mail from:", mailfrom, *str)
# NOTE: self.fp is only an *internal* copy of message data. You
# must use addheader, chgheader, replacebody to change the message
# on the MTA.
self.fp = BytesIO()
self.canon_from = '@'.join(parse_addr(mailfrom))
self.fp.write(b'From %s %s\n' % (self.canon_from.encode(),
time.ctime().encode()))
return Milter.CONTINUE
## def envrcpt(self, to, *str):
@Milter.noreply
def envrcpt(self, to, *str):
rcptinfo = to,Milter.dictfromlist(str)
self.R.append(rcptinfo)
return Milter.CONTINUE
@Milter.noreply
def header(self, name, hval):
self.fp.write(b'%s: %s\n' % (name.encode(),hval.encode())) # add header to buffer
return Milter.CONTINUE
@Milter.noreply
def eoh(self):
self.fp.write(b'\n') # terminate headers
return Milter.CONTINUE
@Milter.noreply
def body(self, chunk):
self.fp.write(chunk)
return Milter.CONTINUE
def eom(self):
self.fp.seek(0)
msg = email.message_from_binary_file(self.fp, policy=policy.default)
#example on how to iterate through attachments
for attachment in msg.iter_attachments():
#attachment holds the attachment object so that it can be used with a new MIMEMultipart() message
self.log("Attachment filename is %s" % (attachment.get_filename(),))
self.log("Attachment content/type is %s" % (attachment.get_content_type(),))
data = attachment.get_content()
self.log("Attachment content is %s" % (data,))
# many milter functions can only be called from eom()
# example of adding a Bcc:
self.addrcpt('<%s>' % 'spy@example.com')
return Milter.ACCEPT
def close(self):
# always called, even when abort is called. Clean up
# any external resources here.
return Milter.CONTINUE
def abort(self):
# client disconnected prematurely
return Milter.CONTINUE
## === Support Functions ===
def log(self,*msg):
t = (msg,self.id,time.time())
if logq:
logq.put(t)
else:
# logmsg(*t)
pass
def logmsg(msg,id,ts):
print("%s [%d]" % (time.strftime('%Y%b%d %H:%M:%S',time.localtime(ts)),id),
end=None)
# 2005Oct13 02:34:11 [1] msg1 msg2 msg3 ...
for i in msg: print(i,end=None)
print()
sys.stdout.flush()
def background():
while True:
t = logq.get()
if not t: break
logmsg(*t)
## ===
def main():
bt = Thread(target=background)
bt.start()
# This is NOT a good socket location for production, it is for
# playing around. I suggest /var/run/milter/myappnamesock for production.
socketname = os.path.expanduser('~/pythonsock')
timeout = 600
# Register to have the Milter factory create instances of your class:
Milter.factory = myMilter
flags = Milter.CHGBODY + Milter.CHGHDRS + Milter.ADDHDRS
flags += Milter.ADDRCPT
flags += Milter.DELRCPT
Milter.set_flags(flags) # tell Sendmail which features we use
print("%s milter startup" % time.strftime('%Y%b%d %H:%M:%S'))
sys.stdout.flush()
Milter.runmilter("pythonfilter",socketname,timeout)
logq.put(None)
bt.join()
print("%s bms milter shutdown" % time.strftime('%Y%b%d %H:%M:%S'))
if __name__ == "__main__":
# You probably do not need a logging process, but if you do, this
# is one way to do it.
logq = Queue(maxsize=4)
main()
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