Build pymilter as separate package.

milter-template.py

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+## To roll your own milter, create a class that extends Milter.  
+#  See the pymilter project at http://bmsi.com/python/milter.html
+#  based on Sendmail's milter API http://www.milter.org/milter_api/api.html
+#  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.
+
+import Milter
+import StringIO
+import time
+import email
+from socket import AF_INET, AF_INET6
+
+def parse_addr(t):
+  """Split email into user,domain.
+
+  >>> parse_addr('user@example.com')
+  ['user', 'example.com']
+  >>> parse_addr('"user@example.com"')
+  ['user@example.com']
+  >>> parse_addr('"user@bar"@example.com')
+  ['user@bar', 'example.com']
+  >>> parse_addr('foo')
+  ['foo']
+  """
+  if t.startswith('<') and t.endswith('>'): t = t[1:-1]
+  if t.startswith('"'):
+    if t.endswith('"'): return [t[1:-1]]
+    pos = t.find('"@')
+    if pos > 0: return [t[1:pos],t[pos+2:]]
+  return t.split('@')
+
+class myMilter(Milter.Milter):
+
+  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.
+  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)
+    self.fp = StringIO.StringIO()
+    self.canon_from = '@'.join(parse_addr(mailfrom))
+    self.fp.write('From %s %s\n' % (self.canon_from,time.ctime()))
+    return Milter.CONTINUE
+
+
+  ##  def envrcpt(self, to, *str):
+  def envrcpt(self, recipient, *str):
+    rcptinfo = to,Milter.dictfromlist(str)
+    self.R.append(rcptinfo)
+    
+    return Milter.CONTINUE
+
+
+  def header(self, name, hval):
+    self.fp.write("%s: %s\n" % (name,hval))	# add header to buffer
+    return Milter.CONTINUE
+
+
+  def eoh(self):
+    self.fp.write("\n")				# terminate headers
+    return Milter.CONTINUE
+
+
+  def body(self, chunk):
+    self.fp.write(chunk)
+    return Milter.CONTINUE
+
+
+  def eom(self):
+    self.fp.seek(0)
+    msg = email.message_from_file(self.fp)
+    self.setreply('250','2.5.1','Grokked by pymilter')
+    # 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):
+    print "%s [%d]" % (time.strftime('%Y%b%d %H:%M:%S'),self.id),
+    # 2005Oct13 02:34:11 [1] msg1 msg2 msg3 ...
+    for i in msg: print i,
+    print
+
+
+## ===
+    
+def main():
+  # 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)
+  print "%s bms milter shutdown" % time.strftime('%Y%b%d %H:%M:%S')
+
+if __name__ == "__main__":
+  main()