Stuart Gathman
126 lines
3.8 KiB
Python
126 lines
3.8 KiB
Python
# Author: Stuart D. Gathman <stuart@bmsi.com>
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# Copyright 2005 Business Management Systems, Inc.
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# This code is under the GNU General Public License. See COPYING for details.
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# Send DSNs, do call back verification,
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# and generate DSN messages from a template
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# $Log$
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import smtplib
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import spf
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import socket
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from email.Message import Message
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import Milter
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def send_dsn(mailfrom,receiver,msg=None):
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"""Send DSN. If msg is None, do callback verification.
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Mailfrom is original sender we are sending DSN or CBV to.
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Receiver is the MTA sending the DSN.
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Return None for success or (code,msg) for failure."""
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user,domain = mailfrom.split('@')
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q = spf.query(None,None,None)
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mxlist = q.dns(domain,'MX')
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if not mxlist:
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mxlist = (0,domain), # fallback to A record when no MX
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else:
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mxlist.sort()
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smtp = smtplib.SMTP()
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for prior,host in mxlist:
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try:
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smtp.connect(host)
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code,resp = smtp.helo(receiver)
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# some wiley spammers have MX records that resolve to 127.0.0.1
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a = resp.split()
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if not a:
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return (553,'MX for %s has no hostname in banner: %s' % (domain,host))
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if a[0] == receiver:
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return (553,'Fraudulent MX for %s: %s' % (domain,host))
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if not (200 <= code <= 299):
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raise smtplib.SMTPHeloError(code, resp)
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if msg:
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try:
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smtp.sendmail('<>',mailfrom,msg)
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except smtplib.SMTPSenderRefused:
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# does not accept DSN, try postmaster (at the risk of mail loops)
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smtp.sendmail('<postmaster@%s>'%receiver,mailfrom,msg)
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else: # CBV
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code,resp = smtp.docmd('MAIL FROM: <>')
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if code != 250:
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raise smtplib.SMTPSenderRefused(code, resp, '<>')
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code,resp = smtp.rcpt(mailfrom)
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if code not in (250,251):
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return (code,resp) # permanent error
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smtp.quit()
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return None # success
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except smtplib.SMTPRecipientsRefused,x:
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return x.recipients[mailfrom] # permanent error
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except smtplib.SMTPSenderRefused,x:
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return x.args[:2] # does not accept DSN
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except smtplib.SMTPDataError,x:
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return x.args # permanent error
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except smtplib.SMTPException:
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pass # any other error, try next MX
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except socket.error:
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pass # MX didn't accept connections, try next one
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smtp.close()
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return (450,'No MX servers available') # temp error
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def create_msg(q,rcptlist,origmsg=None,template=None):
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"Create a DSN message from a template. Template must be '\n' separated."
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heloname = q.h
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sender = q.s
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connectip = q.i
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receiver = q.r
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sender_domain = q.o
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result = q.result
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perm_error = q.perm_error
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rcpt = '\n\t'.join(rcptlist)
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try: subject = origmsg['Subject']
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except: subject = '(none)'
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try:
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spf_result = origmsg['Received-SPF']
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except: spf_result = None
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msg = Message()
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msg.add_header('X-Mailer','PyMilter-'+Milter.__version__)
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msg.set_type('text/plain')
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if not template:
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if spf_result and spf_result.startswith('softfail'):
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template = softfail_msg
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else:
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template = nospf_msg
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hdrs,body = template.split('\n',1)
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for ln in hdrs.splitlines():
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name,val = ln.split(':',1)
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msg.add_header(name,(val % locals()).strip())
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msg.set_payload(body % locals())
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# add headers if missing from old template
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if 'to' not in msg:
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msg.add_header('To',sender)
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if 'from' not in msg:
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msg.add_header('From','postmaster@%s'%receiver)
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if 'auto-submitted' not in msg:
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msg.add_header('Auto-Submitted','auto-generated')
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return msg
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if __name__ == '__main__':
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q = spf.query('192.168.9.50',
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'SRS0=pmeHL=RH==stuart@example.com',
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'red.example.com',receiver='mail.example.com')
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q.result = 'softfail'
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q.perm_error = None
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msg = create_msg(q,['charlie@example.com'],None,
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"""From: postmaster@%(receiver)s
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To: %(sender)s
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Subject: Test
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Test DSN template
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"""
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)
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print msg.as_string()
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# print send_dsn(f,msg.as_string())
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# print send_dsn(q.s,'mail.example.com',msg.as_string())
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