mail_flow_sender

#!/usr/bin/env python

# Mail Flow Checker version 2.0.

#Copyright (C) 2013 by National Board of eHealth, Denmark, and Troels Arvin.
#
#Permission is hereby granted, free of charge, to any person obtaining a copy
#of this software and associated documentation files (the "Software"), to deal
#in the Software without restriction, including without limitation the rights
#to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
#copies of the Software, and to permit persons to whom the Software is
#furnished to do so, subject to the following conditions:
#
#The above copyright notice and this permission notice shall be included in
#all copies or substantial portions of the Software.
#
#THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
#AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
#LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
#OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
#THE SOFTWARE.

import os
import sys
import smtplib
import email
import random
import syslog
from ConfigParser import SafeConfigParser
import getopt
import psycopg2
import platform
import socket

# ====================
# === PREPARATIONS ===
# ====================

# preparing to parse config file
default_config_path_basename = 'mail_flow.cfg'
default_config_path = '/etc/' + default_config_path_basename
alt_config_path = os.path.dirname(__file__)+'/'+default_config_path_basename
config_file = None
# the above paths may be overridden by the -C argument

# don't let database or SMTP connection attempts run for more than 10 seconds:
connect_timeout = 10

this_script = os.path.basename(__file__)
my_hostname = platform.node()

# --------------- Helper functions ---------------
def usage(exit_error=True):
    print """Usage: %s [-C <config file>] [-h|--help]

config_file:  Complete path to optional config file. If no configuration file
              is indicated, the system will look for the configuration at
              the following paths (first path preferred):
               - %s
               - %s""" % (this_script,default_config_path,alt_config_path)
    if exit_error:
        sys.exit(1)

def format_msg(msg):
    with_config = ''
    if config_file is not None:
        with_config = " with config file '%s'" % config_file
    return "When running script '%s'%s: %s" % (this_script,with_config,msg)

def complain(msg):
    sys.stderr.write(format_msg(msg))

def log(msg):
    syslog.syslog(format_msg(msg))

def err(msg):
    complain('Error: '+msg)
    log('Error: '+msg)
    sys.exit(1)

# --------------- Parse args ---------------
try:
    options, args = getopt.getopt \
    (
        sys.argv[1:],
        "hC:",
        [
            "help",
            "config_file="
        ]
    )
except getopt.GetoptError:
    usage()

for name, value in options:
    if name in ("-h", "--help"):
        usage(False)
        sys.exit(0)
    else:
        config_file = value

if config_file is None:
    if os.path.exists(default_config_path):
        config_file = default_config_path
    else:
        config_file = alt_config_path

if not os.path.exists(config_file):
    err("No configuration file '%s'" % config_file)

# --------------- Setup configuration ---------------
defaults = {
    'smtp_server': 'localhost',
    'from_addr': 'nagios',
    'to_addr': 'nagios',
    'subject': 'Mail flow test',
 
    'days_retain': '7',
    'cleanup_seldomness': '100',
    'name': 'nagios',
    'schema': 'mail_flow',
    'sequence': 'messageid_sequence',
    'message_table': 'messages',
}

config = SafeConfigParser(defaults)
config.read(config_file)
try:
    mail_smtp_server =      config.get('mail','smtp_server')
    mail_from_addr =        config.get('mail','from_addr')
    mail_to_addr =          config.get('mail','to_addr')
    mail_subject =          config.get('mail','subject')

    db_days_retain =        int(config.get('db','days_retain'))
    db_cleanup_seldomness = int(config.get('db','cleanup_seldomness'))
    db_name =               config.get('db','name')
    db_schema =             config.get('db','schema')
    db_sequence =           config.get('db','sequence')
    db_message_table =      config.get('db','message_table')
except Exception, e:
    err("Configuration error: %s" % e)

# --------------- Prepare DB ---------------
# prepare db

try:
    os.environ['PGCONNECT_TIMEOUT'] = str(connect_timeout)
    db_conn = psycopg2.connect("dbname='%s'" % db_name);
    cursor = db_conn.cursor()
except psycopg2.DatabaseError, e:
    # Lets not make DB connection errors generate cron error mails:
    log(
        "Could not connect to DB '%s', or could not open cursor, error message: '%s'" % (
            db_name,
            str(e)
        )
    )
    sys.exit(0)


# ===================
# === GET TO WORK ===
# ===================

# --------------- Fetch message ID from DB ---------------
# Prepare message id by getting next integer from db sequence
cursor.execute("select nextval('%s.%s')" % (db_schema,db_sequence))
seq = cursor.fetchone()[0]

# --------------- Prepare outgoing mail ---------------
body = 'Mail flow testing.'
msg_id = "%d.%s.%s@%s" % (seq,mail_smtp_server,this_script,my_hostname)
headers = "From: %s\r\nTo: %s\r\nMessage-ID: %s\r\nSubject: %s\r\nPrecedence: bulk\r\n\r\n" % (
    mail_from_addr,
    mail_to_addr,
    msg_id,
    mail_subject
)
message = headers + body

# --------------- Prepare DB insert ---------------
sql = """
    INSERT INTO %s.%s (msg_id,smtp_server,to_addr,subj)
    VALUES (%%(msg_id)s,%%(mail_smtp_server)s,%%(mail_to_addr)s,%%(mail_subject)s)
""" % (db_schema, db_message_table)

cursor.execute(
    sql,
    {
        'msg_id':msg_id,
        'mail_smtp_server': mail_smtp_server,
        'mail_to_addr':mail_to_addr,
        'mail_subject':mail_subject
    }
)

# --------------- Key step: Send mail, and log it to the database ---------------
try:
    socket.setdefaulttimeout(connect_timeout)
    smtp = smtplib.SMTP(mail_smtp_server)

    # actually send mail
    smtp.sendmail(mail_from_addr,mail_to_addr,message)
    smtp.quit()
except (smtplib.SMTPException,socket.timeout,socket.error), e:
    # Lets not make SMTP connection errors generate cron error mails:
    log(
        "Could not communicate with SMTP server '%s'. Error message: '%s'" %
        (
            mail_smtp_server,
            str(e)
        )
    )
    sys.exit(0)

# most important part done, so commit
db_conn.commit()

# ================================
# === HOUSEKEEPING AND CLEANUP ===
# ================================
# --------------- Clean up database once in a while ---------------
if db_days_retain is not None:
    random.seed()
    r = random.randint(1,db_cleanup_seldomness)
    if r == db_cleanup_seldomness:

        sql = """
            DELETE FROM %s.%s
            WHERE smtp_server=%%(mail_smtp_server)s
              AND to_addr=%%(mail_to_addr)s
              AND subj=%%(mail_subject)s
              AND sent + INTERVAL '%d day' < CURRENT_TIMESTAMP
        """ % (db_schema,db_message_table,db_days_retain)

        cursor.execute(
            sql,{
                'mail_smtp_server':mail_smtp_server,
                'mail_to_addr':mail_to_addr,
                'mail_subject':mail_subject
            }
        )
        db_conn.commit()

# --------------- The end ---------------
db_conn.close()
sys.exit(0)