developer.intra2net.com Git - imap-fix-internaldate/blob - src/mail_date_parser.py

   1 '''
   2 mail_date_parser.py - The module contains the MailDateParser class.
   3
   4 Copyright (c) 2012 Intra2net AG
   5 Author: Plamen Dimitrov
   6
   7 This program is free software: you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation, either version 3 of the License, or
  10 (at your option) any later version.
  11
  12 This program is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16 '''
  17
  18 import datetime, time
  19 import re
  20 import logging
  21
  22 #reg expressions
  23 RECEIVED_DATE = re.compile(r'(0?[1-9]|[1-2][0-9]|3[01])\s+([A-Z][a-z][a-z])\s+'
  24         r'(19[0-9]{2}|[2-9][0-9]{3}|[0-9]{2})\s+(2[0-3]|[0-1][0-9]):([0-5][0-9])(?::(60|[0-5][0-9]))?\s*'
  25         r'(?:([-\+])([0-9]{2})([0-5][0-9]))*')
  26 INTERNAL_DATE = re.compile(r'(?P<day>[ 0123][0-9])-(?P<mon>[A-Z][a-z][a-z])-(?P<year>[0-9][0-9][0-9][0-9])'
  27         r' (?P<hour>[0-9][0-9]):(?P<min>[0-9][0-9]):(?P<sec>[0-9][0-9])'
  28         r' (?P<zonen>[-+])(?P<zoneh>[0-9][0-9])(?P<zonem>[0-9][0-9])')
  29 CONTROL_SYMBOLS = re.compile(r'[\n\r\t]')
  30
  31 class MailDateParser:
  32     """This class extracts dates from imap server responses and compares them.
  33     This class contains only static methods."""
  34
  35     def __init__(self):
  36         return
  37
  38     @classmethod
  39     def extract_internal_date(cls, fetchresult):
  40         """Extracts the internal date from INTERNALDATE, returns datetime."""
  41         return datetime.datetime.fromtimestamp(time.mktime(fetchresult))
  42
  43     @classmethod
  44     def extract_received_date(cls, fetchresult):
  45         """Extracts the first date from RECEIVED, returns datetime."""
  46         fetchresult = CONTROL_SYMBOLS.sub('', fetchresult)
  47         received_dates = RECEIVED_DATE.findall(fetchresult)
  48         if(len(received_dates)==0):
  49             return ""
  50         else: received_date = received_dates[0]
  51         logging.debug("Retrieved date %s from header %s.", received_date, fetchresult)
  52         month = datetime.datetime.strptime(received_date[1],'%b').month
  53
  54         if(received_date[3]!=""):
  55             hours = int(received_date[3])
  56         else: hours = 0
  57         if(received_date[4]!=""):
  58             minutes = int(received_date[4])
  59         else: minutes = 0
  60         if(received_date[5]!=""):
  61             seconds = int(received_date[5])
  62         else: seconds = 0
  63
  64         if(received_date[6]!=""):
  65             zonen = received_date[6]
  66         else: zonen = b'+'
  67         if(received_date[7]!=""):
  68             zoneh = int(received_date[7])
  69         else: zoneh = 0
  70         if(received_date[8]!=""):
  71             zonem = int(received_date[8])
  72         else: zonem = 0
  73         # subtract time zone to get unified time
  74         zone = (zoneh * 60 + zonem) * 60
  75         if(zonen == b'-'):
  76             zone = -zone
  77
  78         time_tuple = (int(received_date[2]), month, int(received_date[0]), hours, minutes, seconds, -1, -1, -1)
  79         #'mktime' assumes arg in local timezone, so add timezone/altzone
  80         utc = time.mktime(time_tuple)
  81         #adjust to DST
  82         if(time.daylight and time.localtime(utc)[-1]):
  83             zone = zone + time.altzone
  84         else:
  85             zone = zone + time.timezone
  86
  87         received_time_tuple = time.localtime(utc - zone)
  88         converted_received_date = datetime.datetime.fromtimestamp(time.mktime(received_time_tuple))
  89         return converted_received_date
  90
  91     @classmethod
  92     def compare_dates(cls, date1, date2, tolerance=1800):
  93         """Compares datetime objects for deviation given certain tolerance.
  94         Returns 1 if there is a significant difference."""
  95         logging.debug("Comparing dates %s <> %s.", date1, date2)
  96         timedelta = abs(date1 - date2)
  97         if(timedelta.total_seconds() > tolerance):
  98             return True
  99         else:
 100             return False