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Viewing File: recipientrules.py
# -*- coding: UTF-8 -*-
# Copyright 2012-2018 Oli Schacher
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
#
#
import re
import logging
import os
import time
from postomaat.shared import ScannerPlugin, apply_template, REJECT,DEFER,ACCEPT,OK,DUNNO,DISCARD,HOLD,PREPEND,REDIRECT,WARN
lg=logging.getLogger('postomaat.plugins.recipientrules')
class RulePart(object):
def __init__(self):
self.field=None
self.operator=None
self.value=''
class RecRule(object):
def __init__(self):
self.parts=[]
self.action=None
self.message=None
def hit(self,suspect):
"""iterates over parts and returns True if all parts match"""
allvals=suspect.values
allvals['from_address']=suspect.from_address
allvals['to_address']=suspect.to_address
allvals['from_domain']=suspect.from_domain
allvals['to_domain']=suspect.to_domain
numeric_values=['recipient_count','size','encryption_keysize']
for nv in numeric_values:
try:
allvals[nv]=int(allvals[nv])
except ValueError:
pass
#lg.debug(allvals)
for part in self.parts:
susval=allvals.get(part.field,'')
try:
susval=susval.strip()
except Exception:
pass
checkval=part.value
if part.field in numeric_values:
try:
checkval=int(checkval)
except ValueError:
pass
if part.operator=='=':
hit=susval==checkval
elif part.operator=='!':
hit=susval!=checkval
elif part.operator=='>':
if susval=='':
susval=0
hit=susval>checkval
elif part.operator=='<':
if susval=='':
susval=0
hit=susval<checkval
elif part.operator=='~':
hit=re.match(checkval,str(susval)) is not None
else:
lg.warn("Unknown rule operator '%s'"%part.operator)
continue
dbgcheckval=checkval
if hasattr(checkval,'pattern'):
dbgcheckval=checkval.pattern
lg.debug(" '%s' %s '%s' ? : %s"%(susval,part.operator,dbgcheckval,hit))
if not hit:
return None
return True
class RecipientRules(ScannerPlugin):
"""
Rule file format:
[<recipient>]
<field><operator><value> [<field><operator><value> ...] <ACTION> <message>
...
[<recipient>]
...
<recipient>: email adress, domain or "global"
<field>: keys as defined in http://www.postfix.org/SMTPD_POLICY_README.html + from_domain,to_domain,from_address,to_address
<operator>:
= : equals
! : does not equal
< : smaller than
> : greater than
~ : match regex
<value> : value to compare the field to using the operator. special value <> means empty
<ACTION>: the usual postfix actions like REJECT,DEFER,DUNNO,...
<message>: any message that should be returned to the client. supports template variables
example:
[recipient@example.net]
from_address=<> REJECT too many bounces to this recipient
[example.org]
size>20000 from_address~/newsletter@/i REJECT size ${size} exceeds maximum allowed newsletter size to ${to_address}.
from_domain~/(somebank.com|someotherbank.com)$/ encryption_keysize<512 REJECT we require strong encryption from ${from_domain}
"""
def __init__(self,config,section=None):
ScannerPlugin.__init__(self,config,section)
self.logger=self._logger()
self.requiredvars={
'configfile':{
'default':'/etc/postomaat/recipient_rules.conf',
'description':'Recipient rule file',
}
}
self.ruledict=None
self.lastreload=0
def filechanged(self):
filename=self.config.get(self.section,'configfile')
statinfo=os.stat(filename)
ctime=statinfo.st_ctime
if ctime>self.lastreload:
return True
return False
def reload_if_necessary(self):
if self.ruledict is None or self.filechanged():
filename=self.config.get(self.section,'configfile')
lg.info("Reloading file: %s"%filename)
self.ruledict=self.load_file(filename)
self.lastreload=time.time()
def examine(self,suspect):
starttime=time.time()
retaction=DUNNO
retmessage=None
self.reload_if_necessary()
to_domain=suspect.to_domain
to_address=suspect.to_address
for rec in [to_address,to_domain,'global']:
if rec in self.ruledict:
lg.debug("Found rules for %s"%rec)
for recrule in self.ruledict[rec]:
result=recrule.hit(suspect)
if result:
return recrule.action,apply_template(recrule.message,suspect)
endtime=time.time()
difftime=endtime-starttime
suspect.tags['RecipientRules.time']="%.4f"%difftime
return retaction,retmessage
def load_file(self,filename):
"""returns dict, key=recipient, val=list of RecRule"""
actions=[REJECT,DEFER,ACCEPT,OK,DUNNO,DISCARD,HOLD,PREPEND,REDIRECT,WARN]
rg="|".join(actions)
rulepattern=re.compile(r'^(?P<rules>.+)\s(?P<action>'+rg+')\s(?P<message>.+)$',re.IGNORECASE)
headerpattern=re.compile(r'^\[[a-zA-Z0-9_@+.-]+\]$')
operators=['=','!','>','<','~']
olist="".join(operators)
reg='(?P<fieldname>[^'+olist+']+)(?P<operator>['+olist+'])(?P<value>.+)'
singlerulepattern=re.compile(reg)
retdict={}
lc=0
#set to None to disable global rules
currentrecipient='global'
retdict['global']=[]
with open(filename,'r') as fp:
lines = fp.readlines()
for line in lines:
lc+=1
line=line.strip()
if line.startswith('#') or line=='':
continue
if re.match(headerpattern, line) is not None:
currentrecipient=line[1:-1]
if currentrecipient not in retdict:
retdict[currentrecipient]=[]
continue
#lg.debug("Line: %s"%line)
m=re.match(rulepattern,line)
if m is not None:
#if we ever don't want global rules anymore
if currentrecipient is None:
lg.warn("%s line %s: not in a recipient section, ignoring: %s"%(filename,lc,line))
continue
gd=m.groupdict()
rulepart=gd['rules']
action=gd['action'].lower()
message=gd['message']
#lg.debug("action=%s message=%s"%(action,message))
recrule=RecRule()
recrule.action=action
recrule.message=message
problem=False
for rule in rulepart.split():
m=re.match(singlerulepattern, rule)
if m is None:
lg.warn("%s line %s: can not parse rule '%s'"%(filename,lc,rule))
problem=True
break
gd=m.groupdict()
fieldname=gd['fieldname']
operator=gd['operator']
value=gd['value']
if value=='<>':
value=''
if operator=='~':
#re precompile
if not value.startswith('/'):
lg.warn("%s line %s: regex must be slash delimited"%(filename,lc))
problem=True
break
endslashindex=value.rfind('/')
if endslashindex<=1:
lg.warn("%s line %s: regex must be slash delimited"%(filename,lc))
problem=True
break
regex=value[1:endslashindex]
flags=value[endslashindex+1:]
#safety feature request axb
if re.search(r'(^|[^\\])\|\|', regex) is not None:
lg.warn("%s line %s: found dangerous two-pipe combination in regex %s -ignoring this rule"%(filename,lc,regex))
problem=True
break
reflags=0
for flag in flags:
flag=flag.lower()
if flag=='i':
reflags|=re.I
elif flag=='m':
reflags|=re.M
else:
lg.warn("%s line %s: unknown/unsupported regex flag '%s' - ignoring this flag"%(filename,lc,flag))
try:
value=re.compile(regex,reflags)
except Exception as e:
lg.warn("%s line %s: invalid regex '%s' : %s"%(filename,lc,regex,str(e)))
problem=True
break
lg.debug("compiled regex '%s' flags %s "%(regex,flags))
rp=RulePart()
rp.field=fieldname
rp.operator=operator
rp.value=value
recrule.parts.append(rp)
if not problem:
retdict[currentrecipient].append(recrule)
#lg.debug("Added rule for %s"%currentrecipient)
else:
lg.warn("%s: cannot parse line %s: %s"%(filename, lc,line))
#remove keys without actual working rules
for k in retdict.keys():
if len(retdict[k])==0:
del retdict[k]
return retdict
def lint(self):
allok=(self.checkConfig() and self.lint_file())
return allok
def lint_file(self):
configfile=self.config.get(self.section,'configfile')
if not os.path.isfile(configfile):
print("Config file %s does not exist"%configfile)
return False
dic=self.load_file(configfile)
for k,v in iter(dic.items()):
print("%s : %s rules"%(k,len(v)))
return True
def __str__(self):
return "RecipientRules Plugin"