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spf.py
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#!/usr/bin/python
from __future__ import print_function
"""SPF (Sender Policy Framework) implementation.
Copyright (c) 2003 Terence Way <terry@wayforward.net>
Portions Copyright(c) 2004,2005,2006,2007,2008,2011,2012 Stuart Gathman <stuart@bmsi.com>
Portions Copyright(c) 2005,2006,2007,2008,2011,2012,2013,2014 Scott Kitterman <scott@kitterman.com>
Portions Copyright(c) 2013,2014 Stuart Gathman <stuart@gathman.org>
This module is free software, and you may redistribute it and/or modify
it under the same terms as Python itself, so long as this copyright message
and disclaimer are retained in their original form.
IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF
THIS CODE, EVEN IF THE AUTHOR HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
DAMAGE.
THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE. THE CODE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS,
AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
For more information about SPF, a tool against email forgery, see
http://www.openspf.net/
For news, bugfixes, etc. visit the home page for this implementation at
http://cheeseshop.python.org/pypi/pyspf/
http://sourceforge.net/projects/pymilter/
http://www.wayforward.net/spf/
"""
# CVS Commits since last release (2.0.12):
# $Log$
# Revision 1.108.2.152 2016/04/26 03:57:04 kitterma
# * Set version and update changelog for 2.0.13 development.
#
# Revision 1.108.2.151 2016/04/26 03:53:04 kitterma
# * Catch ValueError due to improper IP address in connect IP or in ip4/ip6
# mechanisms
#
# See pyspf_changelog.txt for earlier CVS commits.
__author__ = "Terence Way, Stuart Gathman, Scott Kitterman"
__email__ = "pyspf@openspf.org"
__version__ = "2.0.13: UNRELEASED"
MODULE = 'spf'
USAGE = """To check an incoming mail request:
% python spf.py [-v] {ip} {sender} {helo}
% python spf.py 69.55.226.139 tway@optsw.com mx1.wayforward.net
To test an SPF record:
% python spf.py [-v] "v=spf1..." {ip} {sender} {helo}
% python spf.py "v=spf1 +mx +ip4:10.0.0.1 -all" 10.0.0.1 tway@foo.com a
To fetch an SPF record:
% python spf.py {domain}
% python spf.py wayforward.net
To test this script (and to output this usage message):
% python spf.py
"""
import re
import sys
import socket # for inet_ntoa() and inet_aton()
import struct # for pack() and unpack()
import time # for time()
try:
import urllib.parse as urllibparse # for quote()
except:
import urllib as urllibparse
import sys # for version_info()
from functools import reduce
try:
from email.message import Message
except ImportError:
from email.Message import Message
try:
# Python standard libarary as of python3.3
import ipaddress
if bytes is str:
from ipaddress import Bytes
except ImportError:
try:
import ipaddr as ipaddress
from ipaddr import Bytes
except ImportError:
print('ipaddr module required: http://code.google.com/p/ipaddr-py/')
def DNSLookup_pydns(name, qtype, tcpfallback=True, timeout=30):
try:
req = DNS.DnsRequest(name, qtype=qtype, timeout=timeout)
resp = req.req()
#resp.show()
# key k: ('wayforward.net', 'A'), value v
# FIXME: pydns returns AAAA RR as 16 byte binary string, but
# A RR as dotted quad. For consistency, this driver should
# return both as binary string.
#
if resp.header['tc'] == True:
if strict > 1:
raise AmbiguityWarning('DNS: Truncated UDP Reply, SPF records should fit in a UDP packet, retrying TCP')
try:
req = DNS.DnsRequest(name, qtype=qtype, protocol='tcp', timeout=(timeout))
resp = req.req()
except DNS.DNSError as x:
raise TempError('DNS: TCP Fallback error: ' + str(x))
if resp.header['rcode'] != 0 and resp.header['rcode'] != 3:
raise IOError('Error: ' + resp.header['status'] + ' RCODE: ' + str(resp.header['rcode']))
return [((a['name'], a['typename']), a['data'])
for a in resp.answers] \
+ [((a['name'], a['typename']), a['data'])
for a in resp.additional]
except AttributeError as x:
raise TempError('DNS ' + str(x))
except IOError as x:
raise TempError('DNS ' + str(x))
except DNS.DNSError as x:
raise TempError('DNS ' + str(x))
def DNSLookup_dnspython(name, qtype, tcpfallback=True, timeout=30):
retVal = []
try:
# FIXME: how to disable TCP fallback in dnspython if not tcpfallback?
answers = dns.resolver.query(name, qtype)
for rdata in answers:
if qtype == 'A' or qtype == 'AAAA':
retVal.append(((name, qtype), rdata.address))
elif qtype == 'MX':
retVal.append(((name, qtype), (rdata.preference, rdata.exchange)))
elif qtype == 'PTR':
retVal.append(((name, qtype), rdata.target.to_text(True)))
elif qtype == 'TXT' or qtype == 'SPF':
retVal.append(((name, qtype), rdata.strings))
except dns.resolver.NoAnswer:
pass
except dns.resolver.NXDOMAIN:
pass
return retVal
try:
# prefer dnspython (the more complete library)
import dns
import dns.resolver # http://www.dnspython.org
import dns.exception
if not hasattr(dns.rdatatype,'SPF'):
# patch in type99 support
dns.rdatatype.SPF = 99
dns.rdatatype._by_text['SPF'] = dns.rdatatype.SPF
DNSLookup = DNSLookup_dnspython
except:
import DNS # http://pydns.sourceforge.net
if not hasattr(DNS.Type, 'SPF'):
# patch in type99 support
DNS.Type.SPF = 99
DNS.Type.typemap[99] = 'SPF'
DNS.Lib.RRunpacker.getSPFdata = DNS.Lib.RRunpacker.getTXTdata
# Fails on Mac OS X? Add domain to /etc/resolv.conf
DNS.DiscoverNameServers()
DNSLookup = DNSLookup_pydns
RE_SPF = re.compile(br'^v=spf1$|^v=spf1 ',re.IGNORECASE)
# Regular expression to look for modifiers
RE_MODIFIER = re.compile(r'^([a-z][a-z0-9_\-\.]*)=', re.IGNORECASE)
# Regular expression to find macro expansions
PAT_CHAR = r'%(%|_|-|(\{[^\}]*\}))'
RE_CHAR = re.compile(PAT_CHAR)
RE_INVALID_MACRO = re.compile(r'(?<!%)%[^{%_-]|%$')
# Regular expression to break up a macro expansion
RE_ARGS = re.compile(r'([0-9]*)(r?)([^0-9a-zA-Z]*)')
RE_DUAL_CIDR = re.compile(r'//(0|[1-9]\d*)$')
RE_CIDR = re.compile(r'/(0|[1-9]\d*)$')
PAT_IP4 = r'\.'.join([r'(?:\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])']*4)
RE_IP4 = re.compile(PAT_IP4+'$')
RE_TOPLAB = re.compile(
r'\.(?:[0-9a-z]*[a-z][0-9a-z]*|[0-9a-z]+-[0-9a-z-]*[0-9a-z])\.?$|%s'
% PAT_CHAR, re.IGNORECASE)
RE_DOT_ATOM = re.compile(r'%(atext)s+([.]%(atext)s+)*$' % {
'atext': r"[0-9a-z!#$%&'*+/=?^_`{}|~-]" }, re.IGNORECASE)
# Derived from RFC 3986 appendix A
RE_IP6 = re.compile( '(?:%(hex4)s:){6}%(ls32)s$'
'|::(?:%(hex4)s:){5}%(ls32)s$'
'|(?:%(hex4)s)?::(?:%(hex4)s:){4}%(ls32)s$'
'|(?:(?:%(hex4)s:){0,1}%(hex4)s)?::(?:%(hex4)s:){3}%(ls32)s$'
'|(?:(?:%(hex4)s:){0,2}%(hex4)s)?::(?:%(hex4)s:){2}%(ls32)s$'
'|(?:(?:%(hex4)s:){0,3}%(hex4)s)?::%(hex4)s:%(ls32)s$'
'|(?:(?:%(hex4)s:){0,4}%(hex4)s)?::%(ls32)s$'
'|(?:(?:%(hex4)s:){0,5}%(hex4)s)?::%(hex4)s$'
'|(?:(?:%(hex4)s:){0,6}%(hex4)s)?::$'
% {
'ls32': r'(?:[0-9a-f]{1,4}:[0-9a-f]{1,4}|%s)'%PAT_IP4,
'hex4': r'[0-9a-f]{1,4}'
}, re.IGNORECASE)
# Local parts and senders have their delimiters replaced with '.' during
# macro expansion
#
JOINERS = {'l': '.', 's': '.'}
RESULTS = {'+': 'pass', '-': 'fail', '?': 'neutral', '~': 'softfail',
'pass': 'pass', 'fail': 'fail', 'permerror': 'permerror',
'error': 'temperror', 'neutral': 'neutral', 'softfail': 'softfail',
'none': 'none', 'local': 'local', 'trusted': 'trusted',
'ambiguous': 'ambiguous', 'unknown': 'permerror' }
EXPLANATIONS = {'pass': 'sender SPF authorized',
'fail': 'SPF fail - not authorized',
'permerror': 'permanent error in processing',
'temperror': 'temporary DNS error in processing',
'softfail': 'domain owner discourages use of this host',
'neutral': 'access neither permitted nor denied',
'none': '',
#Note: The following are not formally SPF results
'local': 'No SPF result due to local policy',
'trusted': 'No SPF check - trusted-forwarder.org',
#Ambiguous only used in harsh mode for SPF validation
'ambiguous': 'No error, but results may vary'
}
DELEGATE = None
# standard default SPF record for best_guess
DEFAULT_SPF = 'v=spf1 a/24 mx/24 ptr'
#Whitelisted forwarders here. Additional locally trusted forwarders can be
#added to this record.
TRUSTED_FORWARDERS = 'v=spf1 ?include:spf.trusted-forwarder.org -all'
# maximum DNS lookups allowed
MAX_LOOKUP = 10 #RFC 4408 Para 10.1/RFC 7208 4.6.4
MAX_MX = 10 #RFC 4408 Para 10.1/RFC 7208 4.6.4
MAX_PTR = 10 #RFC 4408 Para 10.1/RFC 7208 4.6.4
MAX_CNAME = 10 # analogous interpretation to MAX_PTR
MAX_RECURSION = 20
MAX_PER_LOOKUP_TIME = 20 # Per RFC 7208 4.6.4
MAX_VOID_LOOKUPS = 2 # RFC 7208 4.6.4
ALL_MECHANISMS = ('a', 'mx', 'ptr', 'exists', 'include', 'ip4', 'ip6', 'all')
COMMON_MISTAKES = {
'prt': 'ptr', 'ip': 'ip4', 'ipv4': 'ip4', 'ipv6': 'ip6', 'all.': 'all'
}
#If harsh processing, for the validator, is invoked, warn if results
#likely deviate from the publishers intention.
class AmbiguityWarning(Exception):
"SPF Warning - ambiguous results"
def __init__(self, msg, mech=None, ext=None):
Exception.__init__(self, msg, mech)
self.msg = msg
self.mech = mech
self.ext = ext
def __str__(self):
if self.mech:
return '%s: %s' %(self.msg, self.mech)
return self.msg
class TempError(Exception):
"Temporary SPF error"
def __init__(self, msg, mech=None, ext=None):
Exception.__init__(self, msg, mech)
self.msg = str(msg)
self.mech = mech
self.ext = ext
def __str__(self):
if self.mech:
return '%s: %s'%(self.msg, self.mech)
return self.msg
class PermError(Exception):
"Permanent SPF error"
def __init__(self, msg, mech=None, ext=None):
Exception.__init__(self, msg, mech)
self.msg = msg
self.mech = mech
self.ext = ext
def __str__(self):
if self.mech:
return '%s: %s'%(self.msg, self.mech)
return self.msg
def check2(i, s, h, local=None, receiver=None, timeout=MAX_PER_LOOKUP_TIME, verbose=False, querytime=20):
"""Test an incoming MAIL FROM:<s>, from a client with ip address i.
h is the HELO/EHLO domain name. This is the RFC4408/7208 compliant
pySPF2.0 interface. The interface returns an SPF result and explanation
only. SMTP response codes are not returned since neither RFC 4408 nor RFC
7208 does specify receiver policy. Applications updated for RFC 4408 and
RFC 7208 should use this interface. The maximum time, in seconds, this
function is allowed to run before a TempError is returned is controlled by
querytime. When set to 0 the timeout parameter (default 20 seconds)
controls the time allowed for each DNS lookup. When set to a non-zero
value, it total time for all processing related to the SPF check is
limited to querytime (default 20 seconds as recommended in RFC 7208,
paragraph 4.6.4).
Returns (result, explanation) where result in
['pass', 'permerror', 'fail', 'temperror', 'softfail', 'none', 'neutral' ].
Example:
#>>> check2(i='61.51.192.42', s='liukebing@bcc.com', h='bmsi.com')
"""
res,_,exp = query(i=i, s=s, h=h, local=local,
receiver=receiver,timeout=timeout,verbose=verbose,querytime=querytime).check()
return res,exp
def check(i, s, h, local=None, receiver=None, verbose=False):
"""Test an incoming MAIL FROM:<s>, from a client with ip address i.
h is the HELO/EHLO domain name. This is the pre-RFC SPF Classic interface.
Applications written for pySPF 1.6/1.7 can use this interface to allow
pySPF2 to be a drop in replacement for older versions. With the exception
of result codes, performance in RFC 4408 compliant.
Returns (result, code, explanation) where result in
['pass', 'unknown', 'fail', 'error', 'softfail', 'none', 'neutral' ].
Example:
#>>> check(i='61.51.192.42', s='liukebing@bcc.com', h='bmsi.com')
"""
res,code,exp = query(i=i, s=s, h=h, local=local, receiver=receiver,
verbose=verbose).check()
if res == 'permerror':
res = 'unknown'
elif res == 'tempfail':
res =='error'
return res, code, exp
class query(object):
"""A query object keeps the relevant information about a single SPF
query:
i: ip address of SMTP client in dotted notation
s: sender declared in MAIL FROM:<>
l: local part of sender s
d: current domain, initially domain part of sender s
h: EHLO/HELO domain
v: 'in-addr' for IPv4 clients and 'ip6' for IPv6 clients
t: current timestamp
p: SMTP client domain name
o: domain part of sender s
r: receiver
c: pretty ip address (different from i for IPv6)
This is also, by design, the same variables used in SPF macro
expansion.
Also keeps cache: DNS cache.
"""
def __init__(self, i, s, h, local=None, receiver=None, strict=True,
timeout=MAX_PER_LOOKUP_TIME,verbose=False,querytime=0):
self.s, self.h = s, h
if not s and h:
self.s = 'postmaster@' + h
self.ident = 'helo'
else:
self.ident = 'mailfrom'
self.l, self.o = split_email(s, h)
self.t = str(int(time.time()))
self.d = self.o
self.p = None # lazy evaluation
if receiver:
self.r = receiver
else:
self.r = 'unknown'
# Since the cache does not track Time To Live, it is created
# fresh for each query. It is important for efficiently using
# multiple results provided in DNS answers.
self.cache = {}
self.defexps = dict(EXPLANATIONS)
self.exps = dict(EXPLANATIONS)
self.libspf_local = local # local policy
self.lookups = 0
# New processing limit in RFC 7208, section 4.6.4
self.void_lookups = 0
# strict can be False, True, or 2 (numeric) for harsh
self.strict = strict
self.timeout = timeout
self.querytime = querytime # Default to not using a global check
# timelimit since this is an RFC 4408 MAY
if querytime > 0:
self.timeout = querytime
self.timer = 0
self.ipaddr = None
if i:
self.set_ip(i)
# Document bits of the object model not set up here:
# self.i = string, expanded dot notation, suitable for PTR lookups
# self.c = string, human readable form of the connect IP address
# single letter lowercase variable names (e.g. self.i) are used for SPF macros
# For IPv4, self.i = self.c, but not in IPv6
# self.iplist = list of IPv4/6 addresses that would pass, collected
# when list or list6 is passed as 'i'
# self.addr = ipaddr/ipaddress object representing the connect IP
self.default_modifier = True
self.verbose = verbose
self.authserv = None # Only used in A-R header generation tests
def log(self,mech,d,spf):
print('%s: %s "%s"'%(mech,d,spf))
def set_ip(self, i):
"Set connect ip, and ip6 or ip4 mode."
self.iplist = False
if i.lower() == 'list':
self.iplist = []
ip6 = False
elif i.lower() == 'list6':
self.iplist = []
ip6 = True
else:
try:
try:
self.ipaddr = ipaddress.ip_address(i)
except AttributeError:
self.ipaddr = ipaddress.IPAddress(i)
except ValueError as x:
raise PermError(str(x))
if self.ipaddr.version == 6:
if self.ipaddr.ipv4_mapped:
self.ipaddr = ipaddress.IPv4Address(self.ipaddr.ipv4_mapped)
ip6 = False
else:
ip6 = True
else:
ip6 = False
self.c = str(self.ipaddr)
# NOTE: self.A is not lowercase, so isn't a macro. See query.expand()
if ip6:
self.A = 'AAAA'
self.v = 'ip6'
if self.ipaddr:
self.i = '.'.join(list(self.ipaddr.exploded.replace(':','').upper()))
self.cidrmax = 128
else:
self.A = 'A'
self.v = 'in-addr'
if self.ipaddr:
self.i = self.ipaddr.exploded
self.cidrmax = 32
def set_default_explanation(self, exp):
exps = self.exps
defexps = self.defexps
for i in 'softfail', 'fail', 'permerror':
exps[i] = exp
defexps[i] = exp
def set_explanation(self, exp):
exps = self.exps
for i in 'softfail', 'fail', 'permerror':
exps[i] = exp
# Compute p macro only if needed
def getp(self):
if not self.p:
p = self.validated_ptrs()
if not p:
self.p = "unknown"
elif self.d in p:
self.p = self.d
else:
sfx = '.' + self.d
for d in p:
if d.endswith(sfx):
self.p = d
break
else:
self.p = p[0]
return self.p
def best_guess(self, spf=DEFAULT_SPF):
"""Return a best guess based on a default SPF record.
>>> q = query('1.2.3.4','','SUPERVISION1',receiver='example.com')
>>> q.best_guess()[0]
'none'
"""
if RE_TOPLAB.split(self.d)[-1]:
return ('none', 250, '')
pe = self.perm_error
r,c,e = self.check(spf)
if r == 'permerror': # permerror not useful for bestguess
if self.perm_error and self.perm_error.ext:
r,c,e = self.perm_error.ext
else:
r,c = 'neutral',250
self.perm_error = pe
return r,c,e
def check(self, spf=None):
"""
Returns (result, mta-status-code, explanation) where result
in ['fail', 'softfail', 'neutral' 'permerror', 'pass', 'temperror', 'none']
Examples:
>>> q = query(s='strong-bad@email.example.com',
... h='mx.example.org', i='192.0.2.3')
>>> q.check(spf='v=spf1 ?all')
('neutral', 250, 'access neither permitted nor denied')
>>> q.check(spf='v=spf1 redirect=controlledmail.com exp=_exp.controlledmail.com')
('fail', 550, 'SPF fail - not authorized')
>>> q.check(spf='v=spf1 ip4:192.0.0.0/8 ?all moo')
('permerror', 550, 'SPF Permanent Error: Unknown mechanism found: moo')
>>> q.check(spf='v=spf1 ip4:192.0.0.n ?all')
('permerror', 550, 'SPF Permanent Error: Invalid IP4 address: ip4:192.0.0.n')
>>> q.check(spf='v=spf1 ip4:192.0.2.3 ip4:192.0.0.n ?all')
('permerror', 550, 'SPF Permanent Error: Invalid IP4 address: ip4:192.0.0.n')
>>> q.check(spf='v=spf1 ip6:2001:db8:ZZZZ:: ?all')
('permerror', 550, 'SPF Permanent Error: Invalid IP6 address: ip6:2001:db8:ZZZZ::')
>>> q.check(spf='v=spf1 =a ?all moo')
('permerror', 550, 'SPF Permanent Error: Unknown qualifier, RFC 4408 para 4.6.1, found in: =a')
>>> q.check(spf='v=spf1 ip4:192.0.0.0/8 ~all')
('pass', 250, 'sender SPF authorized')
>>> q.check(spf='v=spf1 ip4:192.0.0.0/8 -all moo=')
('pass', 250, 'sender SPF authorized')
>>> q.check(spf='v=spf1 ip4:192.0.0.0/8 -all match.sub-domains_9=yes')
('pass', 250, 'sender SPF authorized')
>>> q.strict = False
>>> q.check(spf='v=spf1 ip4:192.0.0.0/8 -all moo')
('permerror', 550, 'SPF Permanent Error: Unknown mechanism found: moo')
>>> q.perm_error.ext
('pass', 250, 'sender SPF authorized')
>>> q.strict = True
>>> q.check(spf='v=spf1 ip4:192.1.0.0/16 moo -all')
('permerror', 550, 'SPF Permanent Error: Unknown mechanism found: moo')
>>> q.check(spf='v=spf1 ip4:192.1.0.0/16 ~all')
('softfail', 250, 'domain owner discourages use of this host')
>>> q.check(spf='v=spf1 -ip4:192.1.0.0/6 ~all')
('fail', 550, 'SPF fail - not authorized')
# Assumes DNS available
>>> q.check()
('none', 250, '')
>>> q.check(spf='v=spf1 ip4:1.2.3.4 -a:example.net -all')
('fail', 550, 'SPF fail - not authorized')
>>> q.libspf_local='ip4:192.0.2.3 a:example.org'
>>> q.check(spf='v=spf1 ip4:1.2.3.4 -a:example.net -all')
('pass', 250, 'sender SPF authorized')
>>> q.check(spf='v=spf1 ip4:1.2.3.4 -all exp=_exp.controlledmail.com')
('fail', 550, 'Controlledmail.com does not send mail from itself.')
>>> q.check(spf='v=spf1 ip4:1.2.3.4 ?all exp=_exp.controlledmail.com')
('neutral', 250, 'access neither permitted nor denied')
"""
self.mech = [] # unknown mechanisms
# If not strict, certain PermErrors (mispelled
# mechanisms, strict processing limits exceeded)
# will continue processing. However, the exception
# that strict processing would raise is saved here
self.perm_error = None
self.mechanism = None
self.void_lookups = 0
self.options = {}
try:
self.lookups = 0
if not spf:
spf = self.dns_spf(self.d)
if self.verbose: self.log("top",self.d,spf)
if self.libspf_local and spf:
spf = insert_libspf_local_policy(
spf, self.libspf_local)
rc = self.check1(spf, self.d, 0)
if self.perm_error:
# lax processing encountered a permerror, but continued
self.perm_error.ext = rc
raise self.perm_error
return rc
except TempError as x:
self.prob = x.msg
if x.mech:
self.mech.append(x.mech)
return ('temperror', 451, 'SPF Temporary Error: ' + str(x))
except PermError as x:
if not self.perm_error:
self.perm_error = x
self.prob = x.msg
if x.mech:
self.mech.append(x.mech)
# Pre-Lentczner draft treats this as an unknown result
# and equivalent to no SPF record.
return ('permerror', 550, 'SPF Permanent Error: ' + str(x))
def check1(self, spf, domain, recursion):
# spf rfc: 3.7 Processing Limits
#
if recursion > MAX_RECURSION:
# This should never happen in strict mode
# because of the other limits we check,
# so if it does, there is something wrong with
# our code. It is not a PermError because there is not
# necessarily anything wrong with the SPF record.
if self.strict:
raise AssertionError('Too many levels of recursion')
# As an extended result, however, it should be
# a PermError.
raise PermError('Too many levels of recursion')
try:
try:
tmp, self.d = self.d, domain
return self.check0(spf, recursion)
finally:
self.d = tmp
except AmbiguityWarning as x:
self.prob = x.msg
if x.mech:
self.mech.append(x.mech)
return ('ambiguous', 000, 'SPF Ambiguity Warning: %s' % x)
def note_error(self, *msg):
if self.strict:
raise PermError(*msg)
# if lax mode, note error and continue
if not self.perm_error:
try:
raise PermError(*msg)
except PermError as x:
# FIXME: keep a list of errors for even friendlier diagnostics.
self.perm_error = x
return self.perm_error
def expand_domain(self,arg):
"validate and expand domain-spec"
# any trailing dot was removed by expand()
if RE_TOPLAB.split(arg)[-1]:
raise PermError('Invalid domain found (use FQDN)', arg)
return self.expand(arg)
def validate_mechanism(self, mech):
"""Parse and validate a mechanism.
Returns mech,m,arg,cidrlength,result
Examples:
>>> q = query(s='strong-bad@email.example.com.',
... h='mx.example.org', i='192.0.2.3')
>>> q.validate_mechanism('A')
('A', 'a', 'email.example.com', 32, 'pass')
>>> q = query(s='strong-bad@email.example.com',
... h='mx.example.org', i='192.0.2.3')
>>> q.validate_mechanism('A//64')
('A//64', 'a', 'email.example.com', 32, 'pass')
>>> q.validate_mechanism('A/24//64')
('A/24//64', 'a', 'email.example.com', 24, 'pass')
>>> q.validate_mechanism('?mx:%{d}/27')
('?mx:%{d}/27', 'mx', 'email.example.com', 27, 'neutral')
>>> try: q.validate_mechanism('ip4:1.2.3.4/247')
... except PermError as x: print(x)
Invalid IP4 CIDR length: ip4:1.2.3.4/247
>>> try: q.validate_mechanism('ip4:1.2.3.4/33')
... except PermError as x: print(x)
Invalid IP4 CIDR length: ip4:1.2.3.4/33
>>> try: q.validate_mechanism('a:example.com:8080')
... except PermError as x: print(x)
Invalid domain found (use FQDN): example.com:8080
>>> try: q.validate_mechanism('ip4:1.2.3.444/24')
... except PermError as x: print(x)
Invalid IP4 address: ip4:1.2.3.444/24
>>> try: q.validate_mechanism('ip4:1.2.03.4/24')
... except PermError as x: print(x)
Invalid IP4 address: ip4:1.2.03.4/24
>>> try: q.validate_mechanism('-all:3030')
... except PermError as x: print(x)
Invalid all mechanism format - only qualifier allowed with all: -all:3030
>>> q.validate_mechanism('-mx:%%%_/.Clara.de/27')
('-mx:%%%_/.Clara.de/27', 'mx', '% /.Clara.de', 27, 'fail')
>>> q.validate_mechanism('~exists:%{i}.%{s1}.100/86400.rate.%{d}')
('~exists:%{i}.%{s1}.100/86400.rate.%{d}', 'exists', '192.0.2.3.com.100/86400.rate.email.example.com', 32, 'softfail')
>>> q.validate_mechanism('a:mail.example.com.')
('a:mail.example.com.', 'a', 'mail.example.com', 32, 'pass')
>>> try: q.validate_mechanism('a:mail.example.com,')
... except PermError as x: print(x)
Do not separate mechnisms with commas: a:mail.example.com,
>>> q = query(s='strong-bad@email.example.com',
... h='mx.example.org', i='2001:db8:1234::face:b007')
>>> q.validate_mechanism('A//64')
('A//64', 'a', 'email.example.com', 64, 'pass')
>>> q.validate_mechanism('A/16')
('A/16', 'a', 'email.example.com', 128, 'pass')
>>> q.validate_mechanism('A/16//48')
('A/16//48', 'a', 'email.example.com', 48, 'pass')
"""
if mech.endswith( "," ):
self.note_error('Do not separate mechnisms with commas', mech)
mech = mech[:-1]
# a mechanism
m, arg, cidrlength, cidr6length = parse_mechanism(mech, self.d)
# map '?' '+' or '-' to 'neutral' 'pass' or 'fail'
if m:
result = RESULTS.get(m[0])
if result:
# eat '?' '+' or '-'
m = m[1:]
else:
# default pass
result = 'pass'
if m in COMMON_MISTAKES:
self.note_error('Unknown mechanism found', mech)
m = COMMON_MISTAKES[m]
if m == 'a' and RE_IP4.match(arg):
x = self.note_error(
'Use the ip4 mechanism for ip4 addresses', mech)
m = 'ip4'
# validate cidr and dual-cidr
if m in ('a', 'mx'):
if cidrlength is None:
cidrlength = 32;
elif cidrlength > 32:
raise PermError('Invalid IP4 CIDR length', mech)
if cidr6length is None:
cidr6length = 128
elif cidr6length > 128:
raise PermError('Invalid IP6 CIDR length', mech)
if self.v == 'ip6':
cidrlength = cidr6length
elif m == 'ip4' or RE_IP4.match(m):
if m != 'ip4':
self.note_error( 'Missing IP4' , mech)
m,arg = 'ip4',m
if cidr6length is not None:
raise PermError('Dual CIDR not allowed', mech)
if cidrlength is None:
cidrlength = 32;
elif cidrlength > 32:
raise PermError('Invalid IP4 CIDR length', mech)
if not RE_IP4.match(arg):
raise PermError('Invalid IP4 address', mech)
elif m == 'ip6':
if cidr6length is not None:
raise PermError('Dual CIDR not allowed', mech)
if cidrlength is None:
cidrlength = 128
elif cidrlength > 128:
raise PermError('Invalid IP6 CIDR length', mech)
if not RE_IP6.match(arg):
raise PermError('Invalid IP6 address', mech)
else:
if cidrlength is not None or cidr6length is not None:
if m in ALL_MECHANISMS:
raise PermError('CIDR not allowed', mech)
cidrlength = self.cidrmax
if m in ('a', 'mx', 'ptr', 'exists', 'include'):
if m == 'exists' and not arg:
raise PermError('implicit exists not allowed', mech)
arg = self.expand_domain(arg)
if not arg:
raise PermError('empty domain:',mech)
if m == 'include':
if arg == self.d:
if mech != 'include':
raise PermError('include has trivial recursion', mech)
raise PermError('include mechanism missing domain', mech)
return mech, m, arg, cidrlength, result
# validate 'all' mechanism per RFC 4408 ABNF
if m == 'all' and mech.count(':'):
# print '|'+ arg + '|', mech, self.d,
self.note_error(
'Invalid all mechanism format - only qualifier allowed with all'
, mech)
if m in ALL_MECHANISMS:
return mech, m, arg, cidrlength, result
if m[1:] in ALL_MECHANISMS:
x = self.note_error(
'Unknown qualifier, RFC 4408 para 4.6.1, found in', mech)
else:
x = self.note_error('Unknown mechanism found', mech)
return mech, m, arg, cidrlength, x
def check0(self, spf, recursion):
"""Test this query information against SPF text.
Returns (result, mta-status-code, explanation) where
result in ['fail', 'unknown', 'pass', 'none']
"""
if not spf:
return ('none', 250, EXPLANATIONS['none'])
# Split string by space, drop the 'v=spf1'. Split by all whitespace
# casuses things like carriage returns being treated as valid space
# separators, so split() is not sufficient.
spf = spf.split(' ')
# Catch case where SPF record has no spaces.
# Can never happen with conforming dns_spf(), however
# in the future we might want to give warnings
# for common mistakes like IN TXT "v=spf1" "mx" "-all"
# in relaxed mode.
if spf[0].lower() != 'v=spf1':
if self.strict > 1:
raise AmbiguityWarning('Invalid SPF record in', self.d)
return ('none', 250, EXPLANATIONS['none'])
# Just to make it even more fun, the relevant piece of the ABNF for
# term separations is *( 1*SP ( directive / modifier ) ), so it's one
# or more spaces, not just one. So strip empty mechanisms.
spf = [mech for mech in spf[1:] if mech]
# copy of explanations to be modified by exp=
exps = self.exps
redirect = None
# no mechanisms at all cause unknown result, unless
# overridden with 'default=' modifier
#
default = 'neutral'
mechs = []
modifiers = []
# Look for modifiers
#
for mech in spf:
m = RE_MODIFIER.split(mech)[1:]
if len(m) != 2:
mechs.append(self.validate_mechanism(mech))
continue
mod,arg = m
if mod in modifiers:
if mod == 'redirect':
raise PermError('redirect= MUST appear at most once',mech)
self.note_error('%s= MUST appear at most once'%mod,mech)
# just use last one in lax mode
modifiers.append(mod)
if mod == 'exp':
# always fetch explanation to check permerrors
if not arg:
raise PermError('exp has empty domain-spec:',arg)
arg = self.expand_domain(arg)
if arg:
try:
exp = self.get_explanation(arg)
if exp and not recursion:
# only set explanation in base recursion level
self.set_explanation(exp)
except: pass
elif mod == 'redirect':
self.check_lookups()
redirect = self.expand_domain(arg)
if not redirect:
raise PermError('redirect has empty domain:',arg)
elif mod == 'default':
# default modifier is obsolete
if self.strict > 1:
raise AmbiguityWarning('The default= modifier is obsolete.')
if not self.strict and self.default_modifier:
# might be an old policy, so do it anyway
arg = self.expand(arg)
# default=- is the same as default=fail
default = RESULTS.get(arg, default)
elif mod == 'op':
if not recursion:
for v in arg.split('.'):
if v: self.options[v] = True
else:
# spf rfc: 3.6 Unrecognized Mechanisms and Modifiers
self.expand(m[1]) # syntax error on invalid macro
# Evaluate mechanisms
#
for mech, m, arg, cidrlength, result in mechs:
if m == 'include':
self.check_lookups()
d = self.dns_spf(arg)
if self.verbose: self.log("include",arg,d)
res, code, txt = self.check1(d,arg, recursion + 1)
if res == 'pass':
break
if res == 'none':
self.note_error(
'No valid SPF record for included domain: %s' %arg,
mech)
res = 'neutral'
continue
elif m == 'all':
break
elif m == 'exists':
self.check_lookups()
try:
if len(self.dns_a(arg,'A')) > 0:
break
except AmbiguityWarning:
# Exists wants no response sometimes so don't raise
# the warning.
pass
elif m == 'a':
self.check_lookups()
if self.cidrmatch(self.dns_a(arg,self.A), cidrlength):
break
elif m == 'mx':
self.check_lookups()
if self.cidrmatch(self.dns_mx(arg), cidrlength):
break
elif m == 'ip4':
if self.v == 'in-addr': # match own connection type only
try:
if self.cidrmatch([arg], cidrlength): break
except socket.error:
raise PermError('syntax error', mech)
elif m == 'ip6':
if self.v == 'ip6': # match own connection type only
try:
if self.cidrmatch([arg], cidrlength): break
except socket.error:
raise PermError('syntax error', mech)
elif m == 'ptr':
self.check_lookups()
if domainmatch(self.validated_ptrs(), arg):
break
else:
# no matches
if redirect:
#Catch redirect to a non-existant SPF record.
redirect_record = self.dns_spf(redirect)
if not redirect_record:
raise PermError('redirect domain has no SPF record',
redirect)
if self.verbose: self.log("redirect",redirect,redirect_record)
# forget modifiers on redirect
if not recursion:
self.exps = dict(self.defexps)
self.options = {}
return self.check1(redirect_record, redirect, recursion)
result = default
mech = None
if not recursion: # record matching mechanism at base level
self.mechanism = mech
if result == 'fail':
return (result, 550, exps[result])
else:
return (result, 250, exps[result])
def check_lookups(self):
self.lookups = self.lookups + 1
if self.lookups > MAX_LOOKUP*4:
raise PermError('More than %d DNS lookups'%(MAX_LOOKUP*4))
if self.lookups > MAX_LOOKUP: