Add release date for 1.0.3

change fails on a Unix socket because it hasn't been created yet (libmilter
   will do this correctly on its own based on umask, the milter doesn't need
   to do it) (LP: #1849712)

CHANGES

@@ -1,3 +1,86 @@
+1.0.3 2019-11-22
+ - Make error logging more explicit to aid debugging
+ - Delete own_socketfile to resolve race condition where the permissions
+   change fails on a Unix socket because it hasn't been created yet (libmilter
+   will do this correctly on its own based on umask, the milter doesn't need
+   to do it) (LP: #1849712)
+
+1.0.2 2019-10-07
+ - Fix startup logging so it provides information at a useful time
+ - Fix message extraction so that signing in the same pass through the milter
+   as verifying works correctly
+ - Fix variable initialization so mailformed mails missing body From do not
+   cause a traceback (LP: #1844161)
+ - Catch more ascii encoding errors to improve resilience against bad data
+   (LP: #1844189)
+ - Fix sysv init so it works (LP: #1839487)
+
+1.0.1 2019-02-11
+ * Reorder milter start and dropping privileges so permissions on Unix socket
+   are correct (LP: 1797720)
+ - Make domain checks case insensitive for determining if signing should be
+   done (LP: #1815311)
+ - Add additional Sendmail configuration information to README from OpenDKIM
+   update based on input from Дилян Палаузов (LP: #1801619)
+ - Add information on Ed25519 key creation to README (LP: #1815313)
+
+1.0.0 2018-05-11
+ - Minor documentation updates
+ - Deleted reference to obsolete syslog target in unit file
+
+0.9.7 2018-03-19
+ - Made sysv init executable
+ - Add missing documentation key to system/dkimpy-milter.service
+ - Put version directly in setup.py and do not import dkimpy_milter to ease
+   install via pip
+ - Minor sysv init improvments
+
+0.9.6 2018-03-13
+ - Fixed typo in package installation section of README
+ - Added more to README about first run with systemd
+ - Fixed typo in path for fallback location of the config file if one is not
+   provided
+ - Added protection for malformed From addresses.  If the From does not at
+   least have an '@' in the address, then the signing domain is not extracted
+   and the message will not be signed
+
+0.9.5.1 2018-03-10
+ - Add conf file location to systemd unit file
+ - Fix setup.py install locations so they are installed correctly
+
+0.9.5 2018-03-10
+ - Beta 1 (updated Alpha -> Beta warning in README and trove classifiers)
+ - Added support for MacroList option
+ - Added support for MacroListVerify option
+ - Added example in README to show use of MacroList* to separate inbound and
+   outbound mail streams
+ - Added support for SyslogSuccess option (both signing and verifying)
+ - Rationalized logging to be much less verbose unless SyslogSuccess or
+   debugLevel are set - default is generally start/stop/errors only
+ - Fixed install_requires so either dnspython (preferred if neither is
+   installed) or PyDNS satisfies the install requirements
+ - Updated Authentication Results result comment not to mention key size for
+   ed25519 signatures, since it's irrelevant
+ - Enhanced signature verification logging to provide more useful information
+
+0.9.4 2018-03-09
+ - Create PID directory if it is missing
+ - Fix crash when verifying if domain for signing was not set
+ - Fix header folding to use \n only to align with milter protocol
+   requirements
+ - Added information about creating a dedicated user and PID file directory
+   creation to README
+ - Fixed a bug where dkim fail might be reported as pass when verifying
+   multiple signatures and a previous signature had passed
+ - Make RSA signatures in dkimpy-milter optional, so dkimpy-milter can be
+   added after an existing DKIM signing application to add an Ed25519
+   signature (Thanks to A. Schulze for the patch)
+ - Added support for AuthservID option
+ - Added support for InternalHosts option (ipaddress and either dns (dnspython)
+   or pydns (DNS) modules are now required)
+ - Added support for DiagnosticDirectory and updated dkimpy-milter specifics in
+   dkimpy-milter.conf.5
+
 0.9.3 2018-03-02
  - Fixup csl dataset processing for single item lists
  - file: dataset support

README

@@ -1,11 +1,17 @@
-This is a DKIM signing and verification milter.  In theory it works with both
+OVERVIEW
-Postfix and Sendmail, but the author has zero experience with Sendmail, so
+========
-reports of success/failure with Sendmail and patches are welcom.
+
+This is a DKIM signing and verification milter.  It has been tested with both
+Postfix and Sendmail.
 
 The configuration file is designed to be compatible with OpenDKIM, but only
 a subset of OpenDKIM options are supported.  If an unsupported option is
 specified, an error will be raised.
 
+
+INSTALLATION
+===========
+
 This package includes a default configuration file and man pages.  For those
 to be installed when installing using setup.py, the following incantation is
 required because setuptools developers decided not being able to do this by
@@ -13,29 +19,224 @@ default is a feature:
 
 python setup.py install --single-version-externally-managed --record=/dev/null
 
-For users of Debian Stable (Debian 9, Codename Squueze), all dependencies are
+For users of Debian Stable (Debian 9, Codename Squeeze), all dependencies are
 available in either the main or backports repositories:
 
-[sudo] apt install python-milter python-nacl
+[sudo] apt install python-milter python-nacl python-ipaddress python-dnspython
-[sudo] apt install -t squeeze-backports python-authres python-dkim
+[sudo] apt install -t stretch-backports python-authres python-dkim
 
-The preferred method of installation is from PyPi using pip:
+The preferred method of installation is from PyPi using pip (if distribution
+packages are not available):
 
 [sudo] pip install dkimpy_milter
 
 Using pip will cause required packages to be installed via easy_install if they
-have not been previously installed.
+have not been previously installed.  Because pymilter and PyNaCl are compiled
+Python extensions, the system will need appropriate development packages and
+an C compiler.  Alternately, install these dependencies from dsitribution/OS
+packages and then pip install dkimpy_milter.
+
+The milter will work with either pydns (DNS) or dnspython (dns), preferring
+dnspython if both are available.  The dkimpy DKIM module also works with
+either.
+
+
+SETUP
+====
+
+SIGNING KEYS
+============
+
+In order to create DKIM signatures, a private key must be available.  Signing
+keys should be protected (owned by root:root with permissions 600 in a
+directory that is not world readable).  Different keys are required for RSA
+and (if used) Ed25519.
+
+RSA
+===
+
+Both public and private keys for RSA have standard formats and there are many
+tools available to create them.  Keys must (RFC 8302) have a minimum size of
+1024 bits and should have a size of at least 2048 bits.  The dknewkey script
+that is provided with dkimpy is one such tool:
+
+dknewkey exampleprivkey
+
+will produce both the private key file (.key suffix) and a file with the DKIM
+public key record to be published DNS (.dns suffix).  RSA is the default key
+type.  2048 bits is the default key size.
+
+ED25519
+=======
+
+There is no standardized non-binary representation for Ed25519 private keys,
+so in order to generate Ed25519 keys for dkimpy-milter, dkimpy specific tools
+must be used to be compatible.  The same dknewkey script support Ed25519:
+
+dknewkey --ktype ed25519 anothernewkey
+
+will provide both the private key file (.key suffix) and a file with the DKIM
+public key record to be published DNS (.dns suffix).  Ed25519 keys do not have
+variable bit lengths.
+
+MTA INTEGRATION
+==============
 
 Both a systemd unit file and a sysv init file are provided.  Both make
 assumptions about defaults being used, e.g. if a non-standard pidfile name is
-used, they will need to be updated.  The sysv init file is Debian specific and
+used, they will need to be updated.  The sysv init file uses start-stop-deamon
-untested, since the developers are not using sysv init.  Feedback/patches
+from Debian.  It is not portable to systems without that available.
-welcome.
+
+The dkimpy-milter drops priviledges after setup to the user/group specified in
+UserID.  During initial setup, this system user needs to be manually created.
+As an example, using the default dkimpy-user on Debian, the command would be:
+
+[sudo] adduser --system --no-create-home --quiet --disabled-password \
+               --disabled-login --shell /bin/false --group \
+               --home /var/run/dkimpy-milter dkimpy-milter
+
+Since /var/run or /run is sometimes on a tempfs, if the PID file directory is
+missing, the milter will create it on startup.
+
+To start dkimpy-milter with systemd for the first time, you will need to take
+the following steps:
+
+[sudo] systemctl daemon-reload
+[sudo] systemctl enable dkimpy-milter
+[sudo] systemctl start dkimpy-milter
+[sudo] systemctl status dkimpy-milter (to verify it started correctly)
+
+As with all milters, dkimpy-milter needs to be integrated with your MTA of
+choice (Sendmail or Postfix).
+
+SENDMAIL
+========
+
+Configuration is very similar to opendkim, but needs some adjustment for
+dkimpy-milter. Here's an example configuration line to include in your
+sendmail.mc:
+
+INPUT_MAIL_FILTER(`dkimpy-milter', `S=local:/var/run/dkimpy-milter/dkimpy-milter.sock')dnl
+
+Changing the sendmail.mc file requires a Make (to compile it into sendmail.cf)
+and a restart of sendmail.  Note that S= needs to match the value of Socket in
+the dkimpy-milter configuration file.
+
+Milter support should be present by default in most versions of sendmail
+these days, but if not included in your Sendmail build, see:
+http://www.elandsys.com/resources/sendmail/milter.html
+
+ISSUES USING SENDMAIL TO SIGN AND VERIFY
+========================================
+
+When using the sendmail MTA in both signing and verifying mode, there are
+a few issues of which to be aware that might cause operational problems
+and deserve consideration.
+
+(a) When the MTA will be used for relaying emails, e.g. delivering to other
+    hosts using the aliases mechanism, it is important not to break
+    signatures inserted by the original sender.  This is particularly sensitive
+    particular when the sending domain has published a "reject" DMARC policy.
+
+    By default, sendmail quotes to address header fields when there are no
+    quotes and the display part of the address contains a period or an
+    apostrophe.  However, opendkim only sees the raw, unmodified form of
+    the header field, and so the content that gets verified and what gets
+    signed will not be the same, guaranteeing the attached signature is not
+    valid.
+
+    To direct sendmail not to modify the headers, add this to your sendmail.mc:
+
+    	conf(`confMUST_QUOTE_CHARS', `')
+
+(b) As stated in sendmail's KNOWNBUGS file, sendmail truncates header field
+    values longer than 256 characters, which could mean truncating the domain
+    of a long From: header field value and invalidating the signature.
+    You may wish to consider increasing MAXNAME in sendmail/conf.h to mitigate
+    changing the messages and invalidating their signatures.  This change
+    requires recompiling sendmail.
+
+(c) Similar to (a) above, sendmail may wrap very long single-line recipient
+    fields for presentation purposes; for example:
+
+    To: very long name <a@example.org>,anotherloo...ong name b <b@example.org>
+
+    ...might be rewritten as:
+
+    To: very long name <a@example.org>,
+    	anotherloo...ong name b <b@example.org>
+
+    This rewrite is also done after opendkim has seen the message, meaning
+    the signature opendkim attaches to the message does not match the
+    content it signed.  There is not a known configuration change to
+    mitigate this mutation.
+
+    The only known mechanism for dealing with this is to have distinct
+    instances of opendkim do the verifying (inbound) and signing (outbound)
+    so that the version that arrives at the signing instance is already
+    in the rewritten form, guaranteeing the input and output are the same
+    and thus the signature matches the payload.
+
+POSTFIX
+=======
+
+Integration of dkimpy-milter into Postfix is like any milter (See Postfix's
+README_FILES/MILTER_README).  Here's an example master.cf excerpt that talks
+to two dkimpy-milter instances, one configured for signing and one configured
+for verification:
+
+smtp       inet  n       -       -       -      -       smtpd
+    ...
+    -o smtpd_milters=inet:localhost:8892
+    ...
+
+submission inet  n       -       -       -      -       smtpd
+    ...
+    -o smtpd_milters=inet:localhost:8891
+    ...
+
+These need to match the Socket value for each dkimpy-milter instance.
+
+Care is required to segregate outbound mail to be signed and inbound mail to
+be verified.  The above example uses two instances of dkimpy-milter to do
+this.  There are many possible ways.  Here is another example using milter
+macros to keep the mail streams segregated:
+
+Postfix master.cf:
+
+smtp       inet  n       -       -       -       -       smtpd
+    ...
+    -o smtpd_milters=inet:localhost:8891
+    -o milter_macro_daemon_name=VERIFYING
+    ...
+
+submission inet n       -       -       -       -       smtpd
+    -o syslog_name=postfix/submission
+    -o smtpd_tls_security_level=encrypt
+    -o smtpd_sasl_auth_enable=yes
+    ...
+    -o milter_macro_daemon_name=ORIGINATING
+    -o smtpd_milters=inet:localhost:8891
+    ...
+
+Dkimpy-milter.conf:
+
+...
+Mode			sv
+MacroList		dameon_name|ORIGINATING
+MacroListVerify		daemon_name|VERIFYING
+...
+
+
+NOTES
+=====
 
 The python DKIM library, dkimpy, requires the entire message being signed or
-verified to be in memory, so dkimpy-milter does not write messages out to a temp
+verified to be in memory, so dkimpy-milter does not write messages out to a
-file.  This may impact performance on low-memory systems.
+temp file.  This may impact performance on low-memory systems.
 
-WARNING: This is an alpha grade release to support interoperability testing with
+DKIM with Ed25519 signatures are described in RFC 8463.  Version 1.0.0 and
-Ed25519 signatures and basic functionality.  It is known to be incomplete and
+later support Ed25519 signing and verification.  RFC 8301 removed rsa-sha1
-not suitable for general use.
+from DKIM.  dkimpy-milter does not sign with rsa-sha1, but still considers
+rsa-sha1 signatures as valid for verification because they are still in
+common use and are not known to be cryptographically broken.

TODO

@@ -25,23 +25,30 @@ Sign based on Domain   implemented      verified
 Canonicalization       implemented      verified
 SyslogFacility         implemented      verified
 
-0.9.5 (Beta)
+0.9.3 (Alpha)
-AuthservID
+File dataset           implemented      verified
-Diagnostics
-DiagnosticDirectory
-InternalHosts
 
-SyslogSuccess
+0.9.4 (Alpha)
+AuthservID      implemented     verified
+DiagnosticDirectory     implemented     verified
+InternalHosts   implemented     verified
+
+0.9.5 (Beta)
+MacroList	implemented	verified
+MacroListVerify	implemented	verified
+SyslogSuccess   implemented     verified
 
 1.0.0
-Convert dkim-milter-python config
+No additional features
-No additional features planned
 
-Plannedataset type support:
+1.0.1
-file://
+Bug fix only, improved documentation
-refile:
+
-db:/.db
+1.1.0 (planned)
-csl:
+Port to Python 3
+Subdomain support
+
+Planned dataset type support (if needed):
 mdb:
 
 Considered for near-term feature release
@@ -49,16 +56,17 @@ Considered for near-term feature release
 AlwaysAddARHeader
 ChangeRootDirectory
 ClockDrift (requires dkimpy change)
-DNSTimeout (requires dkmpy change)
+DNSTimeout (requires dkimpy change)
-MacroList
 MilterDebug
 MinimumKeyBits
+OversignHeaders (may require dkimpy changes)
 PeerList
 SignatureAlgorithm
 
 Later
 
 BaseDirectory
+Diagnostics (requires dkimpy changes)
 DontSignMailTo
 ExemptDomains
 ExternalIgnoreList
@@ -82,7 +90,6 @@ On-InternalError
 On-KeyNotFound
 On-NoSignature
 On-SignatureError
-OversignHeaders
 RemoveARAll
 RemoveARFrom
 RemoveOldSignatures 

dkimpy_milter/__init__.py

@@ -25,25 +25,23 @@ import sys
 import syslog
 import Milter
 import dkim
-from dkim.dnsplug import get_txt
-from dkim.util import parse_tag_value
 import authres
 import os
 import tempfile
 import StringIO
 import re
-from Milter.config import MilterConfigParser
+from Milter.utils import parse_addr, parseaddr
-from Milter.utils import iniplist,parse_addr,parseaddr
 import dkimpy_milter.config as config
 from dkimpy_milter.util import drop_privileges
 from dkimpy_milter.util import setExceptHook
 from dkimpy_milter.util import write_pid
 from dkimpy_milter.util import read_keyfile
-from dkimpy_milter.util import own_socketfile
+from dkimpy_milter.util import fold
 
-__version__ = "0.9.3"
+__version__ = "1.0.1"
 FWS = re.compile(r'\r?\n[ \t]+')
 
+
 class dkimMilter(Milter.Base):
     "Milter to check and sign DKIM.  Each connection gets its own instance."
 
@@ -55,78 +53,98 @@ class dkimMilter(Milter.Base):
         self.privatersa = privateRSA
         self.privateed25519 = privateEd25519
         self.fp = None
+        self.fdomain = ''
 
     @Milter.noreply
-  def connect(self,hostname,unused,hostaddr):
+    def connect(self, hostname, unused, hostaddr):
         self.internal_connection = False
+        self.external_connection = False
         self.hello_name = None
         # sometimes people put extra space in sendmail config, so we strip
         self.receiver = self.getsymval('j').strip()
+        try:
+            self.AuthservID = milterconfig['AuthservID']
+        except:
+            self.AuthservID = self.receiver
         if hostaddr and len(hostaddr) > 0:
             ipaddr = hostaddr[0]
-        """if iniplist(ipaddr,self.conf.internal_connect): FIXME
+            if milterconfig['IntHosts']:
-            self.internal_connection = True"""
+                if milterconfig['IntHosts'].match(ipaddr):
-    else: ipaddr = ''
+                    self.internal_connection = True
+        else:
+            ipaddr = ''
         self.connectip = ipaddr
+        if milterconfig.get('MacroList') and not self.internal_connection:
+            macrolist = milterconfig.get('MacroList')
+            for macro in macrolist:
+                macroname = macro.split('|')[0]
+                macroname = '{' + macroname + '}'
+                macroresult = self.getsymval(macroname)
+                if ((len(macro.split('|')) == 1 and macroresult) or macroresult
+                        in macro.split('|')[1:]):
+                    self.internal_connection = True
+        if milterconfig.get('MacroListVerify'):
+            macrolist = milterconfig.get('MacroListVerify')
+            for macro in macrolist:
+                macroname = macro.split('|')[0]
+                macroname = '{' + macroname + '}'
+                macroresult = self.getsymval(macroname)
+                if ((len(macro.split('|')) == 1 and macroresult) or macroresult
+                        in macro.split('|')[1:]):
+                    self.external_connection = True
         if self.internal_connection:
             connecttype = 'INTERNAL'
         else:
             connecttype = 'EXTERNAL'
-    if milterconfig.get('Syslog'):
+        if milterconfig.get('Syslog') and milterconfig.get('debugLevel') >= 1:
-        syslog.syslog("connect from {0} at {1} {2}".format(hostname,hostaddr,connecttype))
+            syslog.syslog("connect from {0} at {1} {2}"
+                          .format(hostname, hostaddr, connecttype))
         return Milter.CONTINUE
 
     # multiple messages can be received on a single connection
     # envfrom (MAIL FROM in the SMTP protocol) seems to mark the start
     # of each message.
     @Milter.noreply
-  def envfrom(self,f,*str):
+    def envfrom(self, f, *str):
-    if milterconfig.get('Syslog'):  
+        if milterconfig.get('Syslog') and milterconfig.get('debugLevel') >= 2:
-        syslog.syslog("mail from: {0} {1}".format(f,str))
+            syslog.syslog("mail from: {0} {1}".format(f, str))
         self.fp = StringIO.StringIO()
         self.mailfrom = f
         t = parse_addr(f)
-    if len(t) == 2: t[1] = t[1].lower()
+        if len(t) == 2:
+            t[1] = t[1].lower()
         self.canon_from = '@'.join(t)
-    self.user = self.getsymval('{auth_authen}')
         self.has_dkim = 0
         self.author = None
         self.arheaders = []
         self.arresults = []
-    '''if self.user:
-      # Very simple SMTP AUTH policy by default:
-      #   any successful authentication is considered INTERNAL
-      self.internal_connection = True
-      auth_type = self.getsymval('{auth_type}')
-      ssl_bits =  self.getsymval('{cipher_bits}')
-      if milterconfig.get('Syslog'):
-          syslog.syslog(
-              "SMTP AUTH:",self.user,"sslbits =",ssl_bits, auth_type,
-              "ssf =",self.getsymval('{auth_ssf}'), "INTERNAL"
-      )
-      # Detailed authorization policy is configured in the access file below.
-      self.arresults.append(
-        authres.SMTPAUTHAuthenticationResult(result = 'pass',
-      	result_comment = auth_type+' sslbits='+ssl_bits, smtp_auth = self.user)
-      )'''
         return Milter.CONTINUE
 
     @Milter.noreply
-  def header(self,name,val):
+    def header(self, name, val):
         lname = name.lower()
         if lname == 'dkim-signature':
-        if milterconfig.get('Syslog'):
+            if (milterconfig.get('Syslog') and
-          syslog.syslog("{0}: {1}".format(name,val))
+                    milterconfig.get('debugLevel') >= 1):
+                syslog.syslog("{0}: {1}".format(name, val))
             self.has_dkim += 1
         if lname == 'from':
-        fname,self.author = parseaddr(val)
+            fname, self.author = parseaddr(val)
-        self.fdomain = self.author.split('@')[1]
+            try:
-        if milterconfig.get('Syslog'):
+                self.fdomain = self.author.split('@')[1].lower()
-            syslog.syslog("{0}: {1}".format(name,val))
+            except IndexError as er:
+                pass # self.author was not a proper email address
+            if (milterconfig.get('Syslog') and
+                    milterconfig.get('debugLevel') >= 1):
+                syslog.syslog("{0}: {1}".format(name, val))
         elif lname == 'authentication-results':
             self.arheaders.append(val)
         if self.fp:
-        self.fp.write("%s: %s\n" % (name,val))
+            try:
+                self.fp.write("%s: %s\n" % (name, val))
+            except:
+                # Don't choke on header fields with garbage in them.
+                pass
         return Milter.CONTINUE
 
     @Milter.noreply
@@ -137,7 +155,7 @@ class dkimMilter(Milter.Base):
         return Milter.CONTINUE
 
     @Milter.noreply
-  def body(self,chunk):         # copy body to temp file
+    def body(self, chunk):        # copy body to temp file
         if self.fp:
             self.fp.write(chunk)  # IOError causes TEMPFAIL in milter
             self.bodysize += len(chunk)
@@ -147,39 +165,46 @@ class dkimMilter(Milter.Base):
         if not self.fp:
             return Milter.ACCEPT  # no message collected - so no eom processing
         # Remove existing Authentication-Results headers for our authserv_id
-    for i,val in enumerate(self.arheaders,1):
+        for i, val in enumerate(self.arheaders, 1):
             # FIXME: don't delete A-R headers from trusted MTAs
             try:
-          ar = authres.AuthenticationResultsHeader.parse_value(FWS.sub('',val))
+                ar = (authres.AuthenticationResultsHeader
-          if ar.authserv_id == self.receiver:
+                      .parse_value(FWS.sub('', val)))
-              self.chgheader('authentication-results',i,'')
+                if ar.authserv_id == self.AuthservID:
-              if milterconfig.get('Syslog'):
+                    self.chgheader('authentication-results', i, '')
+                    if (milterconfig.get('Syslog') and
+                            milterconfig.get('debugLevel') >= 1):
                         syslog.syslog('REMOVE: {0}'.format(val))
             except:
                 # Don't error out on unparseable AR header fiels
                 pass
-    # Check or sign DKIM
+        # Check and/or sign DKIM
         self.fp.seek(0)
-    if (self.fdomain in milterconfig.get('Domain')) and (not milterconfig.get('Mode') == 'v'):
         txt = self.fp.read()
-      self.sign_dkim(txt)
+        if milterconfig.get('Domain'):
-      result = None
+            domain = milterconfig.get('Domain')
-    if (self.has_dkim) and (not self.internal_connection) and (milterconfig.get('Mode') == 'v' or milterconfig.get('Mode') == 'sv'):
-      txt = self.fp.read()
-      self.check_dkim(txt)
         else:
-      result = 'none'
+            domain = ''
+        if ((self.fdomain in domain) and not milterconfig.get('Mode') == 'v'
+                and not self.external_connection):
+            self.sign_dkim(txt)
+        if ((self.has_dkim) and (not self.internal_connection) and
+            (milterconfig.get('Mode') == 'v' or
+             milterconfig.get('Mode') == 'sv')):
+            self.check_dkim(txt)
         if self.arresults:
-        h = authres.AuthenticationResultsHeader(authserv_id = self.receiver, 
+            h = authres.AuthenticationResultsHeader(authserv_id=
+                                                    self.AuthservID,
                                                     results=self.arresults)
-        h = dkim.fold(str(h))
+            h = fold(str(h))
-        if milterconfig.get('Syslog'):
+            if (milterconfig.get('Syslog') and
+                    milterconfig.get('debugLevel') >= 2):
                 syslog.syslog(str(h))
-        name,val = str(h).split(': ',1)
+            name, val = str(h).split(': ', 1)
-        self.addheader(name,val,0)
+            self.addheader(name, val, 0)
         return Milter.CONTINUE
 
-  def sign_dkim(self,txt):
+    def sign_dkim(self, txt):
         canon = milterconfig.get('Canonicalization')
         canonicalize = []
         if len(canon.split('/')) == 2:
@@ -188,19 +213,41 @@ class dkimMilter(Milter.Base):
         else:
             canonicalize.append(canon)
             canonicalize.append(canon)
+            if (milterconfig.get('Syslog') and
+                    milterconfig.get('debugLevel') >= 1):
                 syslog.syslog('canonicalize: {0}'.format(canonicalize))
         try:
+            if privateRSA:
                 d = dkim.DKIM(txt)
-        h = d.sign(milterconfig.get('Selector'), self.fdomain, privateRSA,
+                h = d.sign(milterconfig.get('Selector'), self.fdomain,
-                canonicalize=(canonicalize[0], canonicalize[1]))
+                           privateRSA, canonicalize=(canonicalize[0],
-        name,val = h.split(': ',1)
+                                                     canonicalize[1]))
-        self.addheader(name,val.strip().replace('\r\n','\n'),0)
+                name, val = h.split(': ', 1)
+                self.addheader(name, val.strip().replace('\r\n', '\n'), 0)
+                if (milterconfig.get('Syslog') and
+                    (milterconfig.get('SyslogSuccess')
+                     or milterconfig.get('debugLevel') >= 1)):
+                    syslog.syslog('{0}: {1} DKIM-Signature field added (s={2} '
+                                  'd={3})'.format(self.getsymval('i'),
+                                                  d.signature_fields.get(b'a'),
+                                                  d.signature_fields.get(b's'),
+                                                  d.domain.lower()))
             if privateEd25519:
                 d = dkim.DKIM(txt)
-            h = d.sign(milterconfig.get('SelectorEd25519'), self.fdomain, privateEd25519,
+                h = d.sign(milterconfig.get('SelectorEd25519'), self.fdomain,
-                    canonicalize=(canonicalize[0], canonicalize[1]), signature_algorithm='ed25519-sha256')
+                           privateEd25519, canonicalize=(canonicalize[0],
-            name,val = h.split(': ',1)
+                                                         canonicalize[1]),
-            self.addheader(name,val.strip().replace('\r\n','\n'),0)
+                           signature_algorithm='ed25519-sha256')
+                name, val = h.split(': ', 1)
+                self.addheader(name, val.strip().replace('\r\n', '\n'), 0)
+                if (milterconfig.get('Syslog') and
+                    (milterconfig.get('SyslogSuccess')
+                     or milterconfig.get('debugLevel') >= 1)):
+                    syslog.syslog('{0}: {1} DKIM-Signature field added (s={2} '
+                                  'd={3})'.format(self.getsymval('i'),
+                                                  d.signature_fields.get(b'a'),
+                                                  d.signature_fields.get(b's'),
+                                                  d.domain.lower()))
         except dkim.DKIMException as x:
             if milterconfig.get('Syslog'):
                 syslog.syslog('DKIM: {0}'.format(x))
@@ -209,17 +256,27 @@ class dkimMilter(Milter.Base):
                 syslog.syslog("sign_dkim: {0}".format(x))
             raise
 
-  def check_dkim(self,txt):
+    def check_dkim(self, txt):
         res = False
-      conf = self.conf
+        self.header_a = None
         for y in range(self.has_dkim):  # Verify _ALL_ the signatures
             d = dkim.DKIM(txt)
             try:
                 res = d.verify(idx=y)
                 if res:
-              self.dkim_comment = 'Good {0} bit {1} signature.'.format(d.keysize, d.signature_fields.get(b'a'))
+                    if d.signature_fields.get(b'a') == 'ed25519-sha256':
+                        self.dkim_comment = ('Good {0} signature'
+                                             .format(d.signature_fields
+                                                     .get(b'a')))
                     else:
-              self.dkim_comment = 'Bad {0} bit {1} signature.'.format(d.keysize, d.signature_fields.get(b'a'))
+                        self.dkim_comment = ('Good {0} bit {1} signature'
+                                             .format(d.keysize,
+                                                     d.signature_fields
+                                                     .get(b'a')))
+                else:
+                    self.dkim_comment = ('Bad {0} bit {1} signature.'
+                                         .format(d.keysize,
+                                                 d.signature_fields.get(b'a')))
             except dkim.DKIMException as x:
                 self.dkim_comment = str(x)
                 if milterconfig.get('Syslog'):
@@ -227,31 +284,64 @@ class dkimMilter(Milter.Base):
             except Exception as x:
                 self.dkim_comment = str(x)
                 if milterconfig.get('Syslog'):
-                syslog.syslog("check_dkim: {0}".format(x))
+                    syslog.syslog("check_dkim: Internal program fault while verifying: {0}".format(x))
+            try:
                 self.header_i = d.signature_fields.get(b'i')
+            except TypeError as x:
+                self.header_i = None
+            try:
                 self.header_d = d.signature_fields.get(b'd')
                 self.header_a = d.signature_fields.get(b'a')
-          if res:
+            except Exception as x:
+                self.dkim_comment = str(x)
                 if milterconfig.get('Syslog'):
-                  syslog.syslog('DKIM: Pass ({0})'.format(d.domain))
+                    syslog.syslog("check_dkim: Internal proram fuault extracting header a or d: {0}".format(x))
-              self.dkim_domain = d.domain
+                self.header_d = None
+            if not self.header_a:
+                self.header_a = 'rsa-sha256'
+            if res:
+                if (milterconfig.get('Syslog') and
+                        (milterconfig.get('SyslogSuccess') or
+                         milterconfig.get('debugLevel') >= 1)):
+                    syslog.syslog('{0}: {1} DKIM signature verified (s={2} '
+                                  'd={3})'.format(self.getsymval('i'),
+                                                  d.signature_fields.get(b'a'),
+                                                  d.signature_fields.get(b's'),
+                                                  d.domain.lower()))
+                self.dkim_domain = d.domain.lower()
             else:
-            fd,fname = tempfile.mkstemp(".dkim")
+                if milterconfig.get('DiagnosticDirectory'):
-            with os.fdopen(fd,"w+b") as fp:
+                    fd, fname = tempfile.mkstemp(".dkim")
+                    with os.fdopen(fd, "w+b") as fp:
                         fp.write(txt)
                     if milterconfig.get('Syslog'):
-                syslog.syslog('DKIM: Fail (saved as {0})'.format(fname))
+                        syslog.syslog('DKIM: Fail (saved as {0})'
+                                      .format(fname))
+                else:
+                    if milterconfig.get('Syslog'):
+                        if d.domain:
+                            syslog.syslog('DKIM: Fail ({0})'
+                                          .format(d.domain.lower()))
+                        else:
+                            syslog.syslog('DKIM: Fail, unextractable domain')
             if res:
                 result = 'pass'
             else:
                 result = 'fail'
+            res = False
+            if self.header_d:
                 self.arresults.append(
                     authres.DKIMAuthenticationResult(result=result,
-              header_i = self.header_i, header_d = self.header_d, header_a = self.header_a,
+                                                 header_i=self.header_i,
-              result_comment = self.dkim_comment)
+                                                 header_d=self.header_d,
+                                                 header_a=self.header_a,
+                                                 result_comment=
+                                                 self.dkim_comment)
             )
+            self.header_a = None
         return
 
+
 def main():
     # Ugh, but there's no easy way around this.
     global milterconfig
@@ -259,15 +349,16 @@ def main():
     global privateEd25519
     privateRSA = False
     privateEd25519 = False
-    configFile = '/etc/dkimpy-milter.conf'
+    configFile = '/usr/local/etc/dkimpy-milter.conf'
     if len(sys.argv) > 1:
-        if sys.argv[1] in ( '-?', '--help', '-h' ):
+        if sys.argv[1] in ('-?', '--help', '-h'):
             print('usage: dkimpy-milter [<configfilename>]')
             sys.exit(1)
         configFile = sys.argv[1]
-    milterconfig = config._processConfigFile(filename = configFile)
+    milterconfig = config._processConfigFile(filename=configFile)
     if milterconfig.get('Syslog'):
-        facility = eval("syslog.LOG_{0}".format(milterconfig.get('SyslogFacility').upper()))
+        facility = eval("syslog.LOG_{0}"
+                        .format(milterconfig.get('SyslogFacility').upper()))
         syslog.openlog(os.path.basename(sys.argv[0]), syslog.LOG_PID, facility)
         setExceptHook()
     pid = write_pid(milterconfig)
@@ -279,12 +370,12 @@ def main():
     Milter.set_flags(Milter.CHGHDRS + Milter.ADDHDRS)
     miltername = 'dkimpy-filter'
     socketname = milterconfig.get('Socket')
-    if milterconfig.get('Syslog'):
-        syslog.syslog('dkimpy-milter started:{0} user:{1}'.format(pid,milterconfig.get('UserID')))
-    sys.stdout.flush()
-    Milter.runmilter(miltername,socketname,240)
-    own_socketfile(milterconfig)
     drop_privileges(milterconfig)
+    sys.stdout.flush()
+    if milterconfig.get('Syslog'):
+        syslog.syslog('dkimpy-milter starting:{0} user:{1}'
+                      .format(pid, milterconfig.get('UserID')))
+    Milter.runmilter(miltername, socketname, 240)
 
 if __name__ == "__main__":
     main()

dkimpy_milter/config.py

@@ -27,39 +27,207 @@
 import syslog
 import os
 import sys
-import re
-import urllib
 import stat
 import dkim
-
+import socket
+import ipaddress
+from dnsplug import Session
 
 #  default values
 defaultConfigData = {
-        'Syslog' : 'yes',
+    'Syslog': 'yes',
-        'SyslogFacility' : 'mail',
+    'SyslogFacility': 'mail',
-        'UMask' : 007,
+    'UMask': 007,
-        'Mode' : 'sv',
+    'Mode': 'sv',
-        'Socket' : 'local:/var/run/dkimpy-milter/dkimpy-milter.sock',
+    'Socket': 'local:/var/run/dkimpy-milter/dkimpy-milter.sock',
-        'PidFile'  : '/var/run/dkimpy-milter/dkimpy-milter.pid',
+    'PidFile': '/var/run/dkimpy-milter/dkimpy-milter.pid',
-        'UserID' : 'dkimpy-milter',
+    'UserID': 'dkimpy-milter',
-        'Canonicalization' : 'relaxed/simple'
+    'Canonicalization': 'relaxed/simple',
+    'InternalHosts': '127.0.0.1',
+    'IntHosts': False,
+    'DiagnosticDirectory': '',
+    'MacroList': '',
+    'MacroListVerify': '',
+    'debugLevel': 0  # Undocumented config item for developer use
     }
 
 
-#################################
 class ConfigException(Exception):
     '''Exception raised when there's a configuration file error.'''
     pass
 
-####################################################################
+
-def _processConfigFile(filename = None, configdata = None, useSyslog = 1,
+class HostsDataset(object):
-        useStderr = 0):
+    '''Hold a group of host related dataset objects'''
+
+    def __init__(self, dataset):
+        self.dataset = []
+        # Self.dataset will end up being a list of DataSetItem(s).
+        for item in dataset:
+            item = item.rstrip(']')
+            item = item.lstrip('[')
+            self.dataset.append(self.DatasetItem(item))
+
+    class DatasetItem(object):
+        '''Individual dataset item'''
+
+        def __init__(self, item):
+            self.item = item
+            self.isipv4 = False
+            self.isipv4cidr = False
+            self.isipv6 = False
+            self.isipv6cidr = False
+            self.ishostname = False
+            self.isdomain = False
+            self.negative = False
+            if self.item[0] == '!':
+                self.item = item[1:]
+                self.negative = True
+            try:
+                self.item = ipaddress.ip_address(unicode(self.item, "utf-8"))
+                if isinstance(self.item, ipaddress.IPv4Address):
+                    self.isipv4 = True
+                elif isinstance(self.item, ipaddress.IPv6Address):
+                    self.isipv6 = True
+            except ValueError as e:
+                try:
+                    self.item = ipaddress.ip_network(unicode
+                                                     (self.item, "utf-8"),
+                                                     strict=False)
+                    if isinstance(self.item, ipaddress.IPv4Network):
+                        self.isipv4cidr = True
+                    elif isinstance(self.item, ipaddress.IPv6Network):
+                        self.isipv6cidr = True
+                except ValueError as e2:
+                    if self.item[0] == '.' and len(self.item.split('.')) > 2:
+                        self.isdomain = True
+                    elif len(self.item.split('.')) > 1:  # It has a '.' in it
+                        self.ishostname = True
+                    else:
+                        raise ConfigException('Unknown dataset item: {0}'
+                                              .format(item))
+
+    def match(self, connectip):
+        '''Check if the connect IP is part of the dataset'''
+        source = ipaddress.ip_address(unicode(connectip, "utf-8"))
+        for item in self.dataset:
+            if item.isdomain or item.ishostname:
+                result = self.matchname(source)   # Match host/domains first
+                if result:
+                    return(result)
+            elif item.isipv4 or item.isipv4cidr:  # Then IPv4/6 addresses or
+                if isinstance(source, ipaddress.IPv4Address):  # networks
+                    return(self.match4(source))   # depending on the item type
+            elif item.isipv6 or item.isipv6cidr:  # and connect type
+                if isinstance(source, ipaddress.IPv6Address):
+                    return(self.match6(source))
+
+    def matchname(self, source):
+        '''Does source IP address relate to a domain/hostname in the dataset'''
+        match = False
+        matchone = False
+        negativeone = False
+        matchdomain = False
+        negativedomain = False
+        ptrlist = self.getptr(source)
+        for item in self.dataset:
+            if item.isdomain:
+                for ptr in ptrlist:
+                    # Strip the leading '.' off the domain name for exact match
+                    if item.item[1:] == ptr[-len(item.item)+1:]:
+                        matchdomain = True
+                        negativedomain = item.negative
+            elif item.ishostname:
+                for ptr in ptrlist:
+                    if item.item == ptr:
+                        matchone = True
+                        negativeone = item.negative
+        if matchdomain and not negativedomain:
+            match = True
+        if matchone and not negativeone:
+            return True
+        if matchone and negativeone:
+            match = False
+        return(match)
+
+    def getptr(self, source):
+        '''Get validated PTR name of IP address'''
+        results = []
+        s = Session()
+        ptrnames = s.dns(source.reverse_pointer, 'PTR')
+        for name in ptrnames:
+            if isinstance(source, ipaddress.IPv4Address):
+                ips = s.dns(name, 'A')
+                for ip in ips:
+                    ip = ipaddress.IPv4Address(unicode(ip, 'UTF-8'))
+                    if ip == source:
+                        results.append(name)
+            if isinstance(source, ipaddress.IPv6Address):
+                ips = s.dns(name, 'AAAA')
+                for ip in ips:
+                    ip = ipaddress.IPv6Address(unicode(ip, 'UTF-8'))
+                if ip == source:
+                    results.append(name)
+        return results
+
+    def match4(self, source):
+        '''Is the source IP related to a IPv4 address/network in the dataset'''
+        match = False
+        matchone = False
+        negativeone = False
+        matchcidr = False
+        negativecidr = False
+        for item in self.dataset:
+            if item.isipv4:
+                if source == item.item:
+                    matchone = True
+                    negativeone = item.negative
+            elif item.isipv4cidr:
+                if source in item.item:
+                    matchcidr = True
+                    negativecidr = item.negative
+        if matchcidr and not negativecidr:
+            match = True
+        if matchone and not negativeone:
+            return True
+        if matchone and negativeone:
+            match = False
+        return(match)
+
+    def match6(self, source):
+        '''Is the source IP realted to a IPv6 address/network in the dataset'''
+        match = False
+        matchone = False
+        negativeone = False
+        matchcidr = False
+        negativecidr = False
+        for item in self.dataset:
+            if item.isipv6:
+                if source == item.item:
+                    matchone = True
+                    negativeone = item.negative
+            elif item.isipv6cidr:
+                if source in item.item:
+                    matchcidr = True
+                    negativecidr = item.negative
+        if matchcidr and not negativecidr:
+            match = True
+        if matchone and not negativeone:
+            return True
+        if matchone and negativeone:
+            match = False
+        return(match)
+
+
+def _processConfigFile(filename=None, configdata=None, useSyslog=1,
+                       useStderr=0):
     '''Load the specified config file, exit and log errors if it fails,
     otherwise return a config dictionary.'''
 
     import config
-    if configdata == None: configdata = config.defaultConfigData
+    if configdata is None:
-    if filename != None:
+        configdata = config.defaultConfigData
+    if filename is not None:
         try:
             _readConfigFile(filename, configdata)
         except Exception, e:
@@ -71,7 +239,7 @@ def _processConfigFile(filename = None, configdata = None, useSyslog = 1,
             sys.exit(1)
     return(configdata)
 
-####################
+
 def _find_boolean(item):
     if type(item) == int:
         item = str(item)
@@ -84,6 +252,13 @@ def _find_boolean(item):
     return item
 
 
+def _make_authserv_id(as_id):
+    """Determine AuthservID if needed"""
+    if as_id == 'HOSTNAME':
+        as_id = socket.gethostname()
+    return as_id
+
+
 def _dataset_to_list(dataset):
     """Convert a dataset (as defined in dkimpymilter.8) and return a python
        list of values."""
@@ -118,63 +293,79 @@ def _dataset_to_list(dataset):
             return [dataset[4:].strip().strip(',')]
         else:
             return [dataset.strip().strip(',')]
+        if dataset[-3:] == '.db' or dataset[:3] == 'db:':
+            #  This is a Sleepycat (Oracle) DB  dataset, which we dont support
+            raise dkim.ParameterError('Unsupported dataset db datase: {0}'
+                                      .format(type(dataset)))
 
-    raise dkim.ParameterError('Unimplmented dataset type: {0}'.format(type(dataset)))
+    raise dkim.ParameterError('Unimplmented dataset type: {0}'
+                              .format(type(dataset)))
 
-###############################################################
+
-commentRx = re.compile(r'^(.*)#.*$')
+def _readConfigFile(path, configData=None, configGlobal={}):
-def _readConfigFile(path, configData = None, configGlobal = {}):
     '''Reads a configuration file from the specified path, merging it
     with the configuration data specified in configData.  Returns a
     dictionary of name/value pairs based on configData and the values
     read from path.'''
 
     debugLevel = configGlobal.get('debugLevel', 0)
-    if debugLevel >= 5: syslog.syslog('readConfigFile: Loading "%s"' % path)
+    if debugLevel >= 5:
-    if configData == None: configData = {}
+        syslog.syslog('readConfigFile: Loading "%s"' % path)
+    if configData is None:
+        configData = {}
     nameConversion = {
-        'AuthservID' : 'str',
+        'AuthservID': 'str',
-        'Syslog' : 'bool',
+        'Syslog': 'bool',
-        'SyslogFacility' : 'str',
+        'SyslogFacility': 'str',
-        'SyslogSuccess' : 'bool',
+        'SyslogSuccess': 'bool',
-        'UMask' : 'int',
+        'UMask': 'int',
-        'Mode' : 'str',
+        'Mode': 'str',
-        'Socket' : 'str',
+        'Socket': 'str',
-        'PidFile'  : 'str',
+        'PidFile': 'str',
-        'UserID' : 'str',
+        'UserID': 'str',
-        'Domain' : 'dataset',
+        'Domain': 'dataset',
-        'KeyFile' : 'str',
+        'KeyFile': 'str',
-        'KeyFileEd25519' : 'str',
+        'KeyFileEd25519': 'str',
-        'Selector' : 'str',
+        'Selector': 'str',
         'SelectorEd25519': 'str',
-        'Canonicalization' : 'str',
+        'Canonicalization': 'str',
+        'InternalHosts': 'dataset',
+        'IntHosts': 'bool',
+        'DiagnosticDirectory': 'str',
+        'MacroList': 'dataset',
+        'MacroListVerify': 'dataset',
+        'debugLevel': 'int'
         }
 
     #  check to see if it's a file
     try:
         mode = os.stat(path)[0]
     except OSError, e:
-        syslog.syslog(syslog.LOG_ERR,'ERROR stating "%s": %s' % ( path, e.strerror ))
+        syslog.syslog(syslog.LOG_ERR, 'ERROR stating "%s": %s'
+                      % (path, e.strerror))
         return(configData)
     if not stat.S_ISREG(mode):
-        syslog.syslog(syslog.LOG_ERR,'ERROR: is not a file: "%s", mode=%s' % ( path, oct(mode) ))
+        syslog.syslog(syslog.LOG_ERR, 'ERROR: is not a file: "%s", mode=%s'
+                      % (path, oct(mode)))
         return(configData)
 
     #  load file
     fp = open(path, 'r')
     while 1:
         line = fp.readline()
-        if not line: break
+        if not line:
+            break
 
         #  parse line
         line = line.split('#', 1)[0].strip()
-        if not line: continue
+        if not line:
+            continue
         data = line.split()
         if len(data) != 2:
             if len(data) == 1:
                 if debugLevel >= 1:
-                    syslog.syslog('Configuration item "%s" not defined in file "%s"'
+                    syslog.syslog('Config item "%s" not defined in file "%s"'
-                        % ( line, path ))
+                                  % (line, path))
         if len(data) == 1:
             name = data
             value = ''
@@ -186,12 +377,14 @@ def _readConfigFile(path, configData = None, configGlobal = {}):
 
         #  check validity of name
         conversion = nameConversion.get(name)
-        if conversion == None:
+        if conversion is None:
-            syslog.syslog('ERROR: Unknown name "%s" in file "%s"' % ( name, path ))
+            syslog.syslog('ERROR: Unknown name "%s" in file "%s"'
+                          % (name, path))
             continue
 
-        if debugLevel >= 5: syslog.syslog('readConfigFile: Found entry "%s=%s"'
+        if debugLevel >= 5:
-                % ( name, value ))
+            syslog.syslog('readConfigFile: Found entry "%s=%s"'
+                          % (name, value))
         if conversion == 'bool':
             configData[name] = _find_boolean(value)
         elif conversion == 'str':
@@ -201,8 +394,14 @@ def _readConfigFile(path, configData = None, configGlobal = {}):
         elif conversion == 'dataset':
             configData[name] = _dataset_to_list(value)
         else:
-            syslog.syslog(str('name: ' + name + ' value: ' + value + ' conversion: ' + conversion))
+            syslog.syslog(str('name: ' + name + ' value: ' + value +
+                              ' conversion: ' + conversion))
             configData[name] = conversion(value)
     fp.close()
+    try:
+        configData['AuthservID'] = _make_authserv_id(configData['AuthservID'])
+        configData['IntHosts'] = HostsDataset(configData['InternalHosts'])
+    except:
+        pass
 
     return(configData)

dkimpy_milter/dnsplug.py

@@ -0,0 +1,168 @@
+## @package dnsplug
+# Provide a higher level interface to pydns or dnspython (or other provider).
+# NOT RELEASED: this is a proposed API and implementation.
+# Goals - work with both pydns and dnspython (and possibly other libraries)
+# at a simplied level.
+# TODO:
+# 1. map exceptions to common dnsplug.DNSError exception (with
+#    original exception saved as a member).
+# 2. include dict based implementation (handy for test suites)
+# 3. move implementations to subpackages to enable autoselect on first call.
+
+## Maximum number of CNAME records to follow
+MAX_CNAME = 10
+
+## Lookup DNS records by label and RR type.
+# The response can include records of other types that the DNS
+# server thinks we might need.  FIXME: empty result
+# could mean NXDOMAIN or NOANSWER.
+# @param name the DNS label to lookup
+# @param qtype the name of the DNS RR type to lookup
+# @param tcpfallback if False, raise exception instead of TCP fallback
+# @return a list of ((name,type),data) tuples
+def DNSLookup(name, qtype, tcpfallback=True, timeout=30):
+    raise NotImplementedError('No supported dns library found')
+
+class Session(object):
+  """A Session object has a simple cache with no TTL that is valid
+   for a single "session", for example an SMTP conversation."""
+  def __init__(self):
+    self.cache = {}
+
+  ## Additional DNS RRs we can safely cache.
+  # We have to be careful which additional DNS RRs we cache.  For
+  # instance, PTR records are controlled by the connecting IP, and they
+  # could poison our local cache with bogus A and MX records.  
+  # Each entry is a tuple of (query_type,rr_type).  So for instance,
+  # the entry ('MX','A') says it is safe (for milter purposes) to cache
+  # any 'A' RRs found in an 'MX' query.
+  SAFE2CACHE = frozenset((
+    ('MX','MX'), ('MX','A'),
+    ('CNAME','CNAME'), ('CNAME','A'),
+    ('A','A'),
+    ('AAAA','AAAA'),
+    ('PTR','PTR'),
+    ('NS','NS'), ('NS','A'),
+    ('TXT','TXT'),
+    ('SPF','SPF')
+  ))
+
+  ## Cached DNS lookup.
+  # @param name the DNS label to query
+  # @param qtype the query type, e.g. 'A'
+  # @param cnames tracks CNAMES already followed in recursive calls
+  def dns(self, name, qtype, cnames=None):
+    """DNS query.
+
+    If the result is in cache, return that.  Otherwise pull the
+    result from DNS, and cache ALL answers, so additional info
+    is available for further queries later.
+
+    CNAMEs are followed.
+
+    If there is no data, [] is returned.
+
+    pre: qtype in ['A', 'AAAA', 'MX', 'PTR', 'TXT', 'SPF']
+    post: isinstance(__return__, types.ListType)
+    """
+    result = self.cache.get( (name, qtype) )
+    cname = None
+
+    if not result:
+        safe2cache = Session.SAFE2CACHE
+        for k, v in DNSLookup(name, qtype):
+            if k == (name, 'CNAME'):
+                cname = v
+            if (qtype,k[1]) in safe2cache:
+                self.cache.setdefault(k, []).append(v)
+        result = self.cache.get( (name, qtype), [])
+    if not result and cname:
+        if not cnames:
+            cnames = {}
+        elif len(cnames) >= MAX_CNAME:
+            #return result    # if too many == NX_DOMAIN
+            raise DNSError('Length of CNAME chain exceeds %d' % MAX_CNAME)
+        cnames[name] = cname
+        if cname in cnames:
+            raise DNSError, 'CNAME loop'
+        result = self.dns(cname, qtype, cnames=cnames)
+    return result
+
+def DNSLookup_pydns(name, qtype, tcpfallback=True, timeout=30):
+    try:
+	# FIXME: To be thread safe, we create a fresh DnsRequest with
+	# each call.  It would be more efficient to reuse
+	# a req object stored in a Session.
+        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 not tcpfallback:
+              raise DNS.DNSError, 'DNS: Truncated UDP Reply, SPF records should fit in a UDP packet'
+          try:
+              req = DNS.DnsRequest(name, qtype=qtype, protocol='tcp',
+                        timeout=timeout)
+              resp = req.req()
+          except DNS.DNSError, x:
+              raise DNS.DNSError, 'TCP Fallback error: ' + str(x)
+        return [((a['name'], a['typename']), a['data']) for a in resp.answers]
+    except IOError, x:
+        raise DNS.DNSError, '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
+
+if __name__ == '__main__':
+  import sys
+  s = Session()
+  for n,t in zip(*[iter(sys.argv[1:])]*2):
+    print n,t
+    print s.dns(n,t)

dkimpy_milter/util.py

@@ -16,6 +16,40 @@
 # with this program; if not, write to the Free Software Foundation, Inc.,
 # 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+
+def fold(header):
+    """Fold a header line into multiple crlf-separated lines at column 72.
+    Borrowed from dkimpy and updated to only add \n instead of \r\n because
+    that's what the milter protocol wants.
+
+    >>> text(fold(b'foo'))
+    'foo'
+    >>> text(fold(b'foo  '+b'foo'*24).splitlines()[0])
+    'foo  '
+    >>> text(fold(b'foo'*25).splitlines()[-1])
+    ' foo'
+    >>> len(fold(b'foo'*25).splitlines()[0])
+    72
+    """
+    i = header.rfind(b"\r\n ")
+    if i == -1:
+        pre = b""
+    else:
+        i += 3
+        pre = header[:i]
+        header = header[i:]
+    maxleng = 72
+    while len(header) > maxleng:
+        i = header[:maxleng].rfind(b" ")
+        if i == -1:
+            j = maxleng
+        else:
+            j = i + 1
+        pre += header[:j] + b"\n   "
+        header = header[j:]
+    return pre + header
+
+
 def user_group(userid):
     """Return user and group from UserID"""
     import grp
@@ -31,13 +65,14 @@ def user_group(userid):
     running_gid = grp.getgrnam(gidname).gr_gid
     return running_uid, running_gid
 
+
 def drop_privileges(milterconfig):
     import os
     import syslog
 
     if os.getuid() != 0:
         if milterconfig.get('Syslog'):
-            syslog.syslog('drop_privileges: Not running as root. Cannot drop permissions.')
+            syslog.syslog('drop_privileges: Not root. No action taken.')
         return
 
     # Get user and group
@@ -53,9 +88,9 @@ def drop_privileges(milterconfig):
     # Set umask
     old_umask = os.umask(milterconfig.get('UMask'))
 
-#################
+
 class ExceptHook:
-    def __init__(self, useSyslog = 1, useStderr = 0):
+    def __init__(self, useSyslog=1, useStderr=0):
         self.useSyslog = useSyslog
         self.useStderr = useStderr
 
@@ -71,12 +106,11 @@ class ExceptHook:
                 sys.stderr.write(line)
 
 
-####################
 def setExceptHook():
     import sys
-    sys.excepthook = ExceptHook(useSyslog = 1, useStderr = 1)
+    sys.excepthook = ExceptHook(useSyslog=1, useStderr=1)
+
 
-####################
 def write_pid(milterconfig):
     """Write PID in pidfile.  Will not overwrite an existing file."""
     import os
@@ -86,8 +120,18 @@ def write_pid(milterconfig):
         try:
             f = open(milterconfig.get('PidFile'), 'w')
         except IOError as e:
+            if str(e)[:35] == '[Errno 2] No such file or directory':
+                piddir = milterconfig.get('PidFile').rsplit('/', 1)[0]
+                os.mkdir(piddir)
+                user, group = user_group(milterconfig.get('UserID'))
+                os.chown(piddir, user, group)
+                f = open(milterconfig.get('PidFile'), 'w')
                 if milterconfig.get('Syslog'):
-                syslog.syslog('Unable to write pidfle {0}.  IOError: {1}'.format(milterconfig.get('PidFile'), e))
+                    syslog.syslog('PID dir created: {0}'.format(piddir))
+            else:
+                if milterconfig.get('Syslog'):
+                    syslog.syslog('Unable to write pidfle {0}.  IOError: {1}'
+                                  .format(milterconfig.get('PidFile'), e))
                 raise
         f.write(pid)
         f.close()
@@ -95,20 +139,13 @@ def write_pid(milterconfig):
         os.chown(milterconfig.get('PidFile'), user, group)
     else:
         if milterconfig.get('Syslog'):
-            syslog.syslog('Unable to write pidfle {0}.  File exists.'.format(milterconfig.get('PidFile')))
+            syslog.syslog('Unable to write pidfle {0}.  File exists.'
-        raise RuntimeError('Unable to write pidfle {0}.  File exists.'.format(milterconfig.get('PidFile')))
+                          .format(milterconfig.get('PidFile')))
+        raise RuntimeError('Unable to write pidfle {0}.  File exists.'
+                           .format(milterconfig.get('PidFile')))
     return pid
 
-def own_socketfile(milterconfig):
-    """If socket is Unix socket, chown to UserID before dropping privileges"""
-    import os
-    user, group = user_group(milterconfig.get('UserID'))
-    if milterconfig.get('Socket')[:1] == '/':
-        os.chown(milterconfig.get('Socket')[1:], user, group)
-    if milterconfig.get('Socket')[:6] == "local:":
-        os.chown(milterconfig.get('Socket')[6:], user, group)
 
-####################
 def read_keyfile(milterconfig, keytype):
     """Read private key from file."""
     import syslog
@@ -121,7 +158,8 @@ def read_keyfile(milterconfig, keytype):
         keylist = f.readlines()
     except IOError as e:
         if milterconfig.get('Syslog'):
-            syslog.syslog('Unable to read keyfile {0}.  IOError: {1}'.format(keyfile, e))
+            syslog.syslog('Unable to read keyfile {0}.  IOError: {1}'
+                          .format(keyfile, e))
         raise
     f.close()
     key = ''

man/dkimpy-milter.8

@@ -127,7 +127,6 @@
 .rm #[ #] #H #V #F C
 .\" ========================================================================
 .\"
-.IX Title "dkimpy-milter 8"
 .TH dkimpyy-milter 8
 .SH NAME
 .B dkimpy
@@ -156,7 +155,7 @@ values, or to a file that contains them, or a database containing the data.
 
 Some data sets require that the value contain more than one entry.  How this
 is done depends on which data set type is used.  Not all these datasets are
-currently used by dkimp-milter.  See
+currently used by dkimpy-milter.  See
 .B dkimpy-milter.conf(5)
 for details about specific options and which dataset types they use.
 
@@ -169,17 +168,7 @@ one per line.  If a line contains whitespace-separated values, then the
 line is presumed to define a key and its corresponding value.  Blank lines
 are ignored, and the hash ("#") character denotes the start of a comment.
 If a value contains multiple entries, the entries should be separated by
-colons. [Not implemented yet]
+colons.
-.TP
-.I b)
-If the string begins with "refile:", then the remainder of the string is
-presumed to specify a file that contains a set of patterns, one per line,
-and their associated values.  The pattern is taken as the start of the line
-to the first whitespace, and the portion after that whitespace is taken as
-the value to be used when that pattern is matched.  Patterns are simple
-wildcard patterns, matching all text except that the asterisk ("*") character
-is considered a wildcard.  If a value contains multiple entries, the entries
-should be separated by colons. [Not implemented yet]
 .TP
 .I c)
 If the string begins with "db:" and the program was compiled with
@@ -196,11 +185,11 @@ is compiled in).  [Not implemented yet]
 .TP
 .I i)
 If the string contains none of these prefixes but starts with a slash ("/")
-character, it is presumed to be a flat file as described above.  [Not implemented yet]
+character, it is presumed to be a flat file as described above.
 .TP
 .I j)
 If the string begins with "csl:", the string is treated as a comma-separated
-list as described in m) below.  [Not implemented yet]
+list as described in m) below.
 .TP
 .I l)
 If the string begins with "mdb:", it refers to a directory that contains
@@ -279,7 +268,7 @@ proposal, and Cisco's
 .B Internet Identified Mail
 (IIM) proposal.
 .SH VERSION
-This man page covers version 0.9.2 of
+This man page covers version 1.1.0 of
 .I dkimpy-milter.
 .SH COPYRIGHT
 Copyright (c) 2005-2008, Sendmail, Inc. and its suppliers.  All rights
@@ -288,7 +277,7 @@ reserved.
 Copyright (c) 2009-2013, 2015, The Trusted Domain Project.
 All rights reserved.
 
-Copyright (c) 2018 Scott Kitterman <scott@kitterman.com>
+Copyright (c) 2018, 2019 Scott Kitterman <scott@kitterman.com>
 .SH SEE ALSO
 .I dkimpy-milter.conf(5), sendmail(8)
 .P
@@ -302,4 +291,6 @@ RFC6376 - DomainKeys Identified Mail
 .P
 RFC7601 - Message Header Field for Indicating Message Authentication Status
 .P
-draft-ietf-dcrup-dkim-crypto - A new cryptographic signature method for DKIM
+RFC8301 - Cryptographic Algorithm and Key Usage Update to DomainKeys Identified Mail (DKIM)
+.P
+RFC8463 - A New Cryptographic Signature Method for DomainKeys Identified Mail (DKIM)

man/dkimpy-milter.conf.5

@@ -127,16 +127,13 @@
 .rm #[ #] #H #V #F C
 .\" ========================================================================
 .\"
-.IX Title "dkimpy-milter.conf 5"
 .TH dkimpy-milter.conf 5 "2018-02-12"
 .SH "NAME"
 dkimpy-milter \- Python milter for DKIM signing and validation
 .SH "VERSION"
-.IX Header "VERSION"
 0\.9\.2
 
 .SH "DESCRIPTION"
-.IX Header "DESCRIPTION"
 .I dkimpy-milter(8)
 implements the
 .B DKIM
@@ -160,18 +157,15 @@ The provided setup.py installs this configuration file in /etc or
 Command line invocation of parameters as is done by OpenDKIM is not supported.
 
 .SH "USAGE"
-.IX Header "USAGE"
 Usage:
   dkimpy-milter [/etc/dkimpy-milter.conf]
 
 .SH "OTHER DOCUMENTATION"
-.IX Header "OTHER DOCUMENTATION"
 This documentation assumes you have read Postfix's README_FILES/MILTER_README
 (or Sendmail equivalent) and are generally familiar with Domain Keys Identified
 Mail (DKIM).  See RFC 6376 for details.
 
 .SH "SYNOPSIS"
-.IX Header "SYNOPSIS"
 
 dkimpy-milter operates with a default installed configuration file and 
 set of default configuration options that are used if the configuration file
@@ -181,14 +175,12 @@ files can be used directly.  Not all OpenDKIM options are supported.  If an
 unsupported option from OpenDKIM is specified, an error will be raised.
 
 .SH "DESCRIPTION"
-.IX Header "DESCRIPTION"
 
 Configuration options are described here and in the configuration file 
 provided with the package.  The provided setup.py installs this configuration 
 file in /etc or /usr/local/etc.
 
 .SH "OPTIONS"
-.IX Header "OPTIONS"
 
 .TP
 .I AuthservID (string)
@@ -215,18 +207,12 @@ The value may include two different canonicalizations separated by a
 slash ("/") character, in which case the first will be applied to the
 header and the second to the body.
 
-.TP
-.I Diagnostics (Boolean)
-Requests the inclusion of "z=" tags in signatures, which encode the
-original header field set for use by verifiers when diagnosing verification
-failures.  Not recommended for normal operation. [dkimpy-milter specific: also
-increases the verbosity of Syslog logging if enabled.]
-
 .TP
 .I DiagnosticDirectory (string)
 Directory into which to write diagnostic reports when message verification
-fails on a message bearing a "z=" tag.  If not set (the default), these files
+fails.  If not set (the default), these files are not generated.  [Unlike
-are not generated.
+OpenDKIM, this applies to all messages, not just  on messages bearing a "z=" tag
+because dkimpy does not yet support "z=".]
 
 .TP
 .I Domain (dataset)
@@ -261,13 +247,50 @@ all messages.  Ignored if a
 is defined. [KeyTable NOT IMPLEMENTED]
 
 .TP
-.I KeyFileEd25119 (string)
+.I KeyFileEd25519 (string)
 Gives the location of a Ed25519 private key to be used for Ed25519 signing
 all messages.  File is the Base64 encoded output of RFC 8032 Ed25519 private Key
 generation (as used in dkimpy).  Ignored if a 
 .I KeyTableEd25519
 is defined.  [KeyTableEd25519 NOT IMPLEMENTED]
 
+.TP
+.I MacroList (dataset)
+Defines a set of MTA-provided
+.I macros
+that should be checked to see if the sender has been determined to be a
+local user and therefore whether or not the message should be signed.  If
+a
+.I value
+is specified matching a macro name in the data set, the value of the macro
+must match a value specified (matching is case-sensitive), otherwise the
+macro must be defined but may contain any value.  The set is empty by
+default, meaning macros are not considered when making the sign-verify
+decision.  The general format of the value is
+.I value1[|value2[|...]];
+if one or more value is defined then the macro must be set to one of the
+listed values, otherwise the macro must be set but can contain any
+value.
+
+In order for the macro and its value to be available to the filter for
+checking, the MTA must send it during the protocol exchange.  This is either
+accomplished via manual configuration of the MTA to send the desired macros
+or, for MTA/filter combinations that support the feature, the filter can
+request those macros that are of interest.  The latter is a feature negotiated
+at the time the filter receives a connection from the MTA and its availability
+depends upon the version of milter used to compile the filter and the version
+of the MTA making the connection.
+
+.TP
+.I MacroListVerify (dataset)
+Defines a set of MTA-provided
+.I macros
+that should be checked to see if the sender has been determined to be an
+external source and therefore whether or not the message should be signed.
+Entries in this data set follow the same form as those of the
+.I MacroList
+option above.  [this option is not inhereted from OpenDKIM]  
+
 .TP
 .I Mode (string)
 Selects operating modes.  The string is a concatenation of characters that
@@ -374,7 +397,7 @@ Log via calls to
 using the named facility.  The facility names are the same as the ones
 allowed in
 .I syslog.conf(5).
-The default is "mail".  [Hardcoded to default for now]
+The default is "mail".
 
 .TP
 .I SyslogSuccess (Boolean)
@@ -410,7 +433,6 @@ unless an alternate
 is specified.
 
 .SH "AUTHORS"
-.IX Header "AUTHORS"
 \ddkimpy-milter\fR was written by Scott Kitterman <scott@kitterman.com>.
 It is based on dkimpy-milter.py  Copyright (c) 2001-2013 Business Management Systems, Inc.
 Copyright (c) 2013-2015 Stuart D. Gathman

setup.py

@@ -18,20 +18,26 @@
 
 from setuptools import setup
 import os
-import dkimpy_milter
 
 description = "Domain Keys Identified Mail (DKIM) signing/verifying milter for Postfix/Sendmail."
 
+kw = {}  # Work-around for lack of 'or' requires in setuptools.
+try:
+    import DNS
+    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'PyDNS']
+except ImportError:  # If PyDNS is not installed, prefer dnspython
+    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'dnspython']
+
 setup(
     name='dkimpy-milter',
-    version=dkimpy_milter.__version__,
+    version='1.0.3',
     author='Scott Kitterman',
     author_email='scott@kitterman.com',
     url='https://launchpad.net/dkimpy-milter',
     description=description,
     download_url = "https://pypi.python.org/pypi/dkimpy-milter",
     classifiers= [
-        'Development Status :: 3 - Alpha',
+        'Development Status :: 5 - Production/Stable',
         'Environment :: No Input/Output (Daemon)',
         'Intended Audience :: System Administrators',
         'License :: OSI Approved :: GNU General Public License (GPL)',
@@ -52,9 +58,9 @@ setup(
     data_files=[(os.path.join('share', 'man', 'man5'),
         ['man/dkimpy-milter.conf.5']), (os.path.join('share', 'man', 'man8'),
         ['man/dkimpy-milter.8']), ('etc', ['etc/dkimpy-milter.conf']),
-        (os.path.join('/lib', 'systemd', 'system'),
+        (os.path.join('lib', 'systemd', 'system'),
-        ['system/dkimpy-milter.service']),(os.path.join('/etc', 'init.d'),
+        ['system/dkimpy-milter.service']),(os.path.join('etc', 'init.d'),
         ['system/dkimpy-milter'])],
-    install_requires = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl'],
     zip_safe = False,
+    **kw
 )

system/dkimpy-milter

@@ -13,8 +13,6 @@
 # Provides:          dkim-milter dkim-milter-python dkimpy-milter
 # Required-Start:    $remote_fs $syslog $network $time
 # Required-Stop:     $remote_fs $syslog $network
-# Should-Start:
-# Should-Stop:
 # Default-Start:     2 3 4 5
 # Default-Stop:      0 1 6
 # Short-Description: dkimpy-milter
@@ -22,16 +20,16 @@
 ### END INIT INFO
 prefix="/usr/local"
 exec_prefix=${prefix}
-sysconfdir="/etc/dkimpy-milter"
+sysconfdir="/usr/local/etc"
 bindir="${exec_prefix}/bin/"
-RUNDIR="/var/run/dkimpy-milter"
+RUNDIR="/run/dkimpy-milter"
 DAEMON=${bindir}/dkimpy-milter
 PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/bin:
 NAME=dkimpy-milter
 DESC="Python DKIM Milter"
 USER=dkimpy-milter
 GROUP=dkimpy-milter
-SOCKET=$RUNDIR/dkimpy-milter.pid
+SOCKET=$RUNDIR/dkimpy-milter.sock
 
 test -x $DAEMON || exit 0
 
@@ -69,14 +67,14 @@ case "$1" in
 			fi
 		fi
 	fi
-
+        start-stop-daemon --start --background --quiet --pidfile \
-	start-stop-daemon --start --chuid $USER --background --quiet --pidfile \
                 $RUNDIR/$NAME.pid --exec $DAEMON $sysconfdir/$NAME.conf
 	echo "$NAME."
 	;;
   stop)
 	echo -n "Stopping $DESC: "
 	if [ -f $RUNDIR/$NAME.pid ]; then
+		chown root:root $RUNDIR/$NAME.pid
 		start-stop-daemon --stop --pidfile $RUNDIR/$NAME.pid 
 		rm $RUNDIR/$NAME.pid
 		#echo $SOCKET
@@ -89,6 +87,7 @@ case "$1" in
   force-reload)
         echo -n "Force reloading $DESC: "
         if [ -f $RUNDIR/$NAME.pid ]; then
+                chown root:root $RUNDIR/$NAME.pid
                 start-stop-daemon --stop --pidfile $RUNDIR/$NAME.pid
                 rm $RUNDIR/$NAME.pid
                 #echo $SOCKET
@@ -97,7 +96,7 @@ case "$1" in
                 fi
         fi
         sleep 1
-        start-stop-daemon --start --chuid $USER --background --quiet --pidfile \
+        start-stop-daemon --start --background --quiet --pidfile \
                 $RUNDIR/$NAME.pid --exec $DAEMON $sysconfdir/$NAME.conf
         echo "$NAME."
         ;;
@@ -105,6 +104,7 @@ case "$1" in
         echo "Restarting $DESC: "
         echo -n "Stopping $DESC: "
         if [ -f $RUNDIR/$NAME.pid ]; then
+                chown root:root $RUNDIR/$NAME.pid
                 start-stop-daemon --stop --pidfile $RUNDIR/$NAME.pid
                 rm $RUNDIR/$NAME.pid
                 #echo $SOCKET
@@ -115,7 +115,7 @@ case "$1" in
         echo "$NAME."
 	sleep 1
         echo -n "Starting $DESC: "
-        start-stop-daemon --start --chuid $USER --background --quiet --pidfile \
+        start-stop-daemon --start --background --quiet --pidfile \
                 $RUNDIR/$NAME.pid --exec $DAEMON $sysconfdir/$NAME.conf
         echo "$NAME."
 	;;

system/dkimpy-milter.service

@@ -1,11 +1,12 @@
 [Unit]
 Description=DKIMpy Milter
-After=syslog.target network.target
+Documentation=man:dkimpy-milter(8) man:dkimpy-milter.conf(5) 
+After=network.target
 
 [Service]
 Type=simple
 PIDFile=/var/run/dkimpy-milter/dkimpy-milter.pid
-ExecStart=/usr/local/bin/dkimpy-milter 
+ExecStart=/usr/local/bin/dkimpy-milter /usr/local/etc/dkimpy-milter.conf 
 
 [Install]
 WantedBy=multi-user.target