Convert __init__.py to python3

The main work here is about bytes vs. strings.  This work was
confusing for several reasons:

 * pymilter thinks that headers are all strings, but body is bytes

 * dkimpy wants to deal with bytes objects generally (though it
   accepts a string object as an ed25519 secret key for some reason,
   despite requiring bytes as an RSA secret key)

 * authres.AuthenticationResultsHeader object converts easily to a
   string, but has no direct bytes conversion.  meanwhile, it wants
   its arguments as strings, but will accept them if they are bytes
   and convert them with something like str(), which leaves weird
   cruft like "header.a=b'ed25519-sha256'"

 * dkimpy_milter/utils.py contains fold() which expects bytes

 * self.fp needs to accumulate the on-the-wire version of the message
   as a whole (so it needs to be bytes).  That means converting the
   headers.  Header names and values are US-ASCII, per §2.2 of RFC
   5322, so they should be convertible cleanly, but we still have to
   convert them explicitly so that python knows the right thing to do.

At any rate, tests/runtests all passes with these changes, and the
output for both Authentication-Results: and DKIM-Signature headers
looks the same.

dkimpy_milter/__init__.py

@@ -1,4 +1,4 @@
-#! /usr/bin/python2
+#! /usr/bin/python3
 # Original dkim-milter.py code:
 # Author: Stuart D. Gathman <stuart@bmsi.com>
 # Copyright 2007 Business Management Systems, Inc.
@@ -28,8 +28,9 @@ import dkim
 import authres
 import os
 import tempfile
-import StringIO
+import io
 import re
+import codecs
 from Milter.utils import parse_addr, parseaddr
 import dkimpy_milter.config as config
 from dkimpy_milter.util import drop_privileges
@@ -110,7 +111,7 @@ class dkimMilter(Milter.Base):
     def envfrom(self, f, *str):
         if milterconfig.get('Syslog') and milterconfig.get('debugLevel') >= 2:
             syslog.syslog("mail from: {0} {1}".format(f, str))
-        self.fp = StringIO.StringIO()
+        self.fp = io.BytesIO()
         self.mailfrom = f
         t = parse_addr(f)
         if len(t) == 2:
@@ -142,13 +143,13 @@ class dkimMilter(Milter.Base):
         elif lname == 'authentication-results':
             self.arheaders.append(val)
         if self.fp:
-            self.fp.write("%s: %s\n" % (name, val))
+            self.fp.write(b"%s: %s\n" % (codecs.encode(name, 'ascii'), codecs.encode(val, 'ascii')))
         return Milter.CONTINUE
 
     @Milter.noreply
     def eoh(self):
         if self.fp:
-            self.fp.write("\n")   # terminate headers
+            self.fp.write(b"\n")   # terminate headers
         self.bodysize = 0
         return Milter.CONTINUE
 
@@ -195,20 +196,20 @@ class dkimMilter(Milter.Base):
             h = authres.AuthenticationResultsHeader(authserv_id=
                                                     self.AuthservID,
                                                     results=self.arresults)
-            h = fold(str(h))
+            h = fold(codecs.encode(str(h), 'ascii'))
             if (milterconfig.get('Syslog') and
                     milterconfig.get('debugLevel') >= 2):
-                syslog.syslog(str(h))
-            name, val = str(h).split(': ', 1)
+                syslog.syslog(codecs.decode(h, 'ascii'))
+            name, val = codecs.decode(h, 'ascii').split(': ', 1)
             self.addheader(name, val, 0)
         return Milter.CONTINUE
 
     def sign_dkim(self, txt):
-        canon = milterconfig.get('Canonicalization')
+        canon = codecs.encode(milterconfig.get('Canonicalization'), 'ascii')
         canonicalize = []
-        if len(canon.split('/')) == 2:
-            canonicalize.append(canon.split('/')[0])
-            canonicalize.append(canon.split('/')[1])
+        if len(canon.split(b'/')) == 2:
+            canonicalize.append(canon.split(b'/')[0])
+            canonicalize.append(canon.split(b'/')[1])
         else:
             canonicalize.append(canon)
             canonicalize.append(canon)
@@ -218,11 +219,12 @@ class dkimMilter(Milter.Base):
         try:
             if privateRSA:
                 d = dkim.DKIM(txt)
-                h = d.sign(milterconfig.get('Selector'), self.fdomain,
-                           privateRSA, canonicalize=(canonicalize[0],
+                h = d.sign(codecs.encode(milterconfig.get('Selector'), 'ascii'), codecs.encode(self.fdomain, 'ascii'),
+                           codecs.encode(privateRSA, 'ascii'),
+                           canonicalize=(canonicalize[0],
                                          canonicalize[1]))
-                name, val = h.split(': ', 1)
-                self.addheader(name, val.strip().replace('\r\n', '\n'), 0)
+                name, val = h.split(b': ', 1)
+                self.addheader(codecs.decode(name, 'ascii'), codecs.decode(val, 'ascii').strip().replace('\r\n', '\n'), 0)
                 if (milterconfig.get('Syslog') and
                     (milterconfig.get('SyslogSuccess')
                      or milterconfig.get('debugLevel') >= 1)):
@@ -233,12 +235,12 @@ class dkimMilter(Milter.Base):
                                                   d.domain.lower()))
             if privateEd25519:
                 d = dkim.DKIM(txt)
-                h = d.sign(milterconfig.get('SelectorEd25519'), self.fdomain,
+                h = d.sign(codecs.encode(milterconfig.get('SelectorEd25519'), 'ascii'), codecs.encode(self.fdomain, 'ascii'),
                            privateEd25519, canonicalize=(canonicalize[0],
                                                          canonicalize[1]),
-                           signature_algorithm='ed25519-sha256')
-                name, val = h.split(': ', 1)
-                self.addheader(name, val.strip().replace('\r\n', '\n'), 0)
+                           signature_algorithm=b'ed25519-sha256')
+                name, val = h.split(b': ', 1)
+                self.addheader(codecs.decode(name, 'ascii'), codecs.decode(val, 'ascii').strip().replace('\r\n', '\n'), 0)
                 if (milterconfig.get('Syslog') and
                     (milterconfig.get('SyslogSuccess')
                      or milterconfig.get('debugLevel') >= 1)):
@@ -266,20 +268,17 @@ class dkimMilter(Milter.Base):
                     res = d.verify(idx=y, dnsfunc=lambda _x: dnsoverride)
                 else:
                     res = d.verify(idx=y)
+                algo = codecs.decode(d.signature_fields.get(b'a'), 'ascii')
                 if res:
-                    if d.signature_fields.get(b'a') == 'ed25519-sha256':
+                    if algo == 'ed25519-sha256':
                         self.dkim_comment = ('Good {0} signature'
-                                             .format(d.signature_fields
-                                                     .get(b'a')))
+                                             .format(algo))
                     else:
                         self.dkim_comment = ('Good {0} bit {1} signature'
-                                             .format(d.keysize,
-                                                     d.signature_fields
-                                                     .get(b'a')))
+                                             .format(d.keysize, algo))
                 else:
                     self.dkim_comment = ('Bad {0} bit {1} signature.'
-                                         .format(d.keysize,
-                                                 d.signature_fields.get(b'a')))
+                                         .format(d.keysize, algo))
             except dkim.DKIMException as x:
                 self.dkim_comment = str(x)
                 if milterconfig.get('Syslog'):
@@ -288,9 +287,9 @@ class dkimMilter(Milter.Base):
                 self.dkim_comment = str(x)
                 if milterconfig.get('Syslog'):
                     syslog.syslog("check_dkim: {0}".format(x))
-            self.header_i = d.signature_fields.get(b'i')
-            self.header_d = d.signature_fields.get(b'd')
-            self.header_a = d.signature_fields.get(b'a')
+            self.header_i = codecs.decode(d.signature_fields.get(b'i'), 'ascii')
+            self.header_d = codecs.decode(d.signature_fields.get(b'd'), 'ascii')
+            self.header_a = codecs.decode(d.signature_fields.get(b'a'), 'ascii')
             if res:
                 if (milterconfig.get('Syslog') and
                         (milterconfig.get('SyslogSuccess') or

dkimpy_milter/__main__.py

@@ -1,4 +1,4 @@
-#!/usr/bin/python2
+#!/usr/bin/python3
 
 from dkimpy_milter import main
 

dkimpy_milter/config.py

@@ -31,13 +31,13 @@ import stat
 import dkim
 import socket
 import ipaddress
-from dnsplug import Session
+from .dnsplug import Session
 
 #  default values
 defaultConfigData = {
     'Syslog': 'yes',
     'SyslogFacility': 'mail',
-    'UMask': 007,
+    'UMask': 0o07,
     'Mode': 'sv',
     'Socket': 'local:/var/run/dkimpy-milter/dkimpy-milter.sock',
     'PidFile': '/var/run/dkimpy-milter/dkimpy-milter.pid',
@@ -85,14 +85,14 @@ class HostsDataset(object):
                 self.item = item[1:]
                 self.negative = True
             try:
-                self.item = ipaddress.ip_address(unicode(self.item, "utf-8"))
+                self.item = ipaddress.ip_address(str(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 = ipaddress.ip_network(str
                                                      (self.item, "utf-8"),
                                                      strict=False)
                     if isinstance(self.item, ipaddress.IPv4Network):
@@ -110,7 +110,7 @@ class HostsDataset(object):
 
     def match(self, connectip):
         '''Check if the connect IP is part of the dataset'''
-        source = ipaddress.ip_address(unicode(connectip, "utf-8"))
+        source = ipaddress.ip_address(str(connectip, "utf-8"))
         for item in self.dataset:
             if item.isdomain or item.ishostname:
                 result = self.matchname(source)   # Match host/domains first
@@ -160,13 +160,13 @@ class HostsDataset(object):
             if isinstance(source, ipaddress.IPv4Address):
                 ips = s.dns(name, 'A')
                 for ip in ips:
-                    ip = ipaddress.IPv4Address(unicode(ip, 'UTF-8'))
+                    ip = ipaddress.IPv4Address(str(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'))
+                    ip = ipaddress.IPv6Address(str(ip, 'UTF-8'))
                 if ip == source:
                     results.append(name)
         return results
@@ -225,13 +225,13 @@ def _processConfigFile(filename=None, configdata=None, useSyslog=1,
     '''Load the specified config file, exit and log errors if it fails,
     otherwise return a config dictionary.'''
 
-    import config
+    from . import config
     if configdata is None:
         configdata = config.defaultConfigData
     if filename is not None:
         try:
             _readConfigFile(filename, configdata)
-        except Exception, e:
+        except Exception as e:
             raise
             if useSyslog:
                 syslog.syslog(e.args[0])
@@ -342,7 +342,7 @@ def _readConfigFile(path, configData=None, configGlobal={}):
     #  check to see if it's a file
     try:
         mode = os.stat(path)[0]
-    except OSError, e:
+    except OSError as e:
         syslog.syslog(syslog.LOG_ERR, 'ERROR stating "%s": %s'
                       % (path, e.strerror))
         return(configData)

dkimpy_milter/dnsplug.py

@@ -84,7 +84,7 @@ class Session(object):
             raise DNSError('Length of CNAME chain exceeds %d' % MAX_CNAME)
         cnames[name] = cname
         if cname in cnames:
-            raise DNSError, 'CNAME loop'
+            raise DNSError('CNAME loop')
         result = self.dns(cname, qtype, cnames=cnames)
     return result
 
@@ -103,16 +103,16 @@ def DNSLookup_pydns(name, qtype, tcpfallback=True, timeout=30):
         #
         if resp.header['tc'] == True:
           if not tcpfallback:
-              raise DNS.DNSError, 'DNS: Truncated UDP Reply, SPF records should fit in a UDP packet'
+              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)
+          except DNS.DNSError as 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)
+    except IOError as x:
+        raise DNS.DNSError('DNS: ' + str(x))
 
 def DNSLookup_dnspython(name,qtype,tcpfallback=True,timeout=30):
   retVal = []
@@ -164,5 +164,5 @@ 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)
+    print(n,t)
+    print(s.dns(n,t))

setup.py

@@ -1,4 +1,4 @@
-#! /usr/bin/python
+#! /usr/bin/python3
 # dkimpy-milter: A DKIM signing/verification Milter application
 # Author: Scott Kitterman <scott@kitterman.com>
 # Copyright 2018 Scott Kitterman
@@ -24,9 +24,9 @@ description = "Domain Keys Identified Mail (DKIM) signing/verifying milter for P
 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', 'dnspython']
+    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'dnspython']
 except ImportError:  # If PyDNS is not installed, prefer dnspython
-    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'ipaddress', 'PyDNS']
+    kw['install_requires'] = ['dkimpy>=0.7', 'pymilter', 'authres>=1.1.0', 'PyNaCl', 'PyDNS']
 
 setup(
     name='dkimpy-milter',
@@ -43,7 +43,7 @@ setup(
         'License :: OSI Approved :: GNU General Public License (GPL)',
         'Natural Language :: English',
         'Operating System :: POSIX',
-        'Programming Language :: Python :: 2 :: Only',
+        'Programming Language :: Python :: 3 :: Only',
         'Topic :: Communications :: Email :: Mail Transport Agents',
         'Topic :: Communications :: Email :: Filters',
         'Topic :: Security',

tests/dkimpy-milter

@@ -1,2 +1,2 @@
 #!/bin/sh
-python2 -m dkimpy_milter "$@"
+python3 -m dkimpy_milter "$@"