Class for parsing and evaluating RFC 5280 NameConstraints.

net/data/name_constraints_unittest/generate_name_constraints.py

Index: net/data/name_constraints_unittest/generate_name_constraints.py
diff --git a/net/data/name_constraints_unittest/generate_name_constraints.py b/net/data/name_constraints_unittest/generate_name_constraints.py
new file mode 100755
index 0000000000000000000000000000000000000000..5f9fa4d7d7ad3c8b5196fea0b29962cddb4ceafc
--- /dev/null
+++ b/net/data/name_constraints_unittest/generate_name_constraints.py
@@ -0,0 +1,533 @@
+#!/usr/bin/env python
+# Copyright 2015 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import base64
+import copy
+import os
+import random
+import subprocess
+import sys
+import tempfile
+
+sys.path += [os.path.join('..', 'verify_name_match_unittest', 'scripts')]
+
+import generate_names
+
+
+def generate(s, out_fn):
+  conf_tempfile = tempfile.NamedTemporaryFile()
+  conf_tempfile.write(str(s))
+  conf_tempfile.flush()
+  der_tmpfile = tempfile.NamedTemporaryFile()
+  description_tmpfile = tempfile.NamedTemporaryFile()
+  subprocess.check_call(['openssl', 'asn1parse', '-genconf', conf_tempfile.name,
+                         '-i', '-out', der_tmpfile.name],
+                        stdout=description_tmpfile)
+  conf_tempfile.close()
+
+  output_file = open(out_fn, 'w')
+  description_tmpfile.seek(0)
+  output_file.write(description_tmpfile.read())
+  output_file.write('-----BEGIN %s-----\n' % s.token())
+  output_file.write(base64.encodestring(der_tmpfile.read()))
+  output_file.write('-----END %s-----\n' % s.token())
+  output_file.close()
+
+
+class SubjectAltNameGenerator:
+  def __init__(self):
+    self.names = []
+
+  def token(self):
+    return "SUBJECT ALTERNATIVE NAME"
+
+  def add_name(self, general_name):
+    self.names.append(general_name)
+
+  def __str__(self):
+    s = "asn1 = OCTWRAP,SEQUENCE:subjectAltNameSequence\n"
+    s += "[subjectAltNameSequence]\n"
+    s_suffix = ""
+    for n, name in enumerate(self.names):
+      n1, n2 = (str(name) + '\n').split('\n', 1)
+      if n2:
+        s_suffix += n2 + '\n'
+      s += '%s%s\n' % (n, n1)
+
+    return s + s_suffix
+
+
+class NameConstraintsGenerator:
+  def __init__(self,
+               force_permitted_sequence=False,
+               force_excluded_sequence=False):
+    self.permitted = []
+    self.excluded = []
+    self.force_permitted_sequence = force_permitted_sequence
+    self.force_excluded_sequence = force_excluded_sequence
+
+  def token(self):
+    return "NAME CONSTRAINTS"
+
+  def union_from(self, c):
+    self.permitted.extend(c.permitted)
+    self.excluded.extend(c.excluded)
+
+  def add_permitted(self, general_name):
+    self.permitted.append(general_name)
+
+  def add_excluded(self, general_name):
+    self.excluded.append(general_name)
+
+  def __str__(self):
+    s = "asn1 = SEQUENCE:nameConstraintsSequence\n[nameConstraintsSequence]\n"
+
+    if self.permitted or self.force_permitted_sequence:
+      s += "permittedSubtrees = IMPLICIT:0,SEQUENCE:permittedSubtreesSequence\n"
+    if self.excluded or self.force_excluded_sequence:
+      s += "excludedSubtrees = IMPLICIT:1,SEQUENCE:excludedSubtreesSequence\n"
+
+    if self.permitted or self.force_permitted_sequence:
+      s += "[permittedSubtreesSequence]\n"
+      for n, subtree in enumerate(self.permitted):
+        s += 'subtree%i = SEQUENCE:permittedSubtree%i\n' % (n, n)
+
+    if self.excluded or self.force_excluded_sequence:
+      s += "[excludedSubtreesSequence]\n"
+      for n, subtree in enumerate(self.excluded):
+        s += 'subtree%i = SEQUENCE:excludedSubtree%i\n' % (n, n)
+
+    for n, subtree in enumerate(self.permitted):
+      s += '[permittedSubtree%i]\n%s\n' % (n, subtree)
+
+    for n, subtree in enumerate(self.excluded):
+      s += '[excludedSubtree%i]\n%s\n' % (n, subtree)
+
+    return s
+
+
+def other_name():
+  i = random.randint(0, sys.maxint)
+  s = 'otherName = IMPLICIT:0,SEQUENCE:otherNameSequence%i\n' % i
+  s += '[otherNameSequence%i]\n' % i
+  s += 'type_id = OID:1.2.3.4.5\n'
+  s += 'value = FORMAT:HEX,OCTETSTRING:DEADBEEF\n'
+  return s
+
+
+def rfc822_name(name):
+  return 'rfc822Name = IMPLICIT:1,IA5STRING:' + name
+
+
+def dns_name(name):
+  return 'dNSName = IMPLICIT:2,IA5STRING:' + name
+
+
+def x400_address():
+  i = random.randint(0, sys.maxint)
+  s = 'x400Address = IMPLICIT:3,SEQUENCE:x400AddressSequence%i\n' % i
+  s += '[x400AddressSequence%i]\n' % i
+  s += 'builtinstandardattributes = SEQUENCE:BuiltInStandardAttributes%i\n' % i
+  s += '[BuiltInStandardAttributes%i]\n' % i
+  s += 'countryname = EXPLICIT:1A,PRINTABLESTRING:US\n'
+  return s
+
+
+def directory_name(name):
+  return str(name).replace(
+      'asn1 = SEQUENCE', 'directoryName = IMPLICIT:4,SEQUENCE')
+
+
+def edi_party_name():
+  i = random.randint(0, sys.maxint)
+  s = 'ediPartyName = IMPLICIT:5,SEQUENCE:ediPartyNameSequence%i\n' % i
+  s += '[ediPartyNameSequence%i]\n' % i
+  s += 'partyName = IMPLICIT:1,UTF8:foo\n'
+  return s
+
+
+def uniform_resource_identifier(name):
+  return 'uniformResourceIdentifier = IMPLICIT:6,IA5STRING:' + name
+
+
+def ip_address(addr, enforce_length=True):
+  if enforce_length:
+    assert len(addr) in (4,16)
+  addr_str = ""
+  for addr_byte in addr:
+    addr_str += '%02X'%(addr_byte)
+  return 'iPAddress = IMPLICIT:7,FORMAT:HEX,OCTETSTRING:' + addr_str
+
+
+def ip_address_range(addr, netmask, enforce_length=True):
+  if enforce_length:
+    assert len(addr) == len(netmask)
+    assert len(addr) in (4,16)
+  addr_str = ""
+  netmask_str = ""
+  for addr_byte, mask_byte in map(None, addr, netmask):
+    assert (addr_byte & ~mask_byte) == 0
+    addr_str += '%02X'%(addr_byte)
+    netmask_str += '%02X'%(mask_byte)
+  return ('iPAddress = IMPLICIT:7,FORMAT:HEX,OCTETSTRING:' + addr_str +
+          netmask_str)
+
+
+def registered_id(oid):
+  return 'registeredID = IMPLICIT:8,OID:' + oid
+
+
+def with_min_max(val, minimum=None, maximum=None):
+  s = val
+  s += '\n'
+  assert '\n[' not in s
+  if minimum is not None:
+    s += 'minimum = IMPLICIT:0,INTEGER:%i\n' % minimum
+  if maximum is not None:
+    s += 'maximum = IMPLICIT:1,INTEGER:%i\n' % maximum
+  return s
+
+
+def main():
+  dnsname_constraints = NameConstraintsGenerator()
+  dnsname_constraints.add_permitted(dns_name("permitted.example.com"))
+  dnsname_constraints.add_permitted(dns_name("permitted.example2.com"))
+  dnsname_constraints.add_permitted(dns_name("permitted.example3.com."))
+  dnsname_constraints.add_permitted(dns_name("alsopermitted.example.com"))
+  dnsname_constraints.add_excluded(dns_name("excluded.permitted.example.com"))
+  dnsname_constraints.add_permitted(
+      dns_name("stillnotpermitted.excluded.permitted.example.com"))
+  dnsname_constraints.add_excluded(dns_name("extraneousexclusion.example.com"))
+  generate(dnsname_constraints, "dnsname.pem")
+
+  dnsname_constraints2 = NameConstraintsGenerator()
+  dnsname_constraints2.add_permitted(dns_name("com"))
+  dnsname_constraints2.add_excluded(dns_name("foo.bar.com"))
+  generate(dnsname_constraints2, "dnsname2.pem")
+
+  dnsname_constraints3 = NameConstraintsGenerator()
+  dnsname_constraints3.add_permitted(dns_name(".bar.com"))
+  generate(dnsname_constraints3, "dnsname-permitted_with_leading_dot.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_excluded(dns_name("excluded.permitted.example.com"))
+  generate(c, "dnsname-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(dns_name("permitted.example.com"))
+  c.add_excluded(dns_name(""))
+  generate(c, "dnsname-excludeall.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(dns_name("permitted.example.com"))
+  c.add_excluded(dns_name("."))
+  generate(c, "dnsname-exclude_dot.pem")
+
+  ipaddress_constraints = NameConstraintsGenerator()
+  ipaddress_constraints.add_permitted(
+      ip_address_range((192,168,0,0),(255,255,0,0)))
+  ipaddress_constraints.add_excluded(
+      ip_address_range((192,168,5,0),(255,255,255,0)))
+  ipaddress_constraints.add_permitted(
+      ip_address_range((192,168,5,32),(255,255,255,224)))
+  ipaddress_constraints.add_permitted(
+      ip_address_range((192,167,5,32),(255,255,255,224)))
+  ipaddress_constraints.add_excluded(
+      ip_address_range((192,166,5,32),(255,255,255,224)))
+  ipaddress_constraints.add_permitted(ip_address_range(
+      (1,2,3,4,5,6,7,8,9,10,11,12,0,0,0,0),
+      (255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0)))
+  ipaddress_constraints.add_excluded(ip_address_range(
+      (1,2,3,4,5,6,7,8,9,10,11,12,5,0,0,0),
+      (255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0)))
+  ipaddress_constraints.add_permitted(ip_address_range(
+      (1,2,3,4,5,6,7,8,9,10,11,12,5,32,0,0),
+      (255,255,255,255,255,255,255,255,255,255,255,255,255,224,0,0)))
+  ipaddress_constraints.add_permitted(ip_address_range(
+      (1,2,3,4,5,6,7,8,9,10,11,11,5,32,0,0),
+      (255,255,255,255,255,255,255,255,255,255,255,255,255,224,0,0)))
+  ipaddress_constraints.add_excluded(ip_address_range(
+      (1,2,3,4,5,6,7,8,9,10,11,10,5,32,0,0),
+      (255,255,255,255,255,255,255,255,255,255,255,255,255,224,0,0)))
+  generate(ipaddress_constraints, "ipaddress.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,1,3),(255,255,255,255)))
+  generate(c, "ipaddress-permit_singlehost.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((0,0,0,0),(0,0,0,0)))
+  generate(c, "ipaddress-permit_all.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((0x80,0,0,0),(0x80,0,0,0)))
+  generate(c, "ipaddress-permit_prefix1.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,1,2),(255,255,255,254)))
+  generate(c, "ipaddress-permit_prefix31.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,1,0),(255,255,255,253)))
+  generate(c, "ipaddress-invalid_mask_not_contiguous_1.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,0,0),(255,253,0,0)))
+  generate(c, "ipaddress-invalid_mask_not_contiguous_2.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((0,0,0,0),(0x40,0,0,0)))
+  generate(c, "ipaddress-invalid_mask_not_contiguous_3.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,0,0,0),(0xFF,0,0xFF,0)))
+  generate(c, "ipaddress-invalid_mask_not_contiguous_4.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_excluded(ip_address_range((192,168,5,0),(255,255,255,0)))
+  generate(c, "ipaddress-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,0,0),(255,255,0,0)))
+  c.add_permitted(ip_address_range((1,2,3,4,5,6,7,8,9,10,11,12,0,0,0,0),
+                                 (255,255,255,255,255,255,255,255,
+                                  255,255,255,255,0,0,0,0)))
+  c.add_excluded(ip_address_range((0,0,0,0),(0,0,0,0)))
+  c.add_excluded(ip_address_range((0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0),
+                                (0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0)))
+  generate(c, "ipaddress-excludeall.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(ip_address_range((192,168,0,0),(255,255,255,0)))
+  c.add_permitted(ip_address_range((192,168,5,0,0),(255,255,255,0,0),
+                                 enforce_length=False))
+  generate(c, "ipaddress-invalid_addr.pem")
+
+  n_us = generate_names.NameGenerator()
+  n_us.add_rdn().add_attr('countryName', 'PRINTABLESTRING', 'US')
+  generate(n_us, "name-us.pem")
+  n_us_az = copy.deepcopy(n_us)
+  n_us_az.add_rdn().add_attr('stateOrProvinceName', 'UTF8', 'Arizona')
+  generate(n_us_az, "name-us-arizona.pem")
+  n_us_ca = copy.deepcopy(n_us)
+  n_us_ca.add_rdn().add_attr('stateOrProvinceName', 'UTF8', 'California')
+  generate(n_us_ca, "name-us-california.pem")
+  n_us_ca_mountain_view = copy.deepcopy(n_us_ca)
+  n_us_ca_mountain_view.add_rdn().add_attr(
+      'localityName', 'UTF8', 'Mountain View')
+  generate(n_us_ca_mountain_view, "name-us-california-mountain_view.pem")
+
+  n_jp = generate_names.NameGenerator()
+  n_jp.add_rdn().add_attr('countryName', 'PRINTABLESTRING', 'JP')
+  generate(n_jp, "name-jp.pem")
+  n_jp_tokyo = copy.deepcopy(n_jp)
+  n_jp_tokyo.add_rdn().add_attr(
+      'stateOrProvinceName', 'UTF8', '\xe6\x9d\xb1\xe4\xba\xac', 'FORMAT:UTF8')
+  generate(n_jp_tokyo, "name-jp-tokyo.pem")
+
+  n_us_az_foodotcom = copy.deepcopy(n_us_az)
+  n_us_az_foodotcom.add_rdn().add_attr('commonName', 'UTF8', 'foo.com')
+  generate(n_us_az_foodotcom, "name-us-arizona-foo.com.pem")
+
+  n_us_az_permittedexamplecom = copy.deepcopy(n_us_az)
+  n_us_az_permittedexamplecom.add_rdn().add_attr('commonName', 'UTF8',
+                                                 'permitted.example.com')
+  generate(n_us_az_permittedexamplecom,
+           "name-us-arizona-permitted.example.com.pem")
+
+  n_us_ca_permittedexamplecom = copy.deepcopy(n_us_ca)
+  n_us_ca_permittedexamplecom.add_rdn().add_attr('commonName', 'UTF8',
+                                                 'permitted.example.com')
+  generate(n_us_ca_permittedexamplecom,
+           "name-us-california-permitted.example.com.pem")
+
+  n_us_az_ip1111 = copy.deepcopy(n_us_az)
+  n_us_az_ip1111.add_rdn().add_attr('commonName', 'UTF8', '1.1.1.1')
+  generate(n_us_az_ip1111, "name-us-arizona-1.1.1.1.pem")
+
+  n_us_az_192_168_1_1 = copy.deepcopy(n_us_az)
+  n_us_az_192_168_1_1.add_rdn().add_attr('commonName', 'UTF8', '192.168.1.1')
+  generate(n_us_az_192_168_1_1, "name-us-arizona-192.168.1.1.pem")
+
+  n_us_az_ipv6 = copy.deepcopy(n_us_az)
+  n_us_az_ipv6.add_rdn().add_attr('commonName', 'UTF8',
+                                  '102:304:506:708:90a:b0c::1')
+  generate(n_us_az_ipv6, "name-us-arizona-ipv6.pem")
+
+  n_us_ca_192_168_1_1 = copy.deepcopy(n_us_ca)
+  n_us_ca_192_168_1_1.add_rdn().add_attr('commonName', 'UTF8', '192.168.1.1')
+  generate(n_us_ca_192_168_1_1, "name-us-california-192.168.1.1.pem")
+
+  n_us_az_email = copy.deepcopy(n_us_az)
+  n_us_az_email.add_rdn().add_attr('emailAddress', 'IA5STRING',
+                                   'bar@example.com')
+  generate(n_us_az_email, "name-us-arizona-email.pem")
+
+  n_ca = generate_names.NameGenerator()
+  n_ca.add_rdn().add_attr('countryName', 'PRINTABLESTRING', 'CA')
+  generate(n_ca, "name-ca.pem")
+
+  n_de = generate_names.NameGenerator()
+  n_de.add_rdn().add_attr('countryName', 'PRINTABLESTRING', 'DE')
+  generate(n_de, "name-de.pem")
+
+  n_empty = generate_names.NameGenerator()
+  generate(n_empty, "name-empty.pem")
+
+
+  directoryname_constraints = NameConstraintsGenerator()
+  directoryname_constraints.add_permitted(directory_name(n_us))
+  directoryname_constraints.add_excluded(directory_name(n_us_ca))
+  directoryname_constraints.add_permitted(directory_name(n_us_ca_mountain_view))
+  directoryname_constraints.add_excluded(directory_name(n_de))
+  directoryname_constraints.add_permitted(directory_name(n_jp_tokyo))
+  generate(directoryname_constraints, "directoryname.pem")
+
+  c = NameConstraintsGenerator()
+  c.union_from(directoryname_constraints)
+  c.union_from(dnsname_constraints)
+  generate(c, "directoryname_and_dnsname.pem")
+
+  c = NameConstraintsGenerator()
+  c.union_from(directoryname_constraints)
+  c.union_from(dnsname_constraints)
+  c.union_from(ipaddress_constraints)
+  generate(c, "directoryname_and_dnsname_and_ipaddress.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_excluded(directory_name(n_us_ca))
+  generate(c, "directoryname-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(directory_name(n_us))
+  c.add_excluded(directory_name(n_empty))
+  generate(c, "directoryname-excludeall.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(dns_name("permitted.example.com"))
+  san.add_name(ip_address((192,168,1,2)))
+  san.add_name(directory_name(n_us_az))
+  generate(san, "san-permitted.pem")
+
+  san2 = copy.deepcopy(san)
+  san2.add_name(
+      dns_name("foo.stillnotpermitted.excluded.permitted.example.com"))
+  generate(san2, "san-excluded-dnsname.pem")
+
+  san2 = copy.deepcopy(san)
+  san2.add_name(ip_address((192,168,5,5)))
+  generate(san2, "san-excluded-ipaddress.pem")
+
+  san2 = copy.deepcopy(san)
+  san2.add_name(directory_name(n_us_ca_mountain_view))
+  generate(san2, "san-excluded-directoryname.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(other_name())
+  generate(san, "san-othername.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(rfc822_name("foo@example.com"))
+  generate(san, "san-rfc822name.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(x400_address())
+  generate(san, "san-x400address.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(edi_party_name())
+  generate(san, "san-edipartyname.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(uniform_resource_identifier('http://example.com'))
+  generate(san, "san-uri.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(registered_id("1.2.3.4"))
+  generate(san, "san-registeredid.pem")
+
+  san = SubjectAltNameGenerator()
+  generate(san, "san-invalid-empty.pem")
+
+  san = SubjectAltNameGenerator()
+  san.add_name(ip_address((192,168,0,5,0), enforce_length=False))
+  generate(san, "san-invalid-ipaddress.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(other_name())
+  generate(c, "othername-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(other_name())
+  generate(c, "othername-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(rfc822_name("foo@example.com"))
+  generate(c, "rfc822name-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(rfc822_name("foo@example.com"))
+  generate(c, "rfc822name-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(x400_address())
+  generate(c, "x400address-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(x400_address())
+  generate(c, "x400address-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(edi_party_name())
+  generate(c, "edipartyname-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(edi_party_name())
+  generate(c, "edipartyname-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(uniform_resource_identifier("http://example.com"))
+  generate(c, "uri-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(uniform_resource_identifier("http://example.com"))
+  generate(c, "uri-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(registered_id("1.2.3.4"))
+  generate(c, "registeredid-permitted.pem")
+  c = NameConstraintsGenerator()
+  c.add_excluded(registered_id("1.2.3.4"))
+  generate(c, "registeredid-excluded.pem")
+
+  c = NameConstraintsGenerator()
+  generate(c, "invalid-no_subtrees.pem")
+
+  c = NameConstraintsGenerator(force_permitted_sequence=True)
+  generate(c, "invalid-empty_permitted_subtree.pem")
+
+  c = NameConstraintsGenerator(force_excluded_sequence=True)
+  generate(c, "invalid-empty_excluded_subtree.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(with_min_max(dns_name("permitted.example.com"), minimum=0))
+  generate(c, "dnsname-with_min_0.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(with_min_max(dns_name("permitted.example.com"), minimum=1))
+  generate(c, "dnsname-with_min_1.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(with_min_max(
+      dns_name("permitted.example.com"), minimum=0, maximum=2))
+  generate(c, "dnsname-with_min_0_and_max.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(with_min_max(
+      dns_name("permitted.example.com"), minimum=1, maximum=2))
+  generate(c, "dnsname-with_min_1_and_max.pem")
+
+  c = NameConstraintsGenerator()
+  c.add_permitted(with_min_max(dns_name("permitted.example.com"), maximum=2))
+  generate(c, "dnsname-with_max.pem")
+
+
+if __name__ == '__main__':
+  main()