Convert tests that parse a BasicConstraints value to instead

net/data/parse_certificate_unittest/regenerate_pem_from_ascii.py

+#!/usr/bin/python
+# Copyright (c) 2016 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.
+
+"""
+Given a path to a XXX.pem file, re-generates a CERTIFICATE.
+
+The .pem file is expected to contain comments that resemble:
+
+#-----BEGIN XXX-----
+<ascii-der values in here>
+#-----END XXX-----
+
+These are interpreted as substitutions to make inside of the Certificate
+template (v3_certificate_template.txt)
+"""
+
+import sys
+import os
+import re
+import base64
+import subprocess
+
+
+def read_file_to_string(path):
+  """Reads a file entirely to a string"""
+  with open(path, 'r') as f:
+    return f.read()
+
+
+def write_string_to_file(data, path):
+  """Writes a string to a file"""
+  print "Writing file %s ..." % (path)
+  with open(path, "w") as f:
+    f.write(data)
+
+
+def replace_string(original, start, end, replacement):
+  """Replaces the specified range of |original| with |replacement|"""
+  return original[0:start] + replacement + original[end:]
+
+
+def apply_substitution(template, name, value):
+  """Finds a section named |name| in |template| and replaces it with |value|."""
+  # Find the section |name| in |template|.
+  regex = re.compile(r'#-----BEGIN %s-----(.*?)#-----END %s-----' %
+                    (re.escape(name), re.escape(name)), re.DOTALL)
+  m = regex.search(template)
+  if not m:
+    print "Couldn't find a section named %s in the template" % (name)
+    sys.exit(1)
+
+  return replace_string(template, m.start(1), m.end(1), value)
+
+
+def main():
+  if len(sys.argv) != 2:
+    print 'Usage: %s <PATH_TO_PEM>' % (sys.argv[0])
+    sys.exit(1)
+
+  pem_path = sys.argv[1]
+  orig = read_file_to_string(pem_path)
+
+  cert_ascii = read_file_to_string("v3_certificate_template.txt")
+
+  # Apply all substitutions described by comments in |orig|
+  regex = re.compile(r'#-----BEGIN ([\w ]+)-----(.*?)#-----END \1-----',
+                     re.DOTALL)
+  num_matches = 0
+  for m in regex.finditer(orig):
+    num_matches += 1
+    cert_ascii = apply_substitution(cert_ascii, m.group(1), m.group(2))
+
+  if num_matches == 0:
+    print "Input did not contain any substitutions"
+    sys.exit(1)
+
+  # Convert the ascii-der to actual DER binary.
+  cert_der = None
+  try:
+    p = subprocess.Popen(['ascii2der'], stdout=subprocess.PIPE,
+                         stdin=subprocess.PIPE, stderr=subprocess.STDOUT)
+    cert_der = p.communicate(input=cert_ascii)[0]
+  except OSError as e:
+    print ('ERROR: Failed executing ascii2der.\n'
+           'Make sure this is in your path\n'
+           'Obtain it from https://github.com/google/der-ascii')
+    sys.exit(1)
+
+  # Replace the CERTIFICATE block with the newly generated one.
+  regex = re.compile(r'-----BEGIN CERTIFICATE-----\n(.*?)\n'
+                     '-----END CERTIFICATE-----', re.DOTALL)
+  m = regex.search(orig)
+  if not m:
+    print "ERROR: Cannot find CERTIFICATE block in input"
+    sys.exit(1)
+  modified = replace_string(orig, m.start(1), m.end(1),
+                            base64.b64encode(cert_der))
+
+  # Write back the .pem file.
+  write_string_to_file(modified, pem_path)
+
+main()