Migrate from pyOpenSSL to cryptography

pyOpenSSL upstream "strongly suggests" switching to cryptography.

959a031fa3

Resolves #52

requirements.txt

@@ -1,5 +1,5 @@
 pycurl
-pyOpenSSL
+cryptography
 rpkg
 six
 GitPython

src/centpkg/centos_cert.py

@@ -1,8 +1,7 @@
-
 from __future__ import print_function
 
 import os
-from OpenSSL import crypto
+from cryptography import x509
 import urlgrabber
 import datetime
 
@@ -23,8 +22,13 @@ def _open_cert():
     if not os.access(cert_file, os.R_OK):
         raise centos_cert_error("""!!!    cannot read your centos cert file   !!!
 !!! Ensure the file is readable and try again !!!""")
-    raw_cert = open(cert_file).read()
-    my_cert = crypto.load_certificate(crypto.FILETYPE_PEM, raw_cert)
+    raw_cert = open(cert_file, 'rb').read()
+    try:
+        my_cert = x509.load_pem_x509_certificate(raw_cert)
+    except TypeError:
+        # it was required to specify a backend prior to cryptography 3.1
+        from cryptography.hazmat.backends import default_backend
+        my_cert = x509.load_pem_x509_certificate(raw_cert, default_backend())
     return my_cert
 
 def verify_cert():
@@ -35,17 +39,13 @@ def verify_cert():
     Expiry time warn if less than 21 days
     """
     my_cert = _open_cert()
-    serial_no = my_cert.get_serial_number()
-    valid_until = my_cert.get_notAfter()[:8]
     # CRL verification would go here
     #crl = urlgrabber.urlread("https://<url_to_crl>/ca/crl.pem")
-    dateFmt = '%Y%m%d'
-    delta = datetime.datetime.now() + datetime.timedelta(days=21)
-    warn = datetime.datetime.strftime(delta, dateFmt)
+    warn = datetime.datetime.now() + datetime.timedelta(days=21)
 
-    print('cert expires: %s-%s-%s' % (valid_until[:4], valid_until[4:6], valid_until[6:8]))
+    print(my_cert.not_valid_after.strftime('cert expires: %Y-%m-%d'))
 
-    if valid_until < warn:
+    if my_cert.not_valid_after < warn:
         print('WARNING: Your cert expires soon.')
 
 
@@ -57,10 +57,8 @@ def certificate_expired():
     """
     my_cert = _open_cert()
 
-    if my_cert.has_expired():
-        return True
-    else:
-        return False
+    return my_cert.not_valid_after < datetime.datetime.now()
+
 
 def read_user_cert():
     """
@@ -69,9 +67,5 @@ def read_user_cert():
     """
     my_cert = _open_cert()
 
-    subject = str(my_cert.get_subject())
-    subject_line = subject.split("CN=")
-    cn_parts = subject_line[1].split("/")
-    username = cn_parts[0]
-    return username
-
+    [common_name] = my_cert.subject.get_attributes_for_oid(x509.oid.NameOID.COMMON_NAME)
+    return common_name.value