Turn the exception into a warning

This allows for handling of disappeared/expired root certificates which
might still be a dependency for a present cross signed certificate

.gitignore

@@ -1 +1,2 @@
 *.sw?
+__pycache__

sort_certificate.py

@@ -176,7 +176,15 @@ def find_root(x509_objects, root_issuers):
     '''
     Find a suitable anchor by finding the intermediate that was signed by root
     '''
-    root_cert = root_issuers[str(x509_objects[-1].get_issuer())]
+    root_cert = None
+    for x509_object in reversed(x509_objects):
+        if str(x509_object.get_issuer()) in root_issuers:
+            root_cert = root_issuers[str(x509_object.get_issuer())]
+            break
+    if not root_cert:
+        raise CertificateComponentException('Unable to find a suitable '
+                                            'trusted root certificate '
+                                            'for bundle')
     logging.debug('Retrieved root certificate %s', root_cert.get_subject())
     return root_cert
 
@@ -187,17 +195,21 @@ def find_intermediate_root(x509_objects, root_issuers):
     '''
 
     # Some intermediates have the *same* subject as some root certificates.
-    # blacklist them
-    # XXX better use pubkey/hash for that, but can't find the appropriate
-    # interface to that at the moment
+    # blacklist them if their issuer and subject name is present in the root
+    # bundle
     excluded_issuers = [str(x.get_subject()) for x in x509_objects
-                        if x.get_subject() != x.get_issuer()]
+                        if x.get_subject() != x.get_issuer()
+                        and str(x.get_issuer()) in root_issuers
+                        and str(x.get_subject()) in root_issuers]
 
     logging.debug('Known root issuers\n\t%s', '\n\t'.join(root_issuers))
     logging.debug('Excluding issuers because of potential intermediates\n\t%s',
                   '\n\t'.join(excluded_issuers))
-    logging.debug('issuers seen in data\n\t%s',
-                  '\n\t'.join([str(x.get_issuer()) for x in x509_objects]))
+    logging.debug('Certificates seen in data\n\t%s',
+                  '\n\t'.join([f'Subject: {x.get_subject()},'
+                               f' Issuer: {x.get_issuer()}'
+                               for x in x509_objects]))
+
     return [x for x in x509_objects
             if str(x.get_issuer()) in root_issuers
             and str(x.get_issuer()) not in excluded_issuers]
@@ -214,15 +226,14 @@ def order_x509(x509_objects, root_issuers):
         logging.warning('Found self signed (root) certificate %s in input',
                         str(root_crt.get_subject()))
         # Double check if our self signed root certificate is not also present
-        # as an intermediate:
-        # - It is probably invalid input, and doesn't make sense
-        # - It confuses the ordering process
+        # as an cross signed intermediate:
+        # - It might confuse the ordering process
         if next((x for x in x509_objects
                  if x.get_subject() != x.get_issuer()
                  and x.get_subject() == root_crt.get_subject()), None):
-            raise CertificateComponentException('Both present as intermediate '
-                                                'and root certificate: %s' %
-                                                str(root_crt.get_subject()))
+            logging.warning('Both present as intermediate '
+                            'and root certificate: %s' %
+                            str(root_crt.get_subject()))
     else:
         # Get intermediate cert signed by any root from bundle as anchor, and
         # make that our root
@@ -248,11 +259,24 @@ def order_x509(x509_objects, root_issuers):
     while x509_objects:
         sibling = [x for x in x509_objects
                    if x.get_issuer() == bundle[0].get_subject()]
+        parent = [x for x in x509_objects
+                  if x.get_subject() == bundle[-1].get_issuer()]
         if sibling and len(sibling) == 1:
             # insert sibling at beginning of list
             bundle.insert(0, x509_objects.pop(x509_objects.index(sibling[0])))
+        elif parent and len(parent) == 1:
+            # Try to place a (cross signed) intermediate at the end if it matches
+            bundle.append(x509_objects.pop(x509_objects.index(parent[0])))
         else:
             # Lets complain
+            logging.error('Certificates remaining data\n\t%s',
+                          '\n\t'.join([f'Subject: {x.get_subject()},'
+                                       f' Issuer: {x.get_issuer()}'
+                                       for x in x509_objects]))
+            logging.error('Certificates placed in bundle \n\t%s',
+                          '\n\t'.join([f'Subject: {x.get_subject()},'
+                                       f' Issuer: {x.get_issuer()}'
+                                       for x in bundle]))
             raise CertificateComponentException('Non matching certificates in '
                                                 'input:'
                                                 ' No sibling found for %s'
@@ -294,7 +318,8 @@ def load_root_issuers():
                 continue
 
         root_issuers = {str(root_cert.get_subject()): root_cert
-                        for root_cert in root_certs}
+                        for root_cert in root_certs
+                        if not root_cert.has_expired()}
         return root_issuers