isofy: Add prefix parameter (revision 3)

src/cnaas_nms/tools/jinja_filters.py

@@ -1,4 +1,5 @@
 import ipaddress
+import re
 
 
 def increment_ip(ip_string, increment=1):
@@ -29,40 +30,42 @@ def increment_ip(ip_string, increment=1):
         return format(ip + increment)
 
 
-def isofy_ipv4(ip_string, octets=7):
+def isofy_ipv4(ip_string, prefix=''):
     """Transform IPv4 address so it can be used as an ISO/NET address.
     All four blocks of the IP address are padded with zeros and split up into double octets.
     Example: 10.255.255.1 -> 0102.5525.5001.00
     Args:
         ip_string: a valid IPv4 address
-        octets: number of octets to return (default: 7)
+        prefix: optional prefix to be used
     Returns:
-        Last n octets of an ISO address
+        ISO address
     """
     ipaddress.IPv4Address(ip_string)  # fails for invalid IP
-    # split + pad IP
+
+    if prefix != '':
+        prefix_valid = bool(re.match('^.{2}(\..{4})*?$', prefix))
+        if not prefix_valid:
+            raise ValueError(f"{prefix} cannot be used as ISO prefix, please check formatting")
+        prefix += '.'
+
     ip_parts = ip_string.split('.')
     padded = [p.zfill(3) for p in ip_parts]
     joined = ''.join(padded)
-    # make octets
+
     chunksize = 2
-    chunks = [joined[i : i + chunksize] for i in range(0, len(joined), chunksize)]
-    chunks += ['00']
+    ip_octets = [joined[i : i + chunksize] for i in range(0, len(joined), chunksize)]
+    ip_octets += ['00']
 
-    missing_octets = octets - len(chunks)
-    if missing_octets < 0:
-        raise ValueError(f"IP Address {ip_string} cannot be represented in {octets} octets")
-    else:
-        # pad with missing octets
-        chunks = missing_octets * ['00'] + chunks
-        # result array with dots and octets, used for formatting
-        chunks.reverse()
-        resultsize = 2 * len(chunks) - 1
-        result = resultsize * ['']
-        result[1::4] = len(result[1::4]) * '.'
-        result[0::2] = chunks
-        result.reverse()
-        return ''.join(result)
+    # format: add . after every other octet, starting at the end
+    ip_octets.reverse()
+    resultsize = 2 * len(ip_octets) - 1
+    result = resultsize * ['']
+    result[1::4] = len(result[1::4]) * '.'
+    result[0::2] = ip_octets
+    result.reverse()
+
+    iso_address = prefix + ''.join(result)
+    return iso_address
 
 
 def ipv4_to_ipv6(v6network_string, v4address):

src/cnaas_nms/tools/tests/test_jinja_filters.py

@@ -41,14 +41,25 @@ def test_isofy_ipv4(self):
         with self.assertRaises(ValueError):
             isofy_ipv4('10.256.255.1')
 
-    def test_isofy_ipv4_octetcount(self):
-        with self.assertRaises(ValueError):
-            isofy_ipv4('10.255.255.1', 6)
-        self.assertEqual(isofy_ipv4('10.255.255.1', 7), '0102.5525.5001.00')
-        self.assertEqual(isofy_ipv4('10.255.255.1', 8), '00.0102.5525.5001.00')
-        self.assertEqual(isofy_ipv4('10.255.255.1', 9), '0000.0102.5525.5001.00')
-        self.assertEqual(isofy_ipv4('10.255.255.1', 10), '00.0000.0102.5525.5001.00')
-        self.assertEqual(isofy_ipv4('10.255.255.1', 20), '00.0000.0000.0000.0000.0000.0000.0102.5525.5001.00')
+    def test_isofy_ipv4_prefix(self):
+        self.assertEqual(
+            isofy_ipv4('130.242.1.28', prefix='47.0023.0000.0001.0000'),
+            '47.0023.0000.0001.0000.1302.4200.1028.00',
+        )
+        self.assertEqual(
+            isofy_ipv4('130.242.1.28', prefix='47.0023.0000.0001'),
+            '47.0023.0000.0001.1302.4200.1028.00',
+        )
+        self.assertEqual(isofy_ipv4('130.242.1.28', '47'), '47.1302.4200.1028.00')
+        invalid_prefixes = [
+            '47.0023.0000.0001.00',
+            '47.0023.0000.0001.000',
+            '47.0023.0000.0001.0000.',
+            '0047.0023.0000.0001.0000',
+        ]
+        for prefix in invalid_prefixes:
+            with self.assertRaises(ValueError):
+                isofy_ipv4('10.0.0.1', prefix=prefix)
 
     def test_ipv4_to_ipv6(self):
         self.assertEqual(ipv4_to_ipv6('2001:700::/64', '10.0.0.1'), '2001:700::10:0:0:1/64')