updating ip_to_ptr method to be more comprehensive

Author: Dan Lavu

sssd_test_framework/misc/__init__.py

@@ -198,25 +198,42 @@ def seconds_to_timespan(seconds: int) -> str:
     return f"{d:02d}:{h:02d}:{m:02d}:{s:02d}:00"
 
 
-def ip_to_ptr(ip_address: str) -> str:
+def ip_to_ptr(ip_address: str, prefixlen: int | None = None) -> str:
     """
     Get the reverse pointer from given address.
 
     :param ip_address: Address.
     :type ip_address: str
+    :param prefixlen: Prefix  length, optional
+    :type prefixlen: int | None = None
     :return: Reverse pointer.
     :rtype: str
     """
     ip = ipaddress.ip_address(ip_address)
+    network = ipaddress.ip_network(ip)
+
+    if prefixlen is not None:
+        network = network.supernet(new_prefix=prefixlen)
+    elif ip.version == 4:
+        prefixlen = 24
+    else:
+        prefixlen = 64
+
+    if prefixlen > network.max_prefixlen:
+        raise ValueError(f"Prefix {prefixlen} too large for {ip.version}!")
+
+    subnet = network.supernet(new_prefix=prefixlen)
+
     if ip.version == 4:
-        octets = ip.packed
-        ptr = f"{octets[2]}.{octets[1]}.{octets[0]}.in-addr.arpa."
-    elif ip.version == 6:
-        hex_parts = ip.exploded.replace(":", "").lower()
-        ptr = f"{hex_parts[::-1]}.ip6.arpa."
+        octets = subnet.network_address.packed
+        parts = [str(octets[i]) for i in range((prefixlen // 8) - 1, -1, -1)]
+        return ".".join(parts) + ".in-addr.arpa"
     else:
-        raise ValueError("Unsupported IP version")
-    return ptr
+        hex_str = subnet.network_address.exploded.replace(":", "").lower()
+        nibbles = list(hex_str)
+        relevant_nibbles = nibbles[: prefixlen // 4]
+        reversed_nibbles = ".".join(relevant_nibbles[::-1])
+        return f"{reversed_nibbles}.ip6.arpa"
 
 
 def ip_version(ip_address: str) -> int | None:

tests/test_misc.py

@@ -287,14 +287,16 @@ def test_seconds_to_timespan(seconds: tuple[int, str]):
 
 
 @pytest.mark.parametrize(
-    "value, expected",
+    "value, expected, prefixlen",
     [
-        ("192.168.1.0", "1.168.192.in-addr.arpa."),
-        ("2001:db8::1", "1000000000000000000000008bd01002.ip6.arpa."),
+        ("192.168.1.0", "1.168.192.in-addr.arpa", None),
+        ("10.20.30.40", "20.10.in-addr.arpa", 16),
+        ("fe80::48b2:6cff:fefc:17ff", "0.0.0.0.0.0.0.0.0.0.0.0.0.8.e.f.ip6.arpa", None),
+        ("2001:db8:abcd:1234::1", "4.3.2.1.d.c.b.a.8.b.d.0.1.0.0.2.ip6.arpa", None),
     ],
 )
-def test_ip_to_ptr(value, expected):
-    assert ip_to_ptr(value) == expected
+def test_ip_to_ptr(value, expected, prefixlen):
+    assert ip_to_ptr(value, prefixlen) == expected
 
 
 @pytest.mark.parametrize(