[3.13] gh-141497: Make ipaddress.IP{v4,v6}Network.hosts() always returning an iterator (GH-141547) (GH-141695)

(cherry picked from commit 6b1bdf6)

Co-authored-by: Krishna Chaitanya <141550576+XChaitanyaX@users.noreply.github.com>

Author: XChaitanyaX

Lib/ipaddress.py

@@ -1559,7 +1559,7 @@ def __init__(self, address, strict=True):
         if self._prefixlen == (self._max_prefixlen - 1):
             self.hosts = self.__iter__
         elif self._prefixlen == (self._max_prefixlen):
-            self.hosts = lambda: [IPv4Address(addr)]
+            self.hosts = lambda: iter((IPv4Address(addr),))
 
     @property
     @functools.lru_cache()
@@ -2359,7 +2359,7 @@ def __init__(self, address, strict=True):
         if self._prefixlen == (self._max_prefixlen - 1):
             self.hosts = self.__iter__
         elif self._prefixlen == self._max_prefixlen:
-            self.hosts = lambda: [IPv6Address(addr)]
+            self.hosts = lambda: iter((IPv6Address(addr),))
 
     def hosts(self):
         """Generate Iterator over usable hosts in a network.

Lib/test/test_ipaddress.py

@@ -12,6 +12,7 @@
 import pickle
 import ipaddress
 import weakref
+from collections.abc import Iterator
 from test.support import LARGEST, SMALLEST
 
 
@@ -1472,18 +1473,27 @@ def testGetSupernet4(self):
                          self.ipv6_scoped_network.supernet(new_prefix=62))
 
     def testHosts(self):
+        hosts = self.ipv4_network.hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(ipaddress.IPv4Address('1.2.3.1'), next(hosts))
         hosts = list(self.ipv4_network.hosts())
         self.assertEqual(254, len(hosts))
         self.assertEqual(ipaddress.IPv4Address('1.2.3.1'), hosts[0])
         self.assertEqual(ipaddress.IPv4Address('1.2.3.254'), hosts[-1])
 
         ipv6_network = ipaddress.IPv6Network('2001:658:22a:cafe::/120')
+        hosts = ipv6_network.hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(ipaddress.IPv6Address('2001:658:22a:cafe::1'), next(hosts))
         hosts = list(ipv6_network.hosts())
         self.assertEqual(255, len(hosts))
         self.assertEqual(ipaddress.IPv6Address('2001:658:22a:cafe::1'), hosts[0])
         self.assertEqual(ipaddress.IPv6Address('2001:658:22a:cafe::ff'), hosts[-1])
 
         ipv6_scoped_network = ipaddress.IPv6Network('2001:658:22a:cafe::%scope/120')
+        hosts = ipv6_scoped_network.hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual((ipaddress.IPv6Address('2001:658:22a:cafe::1')), next(hosts))
         hosts = list(ipv6_scoped_network.hosts())
         self.assertEqual(255, len(hosts))
         self.assertEqual(ipaddress.IPv6Address('2001:658:22a:cafe::1'), hosts[0])
@@ -1494,6 +1504,12 @@ def testHosts(self):
                  ipaddress.IPv4Address('2.0.0.1')]
         str_args = '2.0.0.0/31'
         tpl_args = ('2.0.0.0', 31)
+        hosts = ipaddress.ip_network(str_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
+        hosts = ipaddress.ip_network(tpl_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
         self.assertEqual(addrs, list(ipaddress.ip_network(str_args).hosts()))
         self.assertEqual(addrs, list(ipaddress.ip_network(tpl_args).hosts()))
         self.assertEqual(list(ipaddress.ip_network(str_args).hosts()),
@@ -1503,6 +1519,12 @@ def testHosts(self):
         addrs = [ipaddress.IPv4Address('1.2.3.4')]
         str_args = '1.2.3.4/32'
         tpl_args = ('1.2.3.4', 32)
+        hosts = ipaddress.ip_network(str_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
+        hosts = ipaddress.ip_network(tpl_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
         self.assertEqual(addrs, list(ipaddress.ip_network(str_args).hosts()))
         self.assertEqual(addrs, list(ipaddress.ip_network(tpl_args).hosts()))
         self.assertEqual(list(ipaddress.ip_network(str_args).hosts()),
@@ -1512,6 +1534,12 @@ def testHosts(self):
                  ipaddress.IPv6Address('2001:658:22a:cafe::1')]
         str_args = '2001:658:22a:cafe::/127'
         tpl_args = ('2001:658:22a:cafe::', 127)
+        hosts = ipaddress.ip_network(str_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
+        hosts = ipaddress.ip_network(tpl_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
         self.assertEqual(addrs, list(ipaddress.ip_network(str_args).hosts()))
         self.assertEqual(addrs, list(ipaddress.ip_network(tpl_args).hosts()))
         self.assertEqual(list(ipaddress.ip_network(str_args).hosts()),
@@ -1520,6 +1548,12 @@ def testHosts(self):
         addrs = [ipaddress.IPv6Address('2001:658:22a:cafe::1'), ]
         str_args = '2001:658:22a:cafe::1/128'
         tpl_args = ('2001:658:22a:cafe::1', 128)
+        hosts = ipaddress.ip_network(str_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
+        hosts = ipaddress.ip_network(tpl_args).hosts()
+        self.assertIsInstance(hosts, Iterator)
+        self.assertEqual(next(hosts), addrs[0])
         self.assertEqual(addrs, list(ipaddress.ip_network(str_args).hosts()))
         self.assertEqual(addrs, list(ipaddress.ip_network(tpl_args).hosts()))
         self.assertEqual(list(ipaddress.ip_network(str_args).hosts()),

Misc/NEWS.d/next/Library/2025-11-14-16-24-20.gh-issue-141497.L_CxDJ.rst

@@ -0,0 +1,4 @@
+:mod:`ipaddress`: ensure that the methods
+:meth:`IPv4Network.hosts() <ipaddress.IPv4Network.hosts>` and
+:meth:`IPv6Network.hosts() <ipaddress.IPv6Network.hosts>` always return an
+iterator.