bpo-27683: Fix a regression for host() of ipaddress network objects (GH-6016)

The result of host() was not empty when the network is constructed by a tuple containing an
integer mask and only 1 bit left for addresses.

1 files changed, 38 insertions, 71 deletions

diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index 77df051..15507d6 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1514,45 +1514,28 @@ class IPv4Network(_BaseV4, _BaseNetwork):
 
         # Constructing from a packed address or integer
         if isinstance(address, (int, bytes)):
-            self.network_address = IPv4Address(address)
-            self.netmask, self._prefixlen = self._make_netmask(self._max_prefixlen)
-            #fixme: address/network test here.
-            return
-
-        if isinstance(address, tuple):
-            if len(address) > 1:
-                arg = address[1]
-            else:
-                # We weren't given an address[1]
-                arg = self._max_prefixlen
-            self.network_address = IPv4Address(address[0])
-            self.netmask, self._prefixlen = self._make_netmask(arg)
-            packed = int(self.network_address)
-            if packed & int(self.netmask) != packed:
-                if strict:
-                    raise ValueError('%s has host bits set' % self)
-                else:
-                    self.network_address = IPv4Address(packed &
-                                                       int(self.netmask))
-            return
-
+            addr = address
+            mask = self._max_prefixlen
+        # Constructing from a tuple (addr, [mask])
+        elif isinstance(address, tuple):
+            addr = address[0]
+            mask = address[1] if len(address) > 1 else self._max_prefixlen
         # Assume input argument to be string or any object representation
         # which converts into a formatted IP prefix string.
-        addr = _split_optional_netmask(address)
-        self.network_address = IPv4Address(self._ip_int_from_string(addr[0]))
-
-        if len(addr) == 2:
-            arg = addr[1]
         else:
-            arg = self._max_prefixlen
-        self.netmask, self._prefixlen = self._make_netmask(arg)
-
-        if strict:
-            if (IPv4Address(int(self.network_address) & int(self.netmask)) !=
-                self.network_address):
+            args = _split_optional_netmask(address)
+            addr = self._ip_int_from_string(args[0])
+            mask = args[1] if len(args) == 2 else self._max_prefixlen
+
+        self.network_address = IPv4Address(addr)
+        self.netmask, self._prefixlen = self._make_netmask(mask)
+        packed = int(self.network_address)
+        if packed & int(self.netmask) != packed:
+            if strict:
                 raise ValueError('%s has host bits set' % self)
-        self.network_address = IPv4Address(int(self.network_address) &
-                                           int(self.netmask))
+            else:
+                self.network_address = IPv4Address(packed &
+                                                   int(self.netmask))
 
         if self._prefixlen == (self._max_prefixlen - 1):
             self.hosts = self.__iter__
@@ -2207,46 +2190,30 @@ class IPv6Network(_BaseV6, _BaseNetwork):
         """
         _BaseNetwork.__init__(self, address)
 
-        # Efficient constructor from integer or packed address
-        if isinstance(address, (bytes, int)):
-            self.network_address = IPv6Address(address)
-            self.netmask, self._prefixlen = self._make_netmask(self._max_prefixlen)
-            return
-
-        if isinstance(address, tuple):
-            if len(address) > 1:
-                arg = address[1]
-            else:
-                arg = self._max_prefixlen
-            self.netmask, self._prefixlen = self._make_netmask(arg)
-            self.network_address = IPv6Address(address[0])
-            packed = int(self.network_address)
-            if packed & int(self.netmask) != packed:
-                if strict:
-                    raise ValueError('%s has host bits set' % self)
-                else:
-                    self.network_address = IPv6Address(packed &
-                                                       int(self.netmask))
-            return
-
+        # Constructing from a packed address or integer
+        if isinstance(address, (int, bytes)):
+            addr = address
+            mask = self._max_prefixlen
+        # Constructing from a tuple (addr, [mask])
+        elif isinstance(address, tuple):
+            addr = address[0]
+            mask = address[1] if len(address) > 1 else self._max_prefixlen
         # Assume input argument to be string or any object representation
         # which converts into a formatted IP prefix string.
-        addr = _split_optional_netmask(address)
-
-        self.network_address = IPv6Address(self._ip_int_from_string(addr[0]))
-
-        if len(addr) == 2:
-            arg = addr[1]
         else:
-            arg = self._max_prefixlen
-        self.netmask, self._prefixlen = self._make_netmask(arg)
-
-        if strict:
-            if (IPv6Address(int(self.network_address) & int(self.netmask)) !=
-                self.network_address):
+            args = _split_optional_netmask(address)
+            addr = self._ip_int_from_string(args[0])
+            mask = args[1] if len(args) == 2 else self._max_prefixlen
+
+        self.network_address = IPv6Address(addr)
+        self.netmask, self._prefixlen = self._make_netmask(mask)
+        packed = int(self.network_address)
+        if packed & int(self.netmask) != packed:
+            if strict:
                 raise ValueError('%s has host bits set' % self)
-        self.network_address = IPv6Address(int(self.network_address) &
-                                           int(self.netmask))
+            else:
+                self.network_address = IPv6Address(packed &
+                                                   int(self.netmask))
 
         if self._prefixlen == (self._max_prefixlen - 1):
             self.hosts = self.__iter__