Move network utils that are used by AWS modules (#45579)

* Separate networking tools that may be used by modules outside of networking so changes to networking-only utilities don't trigger AWS integration tests

* Add unit tests for moved network utils

* Add comment to prevent imports from being mistakenly removed

* Move to_bits as well

lib/ansible/module_utils/common/network.py

@@ -0,0 +1,115 @@
+# Copyright (c) 2016 Red Hat Inc
+# Simplified BSD License (see licenses/simplified_bsd.txt or https://opensource.org/licenses/BSD-2-Clause)
+
+# General networking tools that may be used by all modules
+
+from struct import pack
+from socket import inet_ntoa
+
+from ansible.module_utils.six.moves import zip
+
+
+VALID_MASKS = [2**8 - 2**i for i in range(0, 9)]
+
+
+def is_netmask(val):
+    parts = str(val).split('.')
+    if not len(parts) == 4:
+        return False
+    for part in parts:
+        try:
+            if int(part) not in VALID_MASKS:
+                raise ValueError
+        except ValueError:
+            return False
+    return True
+
+
+def is_masklen(val):
+    try:
+        return 0 <= int(val) <= 32
+    except ValueError:
+        return False
+
+
+def to_netmask(val):
+    """ converts a masklen to a netmask """
+    if not is_masklen(val):
+        raise ValueError('invalid value for masklen')
+
+    bits = 0
+    for i in range(32 - int(val), 32):
+        bits |= (1 << i)
+
+    return inet_ntoa(pack('>I', bits))
+
+
+def to_masklen(val):
+    """ converts a netmask to a masklen """
+    if not is_netmask(val):
+        raise ValueError('invalid value for netmask: %s' % val)
+
+    bits = list()
+    for x in val.split('.'):
+        octet = bin(int(x)).count('1')
+        bits.append(octet)
+
+    return sum(bits)
+
+
+def to_subnet(addr, mask, dotted_notation=False):
+    """ coverts an addr / mask pair to a subnet in cidr notation """
+    try:
+        if not is_masklen(mask):
+            raise ValueError
+        cidr = int(mask)
+        mask = to_netmask(mask)
+    except ValueError:
+        cidr = to_masklen(mask)
+
+    addr = addr.split('.')
+    mask = mask.split('.')
+
+    network = list()
+    for s_addr, s_mask in zip(addr, mask):
+        network.append(str(int(s_addr) & int(s_mask)))
+
+    if dotted_notation:
+        return '%s %s' % ('.'.join(network), to_netmask(cidr))
+    return '%s/%s' % ('.'.join(network), cidr)
+
+
+def to_ipv6_network(addr):
+    """ IPv6 addresses are eight groupings. The first three groupings (48 bits) comprise the network address. """
+
+    # Split by :: to identify omitted zeros
+    ipv6_prefix = addr.split('::')[0]
+
+    # Get the first three groups, or as many as are found + ::
+    found_groups = []
+    for group in ipv6_prefix.split(':'):
+        found_groups.append(group)
+        if len(found_groups) == 3:
+            break
+    if len(found_groups) < 3:
+        found_groups.append('::')
+
+    # Concatenate network address parts
+    network_addr = ''
+    for group in found_groups:
+        if group != '::':
+            network_addr += str(group)
+        network_addr += str(':')
+
+    # Ensure network address ends with ::
+    if not network_addr.endswith('::'):
+        network_addr += str(':')
+    return network_addr
+
+
+def to_bits(val):
+    """ converts a netmask to bits """
+    bits = ''
+    for octet in val.split('.'):
+        bits += bin(int(octet))[2:].zfill(8)
+    return str