Patch by Jp Calderone:

- The socket module now provides the functions inet_pton and inet_ntop
  for converting between string and packed representation of IP addresses.
  See SF patch #658327.

This still needs a bit of work in the doc area, because it is not
available on all platforms (especially not on Windows).

Lib/test/test_socket.py

@@ -318,6 +318,65 @@ class GeneralModuleTests(unittest.TestCase):
         # Check that setting it to an invalid type raises TypeError
         self.assertRaises(TypeError, socket.setdefaulttimeout, "spam")
 
+    def testIPv4toString(self):
+        from socket import inet_aton as f, inet_pton, AF_INET
+        g = lambda a: inet_pton(AF_INET, a)
+
+        self.assertEquals('\x00\x00\x00\x00', f('0.0.0.0'))
+        self.assertEquals('\xff\x00\xff\x00', f('255.0.255.0'))
+        self.assertEquals('\xaa\xaa\xaa\xaa', f('170.170.170.170'))
+        self.assertEquals('\x01\x02\x03\x04', f('1.2.3.4'))
+
+        self.assertEquals('\x00\x00\x00\x00', g('0.0.0.0'))
+        self.assertEquals('\xff\x00\xff\x00', g('255.0.255.0'))
+        self.assertEquals('\xaa\xaa\xaa\xaa', g('170.170.170.170'))
+    
+    def testIPv6toString(self):
+        try:
+            from socket import inet_pton, AF_INET6, has_ipv6
+            if not has_ipv6:
+                return
+        except ImportError:
+            return
+        f = lambda a: inet_pton(AF_INET6, a)
+
+        self.assertEquals('\x00' * 16, f('::'))
+        self.assertEquals('\x00' * 16, f('0::0'))
+        self.assertEquals('\x00\x01' + '\x00' * 14, f('1::'))
+        self.assertEquals(
+            '\x45\xef\x76\xcb\x00\x1a\x56\xef\xaf\xeb\x0b\xac\x19\x24\xae\xae',
+            f('45ef:76cb:1a:56ef:afeb:bac:1924:aeae')
+        )
+    
+    def testStringToIPv4(self):
+        from socket import inet_ntoa as f, inet_ntop, AF_INET
+        g = lambda a: inet_ntop(AF_INET, a)
+
+        self.assertEquals('1.0.1.0', f('\x01\x00\x01\x00'))
+        self.assertEquals('170.85.170.85', f('\xaa\x55\xaa\x55'))
+        self.assertEquals('255.255.255.255', f('\xff\xff\xff\xff'))
+        self.assertEquals('1.2.3.4', f('\x01\x02\x03\x04'))
+    
+        self.assertEquals('1.0.1.0', g('\x01\x00\x01\x00'))
+        self.assertEquals('170.85.170.85', g('\xaa\x55\xaa\x55'))
+        self.assertEquals('255.255.255.255', g('\xff\xff\xff\xff'))
+
+    def testStringToIPv6(self):
+        try:
+            from socket import inet_ntop, AF_INET6, has_ipv6
+            if not has_ipv6:
+                return
+        except ImportError:
+            return
+        f = lambda a: inet_ntop(AF_INET6, a)
+
+        self.assertEquals('::', f('\x00' * 16))
+        self.assertEquals('::1', f('\x00' * 15 + '\x01'))
+        self.assertEquals(
+            'aef:b01:506:1001:ffff:9997:55:170',
+            f('\x0a\xef\x0b\x01\x05\x06\x10\x01\xff\xff\x99\x97\x00\x55\x01\x70')
+        )
+
     # XXX The following don't test module-level functionality...
 
     def testSockName(self):